Water Resource Engineering
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Item Advancing Bioassessment of Water Quality in Wadeable Rivers and Streams in Ethiopia(Addis Ababa University, 2024-01) Melaku Getachew; Seid Tiku (Prof.); Geremew Sahilu (PhD); Worku Legesse (PhD); Mary Kelly-Quinn (Prof.)Numerous international bilateral, plurilateral, and multilateral treaties and conventions were signed between countries to protect human health and environmental pollution. However, most of the signatory countries fail to implement the treaties or conventions (Willis, 2012). For example, though Ethiopia has endorsed or ratified the Basel, Stockholm, and Rotterdam agreements, its legislations and policies for environmentally sound management of hazardous chemicals and wastes are still in infancy and are inefficient in preventing the illegal dumping of waste as well as contamination of water, soil and air resources (Tadesse, 2009). This study reviewed the details of problems of surface water pollution in the metropolitan area of Addis Ababa and the upper Awash River catchment. Urbanisation, population growth, industrialisation without proper waste management facilities, unregulated agricultural practices, uncontrolled liquid and solid wastes, and law enforcement difficulties were the major gaps identified. Furthermore, there are significant gaps limiting efforts to address the magnitude of pesticide pollution in the catchment probably due to the shortage of laboratory facilities and the costs associated with the chemicals and equipment. This study forwarded important conclusions and recommendations to the respective stakeholders. To help the bioassessment of wadeable rivers and streams in Ethiopia, a macroinvertebrate kick sampling protocol has been developed using data from minimally impacted sites and testing it along the pollution gradients. Based on the results, the 2-minute RH kick sampling method is the recommended candidate for the bioassessment of wadeable rivers and streams in the country. Using the developed macroinvertebrate kick sampling protocol in this study, the impacts of the Koka Hydropower dam on benthic macroinvertebrate structure and composition were further investigated. Hydropower has been used for generations to provide reliable, fossil-fuel-free electricity (source of clean energy), water supply for domestic uses and agricultural irrigation, recreational opportunities, several flood-control benefits, as well as a stable system for navigation. However, several disadvantages have also been recognised because of the construction of hydropower dams. It is particularly severe in large dams where there has been extinction of the many fish and other aquatic species, huge losses of forest, the disappearance of birds in floodplains, erosion of deltas, loss of wetland and farmland, and many other irreversible impacts. These impacts can have economic and social (e.g. Community displacement) health implications (consequences). This in turn points towards the need to seek a balance between pros and cons associated with dam construction. Currently, most public and policymakers perceive only the advantages (pros) of the hydropower dam and the impacts mentioned above are largely neglected. To create awareness among stakeholders and to recommend possible solutions to the problem, it was very crucial to conduct the ecological impacts of hydropower dams on the macroinvertebrate communities that include aquatic insects, crustaceans, annelids, mollusks, nematodes, planarians, and other invertebrates as these organisms play a critical role in the transfer of energy from basal resources (bottom layer) (e.g., algae, detritus, and associated microbes) to vertebrate consumers in aquatic food webs, and they serve as the primary food resource for many commercially and economically important fish species. The investigation of the hydropower dam on the structure and composition of macroinvertebrate communities showed that the downstream reach was severely impacted by water pollution compared to the midstream and upstream reaches of the Awash River, however, the results were partly complicated by the nutrient pollution, particularly from the midstream reach. The major factor, amongst others affecting the downstream reach, the water flow change (river velocity) was highlighted as a key variable structuring the macroinvertebrate communities and a variable that can be altered by damming. Similarly, variation partitioning analysis was used to analyze the unique and shared effects of the three sets of predictor variables (environmental, land use, and spatial factors). The findings revealed that the three sets of predictors' shared variation in macroinvertebrate community composition was greater than their contributions. To put it bluntly, anthropogenic activities have a negative global influence on aquatic habitats. As a result, surface water biomonitoring is becoming increasingly crucial in estimating ecosystem deterioration and achieving environmental sustainability. Therefore, the development of methods kick sampling time) based on Ethiopian ecoregions to employ in the bioassessment of surface water quality has been mandatory. This would contribute to the assessment of water quality in wadeable rivers and streams in EthiopiaItem Hydrological processes under changing climate and land use scenarios in the Baro– Akobo River Basin, Ethiopia(Addis Ababa University, 2023-11-04) Abiy Getachew; Tekalegn Ayele (PhD); Yihun Taddele (PhD) Co-AdvisorWater is an essential component of agricultural productivity and is crucial for food security. It is also a vital component of the environment. Water security is becoming a global issue, but the issue is chronic in most developing countries, including sub-Saharan Africa. Therefore, sustainable water resource management is essential to achieve food and water security in Ethiopia. The Baro– Akobo River basin, which is found in the southwest part of Ethiopia, has witnessed a substantial change in population, climate, and land use during the last four decades. The climate of the region is warming at an alarming rate, and it is expected that this tendency will persist in the coming century. On the other hand, the impacts of climate and land use change on the hydrology of this basin are not well understood. Understanding the impacts of climate and land use change on basin hydrology is critical for developing effective water management practices. Therefore, this study examined the individual and combined impacts of climate and land use changes on the basin hydrology. This study combines a statistical, geospatial, and hydrological model to investigate the hydrologic impacts of climate and land use change. First, seven raw and bias-corrected RCMs (RCA4 (CNRM), RCA4 (ICHEC), RCA4 (MPI), CCLM4 (CNRM), CCLM4 (MPI), REMO (MPI)) and the ensemble mean were evaluated for model skill in reproducing the observed baseline climate for the period 1975–2005 at several weather stations in the basin. A pixel-to-point approach was used to compare RCMs against weather stations. Monthly distribution patterns and several statistical metrics were used for evaluating the performance of RCMs in capturing the historical observed climate of the basin. The Mann-Kendall test and Sen's slope estimate were used to examine the decreasing and increasing trend of the climatic variables, as well as to estimate the magnitudes of the significant decreasing and increasing trends. Furthermore, the ensemble mean and five bias corrected RCMs were used to examine climate and hydrological changes in the baseline and future 2021–2050 (2030s) and 2071-2100 (2080s) periods under the representative concentration pathway (RCP4.5 and RCP8.5) scenarios. On the other hand, the geospatial and synergistic techniques of cellular automata (CA) and artificial neural networks (ANN) were used to develop historical and future land use change scenarios. The maximum likelihood classifier (MLC) in the Earth Resource Data Analysis System (ERDAS) was used to conduct land use change classification for Landsat imagery from 1985, 2002, and 2019. Three land use maps with seven classes were identified, and then a change detection process was conducted. The classified (1985–2002) and (2002–2019) land use maps, along with a transition matrix and spatial drivers, were put into the Module for Land-use Change Evaluation (MOLUSCE) model to predict land use maps for 2019 (current) and 2040 (a business-as-usual scenario) land use scenarios, respectively, using the CA-ANN multilayer perceptron methods (MLP). Besides, this study considered a further increase in altitudinal forest expansion and watershed management practices (conservation) in a land use scenario. Then the best-performing climate model (ensemble mean) under RCP4.5 and RCP8.5 for the 2023–2040 time frame and plausible land use scenarios considering the current, business as usual, and conservation was used as inputs to the calibrated models to examine the individual and combined impacts of climate and land use