Catchment Hydrology
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Recent papers in Catchment Hydrology
The infrastructure of the original Guapo river dam project at El Guamito site (Miranda state, Venezuela), built and commissioning during the 1975-1977 period, collapsed in December 1999 as a result of the extraordinary rains observed at... more
The infrastructure of the original Guapo river dam project at El Guamito site (Miranda state, Venezuela), built and commissioning during the 1975-1977 period, collapsed in December 1999 as a result of the extraordinary rains observed at that time, which generated maximum discharges with magnitudes higher than the design discharge of the work. Therefore, it is necessary to analyze the relationship between the hydrogeomorphological response of the Guapo river basin generated by this extraordinary rains event, the characteristics of the physical and biological media, and the conditions that these determined for the collapse of the dam. Variables of the physical and biological media, in particular climatic and hydrological aspects, were characterized. Morphometric parameters of the basin and its drainage network were measured and calculated. Topographic and geomorphological features were described with the construction of profiles. The physical and biological elements (geology, relief, geomorphology, topography, soil, vegetation, climate, drainage and hydrology) that coexist in the area of the basin have an important influence on the hydrogeomorphological responses of the system (floods, sediment production and haulage and mass movements). The morphometric characteristics of the basin indicate a high correspondence between these aspects and the collapse of the spillway, since they favoured the high discharges that were estimated at the dam site during the occurrence of this adverse event.
Lake Burrumbeet, which is located in the basalt plains of western Victoria, Australia, has a much lower salinity than other lakes in the region. To determine the factors causing the freshness of this water body, an assessment was carried... more
Lake Burrumbeet, which is located in the basalt plains of western Victoria, Australia, has a much lower salinity than other lakes in the region. To determine the factors causing the freshness of this water body, an assessment was carried out using existing geological information to reconstruct the palaeotopography beneath basalt flows, and using hydrogeological data, bore hydrographs and hydrological data together with a time variant lake water balance analysis calibrated from 1998 to 2008. The calibrated water balance of Lake Burrumbeet shows that groundwater outflow has a major influence on lake levels (31 % of water losses). The lake water budget analysis confirms that the interaction of Lake Burrumbeet with the surrounding groundwater system is volumetrically significant. Geological re-construction of the course of the buried river valley sediments (Deep Lead underlying the basalt) shows that they run directly beneath Lake Burrumbeet. Groundwater leakage into these sediments is sufficient to transfer enough salt from the lake to maintain a low to moderate lake salinity. The conceptual hydrogeological model of Lake Burrumbeet, coupled with the time variant water budget analysis, show that the difference in salinity among the lakes in the region can be explained by variations in the configuration and hydrogeological setting of the lakes, and this hypothesis provides new understanding of the relative freshness of the lake.
Keywords
Lake–aquifer interaction Wetland Hydrogeology Lake Burrumbeet Australia
Keywords
Lake–aquifer interaction Wetland Hydrogeology Lake Burrumbeet Australia
- by John Webb and +1
- •
- Hydrology/Hydrography, Geology, Hydrogeology, Climate Change
Water quality assessment for water resource protection and management is key towards sustainable provision of potable water supply and in meeting sustainable development goals (SDGs) linked to clean water and sanitation. The spatial and... more
Water quality assessment for water resource protection and management is key towards sustainable provision of potable water supply and in meeting sustainable development goals (SDGs) linked to clean water and sanitation. The spatial and temporal aspects of groundwater quality in the Nseleni catchment, South Africa (SA) was investigated, its suitability for domestic use was considered, and required protection measures were established. Using a hybrid approach methodology based on multiple water quality resource assessment techniques such as groundwater quality index (GQI) and concentration duration curves (CDCs), 72 groundwater samples collected from 1994 to 2017 were analysed for physico-chemical (Na+, Ca2+, Mg2+, Cl−, SO42−, NO3−, F−, EC, pH) parameters. Approximately, 33.3% of groundwater samples in the Nseleni catchment were found suitable for drinking when compared to South African water quality guidelines. The use of a hybrid approach method showed that overall groundwater quality in the study catchment was classified as excellent for domestic water use when the groundwater quality index was calculated to be 39.11. Groundwater quality reserve limits for groundwater resources protection were determined for the nine water quality parameters using CDCs. The study concluded that using groundwater quality index and concentration duration curves, it was feasible to classify groundwater resources for improved groundwater quality of reserve determination in the South African context. The study recommends the application of the hybrid method in various catchments of similar characteristics to the studied catchment for setting groundwater quality limits that would contribute towards achieving the goal of groundwater resources protection in other catchments.
The Metropolis of Manila has poor wastewater management practices which costs the economy around AUD$ 2 Billion per year, results in around a third of all recorded illnesses and has left the rivers biologically dead. However, with a... more
The Metropolis of Manila has poor wastewater management practices which costs the economy around AUD$ 2 Billion per year, results in around a third of all recorded illnesses and has left the rivers biologically dead. However, with a change in wastewater management governance structure in 1997, steady improvements have been realised. Lately, a sewerage system implementation model for river rehabilitation based on a “river basin approach” is being implemented for the first time on a large scale. The implementation is part of a strategy to increase access to sewerage infrastruction, for roughly half of the Manila Metropolis population, from 3% in 1997 to 100% in 2018. The implementation has faced challenges associated with flooding, land availability, above average population growth rates and managing stakeholders. However the bulk of these challenges can be and are being engineered out or managed and the implementation is proceeding.
El propósito fundamental de este trabajo es caracterizar las variables físico-naturales, biológicas y socio-económicas de la micro-cuenca de drenaje de la quebrada Charallave, con la finalidad de establecer su situación ambiental. La... more
El propósito fundamental de este trabajo es caracterizar las variables físico-naturales, biológicas y socio-económicas de la micro-cuenca de drenaje de la quebrada Charallave, con la finalidad de establecer su situación ambiental. La microcuenca de la quebrada Charallave se localiza en el extremo suroccidental del estado Miranda (10º08’15” – 10º18’20” LN y 66º46’25” – 66º58’05” LO). La metodología de trabajo se basó en la recopilación y análisis de la información cartográfica existente para cada una de las variables consideradas en el estudio, así como en el análisis e interpretación de datos climatológicos, y mediciones morfométricas de la cuenca. El procesamiento de la información se corroboró con visitas de campo, y también se realizaron observaciones con relación a la situación ambiental de la cuenca, lo cual se complementó con la interpretación de fotos aéreas. La geología del área consiste fundamentalmente de afloramientos de materiales metasedimentarios, metavolcánicos y sedimentarios. Geomorfológicamente, el área pertenece a los denominados valles del Tuy, los cuales presentan forma de “V”, y son angostos y profundos. La vegetación está constituida por formaciones correspondientes al Bosque Transicional pre-montano – montano bajo, Matorral Tropical semideciduo y Herbazal Transicional pre-montano – montano bajo. Los suelos son clasificados en general como Udorthentic chomusterts, correspondientes al orden de los Vertisoles. La red de drenaje de la cuenca está conformada por quebradas de régimen intermitente y recorridos muy cortos. La quebrada Charallave es el colector principal del sistema, de mayor longitud y régimen permanente, y desemboca en el río Tuy al sur del área. La mayor parte de las tierras del área tienen restricciones para la actividad agrícola, y las pocas con suelos muy fértiles, están emplazadas por las ciudades, donde se practica una agricultura muy precaria. Los principales problemas que determinan la situación ambiental de la cuenca son: procesos de erosión naturales e inducidos, inestabilidad del terreno, degradación de los suelos, alteración antrópica del bosque, incremento poblacional, incremento de la actividad industrial, y contaminación del agua.
Flood modelling and mapping typically entail flood frequency estimation, hydrodynamic modelling and inundation mapping, which require specific datasets that are often unavailable in developing regions due to financial, logistical,... more
Flood modelling and mapping typically entail flood frequency estimation, hydrodynamic modelling and inundation mapping, which require specific datasets that are often unavailable in developing regions due to financial, logistical, technical and organizational challenges. This review discusses fluvial (river) flood modelling and mapping processes and outlines the data requirements of these techniques. This paper explores how open-access remotely sensed and other geospatial datasets can supplement ground-based data and high-resolution commercial satellite imagery in data sparse regions of developing countries. The merits, demerits and uncertainties associated with the application of these datasets, including radar altimetry, digital elevation models, optical and radar images, are discussed. Nigeria, located within the Niger river basin of West Africa is a typical data-sparse country, and it is used as a case study in this review to evaluate the significance of open-access datasets for local and transboundary flood analysis. Hence, this review highlights the vital contribution that open access remotely sensed data can make to flood modelling and mapping and to support flood management strategies in developing regions.
