CH 2 WS Sources of Water Supply

CHAPTER TWO:
Sources of Water Supply

DBU, Institute of Technology
College of Engineering
Department of Civil Engineering
Abraham Atnafu
DBU
Chapter two: Sources of Water Supply
Introduction
Nature of water source determines the components of the

water supply system
Factors to be considered to select source:
Quantity
Quality
Reliability
Safety
of source
Water rights
Environmental impacts
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Hydrologic Cycle:
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Hydrological Cycle
The water cycle, also known as the hydrologic cycle, describes the continuous
movement of water on,above and below the earth surface. The sun, which
drives the water cycle, radiates solar energy on the oceans and land.
Key Hydrological Processes
Precipitation : Condensed water vapor that falls to the earth surface. Most
precipitation occurs as rain, but also includes snow, hail, fog drip, sleet, etc.
Runoff: The variety of ways by which water moves across the land. This
includes both surface runoff and channel runoff. As it flows, the water may
infiltrate into the ground, evaporate into the air, become stored in lakes or
reservoirs, or be extracted for agricultural or other human uses.
Infiltration: The flow of water from the ground surface into the ground.
Once infiltrated, the water becomes soil moisture or groundwater.
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Subsurface Flow: The flow of water underground, in the vadose zone and
aquifers. Subsurface water may return to the surface (e.g. as a spring or by
being pumped) or eventually seep into the oceans. Water returns to the
land surface at lower elevation than where it infiltrated, under the force of
gravity or gravity induced pressures. Groundwater tends to move
slowly, and is replenished slowly, so it can remain in aquifers for thousands
of years.
Evaporation and transpiration: The transformation of water from liquid to
gas phases as it moves from the ground or bodies of water into the
overlying atmosphere. The source of energy for evaporation is primarily
solar radiation. Evaporation often implicitly includes transpiration from
plants, though together they are specifically referred to as
evapotranspiration.
Types of water supply sources

Surface Water Sources
Ground Water Sources
Rain Water
Spring Water
Lakes and reservoirs

River Water
Sea water
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Wells
Infiltration galleries
Rain water
Rain water might contain dust, smoke, bacteria, carbon
dioxide as falling from high altitude
RW Harvesting- roofs are most effective and can be integrated
with tanks
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Rain water
Advantages of rainwater collection:
Disadvantages
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Quality of RW is high
Independent
Local materials can be used for collection
No energy costs
Easy to maintain
Time saving and convenient
High initial cost (i.e. for a family)
Quantity of water is dependent on the roof area and rainy seasons
Flat taste
Lakes and reservoirs

water in wet seasons for usage in dry seasons
It is a standing water; because of this:
AAiT, Zerihun Alemayehu
Store
Quality is very low: turbidity, bacteria and pollutants

Thermal stratification (i.e. for deep lakes/reservoirs)
Lake Tana
River water
Abay river
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River water
A stream or river is a body of running water on
the surface of the earth, from higher to lower
ground.
Their capacity is dependent on minimum flow per
day
Development of rivers requires :
submerged
intake structure
small diversion dams (i.e. for small streams)
Abay river
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Groundwater sources
Aquifer
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Groundwater sources
Advantages :
It
is likely to be free of pathogenic bacteria

free from turbidity and colour
It can be used without further treatment
It can be found in the close vicinity
It is economical to obtain and distribute
The water-bearing stratum provides a natural
storage at the point of intake.
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Groundwater sources
Disadvantages
often
have high in mineral content;

It usually requires pumping.
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CATIONS: calcium, magnesium, iron and manganese

ANIONS: bicarbonate, carbonate, and chloride
Springs
Spring water is a groundwater that
outcrops from ground due to impervious
base that prevents percolation.
Mostly found from sand or gravel aquifers
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Gravity springs
GW flows over an impervious stratum onto the ground

surface
The yield varies with the position of the water table
May dry up during or immediately after a dry season
Gravity overflow spring

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Gravity depression spring

Artesian springs
High quality water due to confinement

High discharge due to high pressure in the confinement
Yield is likely uniform and nearly constant over the seasons
of the year
Artesian depression spring

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Artesian fissure spring
Infiltration gallery
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Horizontal wells that collect water over practically their

entire lengths.
Simple means of obtaining naturally filtered water
Recharge of aquifers
Replenishment (filling) of aquifers is known as recharge