changes on the hydrology. Three independent climate datasets, including observed, Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS), and Climate Forecast System Reanalysis (CFSR), were used to calibrate and validate the Soil and Water Assessment Tool (SWAT) model for the periods 1990–1998 and 1999–2002, respectively. The Sequential Uncertainty Fitting 2 (SUfI2) method in the SWAT-CUP program was used for model calibration and sensitivity. The Nash–Sutcliffe Efficiency (NSE), Coefficient of Determination (R2), and Percent Bias (PBIAS) as well as two uncertainty measurements (r-factor and p-factor), were used to assess the model's performance. Then the calibrated model using the water balance equation was used to examine the individual and combined impacts of climate and land use change scenarios on the basin hydrology. The climate and land use change impacts on hydrology were analyzed on monthly, seasonal, and annual scales with respect to the baseline period. Statistical tests such as the t-test and Levene test were also used to determine the change in mean and standard deviation between the baseline and different climate and land use scenarios. Besides, the Indicators of Hydrologic Alterations (IHA) method was used to assess the hydrologic changes between the baseline conditions and future climate change scenarios. Results from the global climate models (GCMs) downscaled through the CCLM4, RCA4, and REMO modeling schemes are characterized by several biases, such as shifting the rainy season and under- and overestimation of the observed climate. However, the skill of the models was substantially enhanced after bias correction. All models best capture the annual cycle with less bias. Therefore, it was beneficial to account for such biases using a robust statistical bias correction method before utilizing RCM simulations to generate climatic scenarios and climate impact scenarios. Results from future bias-corrected RCMs show a consistent increase in monthly Tmax and Tmin under RCP4.5 and RCP8.5 in the 2030s and 2080s relative to the baseline climate, while rainfall does not show consistency. The future climate change projections from the ensemble mean show an increase in the R20mm, CDD, R95p, RX1, and RX5 indices, but the R10 indices show a decreasing value under both RCPs. Observed climate and CHIRPS rainfall combined with the CFSR dataset yielded reasonable and comparable streamflow simulation performance in terms of statistical metrics at both Baro and Sore hydrological stations. All climate impact scenarios from the ensemble mean demonstrated a decline in surface runoff and water yield and an increase in evapotranspiration. Except for the extreme flow segment (i.e., 0–3% exceedance probability), the projection for simulation under climate change scenarios shows a decrease in flow. The increase in temperature and the decrease in rainfall is attributed to a relatively higher impact than the combined and land-use change-alone scenarios. This will have an impact on future agricultural production and water availability. Moreover, the projected increase in rainfall extremes, the expansion of agricultural land, and urbanization all lead to increased surface runoff and flooding. Therefore, to implement adaptation and mitigation strategies, the inclusion of predicted climate and land use change in hydrological impact studies is useful.Item Groundwater Recharge Estimation: The Case of Hormat-Golina Sub-Basin, Northern Ethiopia(Addis Ababa University, 2024-01) Seyoum Bezabih; Taye Alemayehu (PhD)Water is one of the most essential commodities for mankind and the largest available source of fresh water is obtained from groundwater. The Hormat-Golina sub-basin is one of the groundwater-based irrigation areas located in north wollo zone of Amhara region. Due to the erratic nature of rainfall (both time and space) distribution in the area, people often fail to maintain the soil moisture requirement for growing crops. Thus, the need for agricultural development using groundwater resources in the area is growing continuously. However, the ambitious plans for expanding irrigation have not been adequately strengthened through the assessments of groundwater reserves and groundwater recharge estimations. Understanding the spatial variability of groundwater recharge in response to distributed Land-use, soil texture, topography, groundwater level, and hydrometeorological parameters is significant when considering the safety of groundwater resource development. Thus, this study was aimed at estimating the spatial groundwater recharge of Hormat-Golina sub-basin, in northern Ethiopia using a spatially distributed water balance model (WetSpass). Input data for the model were prepared in the form of grid maps using a 30 m grid size and the parameter attribute tables were adjusted to represent the Hormat-Golina sub-basin condition using expert knowledge and scientific literature. The model result shows there was a good agreement between the observed and simulated surface runoff with R2=0.90 and NSE= 0.85. The results of the model indicated that the long-term temporal and spatial average annual rainfall of 828.5 mm was partitioned as 156.4 mm (19%) of surface runoff, 616.7 mm (73%) of evapotranspiration, and 55.4 mm (8%) of recharge. The recharge corresponds to 4.2*105 cubic meters (m3) for the Hormat-Golina sub-basin (with an area of about 698.25 km2) from which 83% of the recharge takes place during the rainy /wet/ summer/ season, while the remaining 17% takes place during the bega (dry) season. The highest recharge was observed in forest land with sandy soil. The analysis of the simulated result showed that WetSpass works well to simulate water balance components of the Hormat-Golina sub-basin and is especially suitable for studying the effects of Land-use changes on the water regime in the basin.Item Water, Sanitation, and Hygiene Service Status and Its Barriers at Public Healthcare Facility in the City of Addis Ababa: It’s Implication for COVID-19 pandemic and Healthcare Acquired Infection Prevention.(Addis Ababa University, 2022-11) Atimen Derso; Taffere Addis (Assit. Prof.)Background: The public health significance of healthcare Water, Sanitation, and Hygiene (WASH) service in reduction of nosocomial infection and improving quality of care is paramount. However, little is known on the status of WASH service in a health care facility at the time of pandemic and the barriers that hinder the service in the health care setting in Ethiopia. Objective: The aim of this study was to assess status of basic water, sanitation, hand hygiene, healthcare waste management, and environmental cleanliness service and its barriers at public health care facilities in the city of Addis Ababa, Ethiopia 2022. Methods: Institutional-based survey convergent parallel mixed design was conducted among 86 public health care facilities (11 hospitals and 75 health centers located in Addis Ababa city). Stratified sampling technique was used to select health care facilities. A semi-structured observational checklist tool was used to measure the availability of services. For the qualitative study, purposively 16 key informants were selected for the interview. Semi-structured interview guide was used to identify the barriers and thematic data analysis was done. Finding: This study found that no one healthcare facility had basic access to overall WASH services. The independent WASH domain analysis showed that, about 86% healthcare facilities had basic water access, 100% had limited sanitation access, 88.4 % had limited hand hygiene service, 69.8% had limited healthcare waste management service, and 97.7% had limited environmental cleaning service. Built environments of WASH infrastructure; Resource availability and allocation; leadership and stakeholder participation; inadequate training and poor behavior; and legal issues were identified barriers to provision of basic healthcare WASH services. Conclusion and recommendation: The availability of healthcare WASH services in Addis Ababa city remains far from the pace to achieve the sustainable goal target by 2025. The overall availability of healthcare WASH services in Addis Ababa was limited that attributed to inadequate WASH infrastructure, inadequate resource, poor government commitment, and absence of framework and guideline. Limited access to WASH services and multiple existing challenges at healthcare facilities makes worsening the prevention and control of COVID-19 pandemics, healthcare acquired infection which indicating that the country need to act now on more financial investment, capacity building, facilitating committed leadership, and participation of stakeholders to ensuring basic WASH services at healthcare setting.Item Drinking Water Chlorination Byproducts and Cancer Risks in Addis Ababa, Ethiopia(Addis Ababa University, 2023-06) Nebiyou Tafesse; Argaw Ambelu (Prof.); Sirak Robel (Assoc. Prof.)Background: Disinfection byproducts (DBPs) from chlorinated drinking water have been linked to an increased