During the second half of the 20th century farming systems in hilly and mountainous areas of Mediterranean Europe were progressively abandoned and the forest cover subsequently re-expanded. This paper investigates the environmental... more
During the second half of the 20th century farming systems in hilly and mountainous areas of Mediterranean Europe were progressively abandoned and the forest cover subsequently re-expanded. This paper investigates the environmental impacts of land-use/land-cover (LULC) changes on hydrological ecosystem functions (HEFs) in the Upper Alento River Catchment (UARC) in southern Italy. We document the human-driven post-war landscape in 1955 with its maximum expansion of pasture and crops. By 1998 forest cover had doubled and cropland had roughly halved due to decades of land abandonment and reduction in human pressure. In 2015 secondary forests occupied about 70% of the catchment and orchards about 20%. The 1998 land-use scenario was implemented within the Automated Geospatial Watershed Assessment (AGWA) model which was calibrated and validated by direct water yield measurements recorded in the period 1995-2004 in the water reservoir delimited by an earth-dam located at the UARC outlet. Numerical simulations, assumed under “steady” climate conditions, offer “pseudo-realistic” scenarios that help interpret differences in water budget and sediment transport when the 1998 land-use scenario is compared to those of 1955 and 2015. With reference to funding opportunities offered by the European Union in the recent decades, this study provides some practical guidance on the impact of cropland reconversion on HEFs and on measures to mitigate soil erosion in this Mediterranean area. Viewed from the demand-side perspective, natural re-expansion of forest and afforestation reduce water yield and increase actual evapotranspiration. However, our modeling results are framed also within a supply-side approach examining the sensitivity of water yield to precipitation characteristics.
For determining of Muskingum model coefficients, requires to an output hydrograph. Such hydrograph is not available in most rivers. In this research, the Muskingum's new coefficients are determined by the method that which is not require... more
For determining of Muskingum model coefficients, requires to an output hydrograph. Such hydrograph is not available in most rivers. In this research, the Muskingum's new coefficients are determined by the method that which is not require to output hydrograph and its accuracy is high. This coefficient is determined based on kinematic wave model with suitable scheme. The comparison between results of Muskingum model with new coefficients and dynamic wave model, showed that the new coefficients, are valid at special conditions. The new coefficients were adjusted by optimization technique for all conditions. The new adjusted coefficients are function of bed slop, bottom width and Manning's roughness coefficient for the river. The results of these coefficients were validated by dynamic wave model.
Potential (ETp) and actual (ETr) evapotranspiration for different land uses in a watershed in southern Brazil Evapotranspiration can be determined by direct or indirect methods, and its verification is performed by comparison with the... more
Potential (ETp) and actual (ETr) evapotranspiration for different land uses in a watershed in southern Brazil Evapotranspiration can be determined by direct or indirect methods, and its verification is performed by comparison with the measured data. This study aimed to determine the actual evapotranspiration (ETr) for different land uses that make up the agricultural landscape of the Ribeirão Concórdia watershed, compared with the potential evapotranspiration (ETp). The land uses analyzed were: agriculture, native forest, pasture and reforestation. ETp was estimated by the Penman-Monteith method (FAO-56) from surface weather station data, and ETr determined by field-installed equipment such as volumetric lysimeters, runoff gutters and below-canopy rainfall interceptors. vegetation in native forest and reforestation areas. The precipitation in the region was uneven and with values above the regional precipitation, due to the orthographic rainfall occurred in the region. The native forest area had an interception volume of 11.2% greater than the reforestation area. Rainfalls up to 6.5mm were totally intercepted by the vegetative canopy, while in reforestation this value was only 2.1mm. The Penman-Monteith method overestimated evapotranspiration values in all land uses. Soil water storage had little variation as the hydrological cycle is a dynamic system and comes into balance over time. The runoff was high in the agricultural areas due to the soil management adopted by the producers. The water balance method proved to be efficient in the determination of ETr in a decendial time scale.
The scientific initiative Prediction in Ungauged Basins (PUB) (2003–2012 by the IAHS) put considerable effort into improving the reliability of hydrological models to predict flow response in ungauged rivers. PUB’s collective experience... more
The scientific initiative Prediction in Ungauged
Basins (PUB) (2003–2012 by the IAHS) put considerable effort
into improving the reliability of hydrological models to
predict flow response in ungauged rivers. PUB’s collective
experience advanced hydrologic science and defined guidelines
to make predictions in catchments without observed
runoff data. At present, there is a raised interest in applying
catchment models to large domains and large data samples
in a multi-basin manner, to explore emerging spatial patterns
or learn from comparative hydrology. However, such modelling
involves additional sources of uncertainties caused by
the inconsistency between input data sets, i.e. particularly
regional and global databases. This may lead to inaccurate
model parameterisation and erroneous process understanding.
In order to bridge the gap between the best practices
for flow predictions in single catchments and multi-basins
at the large scale, we present a further developed and slightly
modified version of the recommended best practices for PUB
by Takeuchi et al. (2013). By using examples from a recent
HYPE (Hydrological Predictions for the Environment) hydrological
model set-up across 6000 subbasins for the Indian
subcontinent, named India-HYPE v1.0, we explore the PUB
recommendations, identify challenges and recommend ways
to overcome them. We describe the work process related to
(a) errors and inconsistencies in global databases, unknown
human impacts, and poor data quality; (b) robust approaches
to identify model parameters using a stepwise calibration approach,
remote sensing data, expert knowledge, and catchment
similarities; and (c) evaluation based on flow signatures
and performance metrics, using both multiple criteria and
multiple variables, and independent gauges for “blind tests”.
The results show that despite the strong physiographical gradient
over the subcontinent, a single model can describe the
spatial variability in dominant hydrological processes at the
catchment scale. In addition, spatial model deficiencies are
used to identify potential improvements of the model concept.
Eventually, through simultaneous calibration using numerous
gauges, the median Kling–Gupta efficiency for river
flow increased from 0.14 to 0.64. We finally demonstrate the
potential of multi-basin modelling for comparative hydrology
using PUB, by grouping the 6000 subbasins based on
similarities in flow signatures to gain insights into the spatial
patterns of flow generating processes at the large scale.
Basins (PUB) (2003–2012 by the IAHS) put considerable effort
into improving the reliability of hydrological models to
predict flow response in ungauged rivers. PUB’s collective
experience advanced hydrologic science and defined guidelines
to make predictions in catchments without observed
runoff data. At present, there is a raised interest in applying
catchment models to large domains and large data samples
in a multi-basin manner, to explore emerging spatial patterns
or learn from comparative hydrology. However, such modelling
involves additional sources of uncertainties caused by
the inconsistency between input data sets, i.e. particularly
regional and global databases. This may lead to inaccurate
model parameterisation and erroneous process understanding.
In order to bridge the gap between the best practices
for flow predictions in single catchments and multi-basins
at the large scale, we present a further developed and slightly
modified version of the recommended best practices for PUB
by Takeuchi et al. (2013). By using examples from a recent
HYPE (Hydrological Predictions for the Environment) hydrological
model set-up across 6000 subbasins for the Indian
subcontinent, named India-HYPE v1.0, we explore the PUB
recommendations, identify challenges and recommend ways
to overcome them. We describe the work process related to
(a) errors and inconsistencies in global databases, unknown
human impacts, and poor data quality; (b) robust approaches
to identify model parameters using a stepwise calibration approach,
remote sensing data, expert knowledge, and catchment
similarities; and (c) evaluation based on flow signatures
and performance metrics, using both multiple criteria and
multiple variables, and independent gauges for “blind tests”.
The results show that despite the strong physiographical gradient
over the subcontinent, a single model can describe the
spatial variability in dominant hydrological processes at the
catchment scale. In addition, spatial model deficiencies are
used to identify potential improvements of the model concept.
Eventually, through simultaneous calibration using numerous
gauges, the median Kling–Gupta efficiency for river
flow increased from 0.14 to 0.64. We finally demonstrate the
potential of multi-basin modelling for comparative hydrology
using PUB, by grouping the 6000 subbasins based on
similarities in flow signatures to gain insights into the spatial
patterns of flow generating processes at the large scale.
ArcAPEX is an ArcGIS-based user interface designed to automate the input parameterization of the Agricultural Policy Environmental eXtender (APEX) hydrologic/water quality model. The interface integrates topographic, land use, and soil... more
ArcAPEX is an ArcGIS-based user interface designed to automate the input parameterization of the Agricultural Policy Environmental eXtender (APEX) hydrologic/water quality model. The interface integrates topographic, land use, and soil spatial datasets and a built-in APEX-Parameters database that contains model parameter values required to simulate a wide range of plant growth, tillage, fertilizer, and pesticide applications over a farm/field to basin scale drainage area. Other key features of ArcAPEX include its ability to build and save alternative crop management operation schedules and options for integration directly with the Soil and Water Assessment Tool (SWAT) for large watershed simulations. The major components for the ArcAPEX interface are presented, including watershed delineation, analysis of land use and soils, weather data, input parameter definition, model run management, and SWAT model integration. An application of ArcAPEX, conducted to evaluate various agricultura...