Unconfined
aquifers are recharged by precipitation

percolating down from the lands surface
Confined aquifers are generally recharged where the
aquifer materials are exposed at the lands surface -called
an outcrop.
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When surface water loses water to the adjacent

aquifer, the stream is called a losing stream.
water flows from the ground water to the stream, it is
called a gaining stream.
Groundwater
table
Aquifer
Impervious layer
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Water quality considerations

Water quality considerations of sources are required for the following purposes
To evaluate and classify raw water quality
physical, chemical, and bacteriological parameters

raw water can be classified as having poor, fair, and good quality.
To identify sources of pollution

Surface water: urban runoff, agricultural runoff, industrial
discharge, and leachate from landfills;
Groundwater: infiltration from pit-latrines and septic tanks, landfill
leachate, and infiltration from polluted areas.
To assess the treatment required for beneficial uses
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level of treatment and unit process required are dependent on the

raw water quality
Treatment types
For groundwater having excellent quality
Well
Aeration
Disinfection
Fluoridation
For groundwater having moderate quality

Well
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Rapid sand
filtration
Aeration
Disinfection
Fluoridation
Treatment types
Good quality upland reservoir
Reservoir
Microstrainer
Disinfection
Fluoridation
Moderate to poor quality lowland river

Reservoir
Screening
Fluoridation
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Coagulation
Disinfection
Sedimentation
Filtration
Source selection
Surface water sources
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Safe water yield during the drought years

Urbanization and land development in the watershed
Proposed impoundments on tributaries
Water quality
Assessment of reliability
Requirements for construction of water supply system components
Economics of the project
Environmental impacts of the project
Water rights
Source selection
Ground water sources

Aquifer
characteristics (depth, geology)

Safe aquifer yield
Permissible drawdown
Water quality
Source of contamination(gasoline, oil, chemicals)
Saltwater intrusion(areas near to seas or oceans)
Type and extent of recharge area
Rate of recharge
Water rights
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Reservoirs
o Contain dam to hold water
o A spillway to allow excess water to flow
o A gate chamber with valves to regulate flow
An artificial lake formed by the
construction of a dam across a valley
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Reservoirs
The area of land draining to the dam site is called a
catchment or watershed.
Outlet
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Reservoirs
The following investigations are required for reservoir
planning:
A. Topographic surveying- to produce a topo-map which will
be used as a base for
preparing
water surface area vs. elevation curve

plotting storage volume vs. elevation
indicating man-made and natural features that may be
affected
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Reservoirs
B. Geologic investigations
Water
tightness of the reservoir basin

Suitability of foundations for the dam
Geological and structural features, such as faults, fissures, etc
Type and depth of overburden
Location of permeable and soluble rocks if any
Ground water conditions in the region
Location and quantity of materials for the dam construction
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Reservoirs
C. Hydrological investigations
determination
of rainfall, runoff, seepage, and

evaporation in the reservoir catchment from long
years of data.
These information are essential for estimating the reservoir

capacity and design of spill way.
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Criteria for Selecting reservoir sites
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Catchment geology- minimum percolation losses and high runoff

potential
Dam site- strong foundation with minimum seepage loss under the
dam.
Narrow valley- sites that resulting lesser dam length
Topography- should be such that large area and valuable
properties are not submerged
Site that creates deep reservoirs- this has the advantages of
minimizing the evaporation loss and submerged area when
compared to shallow reservoirs
Sites that ensure good water quality- avoid sites that are
downstream of waste discharges and tributaries with high silt loads
Volume of reservoirs
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Yield is the amount of water that can be supplied from a

reservoir within a specified interval of time.
Safe yield or firm yield: is the maximum quantity of
water that can be guarantied during a critical dry
period.
the safe yield from a reservoir > maximum day demand
Methods to determine the storage volume of reservoirs:
mass curve method(Rippl) Method.
analytical method.
Mass curve method
reservoir capacity is determined from accumulated mass inflow and

accumulated demand curves.
Net Inflow= total Inflow-outflow (evaporation, seepage, d/s flow)
Procedure
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Prepare accumulated mass inflow curve from the stream hydrograph

Prepare the accumulated demand curve on the same scale
Draw tangent lines that are parallel to the accumulated demand curve
at the high points of the accumulated mass curve (P1, P2, P3, etc)
Measure the vertical distances between the tangent lines and the mass
inflow curve (V1, V2, V3, etc.)
Determine the required reservoir storage capacity as the largest of the
vertical distances (V1, V2, V3, etc.)
Mass curve method