risk of cancer in the bladder, stomach, colon, and rectum. No previous evidence showed the independent trends and prevalence of these cancers in association with DBPs in Ethiopia. Therefore, the study aimed to determine the prevalence and trends of disinfection byproducts related cancers (DBRCs) in Addis Ababa, Ethiopia. Close scrutiny of the published studies showed that this is the first study conducted indicating the association between drinking water source, chlorinated water and colorectal cancer (CRC) in Ethiopia. The present investigation is also the first study in assessing the trihalomethanes level and lifetime cancer risks in the drinking water supply in Addis Ababa, Ethiopia. Methods: A retrospective record review using the Addis Ababa Cancer Registry (AACR) was conducted in Addis Ababa, Ethiopia. The AACR collects data on cancer cases submitted by three public hospitals and twelve private facilities (the only cancer treatment centers) in Addis Ababa, Ethiopia. Spatial data sets were produced and classified into households receiving chlorinated surface water and unchlorinated groundwater. The Cochran-Armitage trend test was used to evaluate whether there was a disinfection byproduct-related cancers (DBRCs) trend among communities receiving chlorinated water. Negative binomial regression was used to analyze the incidence rate. A facility-based matched case control study was conducted in Tikur Anbessa Specialized Hospital (TASH) involving 224 cases and 448 population controls from June 2020 to May 2021. A multivariable conditional logistic regression was used to identify risk factors of CRC. Stratified analysis was used to detect confounding factors and effect modification. A cross-sectional study design was used to collect water samples in the water supply networks of Addis Ababa, Ethiopia. One hundred twenty (120) drinking water samples were collected from 21 sampling points in Addis Ababa, Ethiopia. The three sampling areas were Legedadi, Gefersa and groundwater sources. The United States Environmental Protection Agency (USEPA) protocol and practice for sample collection and handling were followed. The trihalomethanes (THMs) were separated by a DB-5 capillary column and detected by GC-ECD (gas chromatography-electron capture detector). Spectrophotometric and Insitu methods were used for physicochemical parameters. Canonical Correspondence for data analysis of trihalomethanes and environmental variables using CANOCO 4.5. Cancer and non-cancer risks of THMs via inhalation, ingestion and dermal contact routes have also determined. Results: A total of 11,438 cancer cases were registered between 2012 and 2016, and DBRCs accounted for approximately 17%. The majority of the cases were females; 7,706 (67%). The prevalence of DBRCs was found to be higher in communities supplied with chlorinated water. Approximately 56% of colorectal cancer patients and 53% of stomach cancer patients are known to be using chlorinated surface water for drinking regularly. Of 214 colorectal cancer (CRC) cases, 148 (69.2%) used chlorinated water whereas out of 428 controls 161 (37.6%) used chlorinated water. In the final regression model, drinking chlorinated surface water (adjusted matched odds ratio (adjusted mOR) = 2.6;(95% CI: [1.7 ̶ 4.0]), history of swimming (adjusted mOR= 2.4; 95% CI: [1.4 ̶ 4.1]), years at the place of current residence (adjusted mOR=1.5; (95% CI: [1.1 ̶ 2.2]), hot tap water use for showering (adjusted mOR; 3.8= (95% CI: [2.5 ̶ 5.9]) were significantly associated with CRC. The mean concentration of total trihalomethanes in drinking water in Addis Ababa was 76.3 μg/L. The concentration of chloroform in the drinking water supply in Addis Ababa, Ethiopia, ranged between 4.03-79.4μg/L. The results of the average THM concentration followed the order TCM (Trichloromethane) >BDCM(Bromodichloromethane) > DBCM (Dibromochloromethane) > TBM (Tribromomethane). The mean total THMs in the Gefersa and legedadi water supply systems were 77.4μg/L and 69.66μg/L respectively. The lowest THMs concentration was recorded in the groundwater supply system (15.5μg/L). The residual chlorine, phosphates, UV absorbance at 254 nm, and combined chlorine had positive correlations with THMs formation. However, electron conductivity had negative correlation with THMs formation. The cancer risk study discovered that among the examined routes, ingestion causes the greatest risk. The lifetime cancer risk by chloroform contributes the highest (72%) of the total risk, followed by BDCM (14%), DBCM (10%) and bromoform (4%). Conclusions: The prevalence of DBRCs in this study was found to be high. The colon cancer trends increased substantially in Addis Ababa, Ethiopia. Drinking chlorinated water for extended years is a significant risk factor for CRC in Addis Ababa, Ethiopia. In addition, hot tap water use for showering, and swimming have higher level total THMs than groundwater supply. The residual chlorine, UV absorbance, phosphate and hardness as calcium, and electron conductivity were found to be the main predictors determining the abundance and distribution of trihalomethanes. The cancer risk study discovered that among the examined routes, ingestion causes the greatest risk. The monitoring and regulation of the THMs is required on a regular basis to analyses trends and guide the water treatment and distribution system.history are risk factors for CRC. Surface water supply networksAnalysis (CCA) or Redundancy Analysis (RDA) was usedItem Biomarkers of Toxins in Improved Drinking Water and Diarrhea Patients of South Wollo Communities, Northern Ethiopia(Addis Ababa University, 2022-04) Shibabaw Tadesse; Sirak Robele (PhD.); Adey Feleke (PhD); Jana Jass (Prof.)The world's most vulnerable communities frequently drink contaminated water, which is linked to a variety of public health issues. Escherichia coli toxins are the most common types of contaminants found in association with disease in E. coli bacteria. They are found in nearly all pathogenic E. coli bacteria either released from the bacteria or E. coli cell or both transmitted via the feco-oral route. The objective was to evaluate the safety of improved water supplies using toxins as a biomarker and correlate with the toxins found in patient stools, and identify gaps between water quality and the global classification of improved water supplies in the South Wollo zone, Ethiopia. This dissertation reports the results of a laboratory-based cross-sectional study conducted in South Wollo, Ethiopia, from January 2019 to June 2020. Two hundred forty-eight samples of household water and patient stool were collected (in a 1:1 match) and toxins were tested using polymerase chain reaction (PCR). The targeted toxins used were (enteroaggregative E. coli heat-stable enterotoxin 1 (EAST1), heat-stable (Sta); shiga-like toxin 1 (Stx1), shiga-like toxin 2 (Stx2), and heat-liable (LT)), which cause diarrhea when people drink contaminated water. A survey questionnaire was used to gather information on the types of water sources, as well as the knowledge and practices of the respondents about household water treatment methods. To analyze the data and examine the relationship between the variables, descriptive statistics, Chi-square (χ2), Fisher’s exact test, logistic regression, and Pearson’s bivariate correlation coefficients were used. In general, 24% of households had positive results from both water and stool samples, 63% [Confidence Interval (CI): 55- 67%] had positive results from water samples only, and 46% [CI: 37- 49%] had positive results from only stool frequently, with 33% in the water and 38% in the stool. Frequently founded contaminants in household water brought from improved water sources were the toxins ESAT1, Stx1, and LT, with Sta the least founded (2%). There were fewer (13%) toxins detected in shallow groundwater sources than in piped water, a statistically significant difference (P=0.031). There was a lower proportion of toxins detected in those who did not know about and used cloth filters than in those who did, and the negative relationship is statistically significant (P=0.017). Approximately one-third of the improved water services sampled, which are considered ‘functional’ by international standards, do not provide potable water due to fecal and toxin contaminants. There was a significant positive correlation (r = 0.412) between toxins in the stool and toxins in the water (P < 0.05). The findings indicate that toxin biomarkers can be used to monitor water safety. Water quality parameters are not currently considered in the classification of basic water services. This suggests that international efforts to address SDG 6 should incorporate water quality and its indicators as a key parameter to better track international progress towards ‘clean water and sanitation’ efforts. More research is needed to determine the sources of pathogenic microbial markers that cause water-related diseases, such as diarrhea, as well as focus areas for water contamination prevention.samples for toxins. Out