Temesgen Admas

Fluoride Genesis in Ground water of Butajira-Koshe-Ziway Transect Areas, in Central Ethiopia
ADDIS ABABA UNIVERSITY

SCHOOL OF GRADUATE STUDIES
SCHOOL OF EARTH SCIENCES
Fluoride Genesis in Groundwater of Butajira _Koshe _Ziway Transects

Areas Using Integrated Hydrochemistry and Isotope Techniques, in
Central Ethiopia
By
Temesgen Admas
A thesis submitted to the School of Graduate Studies of Addis Ababa

University in partial fulfillment of the requirements for the degree of
Master of Science in Hydrogeology
June, 2017
Addis Ababa
AAU School of Earth Science MSc. Thesis by Temesgen A. Page i

SCHOOL OF EARTH SCIENCES
Fluoride Genesis in Groundwater of Butajira_Koshe_Ziway transects Areas

Using Integrated Hydrochemistry and Isotope Techniques, in Central Ethiopia
By
Temesgen Admas
Advisor: Tilahun Azagegn (PhD)
A Thesis submitted to the School of Graduate Studies of Addis Ababa University in partial
fulfillment of the requirements for the degree of Master of Science in Hydrogeology
AAU School of Earth Science MSc. Thesis by Temesgen A. Page ii

Declaration of originality
I declare and confirm that this thesis is my original work. I have followed all
ethical and technical principles of research in the preparation, data collection,
data analysis and compilation of this thesis. Any scholarly matter that is
included in the thesis has been given acknowledgment through reference.
Temesgen Admas
Signature: -----------------
Date: June, 2017
AAU School of Earth Science MSc. Thesis by Temesgen A. Page iii

This is to certify that the thesis prepared by Temesgen Admas, entitled: Fluoride
genesis in Groundwater of Butajira_Koshe_Ziway Transect in Central Ethiopia
and submitted in partial fulfillment of the requirements for the Degree of Master
of Science (Hydrogeology)
Approved by the Examining Committee:
Dr. Tilahun Azagegn Signature ____________ Date _____________
Advisor
Prof.Tenalem Ayenew Signature _____________ Date _____________
Internal Examiner
Dr.Seifu kebede Signature _____________ Date ______________
Internal Examiner
Dr. Balemual Atnafu Signature_____________ Date_____________
Chairman, School of Earth Sciences
AAU School of Earth Science MSc. Thesis by Temesgen A. Page iv

ACKNOWLEDGEMENT
First of all, I would like to thank „Almighty God‟ who made it possible, to begin and finish
this work successfully.
I would like to express my feelings of gratitude to my advisor Dr.Tilahun Azagegn for his
continuous guidance and constant encouragement helped me to complete the present research
work successfully. He is the person who has always helped me and his constant
encouragement made me strong enough to face every ups and down with confidence during
the present research study.
I am also thankful to the flowered project for field work and laboratory support and Ministry
of Water Resource, Ethiopian geological survey, Ethiopian mapping agency,Biritish
geological survey and Mareko,Meskan and Dugdaworeda water resource office from where I
received all kind of resource support.
Words cannot express my feelings which I have for my uncle Aba Senay Miskir and my
mam Mulu Chekole Kassie and the whole family. I am highly indebted to them for their
blessing, guidance,advice, encouragement and support.
I would like to convey my special thanks to my friends, Abebeyehu Tadesse,Daniele pittalis
Dagmawi Shiferaw laboratory facilitate with time, Sintayehu Mulu and many others for their
constant encouragement and help.
AAU School of Earth Science MSc. Thesis by Temesgen A. Page v

Table of Contents
Declaration of originality ......................................................................................................iii
Signature of approval ............................................................................................................ iv
Acknowledgement .................................................................................................................. v
Table of content ..................................................................................................................... vi
List of table..........................................................................................................................viii
List of figure ........................................................................................................................viii
List of appendix ...................................................................................................................viii
Abbreviations ........................................................................................................................ ix
ABSTRACT ........................................................................................................................... x
CHAPTER ONE ........................................................................................................................ 1
INTRODUCTION .................................................................................................................. 1
1.2 previous studies ................................................................................................................ 3
1.2.1. Statement of the problems……………………………………………………………....3
1.3. Objective............................................................................................................................7
1.3.1 General objective........................................................................................................... 7
1.3.2 Specific objectives......................................................................................................... 8
1.4. Methodology used ............................................................................................................... 8
CHAPTER TWO ..................................................................................................................... 10
Description of the study Area............................................................................................... 10
2.1. Location and accessibility ............................................................................................. 10
2.2. Physiography and drainage ........................................................................................... 11
2.3 Climate and soil.............................................................................................................. 11
2.4. Geology of the study area.............................................................................................. 12
2.4.1. Stratigraphy outline of the Area ................................................................................. 13
2.4.1. 1.Welded ignimbrite and tuff (Tertiary period) ...................................................... 13
2.4.1.2. Basalts and associated flows of the rift floor ....................................................... 13
2.4.1.3. The rhyolite and trachyte unit (Quaternary period/Pleistocene to Holocene) ..... 14
3.4.1.4. Volcano lacustrine sediments .............................................................................. 14
CHAPTER THREE ................................................................................................................. 17
HYDROGEOLOGY OF THE AREA ................................................................................. 17
3.1. Hydrogeological Setting................................................................................................ 17
3.2. Hydro stratigraphic unit (aquifer and aquifer properties) ............................................. 17
3.2.1. Fractured Ignimbrite and Welded Tuff Aquifer ..................................................... 18
3.2.2. Fractured Basalts and Basaltic Scoria Aquifer ....................................................... 18
AAU School of Earth Science MSc. Thesis by Temesgen A. Page vi

3.2.3. Rhyolite and Trachytic Lava flows Aquifer ........................................................... 18

3.2.4. Volcano Lacustrine Sediment Aquifer ................................................................... 19
3.3. Groundwater Recharge and discharge areas ................................................................. 20
3.4. Groundwater Flow......................................................................................................... 21
CHAPTER FOUR: RESULT AND DISCUSSION ................................................................ 23
HYDROCHEMISTRY AND ISOTOPE HYDROLOGY ................................................... 23
4.1. General Hydrochemistry ............................................................................................... 23
4.2. Physio-chemical parameters .......................................................................................... 24
4.2.1. PH ............................................................................................................................ 25
4.2.2. Temperature ............................................................................................................ 26
4.2.3. Electrical Conductivity ........................................................................................... 27
4.2.4. Total Dissolved Solid (TDS) .................................................................................. 28
4.4. Geochemicalcharacterstics of major cation and anions ............................................. 30
4.5. Minor anions ................................................................................................................. 32
4.5.1. Nitrate ..................................................................................................................... 32
4.5.2. Fluoride of the Study Area ..................................................................................... 33
4.6. WATER type and ground water flow path.................................................................... 36
4.6.1. The Highland and Escarpment zone ....................................................................... 37
4.6.2. The Transitional Zone ............................................................................................ 37
4.6.3. The Enrichment zone .............................................................................................. 38
4.7. Isotope Hydrology ......................................................................................................... 38
4.7.1. Stable isotope in Water .............................................................................................. 39
4.7.2. Deuterium (δ2H) and oxygen (δ18O) isotopes ............................................................ 40
4.7.3.Relation of stable isotope and Hydrochemistry .......................................................... 42
GENERAL DISCUSSION ...................................................................................................... 43
5. Factors for Fluoride Enrichment in ground water ........................................................ 44
5.1. Hydro chemical reaction ............................................................................................... 44
5.2. Geochemical processes for enrichment of fluoride ....................................................... 47
5.2.1Geology, resident time, water- rock/sediment interaction ........................................ 47
5.2.2 Dilution Effect ......................................................................................................... 48
5.2.3. Saturation index (mineral equilibrium) .................................................................. 49
CHAPTER FIVE ..................................................................................................................... 52
CONCLUSION AND RECOMMENDATION ................................................................... 51
Reference .............................................................................................................................. 55
AAU School of Earth Science MSc. Thesis by Temesgen A. Page vii

Fluoride Genesis in Ground water of Butajira_Koshe_ZiwayTransect Areas, in Central Ethiopia
List of table
Table5.1. Correlation Matrix of collected and analyzed watersample……………...………..42
Table5.1. Fluoride concentration with depth in Koshe town test well……………….…..…..47
List of figure
Figure 2.1 location map of the study Area…………………………………..……..………….7
Figure 2.2.Physiographic map of the study area 3D from DEM………………………………8
Figure2.3. Photo from Volcano lacustrine sediment………………...……………………….12
Figure2.4. Geological map modified from (T.Chernet, 1982)……...……………………..…13
Figure2.4.1. Geological cross-section from A to B…………….…………………………….14
Figure3.Hydrogeological map modified from (T.Chernet, 1982 &MoWIE)………………...17
Figure4. Water chemistry sampling point………………..…………………………………..22
Figure4.1. PH distribution map of the study Are......………………………………...………23
Figure4.2. Temperature distribution map of the study area……..……………………..…….24
Figure4.3. EC distribution map of the study Area…………………..……………………….25
Figure4.4. TDS distribution map of the study area…………….…………………………….26
Figure4.5. Schoeller plot of major cat ion and anion………………………………….…..…28
Figure4.6. Lateral and vertical fluoride distribution of the study Area…………………..…..30
Figure 4.9.Hydrochemical evolution vs altitude along ground water flow path…..…………33
Figure.12. A plot of Deuterium (δ2H) vs. δ18O isotopes of water samples............................39
Figure4.13. Chemistry vs. isotope relationship…………………………………………..…..40
Figure5. (a-h) Bivariate plot of water variable…………..……………………………..….…46
Figure5.2. Fluorite vs. calcite saturation……………………………………………………..50
List of appendix
Appendix 1: Over all physiochemical analysis result of water sample in Ziway-Koshe-

Butajira areas…………………………………………………………………………...…58-62
Appendix 2: isotope chemical analysis result of water for the study area……………….63-64
Appendix3: groundwater inventory measured in the field &/collected from MoWIE……...65
Appenix3.2: fluoride distribution with depth………………………………………………74
Appendix 4: Table for lithological log description……………………………………….75-81
AAU School of Earth Science MSc. Thesis by Temesgen A. Page viii

Abbreviations Meaning
AAU Addis Ababa University
CMER Central Main Ethiopian Rift
DEM Digital Elevation Model
EGS Ethiopia Geological Survey
EMA Ethiopian Mapping Agency
GMWL Global Meteoric Water Line
LMWL Local Meteoric Water Line
M.A.S.L Meter above sea level
MoWIE Ministry of Water, Irrigation and Electricity
RE Mean absolute error
SDZFZ Silte Debrezeit Fault Zone
SI Saturation Index
SNNPR Southern Nations, Nationalities and People‟s Region
VSMOW Vienna Standard Mean Oceanic Water
WFB Wonji Fault Belt
WWDSE Water Works Design and Supervision Enterprise
AAU School of Earth Science MSc. Thesis by Temesgen A. Page ix

ABSTRACT
This research is conducted to investigate fluoride problems with it genesis in groundwater of

Butajira_Koshe_Ziway transect of central main Ethiopian rift by using integrated hydro
chemical and isotope analysis techniques. The hydrochemical analysis result reveals that
groundwater type of the area evolves from Ca(Mg)-HCO3water type of early geochemical
evolution in the western highlands and escarpments to Na-HCO3 water type of highly
geochemical evolution in the rift floor (i.e. towards lake Ziway) of the study area.
Groundwater supplied from the highlands is typically characterized by low conductivity, low
TDS, and a calcium bicarbonate facies. The water geochemistry (i.e fluoride content) within
the study area is widely (extremely) variable due to meteoric water recharge from the
surrounding highlands is affected by different degrees of water–rock interaction ,evaporation
processes, rock type, depth variation, chemical and physical characteristics of the aquifer and
acidity of soil and rock, concentration of ion present in the water. The high F geochemical
anomaly is associated with high Na (R2=0.37), alkalinity (R2=0.25), TDS, EC (R2=0.3),
shallow depth and low calcium content. In general, from correlation matrix of collected and
analyzed water sample, there is a negative correlation between calcium, magnesium and
fluoride concentrations and positive correlation between bicarbonate, TDS, EC and fluoride
concentration in groundwater. Saturation indices (SI) were calculated (using PHREEQC) for
the different water groups, highlighting that the studied waters are super saturated with
respect to calcite and under saturated with respect to fluorite. Groundwater is supersaturated
with respect to calcite, which promotes the removal of Ca and HCO3 from solution. As a
result, groundwater is generally under saturated with respect to fluorite, the mineral that
typically controls the upper limit of fluoride concentrations. The stable isotopes result reveals
that highly enriched water from hand dug well, few borehole well and lake itself were
observed in the downstream part of the study area surrounding the lake Ziway due to
evaporation effect and recharged from the lake water rather than precipitation from highlands
while the deep ground water located in the highland and escarpment of the study area reveal
that slightly to highly depleted due to it recharged at lower temperature/from local meteoric
water directly infiltrated rainfall through long subsurface flow from Guragae highland. The
general trend for groundwater flow observed from groundwater contour map, hydro chemical
evolution and isotopic signature indicates that from western highlands toward the rift floor in
the direction of NW to SE of the study area.
Keywords: Fluoride genesis, Ground water flow, Hydrochemistry, Stable isotope (δ18O, δ2H)
AAU School of Earth Science MSc. Thesis by Temesgen A. Page x

CHAPTER ONE
INTRODUCTION
Groundwater proved to be an important source for drinking water supply in the main
Ethiopian Rift, where the surface water is scarce (e.g. Kebede et al., 2007; Ayenew et al.,
2008; Demlie et al., 2008; Kebede et al., 2010). However, the water quality is a major
concern that limits clean water use due to water chemical constitutes. The main aquifer
formations of the boreholes are lacustrine deposits, weathered and fractured Basalt,
ignimbrite, and welded tuff. The volcanic aquifers signify a hydrochemical signature in
which the quality is influenced by the reaction between the recharging water, a mineral of
surrounding rocks and gas phases. Local hydrogeology and geochemical reactions such as
dissolution and precipitation of solids, cation exchange and adsorption also contribute
considerably to the variation of chemical constitute in the groundwater. The hydro chemical
signature of groundwater in volcanic terrains indicates wide spatial variation owing to
differences in rock-water interactions. The Ethiopian Rift Valley waters are the dominantly
sodium-bicarbonate type with high salinity and fluoride content (Kebede et al., 2010). The
larger portion of the groundwater system of the Rift Valley has high salinity and fluoride
content. The high prevalence rate of dental and skeletal fluorosis in several towns in the rift
valley reflects the high-fluoride content in drinking water. The concentration of fluoride in
groundwater exceeds permissible level more than any other inorganic groundwater
contaminants, such as arsenic and hence, special attention has to be given. Fluorides have
received huge public and scientific interest because it is likely to be one of the most serious
inorganic contaminants with well-recognized health implication in the region. In line with the
excessive fluoride contents in drinking water in the Main Rift Valley, the prevalence of
dental and skeletal fluorosis is common phenomena (Tekle-himanot et al., 1987). The
environmental isotopes are the naturally occurring isotopes of elements found in abundance
in our environment: H, C, N, O and S. The environmental stable isotopes of these elements
(deuterium (2H) and oxygen (18O)) serve as tracers of groundwater, recharge process,
subsurface process, geochemical reactions and reaction rates. The relationship of a variety of
global scale and local scale processes can influence the isotope regime of Ethiopian meteoric
waters. The temporal and the spatial variation in the δ18 O and δD composition of natural
water bodies and rainfalls influenced by Temperature, subsurface rock-water interactions,
basin topography, seasonal changes associated with moisture sources and moisture from
continental evapotranspiration. These variations can provide characteristics that are preserved
in the groundwater and useful for tracing. Attempts have been made to organize measured
AAU School of Earth Science MSc. Thesis by Temesgen A. Page 1

geochemical data from several Woredas of the Main Ethiopian Rift to determine the
distribution and the risk of fluoride contamination in groundwater using GIS (Zewge and
Emru, 2011)as cited by DH consultant,2015. These maps may have contributed a great deal
to the understanding of spatial fluoride distribution of the area; nevertheless, they lack
comprehensive approach to deal with the fluoride variability as related to other controlling
factors that determine the mechanisms for such distribution. Therefore, the data generated
from this survey will be an input to the existing data and readily be used to search /located
new low fluoride water sources site and provide safe water for rural communities. Locating
low fluoride groundwater potential sites requires a thorough knowledge of local geology,
hydrogeology, and geochemical reaction that lead to spatial variations in water quality
(Teklehailmanotet‟al,2006).

