Seleshi Bekele Awulachew

Government of Ethiopia

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Tammo S. Steenhuis

Cornell University

Zachary M. Easton

Virginia Tech

Amy S. Collick

Morehead State University

Enyew Adgo

Bahir Dar University

Eric White

Louisiana Coastal Protection and Restoration Authority

Matthew McCartney

International Water Management Institute

Daniel R. Fuka

Virginia Tech

A. A. Ahmed

Semu Ayalew Moges

University of Connecticut

Abebe S. Gebregiorgis

Harris Health System

Cooperative Institutions

Cornell University

Bahir Dar University

International Water Management Institute

Amhara Regional Agricultural Research Institute

Virginia Tech

International Water Management Institute

Addis Ababa University

Ghent University

International Water Management Institute

University of Florida

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Use of Remote Sensing-Based Precipitation Data for Flood Frequency Analysis in Data-Poor Regions

CRC Press eBooks (2016)

Abebe S. Gebregiorgis Semu Ayalew Moges Seleshi Bekele Awulachew

10.1201/9781315370392-14

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Citations (0)

Management of Ground Water in Africa Including Transboundary Aquifers: Implications for Food Security, Livelihood and Climate Change Adaptation

HAL (Le Centre pour la Communication Scientifique Directe) (2011)

Yvan Altchenko Seleshi Bekele Awulachew Benjamin Brida Hama Arba Diallo Dam Mogbante

Groundwater is one of the most important sources for drinking water, livestock water, and irrigation in Africa. It is of vital importance in meeting the Millennium Development Goals (MDGs) target of accessing clean water, as most of rural Africa and a considerable part of urban Africa are supplied by groundwater. Groundwater also has a major role to play in improving food security through expansion of irrigation supplied by shallow and deep wells. As such, groundwater has high relevance to the development and wellbeing of Africa, if adequately assessed and sustainably exploited. However, impacts of rapid development and climate change on water resources, including groundwater, are expected to be very severe unless major actions are taken to address the limited human and institutional capacity and hydrogeological knowledge base needed to devise sustainable adaptive water management strategies. Whilst the potential for groundwater resources development and the extent of their vulnerability due to climate change in the African context continue to be reported in the literature, a quantitative understanding of these issues remains poor. Although groundwater systems respond to human and climatic changes slowly (relative to surface water systems), climate change still could affect groundwater significantly through changes in groundwater recharge as well as groundwater storage and utilization. These changes result from changes in temperature and precipitation or from change in land use/land cover, and increased demand. There is therefore a need for ensuring sustainability and proper management of groundwater resources through instituting proper aquifer management practices such as the establishment of groundwater monitoring systems, better understanding of the role of groundwater storage and groundwater discharges in sustaining aquatic ecosystems, understanding the interactions between various aquifers (including transboundary aquifers) and assessing the impact of increased pumping from various aquifer systems on the sustainability of groundwater abstraction. This paper provides an overview of the regional hydrogeological framework, the current state of knowledge of aquifer systems, their development potential and climate change impacts on groundwater, research gaps, and policy implications for meeting the MDGs of accessing clean water and livelihood goals in Africa.

Climate Change Adaptation

Water security

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Citations (8)

SWAT based runoff and sediment yield modelling: a case study of the Gumera watershed in the Blue Nile basin

Ecohydrology & Hydrobiology (2010)

Meqaunint Tenaw Asres Seleshi Bekele Awulachew

SWAT model

WEPP

10.2478/v10104-011-0020-9

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Citations (46)

Development and application of a physically based landscape water balance in the SWAT model

Hydrological Processes (2010)