of the five toxins examined, EAST1 was the one that was found the mostItem Assessment of Vulnerability of Alluvial Aquifers of Transition Zone to Contamination: The Case of Danakil Basin, Northeastern Ethiopia(Addis Ababa University, 2022-06) Kumneger, Mollalegn; Taye, Alemayehun (PhD)Groundwater is indispensable to humankind, but with the increasing load over this precious resource, it has become necessary to study it in detail with geological as well as hydrogeological aspects to understand the nature of the groundwater resource of a Danakil basin to manage it well and use it sustainably, vulnerability assessment of the resource is conducted to highlight the areas which are more susceptible to contamination. In the present study, an attempt has been made to account for the groundwater vulnerability using an overlay index method, DRASTIC, which is used to prepare a vulnerability map using GIS, of the study area, Danakil basin. The DRASTIC Vulnerability index (DVI) is calculated as the sum of the product of ratings and weights assigned to each of the parameters on a scale of 1 to 10 and 1 to 5 respectively. And a 2D finite element groundwater flow and solute transport model were developed to simulate the spatial and temporal variations of the salinity intrusion in the alluvial aquifer of the Danakil basin taking into account the transition zone between freshwater and saltwater. The available historical records of water table levels were used to calibrate the developed model. Emphasis was devoted to the response of the transition zone to different pumping scenarios in the study area. The vulnerability index ranges from 50-149 and is classified into three classes it reduced approximately 20%, 50% and 30% of the area lies in low, medium, and high vulnerability zones. Results from the solute transport model also indicated that the saltwater intrusion problem has evolved during over-abstraction (pumping). Unlike previous investigations, this study presents the most qualitative assessment of the available groundwater in the alluvial aquifer under different pumping scenarios. In conclusion, Danakil basin alluvial aquifer is vulnerable to geogenic sources of salt intrusion due to over abstraction. Results can be an important input for policymakers in the development of sustainable groundwater protection and abstraction strategies for the region.Item Temporal Changes of Flood Sensitivity in Awash Basin(Addis Ababa University, 2021-09) Tinsae, Seboka; Alemseged, Tamiru (PhD)Flooding is a natural disaster that causes considerable damage. Awash basin is susceptible to flooding due to physical characteristics. Therefore, sensitivity mapping are essential for comprehensive management to reduce the harmful effects of flooding. This research aims to assess flood sensitivity in the Awash basin. The sensitivity maps use geographical information systems (GIS). Indicators for Land use, soil type, river buffer and slope determine the sensitivity of the area. There were significant temporal changes in flood sensitivity in three years which had five time interval for each. Based on the flood sensitivity, the slope, soil, river buffer and land use type were classified into 5 classes which include least sensitive, limited sensitive, moderate, and sever and critical sensitive. Most parts of the basin were found highly sensitive to flood when scores of the criteria were aggregated based on experts’ weight than using equal weight. The flood maps show that the upper part of the basin is highly sensitive due to slope and land use factor but there the flood sensitive areas are expanding to the downstream part of the basin due to increased urbanization. The output of the study can contribute to flood sensitivity management in the Awash basin; it can be used by different institutions like the local disaster management authority, researchers, land use planners, government, and for others who working with flood management. It helps watershed managers to decide based on more informed data for flood mitigation. The most important output of this research is that by using the flood sensitivity indicators, land use, slope and soil, it is possible to obtain a temporal change of sensitivity to flood using a method that uses readily available data instead of more complex flood risk methods.Item Numerical Groundwater Flow Modeling for Sustainable Groundwater Resource Development: The Case of Sibilu River Catchment Abay Basin(Addis Ababa University, 2021-12) Astatike, Kiflu; Taye, Alemayehu (PhD)Groundwater plays an important role in Ethiopia as a significant source of water for domestic, bottling, industrial and /or agriculture uses. In rural areas, which cover more than 85% of the population of Ethiopia, development and utilization of groundwater is most common. When the groundwater is used for irrigation, industry and domestic purposes, it is necessary to maintain the groundwater reservoir in state of dynamic equilibrium over a period of time and the water level fluctuations have to be kept within a particular range over the wet and dry seasons. To do so detail groundwater study, monitoring and quantification through different analysis methods like numerical modeling is a crucial and this study focuses on the numerical groundwater modeling of Sibilu River catchment under the steady state flow conditions. The catchment drains about 650 km2 land areas and covered by alluvial deposit and different types of volcanic geological formation. The surface hydrologic dynamic was modeled by using ArcSWAT integrated with ArcGIS. The area was classified into 1215 HRUs, to simulate the groundwater recharge distribution, evapotranspiration and interactions between Stream network and Aquifers in each Hydrologic Response Units. Accordingly, the recharge and ET distribution of the area were 292.2 and 253.01 mm per annum. As estimated with Base flow separation and CMB method in the validation process the recharge were 318.8 and 304.9 mm/year which is indicating the good agreement between the models with slight differences and the source of the recharge in the catchment were found to occur from direct precipitation and riverbed infiltration. Furthermore, Processing Modflow pro (version Pm 5) has been used to simulate the subsurface dynamism of groundwater of the area. The area discritized by 32,185 finite-difference Block Centered rectangular cells (205 rows, 157 column, 200m*200m cell size) and 350 m thick single upper layer and then in and out flow system of groundwater has been modeled. Zoned horizontal hydraulic conductivity has been used through the trial-and-error method to calibrate the model using the observed and simulated hydraulic heads. The water budget of the catchment reached at equilibrium conditions and annually about 181 and 20.3 million cubic meters of water flowing into the Aquifer system of Sibilu catchment from Precipitation Recharge and River leakage respectively. Similarly, a total of 201.25 million cubic meters of water is flowing out of the Aquifer system of the study area through head dependent boundary (0.91 MCM), Wells abstraction (5.6MCM), Drains (5.47 MCM) ,ET (164 MCM) and leakage of groundwater to the river course (25.1 MCM) in a period of a year. Discharging of groundwater from the Aquifer system is occurred through unregulated Well abstraction, spring discharges, ET and groundwater outflow to the stream. Intensive well abstraction for Water bottling, different industrial uses, Agro processing, commercials, irrigation, hotels and domestic water supplies are the main groundwater abstraction means in the Sibilu Catchments due to an anthropogenic activities. Under increasing abstraction and reducing recharge rates scenarios to see the impact of future potential stresses on the groundwater resources, the result shows that there is a significant groundwater level drop (on average by 31.3 meters for 50% abstraction rate increment and 19.31 meters for 10% recharge reduction) and there is a decrease in base flows to the Sibilu River, evapotranspiration flux from the area and Groundwater outflow through head dependent boundary. However, except under recharge reduction with 10% scenario the River leakage to the Aquifer system is increasing positively.Item Sustainability of Groundwater Use Using Integrated Methods: The Case of Atebala Catchment: Upper Awash Sub-Basin(Addis Ababa University, 2021-08) Dawit, Tsegaye; Taye, Alemayehu (PhD)Atebala River catchment is part of Upper Awash Sub-Basin, it is geologically dominated by Addis Ababa Ignimbrite, specifically in the west and southern parts of the study area. In the study area there are lots of industries which own water boreholes in their compound. In this research detailed hydrogeological investigation is undertaken to understand the groundwater resources of the catchment. To create an ideal picture for the major hydrogeological setting of the field situation of the study area, the study developed a conceptual model which maintain the mathematical representation by identifying the available major