1.2 previous studies
The issue of fluoride concentration and genesis in rift valley is critically important; some of
the studies have been carried out so far. Among those hydrogeochemical studies that have
addressed the fluoride problem in order to elucidate its origin (Gizaw, 1996;
Chernet(1982,1998),Chernet et al., 2001; Ayenew, 2005,Rango et al., 2009a, b,Furi et
al,2011, Ashley and Burley 1994,Kilham and Hecky 1973,Von Damm and Edmond
1984;Reimann et al. 2003 ,Yirgu et al. 1999,)and others to investigate the associated health
problems.
Ashley and Burley (1994)as reported by (Kebede, 2013) found significant difference
between Ca content of soils in theWonji Sugar plantation area with that of Metahara Sugar
plantation areas. The low Ca in Wonji soils eventually lead to higher enrichment of F in
shallow groundwaters. The model is that abundant Ca in soil tends to fix F to form and
remove F from waters as CaF2.
Mineral saturation (Kilham and Hecky 1973; Darling et al. 1996; Gizaw 1996; Chernet
et al. 2001):Groundwaters in volcanic terrain rapidly reach saturation with respect to
carbonates of Ca and Mg (calcites, aragonites, magnesites) prior to carbonates of Na and K
and mineral of F (e.g. Ca5F(PO4)3, CaF2, MgF2, NaF). The fixation of Ca to carbonate
minerals will lead to significant under-saturation of groundwaters with respect to CaF2. This
will lead to eventual uncontrolled enrichment of F in groundwaters of the rift. An important
note here is that as groundwaters move from the recharge areas near the highlands to the
discharge zones in the rift the Ca and Mg content in groundwaters diminish. This is mirrored
by increase in F concentration along the highland-rift transect (Kebede et al. 2010).
TewodrosRango(2009) geochemical and isotopic composition of natural waters in the
central main Ethiopian rift: emphasis on the study of source and genesis of fluoride. The
result showed that high concentrations of fluoride were leached out particularly from the fine
ash fraction which in turn suggests pyroclastic materials and interaction of glassy groundmass
/weathered and redeposit fluvial/volcano lacustrine sediment with water and carbon dioxide
at high PH causes the release of fluoride into the interacting water which leads to the ultimate
reservoir of fluoride.
Base cation softening (Rango et al. 2009): The role of base cation softening is similar to
that of mineral saturation/solubility control but instead of removal of Ca by carbonate
precipitation, base cation softening removes Ca by exchange with Na in the rock matrix. As

groundwater ages or moves along its flow path Ca tends to be fixed to rocks and Na is
removed from rocks instead.
Though this process is a common process in mineral reactions, the viability of this model is
not widely tested in the rift setting.
Double enrichment model (Chernet 1998): This enrichment mechanism shows that F ion
initially leached from rock forming minerals tends to accumulate in groundwaters. Following
short or long term changes in hydrology of the rift, water table fluctuates, lake levels changes,
and sediment deposition and erosion takes place along with hydrological variations. Fluoride
ion in groundwaters is fixed to clay minerals or sediment surfaces when water level is
lowered and sediment accumulates (e.g. the shrinkage of the Ziway Shalla lakes from one
single mega lake to four isolated lakes over the Holocene left extensive lacustrine sediments).
Along with the deposition of extensive alluvio-lacustrine sediments in the rift F which was
initially in the waters is now fixed to the sediments. This makes the alluvio-lacustrine
sediments secondary reservoir of F ion. Groundwaters now circulating in the alluvio
lacustrine sediments remove F from the sediments lead to a significant enhancement of this
ion in shallow groundwaters. This model has been shown experimentally by doing extensive
leaching experiment by Chernet (1998) and Rango et al. (2009) to isolate the sediment grain
size which contributes the highest F in waters.
Porosity and permeability control (Yirgu et al. 1999): In a comparison made between two
aquifers of similar rock geochemistry and mineralogy (Pumice vs. Ignimbrite––both being
rhyolitic composition but one granular and the other fractured aquifer), the authors found that
groundwaters of the Ethiopian rift hosted in pumice (a rock with inter-granular porosity)
contain high F than groundwater contained in fractured ignimbrites. The explanation for this
is that surface area of rock–water interaction affects the enrichment of F. In pumice because
of high water–rock interaction surface area F gets transferred from the rocks to the waters
much easily.
Reverse weathering vs. F depletion from the waters of the rift (Von Damm and Edmond
1984; Kebede 1999): This process removes F ion from lake waters in the rift regardless of
the fact that none of F containing mineral reached saturation. A process of reverse weathering
also called „clay mineral neo-formation‟ is a process whereby clay is formed at high pH
values and is removed from waters (particularly from the lakes). Along with neo-formation of
clay minerals and their eventual removal to lake beds or to the aquifers, F ion is also removed

by being fixed to the clay minerals. The role of reverse weathering in removing F ion from
lake water and moving it to lake bed sediments has been shown by conducing mass balance
modeling (Von Damm and Edmond 1984) for Ziway Shalla Lakes, Kebede 1999 for
BishoftuCrater Lakes). The models, which combines hydrologic model with geochemical
model, show annual flux of F to the lakes is far greater than the annual accumulation of F in
the lake water. A significant portion of F is lost. Although the recentwork by Kebede (1999)
shows the same process to take place in the Bishoftu Crater Lakes; comprehensive mass
balance modeling should be conducted on the wider lakes of Ethiopia in order to validate this
finding.
Evaporative enrichment (Chernet 1982; Gizaw 1996): Lake Waters in the Rift Valley
show the highest F content due to the removal of F by neo clay mineral formation and
evaporative concentration of F in the lake water.
Accumulation of fluoride along groundwater flow path (Kebede et al. 2010): This work
shows how F content in groundwater varies along transects of groundwater flow path from
the highlands bordering the rift to the rift center.However, regional flows are not evident in
the volcanic aquifers of the region because of faulting, heterogeneity in permeability and
dissection of aquifers, and groundwater levels and their development is largely unknown, in
the studied region, Central Ethiopian Rift, there is a clear regional trend in groundwater flow
and geochemistry.The fact that this region falls at the intersection between an E–W running
fault zone and the NNE–SSW running fault zone may be responsible for the flow of
groundwater‟s from the highlands to the rift floor. A regular increase in F content is noted
with sharp peaks near volcanic centers. This is suggestive of successive accumulation of F
along the groundwater flow path.
Geothermal Influx (Darling et al. 1996; Gizaw 1996; Ayenew 2008; Reimann et al.
2003): Direct geothermal input of F is widely mentioned in the literature as pathway of F
input to the hydrologic systems in the rift. The challenge though is to address what proportion
of F in the groundwaters of the rift is from direct magmatic input. The proportion of F
coming from direct input from the geothermal systems to that of rock leaching is unknown
though Chernet (1998) subjectively guess that to be 20:80 %. This will remain unsolvable
question since F has no isotope. Isotopes are the best indicators of sources of certain ions, or
elements in nature and help in deciphering mixing ratios.
Haile, Gashaw.(1999)Hydrogeochemistry of waters in Lake Ziway area.

TenalemAyenew (2008)The distribution and hydrogeological controls of fluoride in the

groundwater of central Ethiopian Rift and adjacent Highlands, the results of the water
samples analysed and their localization with respect to the various volcanic stratigraphy
shows that high F waters are localized in the acidic volcanic especially ignimbrite, rhyolites,
pumice and volcanic glasses in the rift floorand high F groundwater originates in volcanic
bedrock with high Na + K and low Ca + Mg geohydrochemical system with dominant HCO3
anion.
Tenalem Ayenew.et.al (2007). Environmental isotopes and hydro chemical study applied to
surface water and groundwater interaction in the Awash River basin. The dominant source of
recharge to the Rift aquifers comes from shallow groundwater inflow from the adjacent
highlands. However, the presence of variable groundwater chemistry, depth and groundwater
occurrence in the region suggests complex groundwater dynamics, often governed by the
intensity and attitude of the rift faults and the volcanic stratigraphy and its relation with the
various water bodies.
TewodrosRango et al., (2010) Geochemistry and water quality assessment of central Main
Ethiopian Rift natural waters with emphasis on source and occurrence of fluoride and arsenic.
WagariFuri et al (2011).Fluoride enrichment mechanism and geospatial distribution in the

volcanic aquifers of the Middle Awash basin, Northern Main Ethiopian Rift.
All of the research titled mentions above results of hydrochemistry reveal that high
concentration of fluoride are related with high thermal water (temperature) and introduction
of high subsurface CO2 pressure, high concentration of Na+, alkalinity, Evaporative
concentration ,Calcite precipitation, near neutral to alkaline pH and low concentration of
Ca2+,Mg2+ and also Rift associated with acid volcanic rock especially ignimbrite, rhyolites,
pumice and reachability of rock/soil, interaction of volcanic glass /weathered and redeposit
fluvial/volcano lacustrine sediment with water and carbon dioxide at high PH in the rift floor.
Moreover, the current study considers vertical and horizontal fluoride distribution related
with lithology within high fluoride zones and origin of water recharged those high fluoride
water aquifer using hydrochemistry and stable isotopes of δ18O and δ2Hin the area to
critically understand the major source of fluoride and the hydraulic interconnection of the
lakes with groundwater flow patterns. This study will provide valuable information about the
depth wise and lateral distribution of fluoride in the transect, which will be useful in

identifying the sites of low fluoride bearing aquifers and future research work as the
reference towards effective use of the groundwater resources in the area.
1.2.1. Statement of the problems
In the Butajira-Koshe-Ziway transect, surface water resources are generally scarce due to the
arid climate and erratic rainfall in the area,so groundwater is the primary source of water
supply, which is largely characterized by geochemical anomalies of high fluoride
concentration (Kilham and Hecky, 1973; Chernet, (1982,1998,2001), Von Damm and
Edmond 1984; Ashley and Burley 1994, Gizaw, 1996; Darling et al., 1996 Yirgu et al. 1999,
Ayenew 2008; Reimann et al. 2003,Rango,2009) often exceeding the 1.5 mg/L tolerance
limit for drinking water (WHO, 2006). Above this standard, the high fluoride concentration
causes dental fluorosis (above 1.5mg/L), skeletal fluorosis (above 4 mg/L) and crippling
fluorosis (above 10 mg/L; Dissanayaka, 1991). The local population is affected by diseases
such as mottled teeth and skeletal fluorosis (Tekle-Haimanot et al., 1987, Kloos and Tekle-
Haimanot, 1999).As a result, exposure of people to high fluoride water across the rift is still
the main health problem due to the lack of budget and insufficient local management to
identify alternative sources of water supply. Therefore, the principal objective of this study is
to gain a better knowledge and investigate fluoride problem with respect to its sources,
genesis, distribution (vertical) and the origin of waters, mode of enrichment, water/rock
interactions and mixings processes (among surface waters and groundwater) in the transect
using integrated hydrochemistry and stable isotopes of δD, δ18O techniques in order to
support water quality management issues in the central sector of Main Ethiopian Rift (MER).
In this study, the association of fluoride with common hydrochemical variables and
hydrogeochemical processes that cause high levels of fluoride in ground waters was
examined. Finally, this study will provide valuable information about the depth wise and
lateral distribution of fluoride with its sources of recharge along the transect, which will be
useful in identifying the sites of low fluoride bearing aquifers towards effective use of the
groundwater resources of the area.
1.3. Objective
1.3.1 General objective
The main objective of this research is to investigate fluoride Genesis (source) in groundwater
of Butajira _Koshe_Ziway transect of central main Ethiopian rift by using integrated
hydrochemistry and stable isotope

1.3.2 Specific objectives
 To characterize major ions hydro chemical and stable isotopes signature in

groundwater;
 To characterize fluoride distribution in groundwater along the transect, and
 To determine relationship between fluoride with lithology
 To know source of recharge for waters of different fluoride concentration from major
ion chemistry and stable isotope of δ18O and δ2H
 To characterize the groundwater flow dynamics
1.4. Methodology used
In order to achieve the objective of the research, the following method and materials are
listed below.
 Review of existing geological, hydrogeological journal/article, report, related to the

title that located in the study area by searching from a different website (i.e Google
scholar) with an aim of establishing the relationship between fluoride concentration
and geological formations.
 Collect secondary data and review existing geological, topographical map,
hydrogeological, lithological log, pumping test, water quality data/borehole inventory
and report, DEM, from ministry of water, irrigation and energy (MoWIE), geological
survey of Ethiopia (GISE), water work, design and supervision enterprise (WWDSE)
and Ethiopian mapping agency (EMA).
 Preparation of base map based on a topographic map at a scale of 1:50,000 and label
secondary water quality data collected from MOWIE&WWDSE on the map in order
to determine the data gap &sampling site.
 Conducting field work to measure water point inventory of hydrogeological, hydro
geochemical and isotope evidences were conducted in all parts of the area where dug
wells, river and boreholes and lake are available and measure depth of water level by
using deep meter wherever it is accessible (SWL) with water sampling for both
chemistry and isotope laboratory analysis after in situ measurements of Total
Dissolved Solid (TDS), Electrical Conductivity (EC), pH and Temperature (T) and
take appropriate GPS location for sampling point.
 The collected water samples were kept in a100ml and 20ml polyethylene sample
bottles for both chemistry and isotope respectively by completely filled and tightened
with double-sealed plastic caps.

 The distribution of Fluoride ,EC,TDS , PH and ground water contour map in(Shallow
&deep) ground water , lake and river are establishing on the basis of interpolation of
point data measured from the field by using Arc GIS software10.1.
 Produce Groundwater level (contour) maps and determine groundwater flow
directions from water level measurements in the field and relevant water level data
obtained from the MoWIE.
 The collected water samples are analysis by the following method from WWDSEfor
chemistry and AAU School of Earth Science isotope laboratory for stable isotope of
δ2Hand δ 18O.
Ca2+,Mg2+,Alkalinity,Cl-,Total hardness Titration method

Na+andK+ Flame photometer
TDS,EC,PH and Temperature Direct measurement by EC and PH meter
Fluoride, Nitrate and Sulphate. Spectrophotometer
Stable isotope of δ2Hand δ 18O liquid water stable isotope analyzer
 Interpretation of laboratory results data collected in the field and other literature
within the study area by using different software such as
Aquachem4,arcgis10.1,surfur10,strater10,microsoftexcel and publisher 2010,Global
mapper 12,PHREEQC for SI.

CHAPTER TWO
Description of the study Area
2.1. Location and accessibility
The study was conducted within central Main Ethiopian Rift Valley in the northern sector of
the Lakes Region. The study Areas located partly in Oromia (East Shewa zone) and partly in
Southern Nations Nationality and Regional State. All the study area is located within Meki
River Catchment west of Lake Ziway sub-basin and extends from Gurage highlands in the
west to Lake Ziway in the east. The catchment is accessible by Addis Ababa–Ziway and
Addis Ababa-Alemgena-Butajira asphalt road. Intra catchment is accessed by much gravel
and dry weather roads. Geographically the study area is bounded by UTM 865000
to935000m latitude and 415000 to 495000m longitudes (Fig2. 1); with an aerial extent of
3498.4Km2.
Figure 2.1 location map of the Study Area

2.2. Physiography and Drainage
The physiography of the area is primarily determined by the rift system faulting, volcano-
tectonic activities that occurred in the past and deposition of sediments which are largely of
lacustrine origin. As a result, the main landscape features in the area include ridges,
mountains, calderas, fault escarpments, fault controlled depressions. The drainage patterns of
the areas are parallel through the tributaries that fed the main river (Meki) before draining to
Lake Ziway and the highlands are characterized by higher drainage density than the
escarpment due to differences in rock permeability, fault, climate and slope. Most parts of
Plateau area are perennial sources of the river while the tributaries in the Escarpments and rift
floor are almost intermittent sources.
Figure 2.2 physiographic map of the study area from DEM
2.3 Climate and soil
Based on rainfall, the climate of the area can be categorized in to two broad seasons: the dry
season (winter) and the wet season (summer) with autumn and spring receiving a slight
amount of rain. The average annual rainfall of the study area varies spatially from about 720
mm in lowland to 1022mm at extreme highland areas. The total annual rainfall in the area is
818.57mm on average, and the mean annual temperature is 15.7oC.The climate is
characterized by low rainfall and humidity, moderate but persistent winds and by a high rate
of evaporation, which averages 5.3 mm/day (Kassa, 2008). According to Makin et al (1975),
climate of the study area consists of three ecological zones: humid to dry humid lands, dry
sub-humid or semi-arid lands and semiarid or arid lands. Accordingly, the highland areas
West of Butajira are categorized under humid to dry sub-humid land while East of Butajira is
dry sub-humid lands. The rest of the area which is around the lake is in the semiarid or arid
zone.
The major soil types in the Rift Valley clearly show the influence of the parent material and
extent of weathering. So that Soils of the study area are closely related to the main parent
materials of the Rift Valley soils are basalt, ignimbrites, tuff, lava, gneiss, volcanic ash,
alluvium, lacustrine sediment, pumice and degree of weathering (Makin et al 1976).
Generally, the soils of the Ethiopian Rift Valley divided into thirteen major soil mapping
units and a further six sub-units based on the FAO/UNESCO soil classification. The major
soil units in the study area include Luvisoil, Cambisoil,v ertisoil, fluvisoil ,Andosoil Leptisoil
whichcharacterized by higher drainage density than the escarpment due to differences in rock
permeability, fault, climate and slope.
2.4. Geology of the study area
The geologic and geomorphic features observed in the region are the results of Cenozoic
volcano-tectonic and sedimentary processes (TenalemAyenew, 1998). During this era, there
was extensive magmatism and faulting which modified the face of East Africa. Geographic
distribution and compositional diversity among the rock units of the Ethiopian volcanic
province indicate that there has been a relationship between magma composition and rifting
(woldegabriel and Aronson, 1986; Hart et al., 1989) as cited by TewodrosRango, 2009. The
initial phase of development of the MER is attributed to the influence of a mantle plume
beneath the Ethiopian Plateau resulting in widespread flood-basalt volcanism and plateau
uplift with two main episodes dated at 45−30 Ma and 18−14 Ma (Davidson and Rex, 1980;
Mohr, 1983; Hart et al., 1989; WoldeGabriel et al., 1991; Ebinger et al., 1993; Hofmann et
al., 1997) as cited by (TewodrosRango, 2009). The most important volcano−tectonic event in
the central sector of the MER occurred in Early Pliocene, with the eruption of voluminous
flows of rhyolitic ignimbrites and the collapse of very large calderas (Di Paola, 1972;
Woldegabriel et al., 1990). From early Pleistocene to the present, tectonic and volcanic
activity was concentrated along the Wonji Fault Belt (WFB) to the East, and along the

SiltiDebreZeit Fault Zone (SDZFZ) to the west (Mohr, 1962; Di Paola, 1972). The geologic
structure in the study area has been confined to an NNE-SSW trending structures formed by a
line of hundreds of young faults and volcanic centers along the rift floor close to the eastern
escarpment. This volcano-tectonic axis, named the Wonji Fault Belt (WFB), is considered to
be the current axis of crustal extension (Morton et al., 1979 and WoldeGabriel et al., 1990).
The western escarpment is primarily characterised by one major fault scrap. It shows a high
throw in its north-eastern part, which progressively decreases and dies out to the south-west
where it has been covered by volcanic products. However, in the western escarpment of the
Guraghe Mountains, more than 1.5km thick flood basalt is displaced by several step faults
that strike NNE.TheSilteDebrezeit Fault Zone (SDFZ) of the western marginal graben is
more than 100km long and 2-5km wide and converges at its southern end with the WFB. The
SDFZ contains lacustrine sediments and tuff on which rest several nested scoria cones
aligned parallel to the west escarpment (AlemuDrbisa, 2006)
2.4.1. Stratigraphy outline of the Area
The western escarpments are mainly composed of ignimbrite, tuff, recent basalt with some
scoria cones and lacustrine sediments. The rift floor is fully occupied by lacustrine sediments
and acidic rocks (welded and unwelded tuff, ash flow tuff, and pumice and obsidian-rich
lava. Tesfaye Cherenet (1982) indicated that the geology of the large part of the rift valley
areas is characterized by Lacustrine Sediments and Volcano-Sedimentary Rocks.
2.4.1. 1.Welded ignimbrite and tuff (Tertiary period)
This formation extends from the Highland boundaries through much of the valley slopes and
escarpments, and into the rift floor of the west of Lake Ziway in the rift valley.
These units attain a thickness of around 250m in the rift while on the plateau it reaches only
up to 30m that associated with intercalated basalt in the Highland and escarpment and also
occasional lacustrine deposit or reworked water laid pyroclastic in the upper part of rift floor.
Individual basalt flows vary in thickness from one or two meters up to tens of meters and
located in the Escarpment Mountains west of Butajira Area
2.4.1.2. Basalts and associated flows of the rift floor
This unit consists of recent basalts which are located close to the western escarpment, in the
Butajira-Silte area. The formations of this group are from Pleistocene to Holocene and
include recent basalts of outcropping in the rift floor. The pyroclastic consists of the fine
glass material, generally yellowish to brown in color containing small boulders of basaltic
lava. This lava field (Cinder cones and lava flows) are aligned from Silite in the south to
Shershera in the north of Butajira. The formation of this group is from Pleistocene to
Holocene of the Wonji group and includes recent basalts outcropping in the rift floor. The
recent basalts are uninterrupted lava fields elongated parallel to the main tectonic trend of the
rift (NNE-SSW) and were produced by fissure eruption. This basaltic group comprises of
Wonji and Silte-volcanics. The silte volcanic lava field is located close to the western
escarpment just along the main fault which limits the rift in the Butajra-Silte area and in the
island of Tulu Gudu within Lake Ziway.
2.4.1.3. The rhyolite and trachyte unit (Quaternary period/Pleistocene to Holocene)
These lithological units are located in the rift valley of Gademota caldera in the southwest of
Lake Ziway. The rhyolite and trachytic lava flows found associated with the rift floor
ignimbrites and tuffs. The ignimbrites and tuff are the result of gas rich silicic magma and it
is limited in terms of area covered relative to others.
3.4.1.4. Volcano lacustrine sediments
These form the second largest outcrop of the rift floor in the study area, mainly surrounding
the lakes. They comprise alternating fine and coarse sand beds (a complex mixture of
sediments) including sand, gravel, silt, clay, ash, tuff and pumice materials, but are
predominantly fine to medium grained in the river cut exposure and the lithological log of a
borehole. The lithological unit is predominantly comprised of felsic (volcanic
rock)/pyroclastic fall, flow (ashes, tuff,) overlain by lacustrine sediments such as sand, clay
shale beds and their weathered and reworked pumice, flavio/volcano lacustrine sediments,
and associated alluvial deposits. The sediments must have been deposited during a wide time
interval from the end of Pliocene until recent which is suggested by their considerable
thickness and by the fact that in many places they underlie young volcanic products and are
often rather deeply affected by regional faults. In general, these lithology units are located
largely in the Ziway plain of the study area.