Water flow and water quality changes in surface water bodies due to climate change is a major problem worldwide, typically in river ecosystems. To address these issues, proper monitoring of river flow variations and water quality is... more
Water flow and water quality changes in surface water bodies due to climate change is a major problem worldwide, typically in river ecosystems. To address these issues, proper monitoring of river flow variations and water quality is necessary, but daily monitoring and data collection is greatly time consuming and costly. Therefore, a study was done with the objectives to calibrate and validate the HEC-HMS 3.5 and HEC-RAS 4.1.0 models to simulate flow variation and water quality variations respectively in Nillambe Oya, Sri Lanka. The development of such models are a significant requirement in the present scientific world to predict river flow and water quality variations as an adaptation for the climate change. The HEC-HMS 3.5 model was used to generate flow which is needed for HEC-RAS 4.1.0. Daily flow data for five years (from October 1991 to September 1996) were used to calibrate the HEC-HMS 3.5 model and another set of daily flow data for five years (from October 1994 to September 1999) were used to validate the model. HEC-RAS 4.1.0 model was calibrated using water quality data collected and analyzed in five days. The validity of the calibrated model was evaluated using water quality data collected in the other four days. The calibrated and validated HEC-HMS 3.5 model reliably predicted the flow in Nillambe Oya. The calibrated and validated HEC-RAS 4.1.0 model simulated Dissolved Oxygen (DO), Biological Oxygen Demand (BOD) and Nitrate Nitrogen (NO 3-N) splendidly. Orthophosphates was also predicted reliably by the model, but the simulation of organic Phosphorus was not that sensible.
Mounding often occurs beneath engineering structures designed to infiltrate reuse water. AQTESOLV software and a spreadsheet solution for Hantush, together with soil moisture water balance (SWAGMAN farm model), were used for... more
Mounding often occurs beneath engineering structures designed to infiltrate reuse water. AQTESOLV software and a spreadsheet solution for Hantush, together with soil moisture water balance (SWAGMAN farm model), were used for quantitatively predicting the height and extent of groundwater mounding underground to assess the groundwater-flow simulations of infiltration from a hypothetical irrigation site. Horizontal and vertical permeability, aquifer thickness, specific yield, and basin geometry are among the aquifer and recharge properties inputs. For 2.2 ha sites, the maximum heights of the simulated groundwater mound ranges up to 0.29 m. The maximum areal extent of groundwater mounding measured from the edge of the infiltration basins of 0.24 m ranges from 0 to 75 m. Additionally, the simulated height and extent of the groundwater mounding associated with a hypothetical irrigation infiltration basin for 2.2 ha development may be applicable to sites of different sizes, using the recharge rate estimated from the SWAGMAN farm model. For example, for a 2.2 ha site with a 0.0002 m/day recharge rate, the irrigation infiltration basin design capacity (and associated groundwater mound) would be the same as for a 1.1 ha site with a 0.0004 m/day recharge rate if the physical characteristics of the aquifer are unchanged. The study claimed that the present modelling approach overcomes the complications of solving the Hantush equation for transient flow. The approach utilised in this study can be applied for other purposes such as measuring the feasibility of infiltrating water, attenuation zone, risk mitigation essential for decision-makers and planning regulators in terms of environmental effects and water use efficiency.
Los abanicos aluviales morfodinámicamente activos que han sido construidos por depósitos torrenciales, representan áreas altamente inestables, cuyas condiciones definen escenarios de amenaza para las poblaciones asentadas sobre ellos. Se... more
Los abanicos aluviales morfodinámicamente activos que han sido construidos por depósitos torrenciales, representan áreas altamente inestables, cuyas condiciones definen escenarios de amenaza para las poblaciones asentadas sobre ellos. Se consideró analizar los parámetros físicos y morfométricos de las cuencas de la vertiente norte de “El Ávila”, como controles sobre el desarrollo y la morfología de sus abanicos. La metodología comprendió: (a) caracterización de la morfología de los abanicos; (b) mediciones de la morfometría de las cuencas y de los abanicos; (c) construcción de perfiles de cauces principales sobre los abanicos, y perfiles topográficos de éstos; (e) estimación de las superficies de afloramientos litológicos en las cuencas; y (f) correlación entre parámetros morfométricos de los abanicos y de las cuencas. Los abanicos exhiben morfologías del tipo retrollenado desde el frente montañoso, con coalescencia en algunos sectores, y solapamiento en el caso del abanico Quebrada Seca sobre el abanico Punta El Caribe. Sus perfiles longitudinales y transversales muestran las típicas formas cóncava y convexa respectivamente, con ligeras variaciones en sus trazos. Se comportan de igual forma como abanicos-deltas, dado que parte de sus extensiones (depósitos) se encuentran bajo las aguas marinas. Son abanicos de pequeñas dimensiones (áreas entre 0,79 Km2 y 5,71 Km2) y pendientes longitudinales entre 1,67 % y 9,10 %. La litología predominante en cada cuenca, ejerce gran influencia en la morfología, desarrollo y extensión de su abanico. Los parámetros morfométricos de los abanicos de mejores correlaciones con los de las cuencas, son el área y la pendiente de atrincheramiento.
Fluoride levels higher than the World Health Organization (WHO) recommended levels of 1.5 mg/l have to raise serious health issues. Therefore fluoride contamination is a pertinent matter that calls for concern by all people and government... more
Fluoride levels higher than the World Health Organization (WHO) recommended levels of 1.5 mg/l have to raise serious health issues. Therefore fluoride contamination is a pertinent matter that calls for concern by all people and government especially in countries where the phenomenon of volcanicity has been experienced. The study sought to analyse the effects of geological variability and selected physical parameters of water quality on fluoride levels in River Njoro catchment. The study was guided by the following objectives; to determine the relationship between fluoride levels and surface geology in River Njoro catchment, to determine the relationship between borehole stratigraphy formation matrices and fluoride levels in borehole water in River Njoro catchment, determine the relationship between pH, temperature and Electrical conductivity and fluoride levels in groundwater in River Njoro catchment and finally model spatial variation and distribution of fluoride levels in ground water in the River Njoro catchment. The study sought to highlight the levels of fluoride and give recommendations on identification and delineation of potential sites for safe groundwater for the local population and advice on the water treatment and de fluoridation strategies. Past researches on River Njoro catchment gave much emphasis on land use/cover changes and strong condemnation on elevated fluoride levels in the Njoro catchment and therefore the gap in this research was based on the integration of geological variations and geological stratigraphy of River Njoro catchment and ultimately produce a predictive trend. This study adopted purposive longitudinal survey and quasi experimental research designs. In this research borehole and river water, soil and rock samples from designated points along the River Njoro and its tributaries were collected for laboratory analysis of fluoride levels. The research adopted descriptive and correlation statistical analysis. The sources of data included; field surveys which were used to collect data about the fluoride levels, the remotely sensed, GIS and Geostatistical interpolation, content analysis of the literature on the geology of the Njoro catchment and the hydro-meteorological and geological characteristics data. From the results of the study it was observed that; the fluoride levels in River Njoro catchment varied with the geology of the catchment and fluoride levels in groundwater depended on the borehole stratigraphy matrix, the selected physical parameters of water quality (pH, Electrical Conductivity and temperature) had a significant statistical relationship with fluoride levels in River Njoro catchment and land use/cover changes and variations in the borehole depths. The results through Geostatistical interpolation also observed that there is varied distribution and variation of fluoride levels in River Njoro catchment. Therefore geological variations, borehole depths and lithological formations were manifested in the fluoride level variations in the water and rock sampling points that were located either upstream, midstream and downstream of the River Njoro catchment. Finally the study recommends isotopic analysis of water samples from the sources of water in River Njoro catchment to assist in tracing their origin, contamination of fluoride and fluoride enrichment pathways and water quality alteration within the catchment.