Eric White Zachary M. Easton Daniel R. Fuka Amy S. Collick Enyew Adgo

Abstract Watershed scale hydrological and biogeochemical models rely on the correct spatial‐temporal prediction of processes governing water and contaminant movement. The Soil and Water Assessment Tool (SWAT) model, one of the most commonly used watershed scale models, uses the popular curve number (CN) method to determine the respective amounts of infiltration and surface runoff. Although appropriate for flood forecasting in temperate climates, the CN method has been shown to be less than ideal in many situations (e.g. monsoonal climates and areas dominated by variable source area hydrology). The CN model is based on the assumption that there is a unique relationship between the average moisture content and the CN for all hydrologic response units (HRUs), and that the moisture content distribution is similar for each runoff event, which is not the case in many regions. Presented here is a physically based water balance that was coded in the SWAT model to replace the CN method of runoff generation. To compare this new water balance SWAT (SWAT‐WB) to the original CN‐based SWAT (SWAT‐CN), two watersheds were initialized; one in the headwaters of the Blue Nile in Ethiopia and one in the Catskill Mountains of New York. In the Ethiopian watershed, streamflow predictions were better using SWAT‐WB than SWAT‐CN [Nash–Sutcliffe efficiencies (NSE) of 0·79 and 0·67, respectively]. In the temperate Catskills, SWAT‐WB and SWAT‐CN predictions were approximately equivalent (NSE > 0·70). The spatial distribution of runoff‐generating areas differed greatly between the two models, with SWAT‐WB reflecting the topographical controls imposed on the model. Results show that a water balance provides results equal to or better than the CN, but with a more physically based approach. Copyright © 2010 John Wiley & Sons, Ltd.

SWAT model

Water balance

Infiltration (HVAC)

10.1002/hyp.7876

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Citations (125)

A simple semi‐distributed water balance model for the Ethiopian highlands

Hydrological Processes (2009)

Amy S. Collick Zachary M. Easton Tegenu Ashagrie Biniam Biruk Seifu A. Tilahun

Abstract The discharge of the Nile River is highly dependent on the flow generated in the highlands of Ethiopia. However, little is known about the local (i.e. small scale) watershed hydrological response, due in part to a lack of long duration, continuous hydrological data. The goal of this paper was to develop a realistic, simple model that is useful as a tool for planning watershed management and conservation activities so that the effects of local interventions on stream flow can be predicted at a larger scale. The developed model is semi‐distributed in that it divides the watershed into different regions that become hydrologically active given different amounts of effective cumulative rainfall after the start of the rainy season. A separate water balance is run for each of the hydrologic regions using rainfall and potential evaporation as the major inputs. Watershed parameters that were calibrated included the amount of water required before each region becomes hydrologically active, the fraction of soil water that becomes runoff and subsurface flow, and aquifer characteristics, Model validation indicated that daily discharge values were predicted reasonably well with Nash Sutcliffe values ranging from 0·56 to 0·78. Despite the large distance between the test watersheds, the input parameter values for the watershed characteristic were remarkably similar for the humid highlands, indicating that the model could be used to predict discharge in un‐gauged basins in the region. As expected, the watershed in the semi‐arid region behaved somewhat differently than the other three watersheds. Good quality precipitation data, even for short durations, were key to the effective modelling of runoff in the highland watersheds. Copyright © 2009 John Wiley & Sons, Ltd.

Water balance

Distributed element model

Discharge

Potential evaporation

10.1002/hyp.7517

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Citations (66)

The Nile Basin: tapping the unmet agricultural potential of Nile waters

Water International (2010)

Seleshi Bekele Awulachew Lisa‐Maria Rebelo David Molden

This paper provides an overview of poverty levels, hydrology, agricultural production systems and water productivity in the Nile Basin. There are opportunities to manage water better in the basin for use in agriculture to improve food security, livelihoods and economic growth by taking into account not only the water in the river, but also by improving management of the rain water. Crops, livestock, fisheries and aquaculture have long been important in the Nile but do not feature in the water discourse.

10.1080/02508060.2010.513091

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Citations (31)

A multi basin SWAT model analysis of runoff and sedimentation in the Blue Nile, Ethiopia

Hydrology and earth system sciences (2010)