.
Figure 2.3.Photofromvolcano-lacustrinesediment
Figure2.4. Geological map modified from (Tesfaye Chernet, 1982)

Figure 2.4.1 Geological cross-section from A to B

CHAPTER THREE
HYDROGEOLOGY OF THE AREA
3.1. Hydrogeological Setting
Nazareth Group and Dino Formation undifferentiated include ignimbrite, unwelded tuff, ash
flow; rhyolites and trachytes occupy the Mareko and western part of the AdamiTuluJido
Kombolcha woredas.These lithological units are well jointed and where dense Wonji Fault
Belt cut these rocks their permeability increase.
Fractured ignimbrite and welded tuff which is reported in the western rift escarpment, west of
the study areas. They are reported to have a high or moderate permeability (TesfayeCherent,
19982). Silicic pyroclastic materials cover most of the escarpments and the rift floor. They
are mainly per alkaline rhyolitic ignimbrites, interlayered with basalt and tuffs layered with
pumices. The flow thicknesses in this lithology unit reach up to 250m in the rift.
Pleistocene and Recent to basaltic flows and cones have also been reported in the area, which
belongs to Wonji Group. They are up to 100m thick as in the east of Ziway Lake and have
moderate to high permeability (TesfayeCherent, 1982).
Rhyolitic and trachytic lava flows and domes (Holocene) and pyroclastic (pumice and
unwellded tuff), are also reported around the western part of AdamiTuluJidoKombolcha area.
These rocks are reported to have moderate productivity while the pyroclastic have low
productivity (Halcrow, 2007).
Lacustrine sediments are reported close to the Lake Ziway that extends up to Langano and
Abijata Lakes. Lacustrine sediments include silts, clays, volcanoclastic sediments and tuffs,
and rest on ignimbrite (TesfayeCherent, 1982). The yield of boreholes often ranges 1 to 5 l/s.
The permeability of sediments becomes higher where there are a higher proportion of coarser
materials like pumice sand beds. The thickness of lacustrine deposit ranges from 40 to more
than 200m, with the average of 40 to 50m. They have moderate to high permeability
(TesfayeCherent, 1982). According to Kokusai Kogyo (2012), volcanic rocks' aquifer with
high productivity occurs around the western rift escarpment and moderate and low productive
aquifers in acidic volcano-sedimentary rock at moderate slope and lacustrine sediments in the
rift floor, respectively have been reported
3.2. Hydro stratigraphic unit (aquifer and aquifer properties)

The rocks in the study area possess different permeability due to variation in lithology,
primary and secondary structure, fragment size of pyroclastic dusts, and grade of weathering.
3.2.1. Fractured Ignimbrite and Welded Tuff Aquifer
This area is mainly composed of pyroclastic fall, pyroclastic deposits such as tuff and
Ignimbrite. These are less welded ignimbrites intercalated with pumice fragments, alluvial
and colluvial deposits located at the foot of volcanic mountains. Ignimbrites are widespread,
occurring in the escarpment slopes and piedmont areas, the plains of eastern and western
escarpment and on the rift floor. From indicative hydrogeological parameters, the formation
is productive as a result of its secondary fracture porosity and permeability. The formation
may have a high or moderate permeability, although yields from both boreholes and springs
may vary widely. This permeability zone covers large area. Based on the characteristics of
ignimbrite, fracturing and weathering grade, the units possess medium to high permeability.
The groundwater in this part of the study area is deep, confined aquifer and typical borehole
yields 0 – 6l/s with thickness mostly greater than 200m. The groundwater level in this region
suddenly gets deeper probably as a result of the major fault. Existing borehole data indicates
the aquifer is composed of ignimbrites and tuffs. Transmissivity varies from 6m2/day to 171
m2/day and hydraulic conductivity 0.25m/day to 4.75 m/day.
3.2.2. Fractured Basalts and Basaltic Scoria Aquifer
These are situated to the east of Butajira and dominantly composed of vesicular basalts and.
associated scoria cones. Groundwater occurs in these areas are at a relatively deeper level
with respect to surface topography. Permeability is largely related to joints, faults, vesicles
and fragment size of scoria. The existing borehole data indicates the aquifer is composed of
scoria, vesicular basalt and at some places sand and gravel deposit underlying thin layer of
basaltic flows. The thickness of the basaltic flow is highly variable in areas, such as
Shereshera EleDirama Shershera Jole areas the underlying sand and gravel deposits
contribute to the aquifer. The existing data shows it has transmissivity varying between
16m2/day to 242m2/day and hydraulic conductivity 0.9m/day to 20 m/day. The aquifer varies
from unconfined to semi confined. The aquifer within the basaltic formation is unconfined
and the one in the underlying sediment is semi-confined. These units have a thickness up to
100m and in general possess moderate to high permeability.
3.2.3. Rhyolite and Trachytic Lava flows Aquifer

These are intermediate to acid lavas, which tend to be more viscous, often thicker than basalts
and less widespread (i.e. more closely associated with the source volcano or extrusion)
specifically in the Gademotta caldera (Consult, 2015)
3.2.4. Volcano Lacustrine Sediment Aquifer
These form the second largest out crop of the rift floor in the study area, mainly surrounding
the lakes. The lacustrine sediments are situated in low lying areas of rift floor and they store
large quantities of both fresh and saline groundwater. Generally, hand dug wells or boreholes
in volcano lacustrine sediments strike groundwater at depth of less than 50 m having a yield
of between 1 and 5 l/s. They comprise alternating fine and coarse sand beds (a complex
mixture of sediments) including sand, gravel, silt, clay, ash, and tuff, pumice materials, but
are predominantly fine to medium grained. The lithologic groups found in this area are
ignimbrites and ash overlain by lacustrine sediments such as: clay and reworked pumice.
Thickness of the lake sediments rages from 40m to more than 260m and important
unconfined aquifer in the study area. Groundwater is fairly shallow when it is close to the
surface at the lake‟s shore area and deeper further away from the lake. The depth to water
level varies from surface to about 20 m meters below the ground. Because of this there are a
number of family owned dug wells and community wells in the area. The Aquifer
Characteristics as Poor yields for Massive and/or pumices/pyroclastic, good yields for well
jointed or fractured Ignimbrite, Low to medium potential for Lacustrine Sediments. There are
local sands and gravels, which often form the primary groundwater bodies within these
sediments. The existing data shows it has Transmissivity varying between 1-137(m2/day) and
hydraulic conductivity 0.02m/day to 3.8 m/day.

Figure 3.Hydrogeological map of the study Area modified from (Tesfayechernet, 1982 and
MoWIE, 2008)
3.3. Groundwater Recharge and discharge areas
Recharge mechanism in the study area has been explained based on lithology, topography
and structures through direct infiltration from those highlands of precipitation into the aquifer
system, localized recharge through tectonic discontinuities (such as faults, joints, fractures)
into the aquifer system. The recharge and discharge area usually determine by high
topography and hydraulic gradient which means topographically high area considered as
recharge whereas topographically low area considered as discharge area. The Garage
Mountain (highland) which is located at high elevation 3600 above mean sea level and the
rift floor or ziway plain at elevation 1635 above mean sea level before drain to Lake Ziway is
also considered as discharge area. The other possible recharge is direct infiltration of the
precipitation on the rift floor (i.e. discharge area). However, due to the relatively higher

annual potential evapotranspiration over the total annual precipitation in the rift floor, direct
recharge from precipitation for this lower valley part is unusual.
Based on Geomorphology, the study area can be categorized with different hydrogeological
characteristics.
The highland volcanic mountains: The western Garage Mountain ranges (main recharge area
of the basin). Mountain front recharge is characteristic feature, defined as recharge occurring
along a boundary of the regional aquifer system that parallels a mountain area. Source of
recharge is from precipitation of infiltration or in direct recharge from stream flow
infiltration. Small portion of the recharge contributes to a deeper groundwater flow system
which discharges in the valleys further downstream in the plateau and escarpments.
Escarpment Areas: Are characterized by low rainfall and higher evapotranspiration; Direct
and localized recharge from precipitation along high fracture zones; Large depressions of
volcano tectonic origin. Some of these depressions are discharge areas of local and
intermediate groundwater flow systems. The water in the high altitude depressions is
characterized by low EC and TDS indicating possible release of water to the deeper rift
groundwater system, Rift Floor: Channel loses from the large rivers in permeable lacustrine
sediments. Local flow systems exist in the rift valley. Groundwater flow in the rift is
generally characterized by relatively low gradients recharged mainly by indirect sources.
3.4. Groundwater Flow
Major fault systems are aligned NNE-SSW, parallel or sub parallel to the Main Ethiopian
Rift, with well-defined escarpments. These are often associated with depressions and plateau
that may provide for storage and transmission of groundwater. In some locations, these
fault/fracture systems are the major controls over groundwater flow direction. Groundwater
contour map has been generated based on the collected (measured static water level) in the
field. This map has been constructed to show the groundwater flow direction. Groundwater
flow is generally towards the east and southeast from the western and northwestern high
lands. The groundwater level is generally flat to gentle slope except at Tora-Koshe-Dugda
ridge. In these areas the groundwater contour shows steep slope showing lower permeability,
probably due to the nature of the rocks or the fault systems separating these zones. The
groundwater level drops from about 2040 m in Butajira to 1640 m amsl in Lake
Ziway.Fromgroundwater contour map,hydrochemical evolution and isotope result ground
water flow directions radiate from the Guraghe highland and its escarpment towards eastern
and south-eastern part of the catchment. The flow direction converts to wards west and
northwest in the vicinity of Lake Ziway. There is a divergent zone at the western escarpment
around mareko; which may probably because of recharging of water from the highlands.
Divergent zone is a specific area where the water starts to flow to any other area of different
direction and considered as recharging zone. In addition there is also a convergent zone in the
rift floor around dugdaworeda in the vicinity of Lake Ziway; which might be considered as
discharging zone. Convergent zone is specific area where the water flows toward specific
zones that comes from its surrounding of any direction.

CHAPTER FOUR: RESULT AND DISCUSSION

4. HYDROCHEMISTRY AND ISOTOPE HYDROLOGY
4.1. General Hydrochemistry
The chemical composition of natural water is derived from many different sources of solutes,
including gases and aerosols from the atmosphere, weathering and erosion of rocks and soil,
solution or precipitation reactions occurring below the surface, and cultural effects resulting
from human activities (Hem, 1992).
The chemistry of groundwater in the saturated zone is controlled by chemical reaction rate,
residence time within the saturated zone, and mineralogy of the rock matrix, where residence
time and flow path are determined by factors such as aquifer thickness, permeability and
amount of recharge (Griffioen, 2004). These factors combine to different degrees to create
diverse water types with compositions that vary with space and time.
Hydrochemical investigations are conducted to understand the functioning of the

hydrogeological system by relating the quality of the groundwater to different processes in
the aquifer system.
Water chemistry data can be used to infer groundwater flow directions, identify sources and
amounts of recharge, estimate groundwater flow rates, and define local, intermediate, and
regional flow systems (Anderson and Woessner, 1992). Underlying this hydrochemical
approach are a number of assumptions including (1) natural water chemistry is a result of
rock-water reaction such as dissolution/precipitation, reactions on aquifer surfaces and
biological reactions, (2) distinctive chemical signatures are related to specific sets of
reactions, (3) dissolved concentration generally increase along the surface flow path until a
maximum value dictated by mineral equilibrium, and (4) hydrochemicalfacies are directly
related to the dominant processes (Thyne et al., 2004).The hdrogeochemistry of water can
provide information that can distinguish recharge zone water from transition and discharge
ones based on the chemical composition of water type. Moreover, in hydro geochemistry
major cations are the most widely and frequently used parameters for characterization of the
various water types and deduction of the flow processes and origin of salinity
(AddisuDeressa, 2012).

4.2. Physiochemical parameters
Physiochemical parameters analysed for the water samples are characterised into two: those
that have been measured both at the field and in the laboratory, and those that have been only
analysis in the laboratory. For that reason, the measurement of PH, Temperature, total
dissolved solid (TDS), Electrical conductivity (EC) are measured both at the field and in the
laboratory while sodium, potassium, hardness (calcium, magnesium)alkalinity ,sulphate.The
selection of the sampling locations was planned to take into consideration the previous
hydrogeological/geochemical studies of the area (Fig.3). A total of 60 water samples were
collected 57 sample from groundwater wells (both hand dug and borehole well) 2lakes and
1rivers on December 2016 and samples were stored in 100 ml((chemistry)&20mlisotope)
polyethylene bottles for chemistry and completely filled and tightened with plastic caps.
Out of the total; 30samples were analysed for major ions(Na+, K+, Ca2+, Mg2+ F-, Cl-, NO3- ,
SO42- and HCO3- ), 30 for stable isotopes of δ18O and δD.
TDS, EC, Temperature and pH of waters were measured in situ using the appropriate field
kits. Locations of the sampling points are recorded during the fieldworks using Global
Positioning System (GPS) and measuring of static water level using deep meter for
preparation of groundwater contour map in order to determine flow direction.
Generally,14 water samples for isotopic data points from a previous study (ShimelisFikre,
2006; Winter, 1973,(TenalemAyenew 1994,1996), Crag etal, 77,Rango ,2009) and 40 water
samples for major ions /chemistry from (DH Consultant, 2015) Ministry of Water Resource
were included in the database.
Samples were analyses of major elements were carried out at the Ethiopian water work
design & supervision enterprise by using flame photometry for (Na+, K+),titration( Ca2+,
Mg2+,alkalinity,total hardness and chloride),spectrophotometry for anions (F- , NO3-, SO42- )
and Addis Ababa University School of Earth Science hydrogeology isotope laboratory for
stable isotope by using liquid water stable isotope analyzer. The reaction error is the
difference between total cations and total anions, expressed as a percentage of the TDI.
Analytical accuracy of the analysis for major ions can be estimated from RE (Electrical
neutrality) conditions since the sum of anions and cations must balance
RE= ∑cations-∑anions/∑cations+∑anions*100, Where cations and anions are expressed in

meq/l.

Figure4. Water chemistry sampling point
4.2.1. PH
The PH values of the sample collected in the Study area ranges from 6.5 to 8.75.The lowest
values measured in the sample from Twp55 at Butajira and the highest value measured in
Twp59 at Meki town. The alkalinity of water is due to the presence of carbonates,
bicarbonates, alkaline and alkaline-earth hydrates.

Figure4.1. PH distribution map of the Study Area
4.2.2. Temperature
The temperature of the water is controlled primarily by climate. Temperature also affects PH,
electrical conductivity, the rate of chemical reaction as well as the concentration of the
reactants and the products, and solubility of gases in the water. It must be measured in situ or
immediately after collecting the water sample. In fact, the temperature of sub-surface waters
reflects the environmental condition on which the water flows. In the study area, the water
temperature of the sample ranges from 17.9oC to 29.1oC in the field. In general, the
temperatures of the water samples show a progressive increase from west to east in the
direction of flow paths.

Figure4.2. Temperature distribution map of the Study area
4.2.3. Electrical Conductivity
It is the ability of a substance to conduct an electric current and measured in micro Siemens
per centimeter (µS/cm). As ion concentrations increase, a conductance of the solution
increases, therefore, the conductance measurement provides an indication of ion
concentration(Roaring Fork Conservancy, 2007). The values of EC increase with
temperature, between 20ºC and 30ºC, an increase in 1ºC, increases the EC by two percent on
the average (Hem, 1992). The EC value indicates that how much is the concentration of
dissolved substance in the water which in turn tells us that how far the water travels and how
long it stays in the subsurface and the nature of geologic formation. It also helps to identify
recharge and discharge areas. The more salts are dissolved in the water; the higher is the
value of the electric conductivity. The minimum and maximum EC value for the study areas
are 370 (µS/cm) of TWSs at Sodo Renfenso and 3480(µS/cm) Twp25 at Edokontola near
Abosa town respectively. EC does not give specific information about the chemical species
present in water, but it gives a determination of TDS, which is an acceptable indicator of
water quality.