system, the possible boundaries and aquifer characteristic which results an input data base, cross section and simplified map for the modeling. The study will recommend to enhance the groundwater potential by identification of recharge and evapotranspiration; by using SWAT model and the result is taken as an input data for the numerical model. Numerical modeling is being simulated using the USGS three-dimensional finite difference groundwater flow model MODFLOW to quantify the water resource availability of the complex, dynamic groundwater/surface water systems and to take account of the environmental impact of abstraction. The calibration technique that the model used in this study is Manual trial and error calibration technique. From the model result the general groundwater flow direction is towards the Atebala River from all directions. It also assures that the groundwater withdrawal from the water boreholes of the catchment do not reach at the over abstraction rate, however the modeler has tried for the simulation of two scenarios with the abstraction of the groundwater and the influence of fluctuation of Evapotranspiration. Generally, Atebala river catchment has good groundwater potential for domestic, irrigation and industrial use. But if the well withdrawal and evapotranspiration of Atebala river catchment is increases, then the catchment has needed serious integrated monitoring and control mechanism to sustainably preserve the groundwater resource of the catchment.Item Effect of Topography in Satellite Rainfall Estimation Errors: Observational Evidence across Contrasting Elevation in the Blue Nile Basin(Addis Ababa University, 2013-05) Gebrehiwot, Niguse; Mekonnen, Gebremichael (PhD); Menberu, Meles (PhD)In this study, the effect of topography on spatial and temporal variability of rainfall on local (25 km by 25 km grid) scale was analyzed across two contrasting elevation locations. We deployed 10 in high elevation grid (average elevation 2097m) and 9 tipping rain gauges in low elevation grid (average elevation= 695 m). Based on high quality data from the dense rain gauges, we evaluated the spatio-temporal properties of rainfall and evaluated the errors in widely used high resolution satellite rainfall estimates. Three satellite rainfall estimates; TMPA 3B42RT, TMPA 3B42V7 and CMORPH were evaluated using statistical and categorical verification measures. Our results showed that there is significantly large spatio-temporal variability of rainfall at local scale. Diurnal cycle also indicated that, low elevation receives more rainfall at early morning and the high elevation gets more rainfall between the afternoon and mid-night. Compared to the high elevation grid, low elevation grid receives less seasonal accumulation which is less frequent but intense rainfall. High elevation area has more rain events (varying 91 to 105) than low elevation (range; 66 to 7 5) using 6hour minimum inter-event time. In high elevation maximum event rain rate is 67mm/hour but low elevation is l 22mm/hour. Our results also demonstrated clear difference between the two grid cells not only in terms of rainfall magnitude and property but also on the accuracy of satellite rainfall estimates which could be attributed to topography. 3B42RT, 3B42V7 and CMORPH overestimated total 3hour mean rainfall in low elevation (with bias 1.2, I.land 1.5 and ME 0.2, 0.1 and 0.5 respectively). All underestimated in high elevation by 0.9, 0.8 and 0.7, and ME 0.2, -0.2 and -0.5 for 3B42RT, 3B42V7 and CMORPH respectively. The categorical statistics indicated that CMORPH performed better in its probability of detection (POD), but it is influenced by non rainy clouds. All products highly affected by miss rainy events on high elevation area and by more false alarms at low elevation area. From our results 3B42V7 is best in the low elevation and 3B42RT performed better in the high elevation area.Item Social-Ecological and Behavioural Determinants Of Rural Sanitation: A Mixed Method Study Conducted In Becho District of Ethiopia(Addis Ababa University, 2018-06) Fikralem, Mezgebu; Abera, Kumie (PhD); Teshome, Gebre (PhD)Background: Inadequate sanitation is one of the leading causes of disease in least developed countries. Objective: The general objective of the current study wass to determine the psychosocial, technological and contextual factors associated with the adoption and consistent use of sanitation facilitates in rural Becho district of Ethiopia. Methods: A mix method design cross sectional study was conducted that employed quantitative and qualitative data collection techniques. Quantitative data was collected using a structured questionnaire. Eight rural Kebele (clusters) were selected randomly from the total of 21 kebele in the district. Then every sixth households in the selected clusters were selected to be interviewed using systematic random sampling technique. A total of 1047 household heads (650 male) interviewed, and latrines were inspected. Data were entered using Epi info version 3.5.4 and analysis was conducted using SPSS version 20. Logistic regression analysis was used to assess associations between outcome variables with potential determinants. Statistically significant results with p-value are less than 0.05 were reported. The qualitative data was collected using in-depth interviews and Focus Group Discussions (FGD) to explore beliefs, contextual and technologulcal factors influencing the adoption, sustainability and consistent use of sanitation facilities at multiple levels. The socio-ecological model was employed for the design of the study and for the analysis of data. A total of 10 in-depth interviews were held, and 8 FGDs were undertaken with 75 participants. The FGDs and IDIs were tape-recorded, verbatim transcribed and translated into English. The analysis was supported using Nvivo version 10 software. Results: Overall, 73% of participants owned some kind of latrine, while only 1.5% of participants used improved latrine. The percentage of households that used shared latrine, unimproved or practiced open defecation were 2.2%, 69.3%, and 27%, respectively. Among latrine owners, 79% reported using a latrine consistently, 48% of children's stool disposed in latrine. Only 11% of the observed latrines had handwashing facilities within 10 paces of distance. Among the psychosocial factors, attitude [(AOR 1.88: (95%CI: 1.4-2.5)]; and injunctive norm [(AOR 6.18; (95%CI: 4.46-10.44)] were significantly associated with latrine ownership. Among the demographic factors, households with family size of more than 6 compared to small size families [(AOR 1.43: (95% CI 1.01-1.97)]; households having a child attending school compared to those who did not have [(AOR = 1.88; (95% CI 1.17-3.02)] and, household head having high school education [(AOR 1.98: (95% CI: 1.34-2.87)] were more likely to be latrine owners. With respect to exposure to communication about sanitation (the cues to action), households that had a family member who took part in CLTSH triggering were 3.0 times more likely to be latrine owners than those who did not participate in CLTSH triggering (95% CI 1.92-4.78. Results from adjusted logistic regression analysis of potential predictors of consistent latrine use showed that having positive attitude [(AOR 7.00: (95% CI: 4.55-10.55)]; ownership of a latrine that had superstructure [(AOR 2.3 (95%CI: I1.47-3.48)]; cleanliness of a latrine [(AOR 1.69 (95%CI: 1.00-3.00)]; and latrines that had a protected door [(AOR 1.94 (95%CI: 1.10-3.48)] were significantly associated with consistent latrine use. The qualitative study revealed that latrine ownership was influenced by multi-level ecological barriers. The barriers to sustained adoption and use of sanitation facilities were categorized into 1)individual level (past latrine experience, perception of less health threat to unhygienic child faeces disposal, lack of knowledge and demand to improved latrine), 2) household level (unable to pay the cost of a latrine, lack of space and, absence of physically strong family member), 3) community level (lack of access to public latrine, lack of shared rules against open defecation, lack of financial access for the poor) and, 4) societal level factors (flooding, soil condition and lack of appropriate sanitation technology that can adopt the environment, lack of promotion and demand creation for improved latrine, and the lack of strong leadership at the local level). Conclusions and recommendations: The very limited access to improved latrine needs ctirtical attention. Attitude and perceived social norm were the psychosocial predictors of latrine ownership, which suggests normative and persuasive behaviour change approach are relevant. Sanitation facilities were valued not only for health benefit, but also for providing protection, privacy, and dignity, which needs consideration by policy makers and sanitation programmers. It is critical to increase access to environmentally feasible, affordable and safe toilet options. Multiple level barriers to sustained