Accumulated inflow
V2
Volume
(m3)
Spill
Accumulated demand
V1
Time, Year (month)

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Analytic method
Calculate the net inflow from the given hydrological data

Calculate the deficiency (demand net inflow)
Compute the cumulative deficiency. If the cumulative
deficiency is negative, take the cumulative deficiency as zero
Determine the required reservoir capacity as the maximum
cumulative deficiency
(1)
Net inflow
(m3)
I1
I2
I3
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(2)
Demand (m3)
D1
D2
D3
(3)= (2)-(1)
Deficiency
(m3)
F1
F2
F3
(4) if CF is ve, take 0
Cumulative deficiency
(m3)
CF1 = F1
CF2 = CF1 + F2
CF3 = CF2 + F3
Example 2.1
Compute the storage requirement
needed for an impounding reservoir for
a constant draft of 23 ML/km2/months
of 30.4 days with the given monthly net
river inflow for a critical year.
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Month
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
Inflow
(ML/km2)
94
122
45
5
5
2
0
2
16
7
72
92
21
55
33
Analytical Solution
Month
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
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inflow
94
122
45
5
5
2
0
2
16
7
72
92
21
55
33
draft/
demand
23
23
23
23
23
23
23
23
23
23
23
23
23
23
23
Cummulative
Demand
23
46
69
92
115
138
161
184
207
230
253
276
299
322
345
Cummulative inflow
94
216
261
266
271
273
273
275
291
298
370
462
483
538
571
Defficiency
-71
-99
-22
18
18
21
23
21
7
16
-49
-69
2
-32
-10
cummulative
Deficiency
0
0
0
18
36
57
80
101
108
124
75
6
8
0
0
Graphical Solution
Res. Draw down period
600
Depletion of Res.
400
Reservoir full
419-294=124
300
Cummulative Q
Res. full
500
Replenishment
of Res.
200
End of
Dry period
Start of
Dry period
Cummulative Demand
100
Cummulative inflow
0
10
12
14
16
Month
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Exercise
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Safe yield from a given reservoir capacity
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Prepare the mass inflow curve.

From the apices A1, A2, A3 etc. of the mass curve, draw
tangents in such a way that their maximum departure from
the mass curve does not exceed the specified reservoir
capacity. The ordinates E1D1, E2D2, E3D3, etc. are all equal
to the reservoir capacity (say 1500 ha.m)
Measure the slopes of each of these tangents. The slopes
indicate the yield which can be attained in each year from
the reservoir of given capacity. The slope of the flattest
demand line is the firm yield.
Safe yield from a given reservoir capacity
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Cross section of Dam
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Types of Dams
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Impoundments: Embankment dams

Embankment dam-A dam constructed from natural materials
excavated or obtained nearby. The natural fill materials are placed

and compacted without the addition of any binding agent. Two typesEarth fill dam (if compacted soil constitutes over 50% of the dam
volume) and
Rock fill dam (over 50% of the material is coarse-grained material or
crushed rock with impervious membrane).
Advantages:
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For sites in wide valleys and steep-sided gorges

Adaptability to a broad range of foundation conditions
Use of locally available natural materials
Impoundments: Concrete Dam

Disadvantages:
Easily damaged or destructed by overflow

leakage and internal erosion
They are gravity dam, arch dam, buttress dam, etc.

Gravity dam
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Dependent upon its own mass for stability.
For gorges with very steep side slopes
It can be constructed by Masonry(stone or brick)
Shape: straight or curved
Dam height: can be very high for sound foundation

Impoundments: Concrete Dams...

Arch dam
Functions structurally as a horizontal arch, transmitting the
major portion of the water load to the abutments or
valley sides rather than to the floor of the valley.
structurally more efficient, needs less concrete volume
Buttress dam
consists of a continuous upstream face supported at
regular intervals by downstream buttresses.
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Catchment protection
Activities that take place within the reservoir catchment have impacts on the quality and quantity
of water stored behind the dam. Catchment protection primarily focuses on maintaining the
water quality and capacity of the reservoir. It involves activities that include
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Minimization of diffuse pollution from urban runoff