Figure4.3. EC distribution map of the Study Area
4.2.4. Total Dissolved Solid (TDS)
It is a measure of the amount of material (solid) dissolved in the water. This material can
include calcium, magnesium, sodium, potassium, carbonate, bicarbonate, chloride,
sulphate.Thenitrate, organic ions, and other ions such as silicates. The wide variations of the
value in the study area are mainly due to three major reasons:-
According to (Dennis Nelson, 2002), factors that control the dissolved minerals in
groundwater include:-
•Residence time of the groundwater in the aquifer, the value of TDS in the study area
increases from Butajira-Koshe to Lake Ziway. This indicates that contact time of
groundwater with rocks is longer and the interaction with different earth materials increases.
•The types of minerals that make up the aquifer, in Butajira-Koshe to Lake Ziway most of the
area covered with acidic rock, such as ignimbrite, tuff, lacustrine sediments, which causes a
reaction with aquifer and contribute high TDS to ground water.

•The chemical state of the groundwater.
The minimum and maximum values of total dissolved solid in the study areas are 240mg/l of
sample TWSs1 at SodoRenfenso and 2090mg/l of sampleTwp25 at Edokontola near Abosa
town respectively. The TDS=0.6079EC relationship for collected and analysis water sample
result.
Figure4.4.1 TDS vs. EC

Figure 4.4.TDS distribution map of the Study area
4.4. Geochemical characteristics of major cation and anions
The major caions and anions which have been considered within the study areas are sodium,
calcium, magnesium, potassium, bicarbonate, carbonate, chloride and sulphate.The collected
and analyzed water samples illustrate that water chemistry changes in different parts of the
groundwater flow system. From recharge area to discharge area, the concentrations of various
components such as Na+, H O 3 and F in hydro-geochemical system generally increase
towards discharge zones (towards Lake Ziway) and the hydrochemical type generally
changes from Ca(Mg)-HCO3,Ca-Na-HCO3andNa_Ca_HCO3 to Na_HCO3type of water.
Sodium is the dominant cation followed by calcium and magnesium and Bicarbonate is the
dominant anions which also followed by chloride and sulphate within the volcanic aquifers of
the study area (fig4.5). Sodium shows significance variation ranges from 32 to 910mg/l. The
Na+concentration ranges from minimum values in the high land and rift escarpments to
maximum values in the rift floor close to Lake Ziway. The dominance of Sodium in the study
area is likely to be attributed to the dominance of the acidic volcanic rocks, mainly volcano

lacustrine sediment, ignimbrite, tuff, rhyolite and weathering of Na rich feldspar. In addition
this Na dominance could be attributed because of long time of water-rock interactions.
Calcium ranges between 6mg/l to 96mg/l in the ground waters of the study area, theminimum
and maximum value is located Edokontola (Twp25) and at Twp27 in the butajira area
respectively. This high value is due to the fact that rain water isrecharge of the well through
infiltration from rain water of surrounding highland and waja river drainage While low-Ca
groundwater conditions arise in volcanic regions dominated by alkaline volcanic rocks (e.g.
Ashley and Burley, 1994; Kilham and Hecky, 1973) and also in conditions where cation
exchange occurs naturally. Since, removal of Ca2+ is achieved by exchange with Na+ from
clay minerals.
Magnesium is follows the same trend as calcium but lower than calcium may be due to the
fact that magnesium is present in a much lower concentration than calcium in most igneous
rocks of the study area. Its range is between 1.9mg/l to 22.1mg/l and this maximum range of
magnesium is located at Twp52 of inseno well while lower value was located at Twp25 of
Edokotola hand dug well. This maximum value may be the results of surrounding recent
basalt which contain high content of ferromagnetic minerals.
Bicarbonate is the dominant anion in the catchment and its proportion to carbonate was being
controlled by the PH values of respective groundwater samples. The carbonate concentration
in the study area ranges from 291mg/l to2170mg/l at Meki River and hand dug well near
Lake Ziway. The high concentration of bicarbonate is derived from atmospheric and
magmatic CO2(Gashaw, 1999),according to the reaction
Na, K - Silicates + H2O + CO2 = Na+, K+ + HCO3- + H – silicates
Chloride is another anion known by its conservative nature in the chemical evolution process
and good indicator of the relative age of ground water compare to other major ions. Even
though, more important source of Cl is association with sedimentary rocks, volcanic gases
from geothermal fields may also introduce in the ground water system and in some rift lakes
(TenalemAyenew, 2005). The chloride value of the study area ranges from 1.2mg /lto
131mg/l at inseno to near to Lake Ziway respectively. Generally, Cl concentration increase
from western highlands and rift escarpment towards the floor of the rift. The main chemical
reactions control solubility of fluoride in natural waters are: ion exchange reactions,
dissolution reactions and precipitation reactions(Gashaw, 1999).

Sulphate concentrations in the study area are range from 0 to 160.68 mg/l at the Lake and
shallow well (Twp74) at Ziway Town. The Schoeller plots are used to show the dominant
cation and anions respectively.
Figure4.5Schoeller plot of major cat ion and anion
4.5. Minor anions
The most essential minor chemical constituents for consideration in the study area are nitrate
and fluoride concentrations.
4.5.1. Nitrate
The nitrated concentration in some the hand dug well and boreholes of the study area range
from 0.5 to 90.4m/l which is above the maximum permissible contaminant level of WHO
(2004) drinking water quality standard is 50 mg/l.The relatively higher nitrate value (90.4
mg/l) observed in some sallow hand dug wells in the study area is attributed to the
agricultural practices. Most shallow wells are located at a downstream of extensively
cultivated farmland. In this case both the synthetic fertilizers and the manures should have
their own contribution as people use both in up grading the soil fertility of their farm land in
the area and lowest value of (0.5mg/l) TWM28 at Semen koshe.Excessive presences of these
ions in drinking water are very serious public health problems.
4.5.2. Fluoride of the Study Area
Fluoride is released into the groundwater mostly through water–rock interaction of fluorine-
bearing mineral and leaching out the fluoride from easily weathered and redeposit volcanic
rock/ sediments is the source of high fluoride levels in water resources of the area. The
concentration of fluoride can furthermore be influenced by ion exchange with micaceous
minerals and their clay alteration products as the cause of the F- enrichment in groundwater.
Moreover, pH rise changes the water into a strong anion exchange medium for the exchange
of hydroxyl ions for fluoride, favoring high fluoride concentration. The principal reservoirs
for F ion in nature are rock forming silicate minerals containing OH ion in their structures
(Seifukebede, 2013).The fluoride solubility and enrichment can be increased by weathering
of the volcanic rocks in extended time particularly conspicuous in these tropical
environments because high temperature and humidity promote high rates of weathering
(Hecky, 1973)
Most of the fluoride in groundwater comes from acidic volcanic rocks such as tuffs,
fluvio/volcano lacustrine sediments, pyroclastic deposits, ignimbrite and rhyolite. The
leaching process is facilitated by high permeability and rock water interaction with in the
fluvio/volcano-lacustrine sediment and pyroclastic fall deposits (Rango, 2009, Gashaw,
1999).The most important sources are acidic volcanic rocks such as tuff, pumice and obsidian
and emanations from geothermal systems (TesfayeChernet, 1982; Chernetet al., 2001). High
F in saline lakes of the East African Rift reflects the nearly complete removal of Ca by
carbonate precipitation usually as calcium carbonate ((Kilham and Hecky 1973, Darling et al.
1996, Gizaw 1996; Chernet et al. 2001) probablyfrom CaF2) due to groundwater in volcanic
terrain rapidly reach saturation with respect to carbonates of Ca and Mg (calcites,aragonites,
magnesites) prior to carbonates of Na and K and mineral of F(e.g. Ca5F(PO4)3, CaF2, MgF2,
NaF). The fixation of Ca to carbonate minerals will lead to significant under-saturation of
groundwaters with respect to CaF2.
The fluoride guideline values for World Health Organization and Ethiopian drinking water
quality guidelines are 1.5 and 3.0 mg/l respectively (MoWIE, 2003). Fluoride values over 3
mg/l commonly occur in the Ziway Plain and Tora-Koshe-Dugda ridge. The fluoride
concentration in the study area ranges from 0.27 to 9.49mg/l for ground water&9.52mg/l for
lakes respectively. The fluoride distribution map of the study area is presented to identify
high and low-fluoride zone both in laterally and vertically (depth wise) and will help to
correlate with its source (fig4.6). The map is prepared based on existing and new fluoride
data collected from different woredas.The fluoride distribution map is apparent that the
variations of fluoride from place to place are closely associated to variation in geology and
fault-controlled flow ( the type of rock and tectonic structures.) The map is useful in
identifying high-risk area which corresponds with the complex spatial distribution of the
volcanic rocks and their associated structures. The highly fluoride enriched groundwater
zones is confined in central area known for dominant fluvio/volcano lacustrine sediments,
rhyolite and welded tuff areas located close to lake and major geothermal centers.
Tectonically fault zones in the area are commonly characterized by thermal water that has an
important influence in the spatial distribution of fluoride. The hot springs and wells drilled
close to thermal centers have very high fluoride and those waters are controlled by fault-
related systems. In this context, the thermal springs are developed by geological structures
that allow mineralized deep groundwater‟s to ascend towards to surface and interact with
shallow aquifers. The waters which (emanate) originate from highland, surface and marginal
faults are related to fast circulating groundwater and surface water of low ionic
concentrations and fluoride. The general groundwater flow direction indicates that highland
water can infiltrate to the rift system and changes the ionic composition of the waters along
the flow path. The high spatial ionic variations follows systematic trend reflects the different
groundwater flow systems. When the faults act as conduits of fresh groundwater circulation,
the surface water tends to dilute the groundwater system through large step‐faults. Lake
water and rivers have low ionic composition and fluoride than groundwater, except where
they are influenced by the discharge of thermal springs. On the other hand the fault-
controlled aquifers with dilution effect of substantial meteoric and highland water can be a
source of good quality of groundwater.

Twp1
Fluoride vs. depth with different location Fluoride vs. depth with the same location
Figure4.6.Lateral and Vertical fluoride distribution of the study Area

4.6. WATER type and Ground water flow path
Water type classification of deep bore holes, shallow wells and hand dug well, lake, and river
waters are made to observe the major water groups, their relationship and evolution along the
flow path by using a piper diagram and Microsoft excel (2010) graphical presentation
method. The majority of the shallow well, dug wells and Boreholes from the highlands and
escarpments are calcium -magnesium-bicarbonate and Calcium-sodium-bicarbonate water
type. These types of waters are often regarded as recharge area waters which are at their early
stage of geochemical evolution. In the majority of waters from the rift floor boreholes,
shallow wells and hand-dug well sodium dominate their cation species and bicarbonate
dominate their anions. The groundwater‟s fall in the Na_ a_H O3 and Na_H O3 type,
indicating long duration of rock-water interaction.
The major cat ion and anion ratio indicates that Ca2+/Mg2+, Ca2++Mg2+/Na++K+ ratio decrease
along ground water flow path (upstream towards downstream) maybe due to removal of
calcium with bicarbonate. This variation in ionic ratio used to identify recharge area and flow
direction following ground water flow path while the Na/H O3, Na/∑cat ions,
HCO3/∑anions ratios are increase along ground water flow path indicates the increase of
rock water interaction and long residence time of water in the ground.
The concentrations of in-situ physical parameter measured in the field and concentration of
fluoride from laboratory are also increase following the ground water flow path (from west to
east) indicate long residence time/ water- rock interaction as shown from fig 4.9.
Figure4.7. Piper diagram of different water type in the study area

Figure 4.9.Hydrochemical evolution vs elevation/altitude along ground water flow path
Based on hydrodynamic regime the study area may be categorized into three
hydrogeochemical zones: - Highland and Escarpment, Transitional and Enrichment zones.
4.6.1. The Highland and Escarpment zone
This region mainly concerned on the Butajira Highland and escarpment and the recent basalt,
scoria cones region in the western escarpment situated west of Lake Ziway. When meteoric
water containing the considerable amount of CO2 infiltrates in to the groundwater it
introduces HCO-3 to the groundwater. Generally, groundwater of this region is dominant
Ca(Mg)_ HCO¯3 and Ca-Na-HCO3 type in which cation enrichment (Na, Ca, Mg) is variable
depending on mineral variations within the reservoir and the extent of weathering (Chernet et
al., 2001).Most water samples of this zone have TDS less than 600mg/l and the major ions
concentration in the groundwater is low suggesting that the groundwater has little interaction
with the rock that hosts it. The spatial distribution of Fluoride shows which is relatively well
structured in addition to Low contents of fluoride characterizes the waters from the high
elevation zones, the escarpments and the plateaus.
4.6.2. The Transitional Zone

This zone located next to the Highland and Escarpment within Inseno area and the
groundwater tends to evolve from Calcium-sodium-bicarbonate(Ca-Na-HCO3) type to
Sodium-Calcium Bicarbonate(Na-Ca-HCO3) type with low concentrations of cations.TDS is
a general indicator of the extent of mineralization of groundwater. Most water samples of this
zone have TDS values less than 800 mg/l. Thermal springs generate an increase in sodium
and bicarbonate alkalinity then the water chemistry remains controlled by Na+ and HCO3-,
while the Cl- and SO42- enrichments are more variable.
4.6.3. The Enrichment Zone
This zone located in the Ziway area and Tora-Koshe-Dugda ridge in which water tends to
evolve from sodium- calcium- bicarbonate type with low concentrations of cations in the
recharge zone to sodium- bicarbonate water in the acidic rocks and lacustrine sediments of
the rift floor. Salinity increases from the recharge area that is characterized by high rainfall
and low evaporation to the region of low rainfall and high evaporation of the rift floor.TDS is
a general indicator of the extent of mineralization of groundwater and most of the water
samples collected in this zone have TDS values greater than 1000mg/l. Alkalinity is, in any
case, greater than the equivalents of calcium which characterizes the chemical weathering of
the volcanic rocks in the Main Ethiopian Rift. When these waters concentrate, the alkalinity
increases despite the precipitation of the calcite and the molality in calcium decreases and
stabilizes. The problems of rising are the alkalization and the solidification of the complex
exchange which induce degradation of the physical properties of the soils and a lack of
mineral supply to the vegetation (Chernet et al., 2001).The groundwater shows fast evolution
from Calcium bicarbonate type to sodium bicarbonate type within the short distance in the
order of about 40 Km between the escarpment and the rift plain. This is due to the long
residence of the groundwater in the rift valley that results in the reaction and dissolution of
different minerals.
4.8. Isotope Hydrology
Environmental isotopes now routinely contribute to groundwater investigations,

complementing geochemistry and physical hydrogeology. Measurement of the stable isotope
composition of salinized water is a useful method for discriminating the cause of salinity
because water that is saline due to evaporation will be isotopically more enriched than the
source water, whereas water that is saline due to salt addition or transpiration will not change
isotopic composition. The stable isotopic composition of water for instance, is modified by

meteoric processes, and so the recharge waters in a particular environment will have a
characteristic isotopic signature (Clark and Fritz, 1997). This signature then serves as a
natural tracer for the provenance of groundwater. Depleted isotopic signature found in some
groundwaters of the rift floor could be explained by lower temperatures during recharge
processes, while the enriched portion of the waters is recharged after evaporative process in
the rift floor (Demillei, 2008; Rango et al., 2008). The δ18O and δD values of water groups
from escarpment are recharged dominantly from summer rain and the moisture sources.
Non evaporated or slightly evaporated meteoric waters are generally recognized by their
proximity to the meteoric water line whereas waters directly altered by evaporation or mixed
with water enriched through evaporation, plot to the right of it (IAEA, 2000).The δ18O and
δD values of various water groups from the area (surface waters and groundwater) were
plotted against the GMWL and the LMWL.Precipitation on the Ethiopian highlands is
generally a result of the clouds from oceans, which arrive after several rainout effects (Seifu
Kebede et al., 2012). Evaporation from surface water causes enrichment in δD and δ18O and
the trend line of surface waters plots with slope less than slop of LMWL
Figure 4.11 isotope sampling point
4.8.1. Stable isotope in Water

A water molecule is composed of oxygen and hydrogen, which occurs with different isotopic
combinations in its molecules. The isotopic composition of precipitation containing these two
elements may be reflected directly or modified in the composition of groundwater. The
modification of groundwater composition may be due to fractionation or separation of
heavier and lighter isotopes because of evaporation processes (phase changes) prior to
infiltration or isotopic exchange with aquifer matrixes (Mazor, 2004). The common practice
is to plot water sample data on δ2H versus δ18O diagrams, along with the meteoric line of
local precipitation as a reference line. The meteoric line is a convenient reference line for the
understanding and tracing of local groundwater origins and movements using conservative
isotopes of water molecules (δ2H andδ18O). In order to trace the source and mechanism of
groundwater recharge isotopic signature of δ2H and δ18O in the groundwater sample are used
and 30 representative water samples are gathered from the western and northern part of the
lake Ziway sub-basin during field work (Fig 4.11 and appendix2) from different sources
(such, dug wells, river water emanating from Highlands, boreholes and analyzed at Addis
Ababa University (AAU) isotope laboratory.
4.8.2. Deuterium (δ2H) and oxygen (δ18O) isotopes
Deuterium (δ2H) and Oxygen (δ18O) are the most widely used stable environmental isotopes
in various hydrological sciences for investigating water resource development and
management. The stable isotope content of water molecule 2H/1H and l8O/16O is expressed by
convention as parts per thousand (‰) deviations relative to the standard VSMOW (Vienna
Standard Mean Oceanic Water) VSMOW is standard water prepared from distilled seawater
that was modified to have an isotopic composition close to SMOW (Standard Mean Oceanic
Water) by IAEA (Clark and Fritz, 1997). This reference is identified as VSMOW and
defining the value of δ (delta) = 0 and provide an appropriate reference for meteoric waters,
as the oceans are the basis of the meteorological cycle. Delta notation (δ), which is commonly
used to report isotopic concentrations of the analyzed water samples, is defined as:
Where, RSAMPLE and RSTANDARD refer to the isotopic ratios of 2H /1H and 18O/16O.A
positive δ value means that the sample contains more of the heavy isotope than the standard;
a negative δ value means that the sample contains less of the heavy isotope than the standard.
During phase changes, the ratio of heavy to light isotopes in the water molecules will be

changed. For example, as water vapour condenses into rain clouds (a process typically
viewed as an equilibrium process), the heavier water isotopes (18O and 2H) become enriched
in the liquid phase while the lighter isotopes (16O and 1H) remain in the vapour phase
(depleted).The paleoclimatic effect in arid regions is manifested by depletion in stable
isotopes with respect to modern waters(Seifu kebede, 2013).A plot of δ18O vs δ2H for
sampled waters readily identifies the influence of evaporation and the effects of mixing from
different sources within the hydrologic system. Unevaporated meteoric waters are generally
recognised by their proximity to the Global Meteoric Water Line (GMWL; Craig, 1961)
whereas waters altered directly by evaporation or mixed with evaporative enriched water plot
to the right of the GMWL (δ2H=8 δ18O + 10 ‰ SMOW). LMWLof the basin is obtained
from (Asela, Ziway, Silte, Butajira, and Awasa towns) rainwater that were collected by
(Chernet, 1998) in the period of June-August (1994 -1995) and defined by δD =7.02
δ18O+9.1(Rango, 2009).This equation (LMWL) is used in the basin to determine sources of
ground-water recharge, to evaluate surface-water and groundwater interaction, and to
analyses other geochemical and hydrologic problems.
Figure.12. A plot of Deuterium (δ2H) vs. δ18O isotopes of water samples