Zachary M. Easton Daniel R. Fuka Eric White Amy S. Collick Biniam B. Ashagre

A multi basin analysis of runoff and erosion in the Blue Nile Basin, Ethiopia was conducted to elucidate sources of runoff and sediment. Erosion is arguably the most critical problem in the Blue Nile Basin, as it limits agricultural productivity in Ethiopia, degrades benthos in the Nile, and results in sedimentation of dams in downstream countries. A modified version of the Soil and Water Assessment Tool (SWAT) model was developed to predict runoff and sediment losses from the Ethiopian Blue Nile Basin. The model simulates saturation excess runoff from the landscape using a simple daily water balance coupled to a topographic wetness index in ways that are consistent with observed runoff processes in the basin. The spatial distribution of landscape erosion is thus simulated more correctly. The model was parameterized in a nested design for flow at eight and sediment at three locations in the basin. Subbasins ranged in size from 1.3 to 174 000 km2, and interestingly, the partitioning of runoff and infiltrating flow could be predicted by topographic information. Model predictions showed reasonable accuracy (Nash Sutcliffe Efficiencies ranged from 0.53â0.92) with measured data across all sites except Kessie, where the water budget could not be closed; however, the timing of flow was well captured. Runoff losses increased with rainfall during the monsoonal season and were greatest from areas with shallow soils and large contributing areas. Analysis of model results indicate that upland landscape erosion dominated sediment delivery to the main stem of the Blue Nile in the early part of the growing season when tillage occurs and before the soil was wetted up and plant cover was established. Once plant cover was established in mid August landscape erosion was negligible and sediment export was dominated by channel processes and re-suspension of landscape sediment deposited early in the growing season. These results imply that targeting small areas of the landscape where runoff is produced can be the most effective at controlling erosion and protecting water resources. However, it is not clear what can be done to manage channel erosion, particularly in first order streams in the basin.

Sedimentation

SWAT model

10.5194/hess-14-1827-2010

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Citations (197)

Basin Regionalization for the Purpose of Water Resource Development in a Limited Data Situation: Case of Blue Nile River Basin, Ethiopia

Journal of Hydrologic Engineering (2012)

Abebe S. Gebregiorgis Semu Ayalew Moges Seleshi Bekele Awulachew

It is a familiar exercise in hydrology to characterize river basins into hydrologically homogeneous regions by using parameters suited to explain typical hydrological variables such as extreme and annual flows. This paper discusses regionalization of the Blue Nile River Basin (BNRB) by using statistical techniques and describes the selection of best-fit distribution models to estimate the flood frequency of the basin; such undertakings have not been made before. The BNRB is delineated into five homogeneous regions based on statistical parameters of station data. Approximately 14 different distributions are analyzed. The generalized logistic model is the best fit for Regions I and IV. Log-Pearson Type III distribution is appropriate for Region II. Lognormal and generalized extreme value distributions are selected for Regions III and V, respectively. For all distributions, probability weighted moment parameter estimation method is most efficient, but for log-Pearson Type III, ordinary moments are chosen. For each region, a unique regional flood frequency curve is developed. These curves are important to estimate the flood quantiles of ungauged catchments in the data scarce area of the basin; hence, they meet the needs of water engineers who currently face tremendous challenges in designing small and medium hydraulic structures in the basin.

Quantile

Log-normal distribution

Gumbel distribution

10.1061/(asce)he.1943-5584.0000730

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Citations (12)

Predicting discharge and sediment for the Abay (Blue Nile) with a simple model

Hydrological Processes (2009)

Tammo S. Steenhuis Amy S. Collick Zachary M. Easton Elias S. Leggesse Haimanote K. Bayabil

Abstract Models accurately representing the underlying hydrological processes and sediment dynamics in the Nile Basin are necessary for optimum use of water resources. Previous research in the Abay (Blue Nile) has indicated that direct runoff is generated either from saturated areas at the lower portions of the hillslopes or from areas of exposed bedrock. Thus, models that are based on infiltration excess processes are not appropriate. Furthermore, many of these same models are developed for temperate climates and might not be suitable for monsoonal climates with distinct dry periods in the Nile Basin. The objective of this study is to develop simple hydrology and erosion models using saturation excess runoff principles and interflow processes appropriate for a monsoonal climate and a mountainous landscape. We developed a hydrology model using a water balance approach by dividing the landscape into variable saturated areas, exposed rock and hillslopes. Water balance models have been shown to simulate river flows well at intervals of 5 days or longer when the main runoff mechanism is saturation excess. The hydrology model was developed and coupled with an erosion model using available precipitation and potential evaporation data and a minimum of calibration parameters. This model was applied to the Blue Nile. The model predicts direct runoff from saturated areas and impermeable areas (such as bedrock outcrops) and subsurface flow from the remainder of the hillslopes. The ratio of direct runoff to total flow is used to predict the sediment concentration by assuming that only the direct runoff is responsible for the sediment load in the stream. There is reasonable agreement between the model predictions and the 10‐day observed discharge and sediment concentration at the gauging station on Blue Nile upstream of Rosaries Dam at the Ethiopia–Sudan border. Copyright © 2009 John Wiley & Sons, Ltd.

Interflow

Infiltration (HVAC)

Bedrock

Water balance

10.1002/hyp.7513

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Citations (149)