Il rilievo dell’umidità degli strati più superficiali del suolo alla scala di campo, ossia in pixel di dimensioni nell’ordine degli ettari, è sempre più diffuso grazie alla disponibilità di sensori di ultima generazione. Tuttavia, le... more
Il rilievo dell’umidità degli strati più superficiali del suolo alla scala di campo, ossia in pixel di dimensioni nell’ordine degli ettari, è sempre più diffuso grazie alla disponibilità di sensori di ultima generazione. Tuttavia, le applicazioni di modelli di bilancio idrico del suolo richiedono la conoscenza della distribuzione dell’umidità del suolo riferite alla scala locale, ossia quella di un pixel di dimensioni nell’ordine di pochi metri quadrati. Questo studio esamina la possibilità di trasferire le informazioni sull’umidità del suolo dalla scala di campo alla scala locale con un approccio che associa un modello idrologico “a serbatoio” a di una tecnica fisicamente basta per il passaggio di scala. Il metodo proposto è meno impegnativo rispetto ai rilievi diretti poiché richiede solo la conoscenza di dati climatici (input del modello “a serbatoio”) e di dati topografici (input per il passaggio di scala spaziale). Per la fase di calibrazione sono state utilizzate misure di umidità del suolo in superficie eseguite con sonde TDR (Time Domain Reflectrometry). Il metodo messo a punto in questo studio è stato implementato in tre siti sperimentali italiani, caratterizzati da condizioni differenti sia climatiche sia topografiche. I confronti offrono interessanti spunti interpretativi poiché in questi siti le variazioni di umidità del suolo dipendono da indici topografici legati all’afflusso di acqua verso valle (sito nell’Italia settentrionale) oppure sono legati alle dinamiche idrologiche di versante dominate da processi evapotraspirativi (sito nell’Italia meridionale). Molto interessante è il caso del sito dell’Italia centrale in cui si riscontra una alternanza dei processi idrologici dominanti legati al deflusso laterale durante la stagione umida e alla radiazione solare durante la stagione secca. Tenendo conto di futuri cambiamenti climatici, l’instabilità temporale dei modelli di umidità del suolo rilevati in quest’ultimo sito può essere correlata all’indice di aridità stagionale.
Con base en eventos registrados de movimientos en masa y crecidas, ocurridos en la cuenca del río San Julián y activados por lluvias extraordinarias, se realizó una caracterización hidroclimatológica y morfométrica del sistema, como... more
Con base en eventos registrados de movimientos en masa y crecidas, ocurridos en la cuenca del río San Julián y activados por lluvias extraordinarias, se realizó una caracterización hidroclimatológica y morfométrica del sistema, como aporte a la evaluación de la amenaza hidrogeomorfológica. En la metodología se consideró la fotointerpretación geomorfológica, las mediciones y los cálculos de parámetros morfométricos, así como la estimación del tiempo de concentración, la caracterización del régimen pluviométrico y el análisis de eventos extremos de precipitación. La cuenca analizada es un sistema cuyas respuestas hidrológicas están determinadas por sus características morfométricas, lo cual se evidencia en su corto tiempo de concentración, debido a su ubicación en un ambiente montañoso, y a las magnitudes de los eventos extremos de precipitación.
The allocation of groundwater resources has been a challenge for many years due to its unforeseen side effect and lag time issues, which are often overlooked. The full impact of groundwater utilization/abstraction takes time to realize... more
The allocation of groundwater resources has been a challenge for many years due to its unforeseen side effect and lag time issues, which are often overlooked. The full impact of groundwater utilization/abstraction takes time to realize its effect at its full. In this paper, long‐term effects and groundwater dynamics were assessed using a water balance model and a time series analysis, respectively. Undeveloped groundwater systems are commonly found in a state of equilibrium, where, on average, equal amounts of water are recharged and discharged. A water budget is a static accounting of the state of the system at a given time, often before the system is developed. Water balance analysis was carried out together with the groundwater through flow, hydrograph, and surface‐groundwater interaction analysis (base flow index) to develop a conceptual water balance model, which is a very basic representation of a complex natural aquifer system and is instrumental to constrain and build a robust numerical model that can be readily justified and updated. A noble approach was employed to assess and constrain the discharge coming out of the model area to sustain the lake level, located to the north of the study area, using the whole lake catchment and lake water balance analysis. Based on the lake water balance, there is a deficit between input and output computation, and hence there should be a groundwater input to sustain the historical lake area. The analysis showed that the model area contributes 40% of the lake catchment, and hence the portion of the groundwater inflow feeding the lake was computed. This is one of the means to constrain the discharge, which adds more confidence to the recharge estimation. This is very important because the size of a sustainable groundwater development usually depends on how much of the discharge from the system can be captured by the development. Capture is independent of the recharge. Instead, it depends on the dynamic response of the aquifer system to the development. The idea that knowing the recharge is important in determining the size of a sustainable groundwater development is a myth and has no basis. The important entity in determining how a groundwater system reaches a new equilibrium is capture. How capture occurs in an aquifer system is a dynamic process. Following this study, lake water balance assessment was indirectly considered as prior information for the numerical model calibration of the discharge from the model area using a conductance parameter. Conductance is a key parameter to estimate the discharge volume together with the change in the simulated hydraulic head between time steps. The water balance error highlights which one is more sensitive, and this could help to assist in planning for future data collection/field work and where to invest the money. The water balance computation helps to figure out the degree of surface‐groundwater interaction, uncertainty, sensitive parameter, helps in the decision to invest time and money, and operates as a cross check with other analytical or numerical modelling.
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08”-10º36’23” LN y 66º57’38”-66º59’14” LO), en el sector centro occidental del estado Vargas (Venezuela). Este pequeño sistema... more
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08”-10º36’23” LN y 66º57’38”-66º59’14” LO), en el sector centro occidental del estado Vargas (Venezuela). Este pequeño sistema fue una de las más de veinte cuencas que se activaron hidromorfodinámicamente, como respuesta a las excepcionales precipitaciones ocurridas en Diciembre de 1999, en el Litoral Central de Venezuela. Es por ello que el propósito de este trabajo es, analizar e interpretar la dinámica hidrogeomorfológica de la microcuenca de drenaje de la quebrada Curucutí, en términos del control que ejercen sus parámetros morfométricos en las características de la respuesta hidrológica. La metodología comprendió: (a) Cálculos y mediciones de parámetros morfométricos de la microcuenca y de su red de drenaje, con apoyo en cartas topográficas del área a escalas 1:5.000 y 1:10.000, y ortofotomapa a escala 1:25.000; (b) cálculo del tiempo de concentración de la microcuenca, y de la velocidad media del flujo; y (c) estimación de los hidrogramas unitarios y caudales pico de crecientes. También se realizó un trabajo de campo, para medir el ancho de la sección hidráulica de interés (ápice del abanico). La microcuenca de drenaje de la quebrada Curucutí, es un sistema hidrogeomorfológico cuya respuesta hidrológica está determinada por la pequeña área del mismo, fuertes pendientes en las vertientes y cauces del sector montañoso, la densidad de drenaje media, el orden 5 de la microcuenca, una relación de bifurcación media de 3,73, alta torrencialidad, las dimensiones de las tormentas y la intensidad y duración de las lluvias. En breves palabras, la respuesta hidrológica de la microcuenca, es condicionada y controlada por las características morfométricas del sistema y de su red de drenaje. Los cortos tiempos de concentración, así como las magnitudes estimadas de los caudales pico de crecientes y los picos y tiempos al pico de los hidrogramas unitarios obtenidos, corroboran la influencia que ejercen las características fisiográficas de la microcuenca y la estructura de la red de drenaje, en las respuestas rápidas y violentas del sistema. Ello definen escenarios críticos de inundaciones, para eventos de períodos de retorno de 50, 100 y 500 años principalmente, y en el peor de los casos de 1000 años. Este trabajo aporta elementos de gran importancia para la concepción y/o reevaluación de ser el caso, del diseño hidráulico e hidrológico de estructuras para el control de crecientes y de sedimentos, así como para el análisis, evaluación y zonificación de la amenaza por inundaciones, y el diseño de sistemas de alertas tempranas.
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08"-10º36’23" LN y 66º57’38"-66º59’14" LO), en el sector centro occidental del estado Vargas (Venezuela). Este sistema fue una de... more
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08"-10º36’23" LN y 66º57’38"-66º59’14" LO), en el sector centro occidental del estado Vargas (Venezuela). Este sistema fue una de las más de veinte cuencas que se activaron hidromorfodinámicamente, como respuesta a las excepcionales precipitaciones ocurridas en Diciembre de 1999, en el Litoral Central de Venezuela. Es por ello que el propósito de este trabajo es, analizar e interpretar la dinámica hidrogeomorfológica de la microcuenca de drenaje de la quebrada Curucutí, en términos del control que ejercen sus parámetros morfométricos en las características de la respuesta hidrológica. La metodología comprendió: (a) cálculos y mediciones de parámetros morfométricos; (b) cálculo del tiempo de concentración; y (c) estimación de los hidrogramas unitarios y caudales pico de crecientes. La microcuenca de drenaje de la quebrada Curucutí, es un sistema hidrogeomorfológico cuya respuesta hidrológica está determinada por la pequeña área del mismo, fuertes pendientes en las vertientes y cauces del sector montañoso, la densidad de drenaje media, el orden 5 de la microcuenca, una relación de bifurcación media de 3,73, alta torrencialidad, las dimensiones de las tormentas y la intensidad y duración de las lluvias. Los cortos tiempos de concentración, así como las magnitudes estimadas de los caudales pico de crecientes y los picos y tiempos al pico de los hidrogramas unitarios obtenidos, corroboran la influencia que ejercen las características fisiográficas de la microcuenca y la estructura de la red de drenaje, en las respuestas rápidas y violentas del sistema. Ello define escenarios críticos de inundaciones, para eventos de períodos de retorno de 50, 100 y 500 años principalmente, y en el peor de los casos de 1000 años, para lluvias de 1 hora de duración.