This figure has shown that the majority of ground waters, river waters and rain waters are
plotted near the LMWL .This indicates the importance of present-day precipitation for
groundwater recharge and mainly revealed as secondary fractionation or evaporation after
condensation. The river water plotted near to the evaporative line with the slope of 4.9
values corresponding to extensive evaporation of rain droplets in dry atmosphere can take
place resulting in enrichment of rainwater’s and deviation from the global meteoric water.
The lake Waters are plotted far to the right and shifted right down of the LMWL .This shows
that the lakes are more enriched with δ18O andδ2H.Waters from hot spring from Tulu Gudu
island, cold springs, cold wells from Highland) are scattered at different positions on the plot
and have differences in δ18O and δ2H concentrations. The variations of isotopic
concentrations between ground waters reflect the presence of different groundwater flow
systems (ShemelisFikre, 2006). The sample collected from the borehole, hand-dug well, and
cold springs in the Highland and escarpment started from sampleTwp41 to Twp71, theδ2H
and δ18O isotopic composition are slightly to highly depleted due to the altitude effect
indicate that they are recharged by meteoritic water coming from Highland through
infiltration from rainfall. whereas the samples collected from the rift floor near to the lake
Ziway, Twp.( 1,2,6,21,24,25,36,37,39,59,60,63,64 )and Wl13, Lw29 samples are enriched
with the δ2H and δ18O isotope due to the temperature effect which leads to evaporation.
This enrichment of hand-dug and borehole well near to Lake Ziway indicates that there may
be the interaction of lake water with groundwater. The collected isotopic data from ground
water in the study area is characterized by both highly depleted and enriched isotopic
signature. The δ18O and δ2H values range from –6.08 to 5.9 and-33.4 to 41.63 in (‰)
respectively. Most of the samples collected from the Highland and escarpment areas are
plotted to the left of the GMWL or LMWL and highly depleted compared to Lake Ziway and
its surrounding borehole and, hand-dug well. This depleted ground water from the deep
wells of Highland and Tora-Koshe-Dugda ridge indicates that deep circulation of
groundwater, long residence time and along flow path from adjacent highland. This
depletion isotope in the highland is recharged from the summer rainfall related to the
difference in source of moisture and to local meteorological processes.
4.8.3. Relation of stable isotope and Hydrochemistry

The integration of stable environmental isotopes such as δ2H, δ18O and geochemical
techniques are used for the investigation of the sources of saline water intrusion into potable
fresh groundwater in various parts of the world (IAEA, 1997). During the processes of
leaching salt formations or mineral dissolution, the stable isotope content of the water is not
affected while the salinity of water increases. The enriched δ18O isotope values are directly
proportional to the hydrochemistry (TDS,Na+/Ca2+)which indicate high TDS value have also
highly enriched inδ18O (i.e.Twp25, 2090mg/l and 5.22% inδ18O). This is a unique feature
which will enable identification of such processes based on isotopic and chemical data.
The Origin of high fluoride and enriched groundwater surrounding the lake is recharged from
local precipitation and lake itself rather than meteoric water recharged directly precipitation
(regional) from Guragae highlands.
Figure4.13. Chemistry vs. isotope relationship
GENERAL DISCUSSION
The hydro chemical results obtained from the field data (appendix1) show that 76.7% of the
samples (n=30) have fluoride concentrations above the permitted WHO standard (>1.5 mg/l)
while 23.3% have concentrations below the standard (<1.5 mg/l,n=30). Isotopic and hydro
chemical studies across the region revealed that some ground waters (hand dug wells) are
affected by lakes .The results shows that there is a strong spatial variation of hydrochemical
evolution along ground water flow path i.e. towards Lake Ziway (fig4.9). The highest salinity

and fluoride values are located at lower elevation of the catchment near to Lake Ziway and
Adami Tulu Town due to strong rock- water interaction(interaction of fluvio-volcanic
lacustrine sediment with water), long residence time and evaporation effect. Shallow ground
water (hand-dug well) near to Lake Ziway shows high concentration of fluoride due to the
leaching of weathered and redeposit volcanic rock, soil and intimate association(interaction)
of lake with surrounding ground water (Chernet,1998,Ayenew, 2003,Rango,2009).The low
concentration of TDS,EC and Fluoride in the highland waters indicates that fast circulation
of meteoric water at shallow depth with that relatively at low temperature(Ayenew,
2008).Evapotranspiration leads to a precipitation of calcite, a lowering of Ca activity and
increase in Na/Ca ratios, and this allows an increase in F levels.(Jacks, 2005)
The general trends of fluoride concentration along the transect increase from highland
towards rift floor because of the welded /compacted rock with highly faulted geologic
structure allows fast groundwater flow/circulation that didn‟t have time to dissolve rocks,
while towards rift floor the geologic units changed to volcano lacustrine sediments which is
the results of weathered and redeposit volcanic rocks are easily interact with water takes long
residence time/reduced flow rate i.e. leads to increase fluoride concentration through leaching
of rock and soil. Depth wise fluoride concentration indicate high at shallow depth, but
decrease with depth (fig4.6).However, there is also low concentration within high fluoride
zone (Twp1) due to its depth relative to others.
5. Factors for Fluoride Enrichment/low groundwater quality
5.1. Hydro chemical reaction/thermodynamics control
The role of thermodynamics is to control which kind of reaction is possible under a given
rock type, temperature, saturation indices, and ionic activity. The plot of variables on a
bivariate diagram further explains the geochemical processes involving the change in
hydrochemicalfacies and the fluoride enrichment in solution

Table5.1. Correlation matrix of collected and analyzed water sample
As shown from (table 5.1) of correlation matrix Na+,PH, HCO3,salinity,TDS, have been
positive relation with fluoride but calcium, magnesium has been negative relationship. In the
positive correlation with ratios of Na+/Ca2+vs altitude increasing in the flow direction due to
the decreasing of Na+/Ca2+with increasing altitude (fig 6a) and increasing of fluoride level
with increasing Na/Ca ratio (fig 6c) indicates a systematic hydro chemical reaction involving
the removal of the Ca2+cation from a solution and addition of Na+cation by the solution
fromaquifer material in the flow process. The increasing of Fluoride, Na/Ca ratio in this
direction is due to the uptake of Ca2+ by the aquifer materials in the exchange of Na depends
on the nature of surface charge encounter (available) material and the reaction of cation in the
solution.
Cations exchange is a reaction in which the calcium and magnesium in the water are
exchanged for sodium that is adsorbed to aquifer solids such as clay minerals, resulting in
higher sodium concentrations (Hem, 1985). The generalized reactions are as follow (Hem,
1985) and exchange process between cations of (Ca2+ (Mg2+) /Na+) in the flow process can be
represented by:
Na2X+Ca2+ CaX+2Na+ (1)
Na2X+Mg2+ MgX+2Na+
Where X represents aquifer minerals (aquifer solid) commonly found in volcanic rocks
(plagioclase, Na-feldspar, clay minerals and to a limited extent calcite from secondary
precipitate)in which the major cations can be derived. The increase in the Na+/Ca2+ ratio in
the flow direction( fig 6a) explain that when dilute water with dominant Ca2+ composition,

such as the Ca(Mg)-HCO3, Ca–Na–HCO3-type waters in highland areas, meets Na-

materials(Na-feldspar), Ca2+ is selectively adsorbed close to the site and Na+ is up taken into
solution(Furi et al., 2011). The process of enhanced fluoride enrichment in groundwater as a
result of Ca2+ removal from solution which revealed that compositional changes in the
groundwater from Ca-HCO3/Ca-Na-HCO3 to Na–Ca–HCO3 and Na–HCO3 types from the
highland towards the rift floor, respectively. This geochemical reaction causes a systematic
removal of Ca2+ from solution and enhances fluoride enrichment in the groundwater along
flow direction towards the rift. This geochemical process involving a change in the hydro
chemical facies in the flow direction can be represented as:
(Ca-Mg-HCO3&Ca-Na-HCO3water) + X1 (Na-HCO3 water) + X2 (2)
Where X1 represents aquifer minerals met in the flow path that release Na+ into solution
such as plagioclase feldspar and are involved in the reaction depending on the saturation
index of minerals, X2 represents altered rock materials that consume Ca2+ from solution such
as calcite, Ca-silicate, and clay.
Figure5. (a-d) Bivariate plot of water variable

5.2. Geochemical processes
5.2.1Geology/lithological variation––Rock type is an ultimate control of water quality as it

determines the minerals available to undergo rock water interaction and release the ions to the
groundwaters.It has strong influence on the concentration and distribution of fluoride which
favorable geological and hydrogeological conditions enhance mobilization of the fluoride in
local groundwater. Genesis of high fluoride waters are correlated with low Ca2+
concentrations and high sodium content due to weathering of sodium-rich alkaline igneous
rocks causes increase a pH resulting in an increase in HCO3- and CO32- by dissolution of
CO2. Groundwater becomes oversaturated compared to calcite and calcite precipitation
occurs, leading to a decrease in Ca2+. This causes a sub-saturation with respect to fluorite
and dissolution of fluorite increases the F- concentration (Coetsiers, Kilonzo, &Walraevens,
2009).A preliminary study of TDS/chemical elements relationships carried out by T. Chernet
(1998) showed that: (1) in most diluted waters (escarpment and plateau waters); calcium
content is increasing, and then decreases regularly. This change could be attributed to calcite
precipitation; (2) the Na enrichment seems to be rather uniform and could correspond to
dilution or concentration of a unique salinity source (silicate hydrolysis); (3) chloride and
sulphate mainly follows an evaporative pattern, but are locally enhanced. This evolution may
reflect a distinct secondary salinity source which involves salt supplies of different origins,
like thermal springs of Kontane marsh.
The high fluoride content in the areas is also related to the dominance of volcano-lacustrine
sediments in the AdamitulujidoKombolcha and Dugdaworeda and the welded tuff in the
Marekoworeda while good quality or low levels of fluoride in ground waters from these areas
may be due to either to the absence of fluoride-bearing magmatic solution or of fluoride
containing minerals in the strata through which ground water is circulating and also be due to
too rapid fresh-water exchange, with the result that the normal process of concentration
through evaporation or evapotranspiration is not very effective in raising the fluoride content
of the ground waters to the values prevalent in some areas of fractured ignimbrite and basalt
units in the highland . The solubility and enrichment of fluoride can be increased by
weathering of the acidic volcanic rocks in extended time but fast circulating groundwater
tends to dilute the water. Sample collected (Twp55at Butajira&Twp74at ziway) showed that
fluoride content range from 0.27 mg/l to 9.49 mg/l respectively. The evolution of
groundwater chemistry in relation to fluoride enrichment is controlled by dissociation,
precipitation and cation-exchange reactions (equation 1). Several authors have indicated that
the occurrence of elevated fluoride is mainly associated with the presence of Na-HCO3 water
type that are common for almost all ground waters in the Rift Valley ( e.gRango et al., 2009).
According to Rango et al. (2009) elevated fluoride concentrations exist in wells that have low
Ca2+ content, which controls the precipitation of fluoride as fluorite. Groundwater

characterized by Na-HCO3water type and low Ca2+ has always very high fluoride content.
The high concentration of Na in the rift waters is likely to be attributed to the dominance of
the acidic volcanic. Fluoride solubility can be increased as result of precipitation at high pH,
which removes Ca2+ from solution allowing more fluorite to dissolve (Chernet et al., 2001).
5.2.2 Dilution Effect
Differences in water quality were noted among the samples collected from surface water,
boreholes. Concentrations of fluoride appeared to decrease slightly with depth due to dilution
effect in the process of surface water and ground waters interaction as highland water
recharge. This is mainly the case when the wells are close to major perennial rivers (e.g.
Woja River)and the infiltration water that lack enough time for the influence of mineral
weathering of the volcanic rocks. Groundwater‟s including springs tend to contain higher
fluoride concentrations than river because groundwater contact with the surrounding rocks
for longer time than surface waters.
A vertical water chemistry variation is noted in borehole constructed recently in Koshe town
water supply test well and Samples taken at various depth of 254, 471, and 591 meters shows
different water chemical composition (from table5.2). The water analysis below revealed that
the sodium and fluoride contents decrease with depth while the calcium concentration
increases suggesting dilution effect that might be attributed to the control of geological
structure in groundwater circulation. Analysis of fluoride concentrations of the samples
indicated that highest fluoride contents were found in Twp25 (9.36mg/l) &Twp74 (9.49mg/l)
surrounding the lake Ziway respectively in shallow ground water. The surrounding villages
are entirely dependent on water from shallow (hand-dug) wells of vary quality. The area is
highly mineralized shallow aquifer with salty build-up due to long resident time, strong rock
water interaction, evaporation enrichment effects related with low elevation and high
temperature at the top soil layer that appears to cause high TDS and fluoride water. The
mineralization is attributed to cyclic evaporation of mineralized water of the wetland on the
flat area. Groundwater quality in shallow aquifer in the Ziway area and some parts of
Western Mareko locations is generally showed that high salinity which indicating that water
quality of these area affected by increasing salinity due to above mention reason& in the soil.

depth of well 254m 471m 591m

TDS 460 430 430
EC(µs/cm) 678 626 628
PH 8.15 7.97 8.14
+
Na (mg/l) 128 104 91
Cl-(mg/l) 0.91 5.46 2.73
Ca2+ (mg/l) 22.4 51.20 53.6
Mg2++(mg/l) 14.4 10.56 7.2
F- (mg/l) 1.88 1.34 1.08
Alkalinity(mg/l) 348 360 352
Nitrate(mg/l) 2.33 12.34 11.21
Bicarbonate(mg/l) 348 439.20 429.44
sulphate.( mg/l) 37.12 8.09 0.11
Table 5.2 Fluoride concentrations with different depth in the same location of Koshe town
test well
5.2.3. Saturation index (mineral equilibrium)
Weathering of Na-feldspars consumes protons and causes a rise in pH due to this pH increase,
the equilibrium with CO2 will no longer be attained, and more HCO3- and CO32- will be
produced while more CO2 will dissolve. The increase in HCO3-and CO32- results in calcite
precipitation, as the solution becomes supersaturated compared to calcite. The precipitation
of calcite causes a drop in Ca2+ which makes the solution sub-saturated compared to fluorite.
Fluorite will dissolve leading to elevated fluoride concentrations in groundwater. The high
fluoride content in groundwater can be positively associated to sodium, alkalinity, TDS, EC
and bicarbonate concentration whereas calcium is negatively correlated with fluoride. The
saturation indices of fluorite and calcite of the collected and analyzed water samples were
calculated using PHREEQC in which the result shows the samples of 93 % is
oversaturated with respect to calcite, whereas, all sample except four have been found to be
under saturated with respect to fluorite. The fluoride concentrations of groundwater are
continuously enriched even after the groundwater reaches an equilibrium state with respect to
fluorite (CaF2) due to removal of Ca2+by precipitation of calcite (CaCO3). The sample Twp37
and MR7 indicate near equilibrium with respect to fluorite. These observations indicate that
the higher concentration of fluoride can be explained by the fact that fluoride ions in
groundwater can be increased as a result of precipitation of CaCO3 from solution allowing
more fluorite to dissolve. In general, the saturation indices are used to express the water
tendency towards precipitation or dissolution. The degree of water saturation with respect to a
mineral is given by:
SI = log (KIAP/ Ksp )
Where: KIAP is the ionic activity product,
Ksp: is the solubility product, and
SI: is the saturation index of the concerned mineral.
When SI is equal to zero then the water is at equilibrium with the mineral phase, whereas SI
values less than zero (negative values) indicate under-saturation and that the mineral phase
tends to dissolve, while SI values over zero (positive values) indicate super saturation and
that the mineral phases tends to precipitate. The most SI of Calcite groups oscillates around
zero, suggesting conditions close to equilibrium for this mineral phase and calcite
precipitation is unlikely, and cannot be considered the major cause of calcium depletion. This
means that the observed hydrochemical evolution of groundwater from the highlands to the
rift cannot be related to significant calcite precipitation. This in turn implies that cation
exchange is the most probable process which leads to increase of F concentration in the local
groundwater.