Minimization of agricultural diffuse pollution
Controlling discharges from point sources such as
wastewater treatment plant, industries, etc
Limitation of soil erosion through soil conservation
measures, such as afforestation, etc.
Providing corridors along tributary streams, rivers, and the
reservoir
Ground water
hydraulics
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Occurrence of Groundwater
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Groundwater takes 0.62% of the total water in the

hydrosphere but 99 % of the fresh water
Of 0.31% of the total water in the hydrosphere has depth less
than 800m.
sand, gravel, and sandstones good aquifers
Limestone and shale that have caverns, fissures or faults can
also be considered as good aquifers.
Clays ability to transmit water is very poor due to the very
small particle sizes (< 0.0004 mm).
Groundwater
Groundwater is the water beneath the ground surface contained in void spaces (pore spaces between
rock and soil particles, or bedrock fractures).
Basic Terms
Aquifer
An aquifer is an underground layer of water-bearing permeable rock or unconsolidated

materials(gravel, sand, silt, or clay) from which groundwater can be usefully extracted using a water
well.
Water table
The water table is the level at which the groundwater pressure is equal to atmospheric pressure.
Aquitard
An aquitard is a zone within the earth that restricts the flow of groundwater from one aquifer to another.
Aquitards comprise layers of either clay or non-porous rock with low hydraulic conductivity.
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Unconfined aquifer
It is an aquifer with the water table as its upper boundary. Because the aquifer is not under pressure the
water level in a well is the same as the water table outside the well.
Confined aquifer
It is an aquifer found between two relatively impermeable layers.
Artesian aquifer/well
It is a confined aquifer containing groundwater that will flow upward through a well, called an artesian
well, without the need for pumping. Water may even reach the ground surface if the natural pressure is
high enough, in which case the well is called a flowing artesian well.
Water well
A water well is an excavation or structure created in the ground by digging, driving, boring or drilling
to access groundwater in underground aquifers.
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Borehole
It is a narrow shaft drilled in the ground as part of a groundwater site assessment.
Piezometric surface
The imaginary surface that everywhere coincides with the piezometric head of the water in the aquifer.In
areas of artesian ground water, it is above the land surface.
Base flow
Base flow is the portion of stream flow that comes from groundwater. It sustains flows in a river
during the dry periods between rainstorms.
Groundwater Recharge
The natural or intentional infiltration (percolation) of surface water into the groundwater system.
Fossil water
Fossil water is groundwater that has remained in an aquifer for thousands or even millions of years.
When geologic changes seal the aquifer off from further recharging, the water becomes trapped inside.
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Subsurface Distribution of Water

Vertical zones of groundwater distribution
Ground surface
Soil water zone
Unsaturated
zone
-Large fluctuation in water

Content due to plant transpiration
Vadose zone
Capillary zone
Saturated
Zone(It is the water that is
Zone of saturation
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All voids are filled with water
Under hydrostatic pressure
found in the saturation zone

that can be tapped for
different purposes )
Aquifer is a water-bearing formation that is saturated and that

transmits large quantities of water.
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Aquifer parameters
(The water yield capacity of aquifers depends on different parameters)
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Aquifer parameters
Storage coefficient (S): the volume of water that an aquifer

releases from or takes into storage per unit surface area of the
aquifer per unit change in head
Hydraulic gradient (dh/dx): the slope of the piezometric surface

or water table line in m/m. The magnitude of the head
determines the pressure on the groundwater to move and its
velocity.
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Examples
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Aquifer parameters
Hydraulic conductivity(K): ratio of velocity to hydraulic

gradient, indicating permeability of porous media.
K=
QdL
Adh
Transmissivity: the capacity of an aquifer to transmit water

measure
of how easily water in a confined aquifer can flow through

the porous media.
T = Kb,
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b = saturated thickness
Aquifer Types
Unconfined and confined aquifers(
An unconfined aquifer does not have confining unit and is defined by water-
table. Confined aquifer is overlain by a confining unit that has a lower hydraulic conductivity.)
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Groundwater flow
Groundwater flows in the direction of decreasing head.
equipotential lines lines showing points having equal
pressure.
Flow direction is perpendicular to equipotential lines
145 m
150 m
155 m
140 m
135 m
130 m
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Aquifer boundary
Equipotential line
Flow direction
Velocity of GW
Velocity can be determined by Darcys law V = kS
Darcy law :Q through porous media is proportional to the head loss and inversely
proportional to the length of the flow path.
L
Q
h
V
K
A
L
or
Porous medium
dh
V K dL
; for very small element
Area = A
K = hydraulic conductivity and h is the head loss