A method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a " node " representing the groundwater component is employed in a spreadsheet of water... more
A method is presented to analyze the interaction between groundwater and Lake Linlithgow (Australia) as a case study. A simplistic approach based on a " node " representing the groundwater component is employed in a spreadsheet of water balance modeling to analyze and highlight the effect of groundwater on the lake level over time. A comparison is made between the simulated and observed lake levels over a period of time by switching the groundwater " node " on and off. A bucket model is assumed to represent the lake behavior. Although this study demonstrates the understanding of Lake Linlithgow's groundwater system, the current model reflects the contemporary understanding of the local groundwater system, illustrates how to go about modeling in data‐scarce environments, and provides a means to assess focal areas for future data collection and model improvements. Results show that this approach is convenient for getting first‐hand information on the effect of groundwater on wetland or lake levels through lake water budget computation via a node representing the groundwater component. The method can be used anywhere and the applicability of such a method is useful to put in place relevant adaptation mechanisms for future water resources management, reducing vulnerability and enhancing resilience to climate change within the lake basin.
Catchment flood response consists of multiple components of flow generated by the heterogeneity of catchment surface. This study proposes an analytical framework built upon the Viglione et al. (2010a) to assess the dependence of catchment... more
Catchment flood response consists of multiple components of flow generated by the heterogeneity of catchment surface. This study proposes an analytical framework built upon the Viglione et al. (2010a) to assess the dependence of catchment flood response on different flow components. The analytical framework is compared to simulations from a distributed hydrologic model. A large number of rainfall-runoff events from three catchments 5 of Tar River basin in North Carolina are used to illustrate the analytical framework. Specifically, the framework is used to estimate three flood events characteristics (cumulative runoff volume, centroid and spreadness of hydrograph) through three corresponding framework parameters: the rainfall excess and the mean and variance of catchment response time. Results show that under the smooth topographic setups of the study area, the spatial and/or temporal correlation between rainfall and runoff generation are insignificant to flood response; delay in 10 flood response due to runoff generation and routing are of equal importance; the shape of flood is mainly controlled by the variability in runoff generation stage but with non-negligible contribution from the runoff routing stage. Sensitivity tests show that the framework's main error source is the systematic underestimation of flood event's centroid and spreadness, while the random error is relatively low.
La microcuenca de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08” – 10º36’23” LN y 66º57’38” – 66º59’14” LO), en el sector centro occidental del estado Vargas. El propósito de este trabajo es determinar... more
La microcuenca de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08” – 10º36’23” LN y 66º57’38” – 66º59’14” LO), en el sector centro occidental del estado Vargas. El propósito de este trabajo es determinar e interpretar los parámetros morfométricos de la microcuenca de la quebrada Curucutí, en términos del comportamiento de su red de drenaje y evolución geomorfológica. La metodología se basó en los cálculos y mediciones de los parámetros morfométricos, con apoyo en cartas topográficas del área a escalas 1:5.000 y 1:10.000, y se complementó con visitas de campo. Esta microcuenca presenta una red de drenaje constituida por cursos de agua de cortos recorridos y régimen efímero, que en conjunto exhiben un patrón de drenaje de tipo dendrítico y de textura gruesa, que denotan el control de la litología, las estructuras geológicas, la vegetación y el suelo sobre los procesos morfodinámicos de las vertientes, y determinan una densidad de drenaje baja (6,09 Km/Km2). La pendiente media es de 16,25 %. De acuerdo con la curva hipsométrica de la microcuenca, se pudo establecer que ésta se encuentra en un estadio erosional maduro, lo cual se complementa con el índice de concavidad (0,37) del perfil longitudinal del cauce de la quebrada Curucutí, que expresa un avanzado estadio de erosión vertical. Los resultados obtenidos de la jerarquización de los cursos de agua de la red de drenaje, muestran que ésta es de 4to orden, con relación de bifurcación media de 4,69, relación de longitud media de 2,58 y relación de área media de subcuencas de 5,43.
Entre otros diversos aspectos, el evento de aludes torrenciales de Diciembre de 1999 evidenció a partir de los volúmenes de sedimentos depositados por éstos y la severidad de los daños causados, con diferencias notorias entre distintos... more
Entre otros diversos aspectos, el evento de aludes torrenciales de Diciembre de 1999 evidenció a partir de los volúmenes de sedimentos depositados por éstos y la severidad de los daños causados, con diferencias notorias entre distintos sectores del litoral varguense afectado, que existen elementos del medio físico que controlan las características y magnitudes de las respuestas hidrológicas de las cuencas de drenaje. Es por ello que el propósito de este trabajo se centra en el análisis e interpretación de los parámetros morfométricos (geomorfometría) de las cuencas y redes de drenaje de un sector de la vertiente norte del macizo “El Ávila” (estado Vargas, Venezuela), en términos de sus incidencias e implicaciones en las dinámicas hidrológica y geomorfológica de los sistemas estudiados. La metodología consistió básicamente en estimaciones, mediciones y cálculos de los parámetros morfométricos de las cuencas y sus redes de drenaje sobre la cartografía base digitalizada del sector de estudio seleccionado, con apoyo en la herramienta para SIG software ArcGIS 9.2 y sus módulos Spatial Analysis y ArcHydro y el software Microsoft Excel. Se realizó un análisis descriptivo de los datos de los parámetros morfométricos, cuyos estadísticos fueron estimados con el complemento Xlstat de Microsoft Excel. Estos sistemas hidrogeomorfológicos califican en la categoría de microcuencas debido a sus pequeñas dimensiones, son espacios topográficamente muy accidentados de fuertes pendientes y grandes desniveles altitudinales, y corresponden a sistemas de morfologías planimétricas semi-circulares a semi-alargadas. Las cuencas de drenaje estudiadas albergan redes de desagüe de ramificaciones y densidades considerables con cortas longitudes y canales de escasa sinuosidad (rectilíneos), que se corresponden con sistemas de altas magnitudes y órdenes, así como elevados niveles de torrencialidad. En síntesis, las respuestas morfodinámicas e hidrológicas de las cuencas estudiadas son condicionadas y controladas por sus parámetros morfométricos y los de sus redes de drenaje.
Entre las causas naturales que determinan condiciones de inestabilidad y, en consecuencia, detonan la activación de deslizamientos en los sectores de colinas en la ciudad de Portoviejo, tenemos: (a) una litología predominantemente... more
Entre las causas naturales que determinan condiciones de inestabilidad y, en consecuencia, detonan la activación de deslizamientos en los sectores de colinas en la ciudad de Portoviejo, tenemos: (a) una litología predominantemente arcillosa (arcillas expansivas y limos) muy sensible a los procesos meteóricos y erosivos; (b) suelos de escaso desarrollo vertical con altas tasas de saturación durante los períodos de lluvia; (c) las formas de las laderas y sus altas pendientes ( 15°-30°); (d) períodos de lluvias con eventos de alta intensidad; (e) la sismicidad y, además, (f) una pronunciada intervención antrópica sobre un medio físico muy frágil. A pesar de ello, no existe información temática a escala de detalle de las variables del medio físico que condicionan la ocurrencia de deslizamientos en el sector de colinas San Pablo – Francisco Pacheco. De allí la necesidad de evaluar su susceptibilidad a estos procesos mediante la cuantificación de indicadores morfométricos de las microcuencas desarrolladas en esas colinas, a fin de obtener criterios que permitan discriminar niveles cuali-cuantitativos de sensibilidad entre sistemas de drenaje tan pequeños. La metodología de trabajo contempló: (a) elaboración de capas temáticas para el área de estudio, a partir de shapefiles obtenidos de los geoportales del MAE, IEE e IGM, con apoyo en el software ArcGIS; (b) procesamiento de un modelo digital de elevación (MDE) con el software ArcGIS, cuya imagen en formato raster (resolución 3 m) fue descargada del geoportal del IGM; (c) delimitación de las microcuencas y mediciones de sus parámetros morfométricos básicos con la herramienta Hydrology de ArcGIS; (d) cálculo de otros parámetros morfométricos de las microcuencas, empleando hojas de cálculo del software Microsoft Excel y; (e) elaboración de una matriz de ponderación cuali-cuantitativa de las variables e indicadores morfométricos intervinientes en la susceptibilidad a los deslizamientos. Los resultados indican una secuencia de microcuencas con geometrías correspondientes a sistemas hidrológicos muy pequeños, en su mayoría, de formas alargadas y, otras, de formas más circulares, con pendientes altas en sus laderas y densidades de drenaje de mediana a alta. El cruce matricial de variables del medio físico e indicadores morfométricos, han permitido obtener una ponderación o asignación de pesos a cada uno de los criterios. La cuantificación de las variables e indicadores (pesos) en cada una de las microcuencas del área de estudio, permitió obtener una primera aproximación de niveles de susceptibilidad a deslizamientos en esos microsistemas.