Figure5.2. Fluorite vs. calcite saturation

CHAPTER FIVE
Conclusion
Integrated hydro chemical and isotope techniques were applied to understand the
genesis/source of fluoride, vertical and lateral distribution of fluoride, relationship of fluoride
with lithological unit, groundwater flow system and interaction of lake with surrounding
wells in the Meki River catchment. Interpretations of the graphical analysis coupled with that
of chemical analysis results of the hydrochemical data and results from analysis of the
isotopes data in the area are critically showed the high salinity and groundwater flow system.
 The majority of the highlands and escarpments waters have low TDS, EC and F of
Ca-HCO3 waters type. This shows that there is shallow groundwater circulation /at
their early stage of geochemical evolution from direct recharge of precipitation and
these waters have undergone no marked rock-water interactions.
 The increasing of salinity, total dissolved solid and change of geochemical evolution
to Na-HCO3 facies towards the lake Ziway indicate a long duration of rock-water
interaction, and high evaporation
 The high spatial variations of major cations and anions follow systematic trend along
the transect from W to E. This reflects that when ground water of highland and
escarpment progressively migrating downhill reacts with different interacting
lithology increase dissolved components and changes the hydro chemical evolution of
waters towards rift floor.
 The high fluoride content in relation to the geological unit associated within the
volcano lacustrine sediment and weathered welded tuff of rift floor easily interact
with ground water and reduce its flow rate while the weathered & fractured basalt and
ignimbrite of the highland and escarpment areas are good water quality due to dilution
effect
 Genesis of high fluoride waters are related with low Ca2+ concentrations, shallow
depth and high PH, alkalinity, salinity and high Na+ content ,mineral saturation,
calcite precipitation and Na-HCO3 water type.
 Groundwater becomes oversaturated with respect to calcite and calcite precipitation
occurs, leading to a decrease in Ca2+. This causes a sub-saturation with respect to
fluorite and dissolution of fluorite (CaF2) increases the F- concentration

 The lateral distribution of fluoride in the rift floor and Tora-Koshe-Dugda ridge shows
high F concentration along transect following flow path beyond the WHO standard
(1.5mg/l) and decrease with depth due to dilution effect and
 Shallow ground water (hand-dug well) near to Lake Ziway shows high concentration
of fluoride due to the leaching of weathered and redeposit volcanic rock, soil and
intimate association(interaction) of lake with surrounding ground water.
 The majority of groundwater (hand-dug well, borehole) and rain waters are plotted
near the LMWL.This indicates the importance of present-day precipitation for
groundwater recharge.
 The variation of isotopic concentrations between groundwater of Highland and Rift
water reflects the altitude and evaporation effect in the groundwater flow systems.
 The stable isotopes signature of the deep groundwater of Butajira and Koshe areas
showed highly depleted than aquifers found near to Lake Ziway. This indicates that
the aquifer recharges through long subsurface flow from the adjacent highland
recharged by rainfall and provides an evidence for deep penetration of recently
recharged groundwater into the wide fault zone, indicating that the hydrologic
condition of the fault is also an important factor controlling the occurrence of high F
groundwater
 The high fluoride shallow ground water (i.e. hand-dug well) surrounding lake Ziway
are enriched withδ2H and δ18O stable isotopes due to the extensive evaporative
fractionation and recharged from the lake ziway rather than meteoric water directly
infiltrate from highlands.
 The reacting of water with volcano lacustrine sediment for a long period could
increase the concentrations of F in groundwater even after the groundwater reaches an
equilibrium state with respect to fluorite (CaF2) due to the removal of Ca by
precipitation of calcite (CaCO3). These observations reflect that rock chemistry, well
depth, and geologic structure are the important factors controlling the occurrence of
high F groundwater. However, high F ground waters are rarely observed in the fault
zones of SDZFZ where the associated fractures are widely developed.
 From the groundwater contour map, hydrochemistry and isotope result, shows that
groundwater flows from highland towards Lake Ziway.

Recommendation
 Observation pipes should be installed in the existing and newly constructed boreholes
especially for the wells that could be significant for scientific purpose
 Detailed work on rock-water interaction from hydrochemical, isotope and rock
mineralogy
 It is strongly recommended to drill deep wells than shallow wells in the studied area
especially near to lake Ziway for public water consumption to minimize fluoride
concentration

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Appendix1: Over all physiochemical analysis result of water sample in Ziway-Koshe-Butajira areas
Sampl Longitu Latitud TDS EC Te PH Na K+ T. Ca2+ Mg2 Alk. HC Cl- NO F- Data

+ + 2
e ID. de e m H CO3 O3- SO 3
-
source
- 2-
4
Twp25 468906 883340 2090 3480 26 8.4 91 61 24 6.4 1.9 2002 134 2170 62.3 19. 0.9 9.3 this study
3 0 2 2 9 7 6
Twp26 468990 882659 1075 1791 29. 7.8 31 45 10 24 10. 832 0 1015 74.6 19. 0.8 3.1 this study
1 8 2 4 6 1 2 4
Twp36 467541 868129 690 1149 27. 8.2 25 27 50 12 4.8 525 74.9 488. 26.4 21. 5.6 0.7 this study
8 5 0 5 4 4 4
Twp37 467853 869448 1298 2150 28. 8.1 51 29 72 16 7.6 988 112 977 68.9 10 4.5 7.7 this study
4 5 0 8 3 1 6
Twp39 470120 875770 284 474 19. 8.3 79 29 92 32 2.8 239 0 291. 17 0 2.9 5.9 MoWIE
5 4 8 8 1 7
Twp41 447457 886437 421 702 18 8.1 19 20 56 14.4 4.8 442 0 539. 5.67 2.3 4.8 2.7 this study
7 5 2 4 6 6
Twp42 446999 886226 477 792 20. 7.9 11 29 16 44.8 12. 429 24.9 472. 17 5.4 3.1 4.3 this study
6 8 9 4 5 6 9 5 6
Twp51 443757 889463 725 1205 24 7.0 86 31 22 82.4 4.8 403 0 491. 34.9 27. 15. 0.9 this study
6 6 7 4 9 69
Twp52 441756 890635 521 872 23. 7.5 25 40 26 68.8 22. 515 0 628. 63.2 34. 26. 2.4 this study
7 3 5 4 1 1 7 5 21 1
TWP5 431997 897751 371 612 20. 6.6 32 29 23 80 9.1 247 0 301. 26.4 15. 44. 0.2 this study
5 1 4 8 2 3 4 3 73 7
Twp58 427005 896812 315 526 25. 6.8 36 22 17 56 8.6 283 0 345. 6.61 2.1 2.6 0.7 this study
/bh2 8 5 6 4 8 8 9 6
Twp59 480377 900723 237 394 17. 8.7 56 23 12 32 11. 234 0 285. 14.1 28. 2.0 1.5 this study
9 5 8 5 5 6 3 4 4

Twp60 476526 897409 1067 1779 26. 8.1 79 30 48 10.4 5.2 1134 131 1117 21.7 3.1 0.5 2.5 this study
6 9 0 8 2 6 6 7
TWp6 477550 895728 300 500 21. 7.9 80 27 12 35.2 7.6 252 25.2 256. 17 16. 2.0 9.5 this study
3 7 0 8 2 6 2 2
Twp67 477354 904197 447 740 26. 7.6 19 16 10 20.8 11. 341 0 415. 17.9 10. 1.2 0.7 this study
5 7 7.5 0 5 5 4 6 1 4
Twp69 478094 902659 317 527 22. 7.5 83 18 12 35.2 8.6 291 0 355. 7.55 8.4 0.5 1.6 this study
2 6 4 4 3 2 5
Twp70 480380 900736 394 657 24. 7.9 10 18 70 20.8 4.3 333 0 406 15.1 11. 1.1 1.8 this study
5 7 5 2 1 6 7
Twp71 466207 903427 557 930 28. 8.1 27 33 80 16 9.6 325 37.4 320. 22.6 92. 0.6 1.1 this study
2 5 0 4 6 4 3 3
Twp74 468204 873525 1539 2560 24 7.8 75 11 10 22.4 10. 746 0 909. 85.9 16 90. 9.4 this study
8 0 0 0 6 5 3 0 4 9
TwS1 435852 869258 616 860 24. 7.5 14 26 16 53.4 8.6 483 0 589. 25.2 13. 8.5 3.1 this study
9 9 8 9 4 3 7 6
TwS3 427645 877058 296 450 22 8.2 58 8. 12 32.0 11. 227 14.4 247. 17.5 11. 18. 2.2 this study
7 8 9 2 9 4 1 25
TwSs1 448882 920224 240 370 20 7.6 39. 10 97. 32 4.3 197 0 240. 2.9 1.3 10. 1.6 this study
9 5 8 2 8 2 7
TwM2 445207 888966 432 642 23 7.3 31 15 28 96.1 10. 321 0 392 5.8 0.5 13. 0.8 this study
7 4 4 2 8 3 5
TwM2 450174 886198 399 799 21 8.3 25 14 47 13.1 3.6 680 0 680 36.2 2.8 0.4 1.5 this study
8 6 8.4 9 8 7 2 5
TwM2 448380 884901 494 790 22. 7.8 13 15 79. 21.4 6.4 411 502 8.7 40. 7 3.1 this study
6 1 4 9 9 8 2 6
TwD1 477198 901824 972 1120 23. 7.8 30 16 73. 17.8 7.0 315 0 384. 2.9 1.5 7 3.7 this study
8 0 3 2 3 8
TwD2 469448 901986 360 420 25 8.0 94 10 95. 28.5 5.9 315 0 384. 2.9 1.5 7 3.3 this study
1 5 3 8

TwA6 487538 901528 858 1030 28. 8.1 30 19 44. 15.1 1.6 666 4.8 802. 25 55. 7.5 3.7 this study
7 0 4 3 2 4 4
TwA7 465779 881853 1632 1920 29. 8.6 60 20 20 4.4 2.2 1136 0 1269 131. 13 7.5 3.9 this study
3 7 0 9 8 6
BH4 440020 888300 261 21. 7.3 10 4. 52 18.8 1.2 254 52 202 1.2 7 0.2 1.3 MOWIE(
7 6 7.5 3 8 DH 2015)
BH6 448646 885794 528 22 7.6 20 31 28 8.4 1.6 450 37 413 7.8 7 0.3 5 MOWIE(
6 2.2 8 DH 2015)
BH1 426868 899213 248 381 30. 7.5 78 8 18. 8.04 1.5 186 0 226. 10.4 0.4 1.0 1.3 WWDSE
7 6 9 1 9 1 8 5 3 2015
BH5 446946 888984 400 629 31. 7.5 92 11 12 42.4 3.3 332 0 405 3.64 8.2 9.5 1.7 WWDSE
5 5 0 6 6 9 2015
Mk3 439583 903579 386 644 7.4 64 4. 24 64 19. 400 0 488 9.5 8 3.5 2.5 MoWIE
3 2 0 4 2 2008
Mk4 442225 904758 322 534 7.1 54. 0 19 28 29. 260 0 305 7.5 0 44. 0.5 MoWIE
9 05 0 2 5 2008
Mk8 427667 898301 810 1350 7.1 10 7. 61 108 82. 680 36 756. 52.5 11 15. 1.5 MoWIE
1 8 2 0 6 4 0 4 5 2008
Mk10 426169 897100 295 588 6.7 72 7. 87 32 192 190 0 231. 25.5 2.7 7.9 0.3 MoWIE
5 0 8 2 4 2008
Mk11 44 899505 225 375 7.9 90 1. 18 44 18. 310 0 378. 11 1.4 70 0.3 MoWIE
12 30 8 8 6 5 2 9 2008
MR1 455901 885579 511 850 8.9 30 14 1.7 0.11 0.3 425 0 385 31.9 25. Tra 7.1 MOWIE(
5.6 .2 7 6 3 ce 5 DH 2015)
MR2 452621 880199 490 816 8.1 28 18 83. 27.6 3.4 415 0 415 38.3 30. Tra 4.7 MOWIE(
3 9 .5 2 2 5 4 ce 8 DH 2015)
MR3 444019 883804 495 824 7.7 25 19 10 26.8 8.9 420 0 420 21.3 20. Tra 2.8 MOWIE(
8 1.8 .1 3.8 6 1 3 ce 6 DH 2015)
MR4 447088 886429 470 771 7.6 21 20 15 37.4 14. 410 0 410 31.9 26. Tra 2.5 MOWIE(
5 4.8 .4 3.3 54 4 ce 9 DH 2015)

MR5 442808 883470 459 774 7.5 26 34 15 51.5 7.2 470 0 470 23.4 11. Tra 2.8 MOWIE(
9 5.1 .6 8.8 8 7 5 ce 2 DH 2015)
MR6 442855 887029 402 670 7.7 15 14 99. 20.2 11. 290 0 290 34 82. Tra 0.4 MOWIE(
9 9.2 .4 6 1 92 9 ce 1 DH 2015)
MR7 441906 887872 633 1053 7.5 16 16 39 115. 25. 430 0 430 93.6 10 Tra 2.7 MOWIE(
1 6.2 .2 1.1 1 17 6.4 ce 9 DH 2015)
MR12 450174 886198 399 799 8.3 25 13 18 13.1 3.6 680 0 680 36.2 2.8 0.4 1.5 MOWIE(
6 8.4 .7 1.9 8 7 2 5 DH 2015)
MR13 446690 888662 439 876 7.8 13 12 47. 30.9 9.5 370 0 370 36.2 4.5 3.4 1.4 MOWIE(
8 1.6 .2 9 2 5 8 DH 2015)
MR35 446444 888773 375 626 7.2 10 1. 11 100 21. 420 0 512. 7.5 0.5 26. 0.7 MOWIE(
2 0 6 6 9 4 4 6 DH 2015)
MR39 439588 889537 418 702 7.2 84 5. 41 84 48. 440 48 439. 12.5 0.8 15 0.5 MOWIE(
3 5 0 6 2 1 DH 2015)
MR41 440368 888672 230 459 7.3 32 1. 19 32 26. 196 0 239. 2.5 1.6 10. 1.3 MOWIE(
5 0 7 1 56 5 DH 2015)
MR42 439432 888813 276 550 7 71. 3 26 71.2 19. 370 0 451. 2.5 2.3 5.2 1.6 MOWIE(
2 0 9 4 8 8 DH 2015)
MR44 447688 886575 248 496 6.9 48 4. 21 48 21. 225 0 274. 4 1.4 34. 1.8 MOWIE(
1 0 9 5 76 9 DH 2015)
MR46 445831 891099 288 575 7.1 18 22 85 184 96. 940 0 1147 1161 23 11 1.8 MOWIE(
4 6 2 65 3 DH 2015)
MR47 441252 888594 909 1512 6.8 22 3. 89 224 80. 616 0 751. 105 40. 129 0.5 MOWIE(
8 4 6 2 7 5 7 .8 5 DH 2015)
MR48 444549 891289 711 1184 7.4 44 6. 25 44 34 778 26.4 895. 30 3.8 12. 0.2 MOWIE(
6 2 0 5 32 7 DH 2015)
MR50 439080 888655 200 399 7 32 3. 18 32 24. 216 0 263. 2.5 1.9 3.9 0.2 MOWIE(
8 0 3 5 6 4 DH 2015)
MR53 440738 887646 386 769 6.8 12 5. 52 120 53. 530 0 646. 8.5 18 10. 1 MOWIE(
0 1 0 5 6 56 DH 2015)

MR54 442592 888612 1160 2320 8.5 3.2 6. 30 3.2 5.4 830 0 944. 16 58 15. 4.5 MOWIE(
8 3 1 4 5 DH 2015)
MR61 439437 889185 468 802 8.4 88. 1 26 93.6 6.3 400 0 488 0.5 0 54. 3.3 MOWIE(
6 6 0 21 75 DH 2015)
MR64 450125 894490 367 612 7.8 72. 0 18 56 9.7 300 366 4 10. 11. 5.3 MOWIE(
1 1 0 2 6 6 5 DH 2015)
MR67 448119 894803 481 800 7.5 47. 0 22 64 14. 296 4.2 353 1 0.7 25 2.2 MOWIE(
6 9 0 6 5 DH 2015)
SBH2 446742 872640 676 900 8.7 21 11 4.45 1.6 374 26.4 402. 60.1 55. 12. 3.1 MOWIE(
8 0 3 4 5 6 DH 2015)
Ss2 457559 908463 144 330 8.0 20. 7. 20.5 3.2 113 0 138. 1 1.0 7.5 1.6 MOWIE(
2 5 1 3 5 8 DH 2015)
Ss3 446896 904607 366 709 7.2 68 12 48.1 6.5 315 0 384. 9.7 1.8 7.5 2.5 MOWIE(
9 3 5 8 DH 2015)
SBH4 431044 871595 664 810 7.2
11 44 97.9 8.6 546 0 666 17.5 8.4 10. 2.4 MOWIE(
3 1 4 4 7 8 DH 2015)
Ss4 448587 899749 393 656 7.2
70. 0. 48 24. 340 0 414. 0.5 1.8 31 2.1 MOWIE(
63 1 3 8 7 DH 2015)
Ss6 451897 900673 270 448 7.3 60. 0. 40 9.7 240 0 292. 2.5 0.3 27. 1.9 MOWIE(
5 32 1 2 8 1 75 DH 2015)
Ss7 447478 904432 400 664 7.3 11 0 40 9.7 345 420. 5 1 29 1.8 MOWIE(
6 0.2 2 9 2 DH 2015)
Ss8 446006 904388 410 680 7.1 83. 0 65.6 7.7 340 0 414. 6.5 1.8 31 1.3 MOWIE(
8 23 8 8 5 DH 2015)
Ss9 448997 931321 292 487 7.3 67. 0 44 10. 250 0 305 2.5 2.2 50. 0.8 MOWIE(
3 46 2 3 8 DH 2015)
Note:TDS-total dissolved solid,EC-electrical conductivity,T.H-total hardness,Alk-alkalnity