adoption of sanitation facilities indicating the need to consider interventions that address multi-dimensional and multi-level factors concurrently. Interventional research recommended to investigate the effectiveness of the suggested normative and persuasive approaches in changing behaviour to increasing latrine adoption and use.Item Understanding Runoff Generation Processes and Rainfall Runoff Modeling in Meja Watershed(Addis Ababa University, 2013-06) Solomon, Berhane; Birhanu, Zemadim (PhD); Dereje, Hailu (PhD); Assefa, Melesse (PhD)Understanding the basic relationships between rainfall, runoff, soil moisture and ground water level are vital for an effective and sustainable water resources planning and management activities. But so far there are no hydrological studies in Meja watershed that aims to understand the watershed characteristics and runoff generation processes. This study was conducted to understand runoff generation processes and model rainfall runoff relationship in Meja watershed having a drainage area of 96.6 km2.The watershed is one of the three research sites of International Water Management Institute (IWMI) developed in early 2010 in the upper Blue Nile Basin Ethiopia. In the study, primary data of soil moisture, shallow ground water level, rainfall and runoff were collected from the hydrological monitoring network in the watershed. Two nested sub- watersheds namely Galessa and Kolu were defined in the watershed for detail analysis of hydrologic variables. Galessa has drainage area of 1.6 km2 and Kolu has a drainage area of 2.5 km2. Hydrological models like HBV and RRL SMAR were configured to understand the relationship between rainfall and runoff in the watershed. Relationships between rainfall, soil moisture, shallow ground water level and runoff were developed to understand runoff generation processes in the watershed. Analysis of rainfall data indicated weak daily correlation (r2<0.35) of areal rainfall between Galessa, Serity and Kolu and similar annual total and average rainfall of the three sites of Meja watershed. However monthly correlation of areal rainfall between the three sites was better than daily correlation (r2>0.8). According to one year and three months data, there is no strong daily rainfall and runoff relationship (r2<0.5) in Meja and Kolu which is nested sub - watershed; this may be due to abstractions such as irrigation and human interventions in the watershed. Ground water level and runoff has strong relationship (r2>0.65) in monthly basis of Kolu nested sub watershed but there is moderate relationship of rainfall and ground water level. There is spatial variability of soil moisture content in Meja watershed, this variation occurs due to heterogeneity of the soil, which means the places are different in soil texture and also the variation is due to vegetation cover and change of slope. There is strong linear relationship of rainfall and monthly averaged volumetric soil moisture in most soil moisture layers of Meja and its nested sub-watersheds. The general relationship between runoff and monthly averaged soil moisture at different layers in Meja watershed and Kolu is strong. Analysis of rainfall runoff models indicated that relationships of rainfall with observed and simulated runoff was similar.HBV model performs better than RRL SMAR model in Meja and Kolu. RRL SMAR model couldn’t capture low flow in Meja and Kolu. This inaccurate result of SMAR model in Kolu sub-watershed may be due to inability of the model to simulate runoff in very small catchments like Kolu.Item Application of a Satellite Based Rainfall-Runoff Estimation: in Upper Omo-Gibe Basin to Simulate the Extreme Flood Event at Omorate(Addis Ababa University, 2020-02) Samuel, Bekele; Elias, Tedla (PhD)Satellite-rainfall products are recognized as an essential source of rainfall data, especially in the region where ground based measurements are unavailable. Therefore, the main objective of this study is to Apply a Satellite based Rainfall-Runoff estimation: in Upper Omo-Gibe Basin to simulate the extreme flood event at Omorate and with specific objective of evaluate the capabilities, applicability and limitations of satellite rainfall products such as CMORPH, TRMM 3B42v7 and PERSIANN, and inputs of hydrological models to simulate the Rainfall-Runoff by hydrological model NAM and preparing the Flood Hazard map in the lower water shed using MIKE-11,MIKE-21 and MIKE-FLOOD. These products and inputs were employed to simulate stream flow in the Great Gibe Watershed. The study period 2000-2012 was used for downloading and extracting the selected satellite rainfall estimates with daily-temporal and 0.250 x 0.250 spatial resolution. Sensitivity and uncertainty analysis, calibration and validation of the model were done using MIKE ZERO particularly the Sequential Uncertainty Fitting (SUFI-2) algorism for all rainfall inputs independently. The calibration period was from 2001-2005 leaving one years as a-warm up period and the validation period was from 2006-2012 for satellite rainfall based simulations as well as in situ based simulations. Based on the modeling results of Mike Zero models had showed better performance when calibrated with the in situ rainfall with model performance efficiency of Mean Absolute Error, Maximum Values and Standard Deviation models respectively while, the satellite rainfall estimates (TRMM-3B42v7 and CMORPH) showed relatively good performance when calibrated on the models with Mean Absolute Error (5.21,4.24), Max.Val. (73.74,32.97) and Std. Deva.(7.46,4.24) in the case of Asendabo with relative to the ground based measurements in both satellite based product respectively. But, PERSIANN satellite rainfall estimates showed poor performance for all Mean Absolute Error (3.78), Max. Values (33.06) and Std. Deva. (4.24) before bias corrected. The model output simulation results performance in analyzed of Rainfall-Runoff based up on the coefficient of determination and Nash-Sutcliffe coefficient, during the calibration it is found to be 0.509 and 0.64 respectively and the total water balance error during calibration is 14.75%. And during validation period 0.645 and 0.675 respectively with the total water balance error is 17.5%. Peak and low flows between observed and simulated hydrograph were found matching well. The simulated minimum and maximum runoff for 13 years’ period the maximum annual runoff varies between 1466.3 mm to 7525.4 mm. The simulated runoff was maximum for the month of August (6977.4 m3/s) and minimum for the month of April (5540.6 m3/s). The single flood event of year 100 in the upper part of Gibe confluence flood plain simulated using MIKE FLOOD, which integrated the calibrated and validated 1D MIKE-11 hydrodynamic model with 2D hydrodynamic model MIKE-21 for the flood plain.Item The Influence of El Niño Induced Drought on The Limnology and Dynamics of Cyanotoxins In A Shallow Tropical Reservoirkoka: Implications for Possible Public Health Threat and Restoration Efforts(Addis Ababa University, 2020-02) Samson, Tilahun; Demeke, Kifle (PhD)Studies predict that future climate-change scenarios such as global warming promote the proliferation and dominance of potentially toxic cyanobacteria due to their influence on the limnology of aquatic environments. Lentic systems in the tropics such as Koka Reservoir are largely of riverine origin. They are, therefore, more susceptible to changes in hydrological cycles or rainfall pattern induced by climate change anomalies such as El Niño induced drought and La Niña induced flooding. This study was conducted on Koka Reservoir, which is one of the most severely impacted water bodies by the recurrence of potentially toxic cyanobacteria. Our study period (May 2015-April 2016) coincided with the recent incidence of El Niño induced drought that was reported to be the worst in decades. Physico-chemical and biological parameters were determined using the standard methods. The drought caused a reduction in the flow of Awash River and amount of sediment transported and drying of Modjo River. This expectedly caused a concomitant reduction in the annual nutrient budget of the reservoir received from riverine sources. The consequent low levels of nutrients in the reservoir, which was most pronounced for nitrogen sources, led to the occurrence of Microcystis spp. in unusually low abundance and the emergence and dominance of diazotrophic cyanobacteria, Cylindrospermopsis spp.. The low nitrogen levels (μg L-1) observed in the open water (16.5-135) and near-shore (9.69 -250) sites also suggest that riverine input is probably the major source of nutrients to the reservoir. Total phosphorus (μg L-1), however, exhibited better availability, with its levels varying from 532 (Jul) to 668 (Mar) and 500 (Jul) to 698 (Mar) in the open water and near-shore sites, respectively. The large discrepancy between the model predicted phosphorus concentration (Pλ, 156.6 mg m-3) calculated from the total phosphorus input from allochtonous sources (riverine and atmospheric) and