Los abanicos aluviales morfodinámicamente activos que han sido construidos por depósitos torrenciales, representan áreas altamente inestables y de amenaza para las poblaciones asentadas sobre ellos. Se analizan las características... more
Los abanicos aluviales morfodinámicamente activos que han sido construidos por depósitos torrenciales, representan áreas altamente inestables y de amenaza para las poblaciones asentadas sobre ellos. Se
analizan las características geomorfológicas de los abanicos del piedemonte norte del macizo El Ávila. La metodología consideró: caracterización de a morfología de los abanicos; mediciones morfométricas de las cuencas y abanicos; estimación de superficies de afloramientos litológicos; y correlación entre parámetros morfométricos de abanicos y cuencas de drenaje. Exhiben morfologías del tipo retrollenado con coalescencia en algunos. Sus perfiles longitudinales y transversales muestran las típicas formas cóncava y convexa. Se comportan de igual forma como abanicosdeltas, parte de sus extensiones se encuentran bajo las aguas marinas. Son abanicos de pequeñas dimensiones y pendientes bajas. La litología ejerce gran influencia sobre la morfología, desarrollo y extensión de éstos, aspectos vinculados de igual manera con la morfometría de las cuencas de drenaje.
analizan las características geomorfológicas de los abanicos del piedemonte norte del macizo El Ávila. La metodología consideró: caracterización de a morfología de los abanicos; mediciones morfométricas de las cuencas y abanicos; estimación de superficies de afloramientos litológicos; y correlación entre parámetros morfométricos de abanicos y cuencas de drenaje. Exhiben morfologías del tipo retrollenado con coalescencia en algunos. Sus perfiles longitudinales y transversales muestran las típicas formas cóncava y convexa. Se comportan de igual forma como abanicosdeltas, parte de sus extensiones se encuentran bajo las aguas marinas. Son abanicos de pequeñas dimensiones y pendientes bajas. La litología ejerce gran influencia sobre la morfología, desarrollo y extensión de éstos, aspectos vinculados de igual manera con la morfometría de las cuencas de drenaje.
Los aludes ocurridos en Diciembre de 1999 en el estado Vargas, y el deslizamiento generado (2010) en el sector La Chara (San Julián, parroquia Caraballeda), dejó en evidencia la susceptibilidad del medio físico en la cuenca del río San... more
Los aludes ocurridos en Diciembre de 1999 en el estado Vargas, y el deslizamiento generado (2010) en el sector La Chara (San Julián, parroquia Caraballeda), dejó en evidencia la susceptibilidad del medio físico en la cuenca del río San Julián a los movimientos en masa, por lo que es necesario evaluar la amenaza hidrometeorológica en este sistema. La metodología comprendió: (a) interpretación geomorfológica del área; (b) mediciones y cálculos de parámetros morfométricos; (c) estimación del tiempo de concentración; (d) caracterización del régimen pluviométrico; y (e) análisis de eventos extremos de precipitación. La cuenca de la quebrada San Julián es un sistema cuyas respuestas hidrológicas están determinadas por su pequeña área, fuertes pendientes, densidad de drenaje media a alta, orden 5 de la cuenca, relación de bifurcación media de 4,36, alta torrencialidad, las dimensiones de las tormentas y la intensidad y duración de las lluvias. El corto tiempo de concentración corrobora el control de la morfometría del sistema en las respuestas hidrológicas. Para escenarios críticos de crecidas de 50, 100, 500 y 1000 años de período de retorno con duración de 1 hora, las intensidades corresponden a valores de 66,30 mm/h, 74,81 mm/h, 94,48 mm/h y 102,94 mm/h respectivamente, mientras que para lluvias de 24 horas de duración, los valores son de 5,79 mm/h, 6,52 mm/h y 8,21 mm/h respectivamente. La precipitación máxima probable estimada arrojó valores de 127,94 mm para un evento con una duración de 1 hora, y de 269,73 para un evento con una duración de 24 horas.
La microcuenca de la quebrada Curucutí se ubica en la vertiente norte del macizo del Ávila (10º33’08” – 10º36’23” LN y 66º57’38” – 66º59’14” LO), en el sector centro occidental del estado Vargas. El propósito de este trabajo es determinar... more
La microcuenca de la quebrada Curucutí se ubica en la vertiente norte del macizo del Ávila (10º33’08” – 10º36’23” LN y 66º57’38” – 66º59’14” LO), en el sector centro occidental del estado Vargas. El propósito de este trabajo es determinar e interpretar los parámetros morfométricos de la microcuenca de la quebrada Curucutí, en términos de su incidencia en el comportamiento y respuesta hidrológica del sistema, y en su potencial morfodinámico. La metodología se basó en los cálculos y mediciones de los parámetros morfométricos, con apoyo en cartas topográficas del área a escalas 1:5.000 y 1:25.000. Los resultados indican que esta microcuenca es un sistema hidrogeomorfológico, cuyas respuestas morfodinámica e hidrológica están determinadas por la pequeña área del mismo, fuertes pendientes en las vertientes y cauces del sector montañoso, la densidad de drenaje media, el orden 4 de la red de drenaje, una relación de bifurcación media de 4,69, alta torrencialidad, las dimensiones de las tormentas y la intensidad y duración de las lluvias.
El propósito de este trabajo es evaluar la amenaza hidrogeomorfológica en las microcuencas de las quebradas Catuche, Anauco y Gamboa y del río Cotiza, y en particular la generación de crecidas torrenciales. La metodología comprendió:... more
El propósito de este trabajo es evaluar la amenaza hidrogeomorfológica en las microcuencas de las quebradas Catuche, Anauco y Gamboa y del río Cotiza, y en particular la generación de crecidas torrenciales. La metodología comprendió: Interpretación geomorfológica, mediciones y cálculos de parámetros morfométricos de las microcuencas y sus redes de drenaje; estimación de los tiempos de concentración de las microcuencas y velocidad promedio del flujo; caracterización del régimen pluviométrico; análisis de eventos extremos y estimación de caudales picos de crecientes. Las respuestas hidrológicas rápidas y violentas (crecidas torrenciales), así como las características de los hidrogramas resultantes, y las magnitudes de los caudales pico de las crecientes, están controladas y condicionadas por las magnitudes de sus parámetros morfométricos, las dimensiones de las tormentas que afectan el área, y la intensidad y duración de las lluvias, en particular vinculadas a eventos extremos.
El propósito fundamental de este estudio es caracterizar y analizar algunos aspectos del clima y la hidrología de la cuenca de la quebrada Charallave, la cual se localiza en la parte suroccidental del estado Miranda (10°08'15" - 10°18'20"... more
El propósito fundamental de este estudio es caracterizar y analizar algunos aspectos del clima y la hidrología de la cuenca de la quebrada Charallave, la cual se localiza en la parte suroccidental del estado Miranda (10°08'15" - 10°18'20" LN y 66°46'25" - 66°58'05" LO). La metodología de trabajo se basó en el análisis y tratamiento de datos de precipitación correspondientes a las estaciones Cúa-Tovar, Tumuza, Charallave y Paracotos, y datos de temperatura, evaporación y humedad relativa de la estación Cúa-Tovar. Las precipitaciones en el área presentan patrones de distribución anual de tipo unimodal, cuya distribución en la cuenca es una función de la altitud, la topografía y la dirección de los vientos Alisios. La precipitación media de la cuenca es de 914,0 mm. La probabilidad de ocurrencia de precipitaciones en el área que superen un monto de 1.600 mm es de 3 %. El déficit hídrico promedio es de 836,8 mm, el escurrimiento medio promedio es de 121,5 mm, y el coeficiente de escurrimiento promedio es de 12,74 %.