Appendix 2: isotope chemical analysis result of water for the study area
Sample Longitude€ latitude(N) Elevation δ18O, δ2H, in TDS EC(µs/ Temp pH D=δ2H- sample data source
ID in ‰ ‰ cm) rature 8*δ18O type
TWP 1 469796 886237 1654 5.9 41.63 888 1469 27.9 8.44 -5.57 BH this study
TWP 2 469723 886014 1654 4.23 31.92 789 1310 27 8.64 -1.92 HD this study
TWP 6 469458 883754 1640 4.66 34.8 1153 1933 23.5 7.79 -2.48 HD this study
TWP 21 469643 885338 1654 4.38 30.79 1186 1985 25.4 7.77 -4.25 HD this study
TWP 24 469514 884237 1651 4.92 34.15 1265 2100 22.8 7.99 -5.21 HD this study
TWP 25 468906 883340 1651 5.22 35.12 2090 3480 26 8.43 -6.64 HD this study
TWP 26 468990 882659 1650 5.35 33.47 1075 1791 29.1 7.88 -9.33 BH this study
TWP 36 467541 868129 1652 4.31 27.8 690 1149 27.8 8.25 -6.68 BH this study
TWP 37 467853 869448 1647 3.15 26.04 1298 2150 28.4 8.15 0.84 BH this study
TWP 39 470120 875770 1634 5.19 32.3 284 474 19.5 8.34 -9.22 Lake this study
TWP 41 447457 886437 1817 -6.08 -33.4 421 702 18 8.17 15.24 BH this study
TWP 42 446999 886226 1817 -2.97 -4.42 477 792 20.6 7.98 19.34 BH this study
TWP 44 445875 885396 1819 -2.94 -10.75 536 893 24.3 7.43 12.77 BH this study
TWP 48 444632 888897 1833 -4.09 -11.98 553 926 24.8 7.24 20.74 HD this study
TWP 51 443757 889463 1829 -3.6 -8.76 725 1205 24 7.06 20.04 HD this study
TWP 52 441756 890635 1843 -3.44 -7.46 521 872 23.7 7.53 20.06 BH this study
TWP 54 432668 897231 2058 -2.14 -6.86 237 396 20 6.93 10.26 BH this study
TWP 55 431997 897751 2048 -2.98 0.01 371 612 20.1 6.64 23.85 BH this study
TWP 56 430742 898825 2070 -3 -5.12 220 366 21.8 6.93 18.88 BH this study
TWP 57 427153 897065 2121 -3.6 -7.18 283 472 25.8 6.93 21.62 BH this study
TWP 58 427005 896812 2123 -2.99 -6.94 315 526 25 6.85 16.98 BH this study
TWP 59 480377 900723 1659 1.22 9.6 237 394 17.9 8.75 -0.16 R this study
TWP 60 476526 897409 1651 4.43 37.49 1067 1779 26.6 8.19 2.05 BH this study
TWP 63 477550 895728 1634 4.18 38.44 300 500 21.7 7.9 5 Lake this study
TWP 64 475911 895965 1647 3.91 35.04 1711 2860 23.4 8.83 3.76 BH this study
TWP 65 478196 904468 1649 -3.52 -13.01 322 536 21 7.87 15.15 BH this study
TWP 67 477354 904197 1683 -2.26 -10.9 447 740 26.5 7.67 7.18 HD this study
TWP 69 478094 902659 1677 -2.01 -7.23 317 527 22.2 7.56 8.85 BH this study
TWP 70 480380 900736 1662 -2.57 -13.41 394 657 7.97 7.15 BH this study
TWP 71 466207 903427 1759 -5.1 -32.31 557 930 8.15 8.49 BH this study
R30 477528.98 903418 1760 1.67 6.14 583 -7.22 R Rango 2009
Hs2 484327 8771589 1890 -3.03 -15.65 1728 8.59 HS Rango 2009
LW 29 430213 907159 1632 4.88 33.82 379 -5.22 Lake Rango 2009
RV-3 451466 897888 0.7 7.5 480 8 1.9 R winter 1973
wl-12 479438 899958 -1.95 -3.93 11.67 BH Tenalem1996
wl-13 467892 869314 1643 4.45 32.38 -3.22 BH Tenalem1996
wl-2 467797 878153 161 5.04 36.2 900 24 7.6 -4.12 BH Craig etal 77
wl-3 479815 900819 -2.73 -8.1 1100 45 7.8 13.74 BH Craig etal 77
wl-4 456844 884690 -3.53 -15 690 35 7.6 13.24 BH Craig etal 77
CS-1 424762 885865 -2.44 -3.7 208 15.82 CS Craig etal 77
CS-2 425733 898162 -2.55 -3.1 390 17.3 CS Craig etal 77
CS-5 839648 913371 -2.21 -4.05 13.63 CS Tenalem1996
RN-3 431210 898294 0.49 8.05 4.13 RN Tenalem1996
RN-4 468775 877076 -0.7 12.85 18.45 RN Tenalem1996
HD =hand dug well,L= lake water,BH= bore hole,R= river,Cs=cold spring,HS=hot spring,RN=rain water

Appendix3: groundwater inventory measured in the field &received/collected from MoWIE
Region Zone Woreda Kebele UTM E UTM N Elevation, Depth SWL Altitude Scheme
AMSL (m) (m) of SWL ID
mamsl
SNNPR Guragae Sodo Tiya Town 456837 932873 2318 136 114 2204 BH
SNNPR Guragae Sodo Kela 444918 911937 1886 50 1.86 1884.14 BH
SNNPR Guragae Sodo Dugda Goro 460865 901754 1925 301 185 1740 BH
SNNPR Guragae Sodo Refenso 457559 908463 1891 200 170 1721 BH
SNNPR Guragae Meskan Inseno 441974 890758 1832 63 15.2 1816.8 BH
SNNPR Guragae Meskan Inseno Ousme 440025 890823 1833 66 8.7 1824.3 BH
SNNPR Guragae Meskan Shershera Mechmena 439461 904709 1914 75 33.9 1880.1 BH
SNNPR Guragae Meskan Dirama Shershera 436158 901900 2008 128.55 43.9 1964.1 BH
SNNPR Silte Silty Kibet town 426285 887327 2095 118 50 2045 BH
SNNPR Silte Silty Kibet town 426927 887719 2094 174 50 2044 BH
SNNPR Silte Silty Alkeso 415084 877224 2301 183 162 2139 BH
SNNPR Silte Silty Yekertef Gibato 424695 875670 2054 256 180 1874 BH
SNNPR Silte Silty Woger Ourdubo 427800 871600 1920 202 160 1760 BH
SNNPR Silte Silty Dobo Sabola 436818 892494 1845 65 8.25 1836.75 BH
SNNPR Silte Silty Debub Goto 435517 877276 1860 95 35 1825 BH
SNNPR Silte Silty Udasa 442073 875289 2016 370 300 1716 BH
SNNPR Guragae Mareko Argo Wolilati 454319 891741 1928 267 182 1746 BH
SNNPR Guragae Mareko Ilala Gebiba 455912 885586 1786 216 172 1614 BH
SNNPR Guragae Mareko Ilala Jirano 453015 883724 1809 267 167 1642 BH
SNNPR Guragae Mareko Semen Koshe 450074 886127 1884 210 158 1726 BH
SNNPR Guragae Mareko Koshe 01 448478 885096 1884 220 180 1704 BH
SNNPR Guragae Mareko Koshe Zuria 447700 886562 1834 56 18 1816 BH
SNNPR Guragae Mareko Bidara Faka 452613 880214 1811 218 160 1651 BH

SNNPR Guragae Mareko Shirinto 447720 875620 1894 300 260 1634 BH
SNNPR Guragae Mareko Udasa Washe Faka 447740 875650 1878 267 151.55 1726.45 BH
SNNPR Guragae Mareko Dida Halibo 447247 889418 1830 106 20 1810 BH
Oromiya East Adame Abosa 01 469886 886446 1654 80.7 31 1623 BH
shewa Tulu
Oromiya East Dugda Weyo 472425 890622 1556 90 8 1548 BH
shewa
Oromiya East Dugda Burka Dalocha 492763 900233 1674 73 33.4 1640.6 BH
shewa
Oromiya East Ziway Meja Natile 496211 897486 1676 64 30 1646 BH
shewa Dugda
SNNPR Guragae Sodo Suluke 458882 911780 1934 295 270 1664 BH
Oromiya East Adame Abine Germama 464718 883354 1676 60 1616 BH(Solar)
shewa Tulu
SNNPR Guragae Meskan Butajira Town 432756 897440 2058 154 54.7 2003.3 BH
Oromiya East Adame Adame Tulu 467644 868349 1658 80.5 31 1627 BH
shewa Tulu
Oromiya East Dugda Meki Town 480497 900763 1662 84 49 1613 BH
shewa Bora
SNNPR Guragae Meskan Butajira Town 432084 897957 2056 65 13.4 2042.6 BH
Oromiya East Adame Adame Tulu 467945 869660 1654 66.4 30.47 1623.53 BH
shewa Tulu
Oromiya East Adame Ziway Town 468735 875680 1647 22.15 1624.85 BH
shewa Tulu
Oromiya East Dugda Meki Town 480694 901824 1661 82.5 29 1632 BH
shewa
SNNPR Guragae Meskan Butajira Town 430941 896250 2070 86 22 2048 BTW
Oromiya East Adame Asebo Genet 456338 873026 1710 127 93 1617 BH
shewa Tulu
Oromiya East Adame Galo Repi 462137 883385 1707 108 81 1626 BH

shewa Tulu
Oromiya East Dugda Sera Wekele 477313 906916 1721 92 81 1640 BH
shewa
Oromiya East Dugda Cheleleke 2 (Germeji) 469824 896035 1705 110 79 1626 BH
shewa
Oromiya East Dugda Choroke 471570 898358 1722 93 78 1644 BH
shewa
Oromiya East Dugda Laluna Dero 469448 901986 1721 100 85 1636 BH
shewa
Oromiya East Dugda Ate Meti 472425 902009 1709 80 65 1644 BH
shewa
Oromiya East Dugda Wolda Kocha 481416 909593 1712 105 84 1628 BH
shewa
Oromiya East Adame Haleku Gulenta 465363 869206 1658 82 58 1600 BH
shewa Tulu
Oromiya East Adami Abosa 469796 886237 1654 60 32 1622 BH
shewa tulu
Oromiya Guragae meskan Butajiratown/netsa 432668 897231 2058 150 80 1978 BH
sefer
Oromiya Guragae meskan Butajiratown/police 431997 897751 2048 60 49 1999 BH
station
Oromiya Guragae meskan Butajiratown/hospital 430742 898825 2070 260 59 2011 BH
Oromiya Guragae meskan Butajiratown/mamuja02 427153 897065 2121 213 72.25 2048.75 BH
Oromiya Guragae meskan Butajiratown/mamuja01 427005 896812 2123 220 77 2046 BH
Oromiya East Dugda graba korkadi 476208 897663 1658 35 30 1628 BH
shewa
Oromiya East Dugda graba korkadi 476287 897406 1656 30 28.5 1627.5 BH
shewa
Oromiya East Dugda sera wakelo 478196 904468 1649 135 59.3 1589.7 BH
shewa

shewa
shewa
Oromiya East Dugda meki town/01 480380 900736 1662 182.5 29 1633 BH
shewa
Oromiya Guragae meskan Butajiratown/netsa 432668 897231 2058 150 80 1978 BH
sefer
Oromiya Guragae meskan Butajiratown/police 431997 897751 2048 60 49 1999 BH
station
Oromiya Guragae meskan Butajiratown/hospital 430742 898825 2070 262 59 2011 BH3
Oromiya Guragae meskan Butajiratown/mamuja02 427153 897065 2121 213 72.25 2048.75 BH
Oromiya Guragae meskan Butajiratown/mamuja01 427005 896812 2123 220 77 2046 BH2
Oromiya East Dugda graba korkadi 476208 897663 1658 35 30 1628 BH
shewa
Oromiya East Dugda graba korkadi 476287 897406 1656 30 28.5 1627.5 BH
shewa
shewa
shewa
shewa
Oromiya East Dugda meki town/01 480380 900736 1662 182.5 29 1633 BH
shewa
SNNP Gurage Mareko Gebiba Borehole 455901 885579 1780 192 172 1608 BH
SNNP Gurage Mareko Semen Koshe 450174 886198 1881 222 173.8 1707.2 BH
SNNP Gurage Mareko JICA Test well5 446999 886227 1798 64 9.6 1788.4 BH
SNNP Gurage Mareko Gaye Faro 453015 883724 1809 230 131 1678 BH
SNNP Gurage Mareko Inseno 440020 888300 1854 168 11.44 1842.56 BH

SNNP Gurage Mareko Koshe Test well5 448646 885794 1864 244 132 1732 BH6
SNNP Gurage Mareko Adas Rapa 447720 875620 1894 312 208 1686 BH
SNNP Gurage Mareko Dida Halebo 446946 888984 1855 591 17.46 1837.54 BH5
SNNP Gurage Mareko Koshe 01 440020 888300 1854 163 11.15 1842.85 BH
SNNP Gurage Mareko Koshe Zuria 448646 885794 1864 244 18 1846 BH
SNNP Gurage Mareko Udasa Washe Faka 447700 886562 1834 56 15.55 1818.45 BH
SNNP Gurage Mareko Dida Halibo 440550 883900 1840 230 20 1820 BH
SNNP Gurage Meskan maricho 426868 899213 2147 600 62.5 2084.5 BH1
SNNP Gurage Meskan inseno 440020 888300 1854 168 11.4 1842.6 BH4
Oromiya East Adami ziwy prizon 467227 878173 1655 50 34 1621 BH7
shewa tulu
Appendix 3.1 Shallow and handdug well inventory data
Region Zone Woreda Kebele UTM E UTM N Elevation, Depth SWL Altitude Scheme
AMSL (m) (m) of SWL ID
mamsl
SNNPR Guragae Sodo Gere 449101 931543 2573 85 53 2520 SW
SNNPR Guragae Sodo Amawte Gufutige 449315 931983 2565 61 25 2540 SW
SNNPR Guragae Sodo Semero Michaele 459571 927132 2156 85 58 2098 SW
SNNPR Guragae Sodo Negesa 448077 914575 1950 70 50 1900 SW
SNNPR Guragae Sodo Delelesa 443290 912291 1917 46 16 1901 SW
SNNPR Guragae Sodo Gose Salen 447042 906854 1873 54 18 1855 SW
SNNPR Guragae Meskan Mekicho 429210 898363 2093 32 3 2090 SW
SNNPR Guragae Meskan Mekicho 428066 898717 2107 50 3.65 2103.35 SW
SNNPR Guragae Meskan Inseno 441913 891311 1837 17 14.5 1822.5 SW
SNNPR Guragae Meskan Inseno 441811 891169 1832 17 14.5 1817.5 SW
SNNPR Guragae Meskan Jole 440195 905619 1901 60 15 1886 SW
SNNPR Silte Silty Ashute Burako 431626 885597 1825 17 3 1822 SW

SNNPR Silte Silty Ashute Burako 432220 885690 1823 18 3 1820 SW

SNNPR Silte Silty Shele Washo 437435 888235 1825 4.2 1820.8 SW
SNNPR Silte Silty Shele Washo 437645 890366 1837 30 4 1833 SW
SNNPR Guragae Meskan Ile 439118 899060 1890 30 22.93 1867.07 HDW
SNNPR Guragae Meskan Inseno 442017 891450 1840 17 15 1825 HDW
SNNPR Guragae Meskan Bati Lejano 441186 894429 1846 10 8.6 1837.4 HDW
SNNPR Guragae Meskan Mirab Meskan 426836 895151 2128 12 9.7 2118.3 HDW
SNNPR Silte Silty Danecho Mukere 420549 880486 2345 12 6.2 2338.8 HDW
SNNPR Guragae Silty Dobo Sabola 436810 889806 1831 6 1.35 1829.65 HDW
SNNPR Guragae Mareko Mekak Jare Dembeka 443812 884830 1844 31 27.6 1816.4 HDW
SNNPR Guragae Mareko Gola Jare Dembeka 442910 883379 1855 45 42 1813 HDW
SNNPR Guragae Mareko Gola Jare Dembeka 441641 884059 1848 40 38.3 1809.7 HDW
SNNPR Guragae Mareko Dida Midore 445207 888966 1837 25 19.1 1817.9 HDW
Oromiya East shewa Adame Tulu Adame Tulu pesticide 467495 870454 1644 30 28 1616 HDW
Oromiya East shewa Adame Tulu Gerbi Widena 465326 871755 1653 45 44.7 1608.3 HDW
Boremo
Oromiya East shewa Adame Tulu Gerbi Widena 467869 872202 1647 26 24.2 1622.8 HDW
Boremo
Oromiya East shewa Adame Tulu Abine Germama 465355 881409 1669 45 39.58 1629.42 HDW
Oromiya East shewa Adame Tulu Welinbula 469350 888450 1677 40 36.78 1640.22 HDW
Oromiya East shewa Adame Tulu Elka Chelemo 468819 885619 1661 36 33.9 1627.1 HDW
Oromiya East shewa Adame Tulu Elka Chelemo 469687 885034 1655 20.5 19.6 1635.4 HDW
Oromiya East shewa Adame Tulu Elka Chelemo 469520 883590 1653 15 14.36 1638.64 HDW
Oromiya East shewa Dugda Giraba Korke Adi 477158 900110 1665 35 33.35 1631.65 HDW
Oromiya East shewa Dugda Bekele & Girisa 479270 898325 1647 17 14.5 1632.5 HDW
Oromiya East shewa Dugda Oda Bokata 483933 904334 1670 35 33 1637 HDW

Oromiya East shewa Dugda Burka Dalocha 492403 900545 1674 35 33.4 1640.6 HDW
SNNPR Guragae Sodo Amawte Morege 449205 935753 2784 15 0 2784 HDWP
SNNPR Guragae Sodo Atene Endebuyo 439531 918800 2743 10 0 2743 HDWP
SNNPR Guragae Meskan Misrak Embor 429313 897129 2117 40 25 2092 HDWP
SNNPR Guragae Meskan Bidara 422929 895181 2244 16 13.2 2230.8 HDWP
SNNPR Guragae Meskan Mirab Meskan 424292 894735 2186 27.2 15 2171 HDWP
SNNPR Guragae Meskan Odo 424247 893157 2169 22 8.5 2160.5 HDWP
SNNPR Guragae Meskan Odo 424926 892693 2150 22 10 2140 HDWP
SNNPR Silte Silty Agode 427712 888971 2091 16 10 2081 HDWP
SNNPR Guragae Mareko Hobe Jare Dembeka 440456 888867 1840 30 15 1825 HDWP
SNNPR Guragae Mareko Kuno Kertefa 438218 887357 1824 6.5 4.6 1819.4 HDWP
SNNPR Silte Lamfuro Washa Shanka 431708 870363 1823 24 10 1813 HDWP
SNNPR Silte Lamfuro Lamfuro Gebaba 434772 874449 1857 40 32.9 1824.1 HDWP
SNNPR Silte Lamfuro Lamfuro Gebaba 433909 874956 1842 16 13 1829 HDWP
SNNPR Silte Lamfuro Lamfuro Gebaba 433720 875735 1844 30 27 1817 HDWP
Oromiya East shewa Adame Tulu Welinbula 468848 889123 1684 40 35 1649 Windmill
Oromiya East shewa Adame Tulu Negalegn 468604 886521 1669 40 30 1639 Windmill
Oromiya East shewa Adame Tulu Abosa 01 469440 886823 1671 51 31.5 1639.5 Windmill
Oromiya East shewa Adame Tulu Elka Chelemo 468446 885274 1663 45 35 1628 Windmill
Oromiya East shewa Adame Tulu Edo Kontola 469069 882869 1654 37 18 1636 Windmill
Oromiya East shewa Adame Tulu Abine Germama 468333 879382 1655 25 22 1633 Windmill
Oromiya East shewa Adame Tulu Gush Gula 465797 875905 1661 60 45 1616 Windmill
Oromiya East shewa Adame Tulu Gush Gula 466857 876078 1660 56 42 1618 Windmill
Oromiya East shewa Adame Tulu Ziway Town 467525 877495 1658 50 34 1624 Windmill
Oromiya East shewa Adame Tulu Ziway Town 468215 876905 1658 60 33 1625 Windmill
Oromiya East shewa Dugda Giraba Jarso 477198 901824 1688 75 60 1628 Windmill
Oromiya East shewa Dugda Korke Adi 476306 897835 1664 51 30 1634 Windmill
Oromiya East shewa Dugda Abono 01 471764 892451 1675 50 35 1640 Windmill