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Determination of K
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Determination of K
Laboratory methods
Constant head permeameter:
VL
K
Ath
V = volume water flowing in time t through of area A, length L, and with

constant head h.
Variable head permeameter :
r 2 L h1
K 2 ln
rc t h2
r = radius of the column in which the water level drops

rc = radius of the sample
h1, h2 are heads at times t1 and t2, respectively
t = t2 t 1
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Problems
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Determination of K...
Field Methods
Pumping test: constant removal of water from a single well

and observations of water level declines at several adjacent
wells.
This is the most accurate way
For anisotropic aquifers, the combined horizontal hydraulic

conductivity:
K Z
K
Where, Ki = K in layer i; Zi = thickness of layer I

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Example
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Determination of K...
Field Methods
Slug test or piezometer test: the simplest method
some volume of water is taken out from the piezometer and the
subsequent rise of the water back to its original position is recorded
in time.
ri-inside
radius,
L- the length of the screen section,
ro-the outside radius
to- characteristic time interval
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Hydraulics of water wells

Well: hydraulic structure utilized to access water-bearing aquifers
Allows estimation of aquifer hydraulic properties
Provides direct access to ground water conditions
1)
2)
3)
4)
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Sampling
Testing
Resource Extraction
Environmental Restoration
Hydraulics of water wells
Aquifer test: studies involving analyzing the change, with
time, in water levels in an aquifer caused by withdrawals

through wells.
Drawdown/cone of depression: is the difference between the
water level at any time during the test and the original
Ground
position.
Original GWT
Cone of depression
Drawdown
Well
Impervious
stratum
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Radius of influence of steady state pumping

wells
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Piezometric head
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Steady state Radial flow to a well

assumptions:
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Cone of depression remains in equilibrium

The water table is only slightly inclined
Flow direction is horizontal
Slopes of the water table and the hydraulic gradient are equal
Aquifer: isotropic, homogeneous and infinite extent
Well fully penetrating the aquifer
Steady Radial Flow to a Well-Confined

In a confined aquifer, the drawdown curve or cone of depression varies with distance from a
pumping well
For horizontal flow, Q at any radius r equals, from Darcys law,

dh
dh
Q 2 rbK
2rT
dr
dr
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Steady Radial Flow to a Well-Confined
Integrating after separation of variables, with h = hw at r = rw

at the well, yields Thiem Equation.
Q 2 T
h hw
r
ln
rw
Near the well, transmissivity, T, may be estimated by observing

heads h1 and h2 at two adjacent observation wells located at r1
and r2, respectively, from the pumping well.
r2
ln
r1
T Q
2 (h2 h1 )
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Steady Radial Flow to a Well-Unconfined
radial flow in an unconfined, homogeneous, isotropic, and

dH
horizontal aquifer yields:
Q 2 rHK
dr
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Steady Radial Flow to a Well-Unconfined
Integrating, the flow rate in a unconfined aquifer from 2 to 1

(h2 h1 )
Q K
r
ln 2
r1
2
Solving for K,
Q
r2
K
ln
2
2
(h2 h1 ) r1
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Example
A 0.5 m well fully penetrates an unconfined aquifer of 30 m
depth. Two observation well located 30 and 70 m from the
pumped well have drawdowns of 7 m and 6.4 m, respectively. If
the flow is steady and K = 74 m/d.
what
would be the discharge

Estimate the drawdown at the well
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Solution
For unconfined well Q is given as

(h h1 )
Q K 2
r2
ln
r1
2
h1= 30-7 = 23 m, and h2 = 30 6.4 = 23.6 m

r1 = 30 m and r2 = 70 m
(23.6 2 232 )
Q 74
7671.54 m3 / day
70
ln
30
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Solution
Drawdown at the well,

using
the h1=23 m and rw=0.5m/2=.25 m, we have hw
(h1 hw )
(232 hw )
Q K
74
7671.54 m3 / day
r1
30
ln
ln
rw
0.25
2
Solving for hw, we have hw = 19.26 m