Ancestral Pueblo communities of the central Mesa Verde region (CMVR) became increasingly reliant on agriculture for their subsistence needs during Basketmaker III (BMIII) through Terminal Pueblo III (TPIII) (AD 600–1300) periods.... more
Ancestral Pueblo communities of the central Mesa Verde region (CMVR) became increasingly reliant on agriculture for their subsistence needs during Basketmaker III (BMIII) through Terminal Pueblo III (TPIII) (AD 600–1300) periods. Researchers have been studying the Ancestral Pueblo people for over a century using a variety of methods to understand the relationships between climate, agriculture, population, and settlement patterns. While these methods and research have produced a well-developed cultural history of the region, studies at a smaller scale are still needed to understand the changes in farming behavior and the distribution of individual sites across the CMVR. Soil moisture is the limiting factor for crop growth in the semi-arid region of the Goodman Watershed in the CMVR. Thus, I constructed the soil moisture proxy model (SMPM) that is on a local scale and focuses on variables relevant to soil moisture – soil particle-size, soil depth, slope, and aspect. From the SMPM output, the areas of very high soil moisture are assumed to represent desirable farmland locations. I describe the relationship between very high soil moisture and site locations, then I infer the relevance of that relationship to settlement patterns and how those patterns changed over time (BMIII – TPIII). The results of the model and its application help to clarify how Ancestral Pueblo people changed as local farming communities. The results of this study indicates that farmers shifted away from use of preferred farmland during Terminal Pueblo III, which may have been caused by other cultural factors. The general outcome of this thesis is an improved understanding of human-environmental relationships on the local landscape in the CMVR.
Debris flows are a moving mass composed from water and solids mixture, mainly in form of sediments, with a high destructive power. The debris volume that is transported and deposited outside the drainage system of a watershed has a great... more
Debris flows are a moving mass composed from water and solids mixture, mainly in form of sediments, with a high destructive power. The debris volume that is transported and deposited outside the drainage system of a watershed has a great importance in the definition of its hydrological response. The objective of this work was to propose predictive models generated through the adjustment of multivariate statistical techniques, to estimate the sediment volumes deposited by debris flows. Measurements and calculations of the morphometric parameters of the watersheds and drainage networks have been performed with the support of GIS software and spreadsheets. The relationships between morphometric parameters and sediment volumes have been analyzed by applying multivariate statistical techniques such as linear correlation analysis. The principal component analysis and multiple linear regression analysis have been performed with principal components, which allowed the generation of predictive models. From the predictive models generated for the sediment volumes deposited by the debris flow event of December 1999, raised results closer to reality with better Pearson's correlation coefficients from those related to the gradient and shape of the watershed relief and extension of the drainage network morphometric variables. For the estimation of deposited sediment volumes due pre-and post-1999 event conditions, only the predictive models generated with the gradient and shape of the watershed relief variable have had good results.
A 46 year period (1961 to 2006) long-term sediment yield in Kinta River basin, Perak was analysed for its trends. The dynamic changes of sediment yield were based on total annual sediment discharge from seven hydrological stations... more
A 46 year period (1961 to 2006) long-term sediment yield in Kinta River basin, Perak was analysed for its trends. The dynamic changes of sediment yield were based on total annual sediment discharge from seven hydrological stations monitored by the Department of Irrigation & Drainage (DID) Malaysia in Kinta River basin. Descriptive analysis and Mann-Kendall test was used to analyse sediment yield trends. The findings show that long-term annual sediment yield in the Sungai Kinta basin is 2417.6 t/km 2 /year (1961-2006) with maximum annual sediment yield was recorded in 1973 (8,757.3 t/km 2 /year) and minimum in 2005 (720.4 t/km 2 /year). The Mann-Kendall test showed that long-term trend of sediment yield in the Kinta River basin is decreased by S=-303 and significant (P<0.01). The 46-year sediment record analyses were subdivided into four based on the trend of sediment. The period of 1970-1985 show the highest average sediment yield that is 4,062 t/km 2 /year. High total sediment yield during this period clearly demonstrate that the rapid development processes in the drainage basin has occurred, these are due to initial implementation of the New Economic Policy (NEP) and the Green Book Plan in which large forest areas have been transformed into agricultural, urban areas were expanded as well as infrastructure improvements. Apart from this, an aggressive tin mining activity in the 70's has contributed in increasing sediment yield into the Kinta River basin. The situation clearly shows that the sediment yield into the basin was contributed by various anthropogenic activities although sediment yield indicate downward trend. Thus, relevant management measures are needed due to the fact that sediment yield is a key indicator for declining water quality and the Kinta River is the main source of water supply in the catchment.
Groundwater from a shallow unconfined aquifer at a site in coastal New South Wales has been causing recent water logging issues. A trend of rising groundwater level has been anecdotally observed over the last 10 years. It was not clear... more
Groundwater from a shallow unconfined aquifer at a site in coastal New South Wales has been causing recent water logging issues. A trend of rising groundwater level has been anecdotally observed over the last 10 years. It was not clear whether the changes in groundwater levels were solely natural variations within the groundwater system or whether human interference was driving the level up. Time series topographic images revealed significant surrounding land use changes and human modification to the environment of the groundwater catchment. A statistical model utilising HARTT (multiple linear regression hydrograph analysis method) simulated the groundwater level dynamics at five key monitoring locations and successfully showed a trend of rising groundwater level. Utilising hydrogeological input from field investigations the model successfully simulated the rise in the water table over time to the present day levels, whilst taking into consideration rainfall and land changes. The underlying geological / land conditions were found to be just as significant as the impact of climate variation. The correlation coefficient for the monitoring bores, excluding MB4, show that the groundwater level fluctuation can be explained by the climate variable (rainfall) with the lag time between the atypical rainfall and groundwater level ranging from 4 to 7 months. The low R2 value for MB4 indicates that there are factors missing in the model which are primarily related human interference. The elevated groundwater levels in the affected area are the result of long term cumulative land use changes, instigated by humans, which have directly resulted in detrimental changes to the groundwater aquifer properties.
URL:
https://onlinelibrary.wiley.com/doi/abs/10.2175/106143017X14839994523785
URL:
https://onlinelibrary.wiley.com/doi/abs/10.2175/106143017X14839994523785
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08”-10º36’23” LN y 66º57’38”-66º59’14” LO), en el sector centro occidental del estado Vargas (Venezuela). Este pequeño sistema... more
La microcuenca de drenaje de la quebrada Curucutí se ubica en la vertiente norte del Macizo del Ávila (10º33’08”-10º36’23” LN y 66º57’38”-66º59’14” LO), en el sector centro occidental del estado Vargas (Venezuela). Este pequeño sistema fue una de las más de veinte cuencas que se activaron hidromorfodinámicamente, como respuesta a las excepcionales precipitaciones ocurridas en Diciembre de 1999, en el Litoral Central de Venezuela. Es por ello que el propósito de este trabajo es, analizar e interpretar la dinámica hidrogeomorfológica de la microcuenca de drenaje de la quebrada Curucutí, en términos del control que ejercen sus parámetros morfométricos en las características de la respuesta hidrológica. La metodología comprendió: (a) Cálculos y mediciones de parámetros morfométricos de la microcuenca y de su red de drenaje, con apoyo en cartas topográficas del área a escalas 1:5.000 y 1:10.000, y ortofotomapa a escala 1:25.000; (b) cálculo del tiempo de concentración de la microcuenca, y de la velocidad media del flujo; y (c) estimación de los hidrogramas unitarios y caudales pico de crecientes. También se realizó un trabajo de campo, para medir el ancho de la sección hidráulica de interés (ápice del abanico). La microcuenca de drenaje de la quebrada Curucutí, es un sistema hidrogeomorfológico cuya respuesta hidrológica está determinada por la pequeña área del mismo, fuertes pendientes en las vertientes y cauces del sector montañoso, la densidad de drenaje media, el orden 5 de la microcuenca, una relación de bifurcación media de 3,73, alta torrencialidad, las dimensiones de las tormentas y la intensidad y duración de las lluvias. En breves palabras, la respuesta hidrológica de la microcuenca, es condicionada y controlada por las características morfométricas del sistema y de su red de drenaje. Los cortos tiempos de concentración, así como las magnitudes estimadas de los caudales pico de crecientes y los picos y tiempos al pico de los hidrogramas unitarios obtenidos, corroboran la influencia que ejercen las características fisiográficas de la microcuenca y la estructura de la red de drenaje, en las respuestas rápidas y violentas del sistema. Ello definen escenarios críticos de inundaciones, para eventos de períodos de retorno de 50, 100 y 500 años principalmente, y en el peor de los casos de 1000 años. Este trabajo aporta elementos de gran importancia para la concepción y/o reevaluación de ser el caso, del diseño hidráulico e hidrológico de estructuras para el control de crecientes y de sedimentos, así como para el análisis, evaluación y zonificación de la amenaza por inundaciones, y el diseño de sistemas de alertas tempranas.