Oromiya East shewa Dugda Weyo 471669 891730 1675 60.5 33.2 1641.8 Windmill
Oromiya East shewa Dugda Toch Gabriel 469500 889800 1687 75 53 1634 Windmill
Oromiya East shewa Dugda Alem Tena 472200 902400 1660 90 57 1603 Windmill
Oromiya East shewa Dugda Birbirsa Guda Sabole 470565 914133 1747 62 54 1693 Windmill
Oromiya East shewa Dugda Tuchi Sumeyan 487438 902563 1677 50 26 1651 Windmill
Oromiya East shewa Dugda Oda Bokata 480034 902598 1685 41 34 1651 Windmill
Oromiya East shewa Adami tulu Abosa town 469721 886014 1654 21 20.6 1633.4 HDW
Oromiya East shewa Adami tulu Abosa 469458 885782 1652 21.5 19.3 1632.7 HDW
Oromiya East shewa Adami tulu Elka chalemo 469474 883754 1640 16 13.4 1626.6 HDW
Oromiya East shewa Adami tulu gido Elka chalemo 469450 883811 1643 16 13.75 1629.25 HDW
kombolcha
Oromiya East shewa Adami tulu gido elka/kontola 469361 8837 1646 16 13.5 1632.5 HDW
kombolcha
kombolcha
kombolcha
kombolcha
kombolcha
kombolcha
kombolcha
kombolcha

Oromiya East shewa Adami tulu gido Abosa 469660 886021 1654 35 26.8 1627.2 HDW
kombolcha
kombolcha
kombolcha
Oromiya East shewa Adami tulu gido Gari babiftu 469643 885584 1655 22 19.5 1635.5 HDW
kombolcha
Oromiya East shewa Adami tulu Elka 469562 885338 1654 22 19.01 1634.99 HDW
Oromiya East shewa Adami tulu elka/chefeoda 469529 885020 1652 21 19.1 1632.9 HDW
Oromiya East shewa Adami tulu elka/chefeoda 469514 884723 1656 22 19 1637 HDW
Oromiya East shewa Adami tulu elka/chefeoda 468906 884237 1651 16 14.1 1636.9 HDW
Oromiya East shewa Adami tulu 1th level 469122 883340 1651 22 20.3 1630.7 HDW
Gari/edokolkola
Oromiya East shewa Adami tulu eado kontola 469306 882683 1645 22 19 1626 HDW
Oromiya East shewa Adami tulu eado kontola 469185 882291 1643 15 13.3 1629.7 HDW
Oromiya East shewa Adami tulu Hizbay nuro 468874 879412 1638 12 9.7 1628.3 HDW
Oromiya East shewa Adami tulu Hizbay nuro 467851 878816 1646 12 9.5 1636.5 HDW
Oromiya East shewa Adami tulu tulutown /01 445275 869661 1648 29 25 1623 HDW
Oromiya Guragae Mareko didam edore/ketea01 445155 888626 1829 20 18 1811 HDW
Oromiya Guragae Mareko didam edore/ketea01 444966 888658 1834 25 17.7 1816.3 HDW
Oromiya Guragae Mareko didam edore 444215 888787 1831 22.5 17.55 1813.45 HDW
Oromiya Guragae mareko Didam edore 443757 889042 1831 23 19 1812 HDW
Oromiya Guragae mareko Didam edore 476526 889463 1829 14 13 1816 HDW
Oromiya East shewa dugda graba korkadi/meki 475911 897409 1651 18 15.5 1635.5 HDW
town

Appenix3.2: fluoride distribution with depth
Sample ID. longitude Latitude depth(m) TDS EC PH Na+ K+ Ca2+ Mg2+ Alk. HCO3- Cl- SO4 2- NO3- F-
Twp1 469796 886237 60 888 1469 8.44 222.5 30 17.6 8.64 666 735.7 57.6 14.1 2.02 1.73
Twp25 468906 883340 22 2090 3480 8.43 910 61 6.4 1.92 2002 2170 62.32 19.9 0.97 9.36
Twp26 468990 882659 24 1075 1791 7.88 312 45 24 10.6 832 1015 74.6 19.1 0.82 3.14
Twp36 467541 868129 80 690 1149 8.25 250 27 12 4.8 525 488.5 26.44 21.4 5.6 0.74
Twp37 467853 869448 69 1298 2150 8.15 510 29 16 7.68 988 977 68.93 101 4.56 7.7
Twp41 447457 886437 200 421 702 8.17 195 20 14.4 4.8 442 539.2 5.67 2.34 4.86 2.76
Twp42 446999 886226 90 477 792 7.98 119 29 44.8 12.5 429 472.6 17 5.49 3.15 4.36
Twp51 443757 889463 14 725 1205 7.06 86 31 82.4 4.8 403 491.7 34.94 27.9 15.69 0.9
Twp52 441756 890635 113 521 872 7.53 255 40 68.8 22.1 515 628.1 63.27 34.5 26.21 2.41
TWP55 431997 897751 262 371 612 6.64 32 29 80 9.12 247 301.3 26.44 15.3 44.73 0.27
Twp58/bh2 427005 896812 220 315 526 6.85 36 22 56 8.64 283 345.8 6.61 2.18 2.69 0.76
Twp60 476526 897409 18 1067 1779 8.19 790 30 10.4 5.28 1134 1117 21.72 3.16 0.56 2.57
TWp63 477550 895728 10 300 500 7.9 80 27 35.2 7.68 252 256.2 17 16.6 2.02 9.52
Twp67 477354 904197 130 447 740 7.67 197.5 16 20.8 11.5 341 415.5 17.94 10.6 1.21 0.74
Twp69 478094 902659 80 317 527 7.56 83 18 35.2 8.64 291 355.3 7.55 8.42 0.5 1.65
Twp70 480380 900736 182.5 394 657 7.97 105 18 20.8 4.32 333 406 15.11 11.6 1.17 1.8
Twp71 466207 903427 170 557 930 8.15 270 33 16 9.6 325 320.4 22.66 92.4 0.63 1.13
Twp74 468204 873525 17 1539 2560 7.88 750 110 22.4 10.6 746 909.5 85.93 160 90.4 9.49
TwS1 435852 869258 93 616 860 7.59 148 26 53.4 8.64 483 589.3 25.2 13.7 8.5 3.16
TwSs1 448882 920224 150 240 370 7.69 39.5 10 32 4.32 197 240.8 2.9 1.32 10.7 1.6
Twp27 445207 888966 213 432 642 7.34 31 15 96.12 10.8 321 392 5.8 0.53 13.5 0.8
BH4 440020 888300 168 261 7.36 107.5 4.3 18.8 1.2 254 202 1.2 7 0.28 1.3
BH6 448646 885794 244 528 7.66 202.2 31 8.4 1.68 450 413 7.8 7 0.3 2.79
BH1 426868 899213 600 248 381 7.56 78 8 8.04 1.51 186 226.9 10.41 0.48 1.05 1.33
BH5 446946 888984 591 400 629 7.55 92 11 42.4 3.36 332 405 3.64 8.2 9.56 1.08

Mr25 446946 888984 254 460 678 8.15 128 11 22.4 14.4 348 424.6 0.9137.12 2.33 1.88
Mr25 446946 888984 471 430 626 7.97 104 12 51.2 10.6 360 439.2 5.46 8.09 12.34 1.34
Mr25 446946 888984 571 430 628 8.14 91 12 53.6 7.2 352 429.4 2.73 0.11 11.21 1.08
Aj12 467623 868353 306 590 1155 8.92 336.4 25 2.3 8.92 450 450 119.1 145 0.28 1.23
Appendix 4: Table for lithological log description
Borehole locality-Ziway Depth-143.7m,Swl-32.95m

prison(BH7) Transmissivity-354.5m2/day
Drilled by WWDE,1993 E.C
from To Lithology
0 8 Volcanic Ash? (probably Lacustrine Deposit)
8 12 Volcanic ash
12 42 Fine Indurated white ash? (probably Lacustrine Deposit)
42 48 Grey Indurated Sticky Clay
48 58 Coarse Grained Pyroclastic fall deposit
58 66 Indurated grey ash
66 74 Coarse Grained Pyroclastic fall deposit
74 106 Indurated grey ash
106 114 Ash
114 116 Ash
116 124 Ash
124 126 Ash
126 135 Ash
135 143.7 black cotton clay
Borehole locality-Adami Transnmissivity-95.28m2/day,
Tulu,Depth-71m hydraulic conductivity-3.97m/day
Pump position-47-71m

from To Lithology
0 15 Fine to coarse sand, lake sediment
15 20 lacustrine clay
23 30 lacustrine clay
30 34 Coarse grained Pyroclastic material
66 71 lacus trine clay
Borehole locality-meki
townWSS(08)
from To Lithology
0 4 top soil
4 36 medium grained pumice
36 44 Sand
44 60 fractured ignimbrite
60 66 medium grained sand
66 74 coarse grained pumice
74 85 alluvial deposit
85 94 medium grain pumice
94 126 sand/alluvial deposite
126 130 Pumice
Borehole localilty –Meki
town06
from To Lithology
0 6 top soil
6 16 coarse grain pumice
16 20 alluvial deposit

20 52 fine grain pumice

52 56 sand deposited
56 68 massive ignimbrite
68 74 fractured ignimbrite
74 122 sand/alluvial deposit
122 130 weathered ignimbrite
Borehole locality-Butajira
town(BH3)
from To lithology description

0 10 brownish clay
10 22 tuff, pumice
22 24 Boulder
24 46 decomposed tuff
72 90 fractured &slightly weathered ignimbrite
90 94 slightly fractured ignimbrite
94 102 highly weathered ignimbrite
102 104 contact layer
104 124 fractured and slightly weathered ignimbrite
124 126 reddish contact time
128 158 weathered and fractured ignimbrite
158 164 fresh basalt
164 170 fractured and weathered ignimbrite
170 172 contact layer
172 190 fresh to slightly weathered amygdaloidal basalt
190 200 Pumice

200 214 fractured and decomposed basalt

214 216 Pumice
216 258 highly weathered basalt
258 262 fresh basalt
Borehole locality- Depth -262m
mamuja(BH2) Swl-77m
from To Lithology
0 4 brown clay
4 10 peble,cobble,bouder
10 30 decomposed tuff
30 70 weathered and fractured tuff
70 106 highly weathered tuff
106 122 fresh to slightly weathered ignimbrite
122 144 fresh ignimbrite
148 158 highly weathered and fractured basalt
158 164 weathered and fractured tuff
164 192 highly weathered and fractured basalt
Borehole location- Depth-600m,Swl-62.5m
Mekicho kebele(BH1) Transmissivity-38.75m2/day
From To Lithology
0 34 silt and sandy clay with some basaltic pebbles, Fine sand
with silt with more clay at the bottom 2 meters
34 48 highly weathered and fractured scoriaceous& massive
basalt with slight weathering at the bottom

48 68 highly fractured to slightly weathered Massive basalt

68 74 Basaltic tuff & Highly weathered ignimbrite tuff
74 96 highly weathered and fractured ignimbrite mixed with
basalt
96 178 highly fractured and slightly weathered ignimbrite with
slight and moderate fracturing and tuff
178 196 slightly to highly fractured massive basalt
196 220 Highly fractured and weathered ignimbrite with some
basalt
220 240 Highly fractured and slightly weathered light grayish
ignimbrite
240 280 slightly to highly weathered and fractured ignimbrite
from top to the bottom
280 288 Fractured and moderately weathered basalt with
ignimbrite , occasional fracturing
288 300 slightly fractured basalt
300 310 unwedded tuff and highly weathered and fractured
ignimbrite
310 320 highly weathered and fractured basalt with thin tuff bed at
the bottom
320 322 Welded tuff
322 336 slightly fractured and weathered Rhyolite
336 354 light grey to whitish welded tuff
354 356 slightly fractured Rhyolite
356 400 Ash/tuff with Fractured ignimbrite and welded tuff at the
top and fresh ignimbrite at the bottom
400 406 Highly weathered and fractured ignimbrite
406 436 Slightly fractured ignimbrite with high fracture at the
bottom

436 464 highly weathered and fractured ignimbrite with some heat
effect and slight fracturing
464 466 Welded tuff
466 542 Moderately weathered and slightly fractured ignimbrite
542 600 slightly fractured and weathered ignimbrite and fresh
ignimbrite with fresh rock in the middle
Borehole locality-Inseno deep Depth-168m
test well(BH4)
from To lithology description

0 4 Brown weathredpumaceouspayroclastic fall
4 20 weathredpumaceouspayroclastic fall deposit
20 40 pyroclastic deposit with pumice, ash,
40 56 Grey pyroclastic deposit with pumice and lithic
56 72 Grey pyroclastic deposit with pumice
72 74 Pumaceous, lithic pyroclastic deposit (tuff).
74 78 Pumaceous lithic pyroclastic deposit (tuff).
78 110 Relatively hard tuff
110 116 Pumaceous lithic pyroclastic deposit.
116 168 Pumaceous, lithic pyroclastic deposit.
Bore hole locality- Depth-591m,swl-17.46m
Didahalibo(BH5) Transmissivity-2100m2/day
in Marekoworeda Pumpposition-67.67m
From To Lithological Description
0 4 silly clay with some sandy materials
4 22 fine grained sand with some pyroclastic material
22 32 moderately welded weathered tuff
32 38 less welded tuff

38 60 welded tuff
60 74 loose tuff
74 84 moderately to highly fractured welded tuff
84 104 loose tuff
104 116 moderately fractured ignimbrite
116 132 light brown loose tuff
132 246 light greenish loose tuff
246 258 slightly weathered and fractured ignimbrite
258 306 highly fractured and weathered welded tuff with reddish
stain
306 356 slightly weathered and fractured rhyolite
356 358 loose tuff
358 376 slightly fractured rhyolite(rhyolite tuff)
376 386 highly fractured and moderately weathered rhyolite
386 408 highly weathered &fractured welded tuff
408 426 loose tuff
426 432 highly fractured rhyolite
432 462 loose tuff
462 472 moderately fractured rhyolite
472 486 loose tuff
486 496 welded tuff with rhyolite material
496 522 loose tuff
522 524 fractured rhyolite
524 562 loose tuff
562 583 ignimbrite with rhyolite with thin intercalation
583 591 welded tuff with rhyolite material


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Fluoride Genesis in Ground water of Butajira-Koshe-Ziway Transect Areas, in Central Ethiopia

ADDIS ABABA UNIVERSITY

Fluoride Genesis in Groundwater of Butajira _Koshe _Ziway Transects

A thesis submitted to the School of Graduate Studies of Addis Ababa

AAU School of Earth Science MSc. Thesis by Temesgen A. Page i

ADDIS ABABA UNIVERSITY

SCHOOL OF GRADUATE STUDIES

SCHOOL OF EARTH SCIENCES

Fluoride Genesis in Groundwater of Butajira_Koshe_Ziway transects Areas

Advisor: Tilahun Azagegn (PhD)

AAU School of Earth Science MSc. Thesis by Temesgen A. Page ii

Date: June, 2017

AAU School of Earth Science MSc. Thesis by Temesgen A. Page iii

ADDIS ABABA UNIVERSITY

SCHOOL OF GRADUATE STUDIES

Approved by the Examining Committee:

Dr. Tilahun Azagegn Signature ____________ Date _____________

Prof.Tenalem Ayenew Signature _____________ Date _____________

Dr.Seifu kebede Signature _____________ Date ______________

Dr. Balemual Atnafu Signature_____________ Date_____________

Chairman, School of Earth Sciences

AAU School of Earth Science MSc. Thesis by Temesgen A. Page iv

I would like to convey my special thanks to my friends, Abebeyehu Tadesse,Daniele pittalis

AAU School of Earth Science MSc. Thesis by Temesgen A. Page v

AAU School of Earth Science MSc. Thesis by Temesgen A. Page vi

3.2.3. Rhyolite and Trachytic Lava flows Aquifer ........................................................... 18

AAU School of Earth Science MSc. Thesis by Temesgen A. Page vii

Table5.1. Correlation Matrix of collected and analyzed watersample……………...………..42

Table5.1. Fluoride concentration with depth in Koshe town test well……………….…..…..47

Figure 2.1 location map of the study Area…………………………………..……..………….7

Figure 2.2.Physiographic map of the study area 3D from DEM………………………………8

Figure2.3. Photo from Volcano lacustrine sediment………………...……………………….12

Figure2.4. Geological map modified from (T.Chernet, 1982)……...……………………..…13

Figure2.4.1. Geological cross-section from A to B…………….…………………………….14

Figure3.Hydrogeological map modified from (T.Chernet, 1982 &MoWIE)………………...17

Figure4. Water chemistry sampling point………………..…………………………………..22

Figure4.1. PH distribution map of the study Are......………………………………...………23

Figure4.2. Temperature distribution map of the study area……..……………………..…….24

Figure4.3. EC distribution map of the study Area…………………..……………………….25

Figure4.4. TDS distribution map of the study area…………….…………………………….26

Figure4.5. Schoeller plot of major cat ion and anion………………………………….…..…28

Figure4.6. Lateral and vertical fluoride distribution of the study Area…………………..…..30

Figure 4.9.Hydrochemical evolution vs altitude along ground water flow path…..…………33

Figure.12. A plot of Deuterium (δ2H) vs. δ18O isotopes of water samples............................39

Figure4.13. Chemistry vs. isotope relationship…………………………………………..…..40

Figure5. (a-h) Bivariate plot of water variable…………..……………………………..….…46

Figure5.2. Fluorite vs. calcite saturation……………………………………………………..50

Appendix 1: Over all physiochemical analysis result of water sample in Ziway-Koshe-

Appendix3: groundwater inventory measured in the field &/collected from MoWIE……...65

Appenix3.2: fluoride distribution with depth………………………………………………74

Appendix 4: Table for lithological log description……………………………………….75-81

AAU School of Earth Science MSc. Thesis by Temesgen A. Page viii

AAU Addis Ababa University

CMER Central Main Ethiopian Rift

DEM Digital Elevation Model

EGS Ethiopia Geological Survey

EMA Ethiopian Mapping Agency

GMWL Global Meteoric Water Line

LMWL Local Meteoric Water Line

Dr. Tilahun Azagegn Signature Date _

Prof.Tenalem Ayenew Signature _ Date _

Dr.Seifu kebede Signature _ Date __

Dr. Balemual Atnafu Signature_ Date_