the observed in-lake phosphorus concentration (609 mg m-3), with the former constituting only 25.7 % of the latter, also suggest the supply of phosphorus from autochthonous sources. Frequent horizontal and vertical mixing of the reservoir may have enhanced phosphorus recycling. Horizontal mixing of the reservoir was reflected by the absence of significant differences in limnological parameters. Frequent vertical mixing manifested by turbidity (NTU, 48.39 -2820 and 48.29l-2970), TSS (g L-1), 0.015l-1.672 and 0.029-1.5), Secchi disk transparency (cm,3-17 and 3.05-17.01) between the open water and near-shore sites, respectively, may have promoted the presumed internal phaphorus loading. Despite the low abundance of Microystis spp, the detected intra-cellular concentrations (μg L-1) of the microcystins variants MC-LR (815), MC-YR (466.6) and MC-RR (265.68) by far exceeded the public health safety limit of 1 μg L-1. However, Dolichospermum, the co-occurring diazotrophic cyanobacterium, may have also been responsible for the observed levels of MCs although its confirmation requires further study. The extra-cellular toxins were relatively less concentrated and less frequently detected. However, concentrations (μg L-1) of up to 20 of MC-LR, 6.13 of MC-YR and 1.27 of MC-RR, which also exceeded the permissible limit (μg L-1) set by WHO, were measured. The most potent MC-variant, MC-LR, constituted the greatest proportion (52.6-77.6 %) of total microcystins concentrations in the majority of the samples suggesting the extremely high potential public health risk. The strong positive correlation among the extracellular MCs variants (Spearman Rank Order Correlation, P< 0.05) suggests the possible involvement of a non-specific release mechanism, namely cell lysis, which may have occurred following the collapse of the bloom in May. This study also revealed that all limnological conditions including water residence time (239.5-439.9 days), temperature (22.4 -31.3 oC), and salinity except the limiting level of nitrogen, were within the ranges reported to be optimal for the proliferation of Microcystis and production of microcystins. The strong, positive and significant correlation between Microcystis spp. abundance and nitrogen concentration (Spearman Rank Order Correlation (r= 0.7, P<0.05), and the lack of association with other limnological features suggest that nitrogen was the key environmental factor in the dynamics of Microcystis spp. and microcystins. Absence of correlation between the abundance of diazotrophic cyanobacteria and concentrations of nitrogen (r=-0.173, P>0.05) but the strong and positive correlation with the concentrations of total phosphorus (r=0.718, P<0.05) seem to suggest that phosphorus was the key nutrient influencing this functional group in the reservoir as nitrogen can never be limiting. Considering the long history of sediment deposition and the most likely concurrent nutrient loading since 1960s and the high retention efficiency associated with the prevailing long water residence time, the reservoir may have already accumulated a huge phosphorus reserve in the sediment. Emergence of nitrogen-fixing genera that are capable of satisfying their nitrogen requirement from the inexhaustible atmospheric sources and the presumably huge phosphorus reserve already accumulated in the reservoir implies that reduction in the external input of both nutrients can hardly help in reversing the current situation in Koka Reservoir at least in the near future.Item Remote Sensing Based Estimation of Evapo-Transpiration Using Selected Algorithms; The Case of Wonji Shoa Sugar Cane Estate(Addis Ababa University, 2013-06) Mulugeta, Genanu; Tena, Alamirew (Ph.D); Gabriel, Senay (Ph.D)The goal of every grower is to practice irrigation management to fulfill water needs profitably, safely, and in an environmentally responsible way. For this, accurate knowledge of the amount of evapotranspiration (ET) is critical. The focus of this study was to estimate and compare the actual evapotranspiration (ETa) of the Wonji Shoa Sugarcane Estate using different remote sensing algorithms. The daily ETa of the sugarcane was estimated and thematically mapped pixel-by-pixel using Surface Energy Balance Algorithm for Land (SEBAL), Simplified Surface Energy Balance (SSEB) and Operational Simplified Surface Energy Balance (SSEBop) algorithms on Landsat7 ETM+ and MODIS images acquired on four days in 2002. The algorithms were based on image processing which uses spatially distributed spectral satellite data (visible, near infrared and thermal infrared) and ground meteorological data to derive the surface energy balance components. The results obtained revealed that the ranges of the daily ETa estimated on January 25, February 26, September 06 and October 08, 2002 using SEBAL were 0.0 - 6.85, 0.0 – 9.36, 0.0 – 3.61, 0.0 – 6.83 mm/day; using SSEB 0.0 - 6.78, 0.0 – 7.81, 0.0 – 3.65, 0.0 – 6.46 mm/day, and SSEBop were 0.05 - 8.25, 0.0 – 8.82, 0.2 – 4.0, 0.0 – 7.40 mm/day, respectively. The Root Mean Square Error (RMSE) values between SSEB and SEBAL, SSEBop and SEBAL, and SSEB and SSEBop were 0.548, 0.548, and 0.99 for January 25, 2002; 0.739, 0.753, and 0.994 for February 26, 2002;0.847, 0.846, and 0.999 for September 06, 2002; 0.573, 0.573, and 1.00 for October 08, 2002, respectively. The standard deviation of ETa over the sugarcane estate showed high spatio-temporal variability perhaps due to soil moisture variability and surface cover. Dry periods exhibit greater variability compared to wetter periods. Generally during the dry season, ET is limited to the well watered sugarcane fields and water storage areas only. During the peak rainy season, ETa was high throughout the entire sugarcane estate. All the three algorithm results showed that generally well watered sugarcane fields in the mid-season growing stage of the crop and water storage areas had higher ETa values compared with the other dry agricultural fields confirming that they consumptively use more water. The evaporation fraction (ETrF) results also followed the same pattern as the daily ETa over the sugarcane estate. Comparison of ETa obtained from the MODIS Product (MOD16) with those obtained from the Landsat based algorithms resulted in a very poor correlation. The total crop and irrigation water requirement and effective rainfall estimated using the Cropwat model were 2468.8, 2061.6 and 423.8 mm/yr for January 2001 planted and 2281.9, 1851.0 and 437.8 mm/yr for March 2001planted sugarcanes, respectively. The mean annual ETa estimated for the whole estate were 107 Mm3, 140 Mm3, 178 Mm3 and 80 Mm3 using SEBAL, SSEB, SSEBop and MOD16, respectively. Though the algorithms need to be validated through field observation, either of these algorithms tested in this study have potential to be used for effective irrigation water management.Item Runoff Estimation and Water Management for Holetta River, Awash Subbasin, Ethiopia(Addis Ababa University, 2013-06) Mahtsente, Tibebe; Assefa, Melesse (PhD); Dereje, Hailu (PhD); Birhanu, Zemadim (PhD)The hydrology of Holetta River and its seasonal variability is not fully studied. In addition to this, due to scarcity of the available surface water and increase in water demand for irrigation, the major users of the river are facing a challenge to allocate the available water. Therefore, the aim of this research was to investigate the water availability of Holetta River and to study the water management in the catchment using Geographical Information Systems (GIS) tool, statistical methods, and hydrological model. The rainfall runoff process of the catchment was modeled by Soil and Water Assessment Tool (SWAT). According to SWAT classification, the watershed was divided in to 6 subbasins and 33 hydrological response units (HRUs). The only gauged subbasin in the catchment was subbasin one that is found in the upper part of the area. Therefore, sensitivity analysis, calibration, and validation of the model was performed at subbasin one and then the calibrated model was used to estimate runoff at the ungauged part of the catchment. The performance of SWAT model was evaluated by using statistical (coefficient of determination [R2], Nash-Sutcliffe Efficiency Coefficient [NSE] and Index of Volumetric Fit [IVF]) and graphical methods. The result showed that R2, NSE, and IVF were 0.85, 0.84 and 102.8 respectively for monthly calibration and 0.73, 0.67 and 108.9 respectively for monthly validation. These indicated that SWAT model performed well for simulation of the hydrology of the watershed. After modeling the rainfall runoff relation and studying the availability of water at the Holetta River, the water demand of the area was assessed. The survey form was used to identify information, which includes the number of Holetta River consumers, major crops grown by irrigation and the total area coverage. CropWat model was used to calculate the irrigation water requirement for major crops. Based on the result of CropWat model and survey analysis, the irrigation water