Increasing pressures on water quality due to intensification of agriculture have increased the need for environmental modelling to accurately simulate the movement of diffuse (nonpoint) nutrients in catchments. As hydrological flows drive... more
Increasing pressures on water quality due to intensification of agriculture have increased the need for environmental modelling to accurately simulate the movement of diffuse (nonpoint) nutrients in catchments. As hydrological flows drive the movement and attenuation of nutrients, individual hydrological processes in models should be adequately represented for water quality simulations to be meaningful. In particular, the relative contribution of groundwater and surface runoff to rivers is of interest, as, for example, higher nitrate concentrations in surface waters are strongly linked to catchments with proportionately larger groundwater contributions to the river. In this study, uncertainty analysis was used to investigate parameter sensitivities and flow partitioning of three conceptual hydrological models simulating 31 Irish catchments. We compared two established conceptual hydrological models (NAM and SMARG) and a new model (SMART), produced especially for water quality modelling. In addition to the criteria that assess streamflow simulations, a ratio of average groundwater contribution to total streamflow was calculated for all simulations over the 16 year study period. As measured time-series of groundwater contributions to streamflow are not available at catchment scale, the groundwater ratios were evaluated against average annual indices of base flow (from the OPW) and estimates of deep groundwater flow (from the Geological Survey of Ireland) for each catchment. The exploration of sensitivities of internal flow path partitioning was a specific focus to assist in evaluating model performances. Results highlight that model structure has a strong impact on simulated groundwater flow path contributions. Sensitivities to the internal pathways in the models are not reflected in the usual (flood forecasting) performance criteria results. This demonstrates that simulated groundwater contribution should be constrained by independent data to ensure results within realistic bounds if such models are to be used in the broader environmental sustainability decision making context.
The genetic diversity of feral and ranch American mink was studied in order to detect gene flux among rivers, investigate the processes of invasion, and determine the possible effects of river barriers. Tissue samples of 78 feral American... more
The genetic diversity of feral and ranch American mink was studied in order to detect gene flux among rivers, investigate the processes of invasion, and determine the possible effects of river barriers. Tissue samples of 78 feral American mink from 5 different river catchments and 18 ranch mink, collected between 2007 and 2011 in Biscay, northern Spain, were genotyped at 21 microsatellite loci. Lack of genetic differentiation of feral mink among the sites and high differentiation between feral and ranch mink was suggested. These results confirm that the mink population established on Butrón River at the beginning of the 1990s may be the origin of almost all the feral mink population within the study area. Additionally, the occurrence of American and European mink was used to analyse the effect of fragmentation on the population viability. The size and composition of the home range of male European mink was considered to model minimum viable units for presence/absence. Forty-two minimum viable units were randomly distributed among rivers in order to analyse the effect of fragmentation on mink occurrence. Barriers were mapped and classified as slight, moderate or absolute, depending on the effect on mink movement, and were introduced into the models. The presence of European and American mink depended on the non-fragmented main river stretches and the number of tributaries free from barriers. Results showed that fragmented rivers can be temporarily occupied but the likelihood of death means that these areas are only sink patches for mink.
- by Andrzej Zalewski and +1
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- Conservation, Gene Flow, Ecology, Invasive Species
Las características morfológicas del relieve y la cuantificación morfométrica de sus magnitudes son elementos esenciales para la interpretación de la influencia de este en la dinámica hidrogeomorfológica de cuencas de drenaje en ambientes... more
Las características morfológicas del relieve y la cuantificación morfométrica de sus magnitudes son elementos esenciales para la interpretación de la influencia de este en la dinámica hidrogeomorfológica de cuencas de drenaje en ambientes montañosos. Por ello, es propósito fundamental de esta investigación analizar cuantitativamente los rasgos del relieve en cuencas de la vertiente norte del macizo “El Ávila” (estado Vargas, Venezuela) y su incidencia en el comportamiento hidrogeomorfológico de ellas. La metodología consistió en la caracterización geomorfológica del área; mediciones y cálculos de parámetros morfométricos del relieve; análisis estadístico descriptivo de estos parámetros; análisis de correlación lineal entre ellos y análisis de sus componentes principales. Las cuencas estudiadas categorizan como microcuencas de carácter exorreico, en las que se distinguen un área de recepción, un canal de desagüe principal y abanicos aluviales. Los ríos y quebradas principales de los sistemas son de cortos recorridos, con fuertes cambios en sus gradientes topográficos. En general, se observan muy bajas correlaciones entre los parámetros morfométricos del relieve. Los parámetros morfométricos con mayor peso sobre la dinámica hidrogeomorfológica de las cuencas están representados por: pendiente media del relieve, altitud máxima, relieve máximo, concavidad del perfil longitudinal de la corriente principal y altitud de la naciente.
The hydrological component of the soil and water assessment tool (SWAT) model is adapted for two Ethiopian catchments based on primary knowledge of the coherence spectrum between rainfall and stream flow data. Spectrum analysis using the... more
The hydrological component of the soil and water assessment tool (SWAT) model is adapted for two Ethiopian catchments based on primary knowledge of the coherence spectrum between rainfall and stream flow data. Spectrum analysis using the available nearby climatic data is made to limit the temporal and spatial scales (inverse rate coefficients) subject to the calibration of compartmentalized runoff models. The exclusion of unwarranted time scales in the calibration implies that the model efficiency (r2 values) decrease only moderately between calibration and validation, and the optimization is focused on warranted problems. On the basis of the available data for the two Ethiopian catchments, the implication is that only periods longer than about 50 days can be reliably evaluated in the model. The model structure of SWAT for the surface runoff and groundwater flow response is modified to make the time scales consistent with the results of the spectrum analysis. An optimization algorithm is developed to constrain and combine the model parameters with the spectrum analysis results. Copyright © 2009 John Wiley & Sons, Ltd.
Las intensas y prolongadas precipitaciones registradas durante los días 14, 15 y 16 de Diciembre de 1999 que afectaron principalmente la vertiente norcaribeña de la Serranía del Ávila, constituyeron el efecto “gatillo” que determinó el... more
Las intensas y prolongadas precipitaciones registradas durante los días 14, 15 y 16 de Diciembre de 1999 que afectaron principalmente la vertiente norcaribeña de la Serranía del Ávila, constituyeron el efecto “gatillo” que determinó el umbral de activación de los excepcionales aludes torrenciales, generados por la inestabilidad de los materiales del manto de alteración en las vertientes debido a la sobresaturación de agua en éstos, así como de los sedimentos depositados en los cauces de los ríos y quebradas por la rápida y efectiva concentración de los flujos superficiales. Por ello, el objetivo fundamental del presente trabajo es identificar, caracterizar y analizar los factores físico-naturales y biológicos, cuya interrelación determina condiciones de inestabilidad que propician la génesis y activación de procesos de remoción en masa en la microcuenca de drenaje de la quebrada Curucutí, estado Vargas, Venezuela. La metodología se basó en la recopilación, análisis e interpretación de la información bibliográfica y cartográfica existente, y su adaptación en específico para el área de la microcuenca de drenaje de la quebrada Curucutí. Un gran apoyo de información actualizada para este trabajo, lo constituyen el “Proyecto Ávila: Mapa de Riesgos” llevado a cabo por el Instituto Geográfico de Venezuela “Simón Bolívar” y el Ministerio del Ambiente y de los Recursos Naturales; y el “Plan de Manejo para la Ordenación y Restauración Ambiental del Eje Arrecife – Los Caracas” elaborado por la Autoridad Única de Área para el estado Vargas y la empresa Ecology and Environment. La compleja dinámica que se deriva de la interrelación entre las distintas variables que constituyen los medios físico y biológico en el área de la microcuenca de drenaje de la quebrada Curucutí, le confieren a este sistema hidrogeomorfológico como al resto de las cuencas de la vertiente norte del Macizo del Ávila, características particulares que denotan una alta fragilidad y sensibilidad ante la ocurrencia de fenómenos extremos (lluvias extraordinarias, aludes torrenciales y terremotos principalmente) capaces de generar umbrales y respuestas drásticas y violentas, con impactos severos en el medio socio-económico. Los elementos y/o factores principales que condicionan la estabilidad relativa de los materiales de alteración en la microcuenca de drenaje de la quebrada Curucutí, están representados por : (a) la susceptibilidad del sustrato geológico (rocas y minerales) a los procesos meteóricos y erosivos; (b) el control geológico-estructural (foliación, diaclasas y fallas); (c) la topografía de desniveles altimétricos considerables, y pendientes fuertes y abruptas del relieve montañoso; (d) la escasa profundidad de los perfiles de meteorización de la litología; (e) el rápido humedecimiento de los perfiles de meteorización en presencia de lluvias intensas y duraderas; (f) la ocurrencia de lluvias extremas en intensidad y duración; (g) la actividad sísmica asociada principalmente al sistema de fallas de San Sebastián; y (h) la media a rala densidad de cobertura de la vegetación.
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