So the drawdown would be 30.0 19.26 = 10.74 m
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Example
Design a tube well for the following data

required = 0.1 m3/sec
Thickness of confined aquifer = 25 m
Radius of confined aquifer = 250 m
Permeability coefficient = 70 m/day
Drawdown at the well = 6 m
Yield
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Solution
h hw
Q 2 bK
r
ln
rw
For confined aquifer Q is given by
Taking between the well and at the radius of influence(R) we

have
h
- hw = 6 m
b = 25 m
R = 250 m
70 m / day 6m
Q 0.1m / sec 2 25m

86400sec/ day ln 250
rw
3
Solving for rw, we get rw = 0.12 m or 12 cm

Thus, diameter of the well is 24 cm or 25 cm
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Exercise
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A well 60cm in diameter in a confined aquifer was pumped at a

steady rate of 0.0311 m3/s.When the well level remained
constant at 85.48 m, the observation well level at a distance of
10.4 m was 86.52 m. Calculate the transmissivity.
Solution
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Interference of wells
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The combined drawdown at a point is equal to the sum of the

drawdowns caused by individual wells.
Reduced yield for each of the wells.
AAiT, Zerihun Alemayehu
Resultant drawdown
Pumping and recharging wells

T
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Well construction
Well construction depends

on
the
flow rate,
depth to groundwater,
geologic condition,
casing material, and
economic factors
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Shallow and deep well

construction
Shallow well construction
Shallow wells are less than 30 m deep

constructed by
digging,
boring,
driving,
or
jetting methods.
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Dug wells: excavated by hand and

are vertical wells.
diameter
> 0.5 m and depth < 15 m.

Lining and casing :concrete or brick.
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Driven wells: a series of pipe lengths driven vertically

downward by repeated impacts into the ground.
diameters
25 75 mm
Length below 15 m.
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Bored wells: constructed with

hand-operated or power-driven
augers.
Diameters
of 25 to 900 mm
depths up to 30 m
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Jetted wells: a high-velocity stream

of water directed vertically
downward, while the casing that is
lowered into the hole conducts the
water and cuttings to the surface.
Small-diameter
holes, up to 10
depths up to 15 m
useful for observation wells and wellpoint systems for dewatering
purposes.
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Deep well construction
Deep wells constructed by percussion (cable tool) drilling or
rotary drilling methods.
Percussion drilling: regular lifting and dropping of a string of

tools, with a sharp bit on the lower end to break rock by
impact.
for
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consolidated rock materials to depths of 600 m.
Percussion drilling
Pulley
Tripod
Rope
Casing pipe
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Deep well construction
Rotary method: consists of drilling with a hollow, rotating

bit, with drilling mud or water used to increase efficiency. No
casing is required with drilling mud because the mud forms a
clay lining on the wall of the well. Drilling mud consists of a
suspension of water, bentonite clay, and various organic
additives.
A
rapid method for drilling in unconsolidated formations

Air rotary methods use compressed air in place of drilling mud and
are convenient for consolidated formations.
Drilling depths can exceed 150 m
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Hydraulic rotary drilling
Drilling mud
Tripod
Mud to settling tank
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By:Abraham
END of
Atnafu 2:
chapter
DBU

CH 2 WS Sources of Water Supply

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CHAPTER TWO:

Sources of Water Supply

Chapter two: Sources of Water Supply

Nature of water source determines the components of the

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Types of water supply sources

Ground Water Sources

Lakes and reservoirs

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Advantages of rainwater collection:

Chapter two: Sources of Water Supply

Lakes and reservoirs

Quality is very low: turbidity, bacteria and pollutants

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

is likely to be free of pathogenic bacteria

Chapter two: Sources of Water Supply

have high in mineral content;

CATIONS: calcium, magnesium, iron and manganese

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

GW flows over an impervious stratum onto the ground

Gravity overflow spring

Gravity depression spring

High quality water due to confinement

Artesian depression spring

Artesian fissure spring

Chapter two: Sources of Water Supply

Horizontal wells that collect water over practically their

Chapter two: Sources of Water Supply

Replenishment (filling) of aquifers is known as recharge

aquifers are recharged by precipitation

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

When surface water loses water to the adjacent

Chapter two: Sources of Water Supply

Water quality considerations

To evaluate and classify raw water quality

physical, chemical, and bacteriological parameters

To identify sources of pollution

To assess the treatment required for beneficial uses

level of treatment and unit process required are dependent on the

For groundwater having moderate quality

Chapter two: Sources of Water Supply

Moderate to poor quality lowland river

Chapter two: Sources of Water Supply

Surface water sources

Safe water yield during the drought years

Ground water sources

characteristics (depth, geology)

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply

Chapter two: Sources of Water Supply