demand for the three major users of Holetta River was calculated. The total water demand of all three major users was 0.313, 0.583, 1.004, 0.873 and 0.341 MCM from January to May respectively. The available river flow from January to May was taken from the result of SWAT simulation at subbasins 2,3,4 and 5. The average flow was 0.749, 0.419, 0.829, 0.623 and 0.471 MCM from January to May respectively. From the five months, the demand and the supply showed a gap during February, March and April. This indicated that there is shortage of supply during these months with 0.59 MCM. Therefore, in order to solve this problem alternative source of water supply should be studied and integrated water management system should be implemented.Item Rainfall-Run-Off Simulation and Modeling (The Case of Dechatu Watershed)(Addis Ababa University, 2020-01) Kedir, Hassen; Tena, Alamirew (PhD); Dangenet, Sultan (PhD) Co- AdvisorThis paper presents an application of surface rainfall run-off simulation using the Hydrologic Modelling System (HEC-HMS). A case study was carried out for the Dechatu watershed, a Rainfall is classified as “bi-modal” with the first significant rains from March to May and the second rains from is July to Septembertypical semi-arid and sub-humid geo-climatic region in eastern Ethiopia Awash River basin. The modeling schemes using mechanism of models provided by HEC-HMS for runoff volume. The modeling results were compared with historical observation data. Several River Basins (Watershed) across the world have been simulated using hydrological models to understand hydrological processes and the availability of water resource. Some of these basins are ungauged. In this study in order to evaluate the hydrological process of Dechatu Watershed for sustainable management; HEC-HMS 4.2 hydrologic model (with CN) is used to simulate its runoff (Watershed Modelling) was used as an interface to delineate the watershed and generate some input (basins parameters). The CNparameters are computed in HEC-GeoHMS using land use and soil type data.Using the Chi-Squared test ranking, Dengego rainfall data fits Lognormal 3 parameter distribution. Annual Maximum Daily Rainfall (mm) for selected return periods50years were used for the meteorological inputs. The results showed a total volume of runoff 150.20MM3 during the fifty years of the simulation. The peak discharge was found to be 2,528.7m 3 /s and the model evaluation has showed, indicating that the results of the simulation are satisfactory.Item Hydrogeological and Hydrological Characterizations and Classification using Remote Sensing Datasets and Models(Addis Ababa University, 2013-06) Guta, Wakbulcho; Awange, Joseph L. (Prof.); Mekonnen, Gebremichael (PhD)Ethiopian water resource is facing a range of challenges in water management caused by several natural and man-made impacts, namely over exploitation, deforestation, land degradation and climate variability. Understanding the spatio-temporal characteristics of water storages is therefore crucial for the country, since the welfare of the society depends on the availability of water. The prime objective of this study is to apply remotely sensed and model data to Ethiopia in order to i) analyze the inter-annual, intra-annual and seasonal variabilities of Total Water Storage (TWS), ii) understand the relationship between TWS variations, rainfall and soil moisture anomaly, and iii) study the relationship between the characteristics of aquifers’ and TWS anomalies. The data used in this study includes; monthly gravity field data from the Gravity Recovery And Climate Experiment (GRACE) mission to assess the variation in TWS; monthly rainfall data from the Tropical Rainfall Measuring Mission (TRMM) to assess the response of water storages to the incoming water mass and the effect of rainfall on TWS, and the hydrological model data of Global Land Data Assimilation System (GLDAS) to obtain soil moisture. Our investigation covers a period of 8 years from 2003 to 2011. The results of the study shows that the western part and the north-eastern lowland of the country lost water at a rate of not less than 0.108 cm/year, whereas all the other regions gained water mass at a rate of more than 0.60 cm/year. The impact of rainfall seasonality was also seen on TWS changes, with losing seasons being summer and autumn, and gaining seasons being spring and winter for majority of the regions. From the TWS duration curve (TDC), the percentage time of water mass loss in all regions is also observed as 55% of the study period. Applying the statistical method of Principle Component Analysis (PCA) on TWS, soil moisture, and rainfall variations shows the dominant annual water variability in the western, north-western, northern and central regions, and the dominant seasonal variability in the western, north western and the eastern regions. A correlation analysis between TWS and rainfall indicate a minimum time lag of zero and maximum of six months, whereas no lag has been seen between soil moisture anomaly and TWS. A significant increase in TWS deficit has also been seen in the central highlands of the country over the period of three years (2003 to 2006) with Total Storage Deficit Index (TSDI) ranging from nearly zero in 2003 to -500 % in western region and -800 % in the central and northern regions of the country in 2006. A classification of the country based on TWS Duration Curve shows that TWS variation is high in the western and low in the north eastern parts. The delay response and correlation coefficient between rainfall and TWS is also related to recharge mechanism and revealed that most regions of the country receive indirect recharge. The hydrological characterizations and classification has been carried out as Part-II, separately from the hydrogeologic characterization section only for watersheds in one selected basin which is located in region 2. The Part-II finding shows the possibility of characterizing and classifying watersheds in a data limited regions through the help of remote sensing instruments and models. Here, the characterization and classification has been made using the catchment climate, catchment function and catchment structure descriptors. The detailed findings of this section have been described in a separate “Abstract” provided at the beginning of Part-II.Item Water Supply Coverage and Water Loss in Distribution System with Modeling (The Case Study of Addis Ababa)(Addis Ababa University, 2011-11) Kabeto, Shimeles; Sileshi, Yilma (PhD)Leakage in water distribution pipes is a major problem faced by the water industry. Water utilities often employ traditional audit methods to estimate water lost as leakage. As a result demand for additional water sources and infrastructure is growing. More ever, nearly 37% of the total water production is loss at different level of distribution system before reaching to the consumer. The focus of this study is to evaluate the city’s distribution coverage of the water supply and evaluating the total water loss. The water supply coverage at the city level and the total water loss both at the city level and at the sub system level, the collected data was assembled in EPANET and controls were added to best represent the functioning of the water system. Water production that is only for the city and the water consumption as aggregated from individual customer meter reading was to evaluate the total water loss at the city level. Select the pilot area in around Gottera the selection of the area from the branch based on the following criteria. Hydraulically easily desecrate area, 24hr water availability, Customer not more than 1000, and more leakage complain. The sub-system that has isolated networks and production and consumption data were used to evaluate and compare the spatial distribution of water loss. There are several reasons for the high level of water loss in Addis Ababa., and some advisory solutions were briefly proposed for the major effect of the water loss like age of pipe networks, poor maintenance of networks, water scheduling, customer side leakage and illegal connection. The reduction of NRW (Non Revenue Water) by Water Balance Method shows the difference between predicted and actual water losses in water distribution network, The results also shows that after leakage reduction control works took place, the volume of water loss in water distribution network has reduce about 39% of the total production supply to the sub-system. The distribution system model was then used to evaluate three alternative scenarios to improve system performance. The objective of the first and second scenario was to increase the flow rate at taps of low supply; the third scenario aimed at adding taps to parts of the sub-system without easy access to running water. The first scenario consisted in opening valves to connect subsystems: it increased the flow rate at taps of large supply more so than at taps of low supply. This scenario was not recommended because it would quickly drain parts of the water supply.