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Item GIS BASED GROUNDWATER POTENTIAL MAPPING AND RECHARGE 1 ESTIMATION: A CASE STUDY IN MELKAODA WATERSHED RIFT VALLEY LAKES 2 BASIN, OROMIA, ETHIOPIA(Hawassa University, 2021-10-24) ADEM BUTA DEKEBOThe groundwater potential zones of the Melkaoda Watershed were demarcated with the help of remote sensing and Geographic Information System (GIS) techniques. The parameters that were considered for identifying the groundwater potential zone like geology, slope, drainage density, geomorphic units, and lineament density were generated from satellite data and they were then integrated with weighted overlay in ArcGIS. Suitable ranks were assigned for each category of these parameters and weight factors were decided for them based on their capability to store groundwater using AHP approach and then the groundwater potential zones were classified into four categories as very low, low, high & very high. In addition, the groundwater recharge was estimated with the help of the WetSpass model using water balance approach. The parameters considered for this case generally included three types: hydro-meteorological (rainfall, temperature, wind speed, PET, and GWD), bio-physical (soil, landuse, topography, and slope), and attribute lookup (soil lookup, landuse lookup, and rain day lookup) tables. All the hydro-meteorological parameters were interpolated in ArcGIS for grid map preparation of each parameter and the prepared grid map was converted to ASCII file format for the effective model run. The model performance was checked through calibration and the obtained groundwater recharge result ranges 0.45 to 65.5 mm/year with the mean value of 32.87 mm/years and 3.4% contributed to groundwater as recharge. finally, the changes in groundwater recharge between two simulation period was stated again with help of WetSpass model using the LULC images of 1989 and 2018 to quantify the impacts of the LULCC. The parameters used for this analysis were the same as those used for groundwater recharge estimation except for the satellite image of 1989 and the LULCC analysis depicted that there was the expansion of built-up land and agricultural land. Agricultural land and built-up land were increased by 0.046, 2.56 rate per a year from 1989 to 2018 respectively. This paper finalized that there was access to the groundwater potential in the Melkaoda Watershed and this could overcome the water scarcity challenging the community in and around the area. The recharge which has been the main source of groundwater is decreasing from time to time as the result of this paper is indicating. Thus, to get sustainable groundwater potential, the recharge has to be well treated by increasing groundwater rechargeItem ASSESSING THE IMPACT OF LU/LC CHANGE ON HYDROLOGICAL RESPONSE BY USING SWAT MODEL: A CASE STUDY AT DEDABA WATERSHED, ETHIOPIA.(Hawassa University, 2021-04-26) IBSA DIBO DEKOWater is a precious and finite resource and must be managed in sustainable way to meet human as well as environmental needs. Land use/land cover change has an impact for alteration of watershed hydrology. The watershed is undergoing land use change due to intensive cultivation andurbanization as a result of population growth which has an impact on hydrologicresponse of the watershed. This study quantified watershed runoff volume using SWAT modeland assessed the effect of land use/land cover change on the stream flow. In this study, the impact of LU/LCchange was carried out by using the Soil Water Assessment Tool (SWAT2012) model, which was integrated with GIS10.3 software. GIS and ERDAS IMAGINE2014 were used to generate LU/LCmaps from Landsat TM, TM, and OLI acquired in the years 1990, 2001 and 2018 respectively. The land cover maps were generated using the maximum likelihood algorithm of supervised classification. The classified maps were assessed using confusion metrics. The results of the analysis showed that the Agricultural land has expanded during the study period of 1990-2018. During the study period, forest land, and shrub and grassland decreased by 19.5% and 15.61% respectively while Agricultural land and Built-up area increased by 33..63% and 1.48% respectively. Using three land cover maps, three SWAT model setup were run to evaluate the impacts of LU/LC changes on the streamflow of the study watershed. The performance of the SWAT model was evaluated through sensitivity analysis, calibrationand validation by using SWAT-CUP. The Coefficients of determination and Nash–Sutcliffe were used to evaluate the model and it resulted in 0.87 and 0.73 for calibration and 0.82 and 0.68 for validation respectively. During the study periods, the simulation result indicated that streamflow increased in the wet season and short rainy season streamflow by 9.64% and 3.05% respectively, while decreasing by 5.6% in the dry season. The Surface Flow (SURQ) increased by 12.58% while Groundwater Flow (GW_Q) decreased by 14.83% due to the increment of Agricultural land. The study resultsshowed change in flow with change in land use/landcover, so it needs landuse planning and sustainable water resource managementItem PHYSICAL IRRIGATION POTENTIAL ASSESSMENT FOR SURFACE IRRICATION: A CASE STUDY IN CHEMOGA WATERSHED, UPPER BLUE NILE BASIN, ETHIOPIA(Hawassa University, 2020-10-11) KASSANESH MELKAM MENGISTEAssessment of available land and water resources for irrigation is essential for planning their use, to utilize limited resources efficiently and for the sustainable production of crops and food security of the ever increasing people in developing countries like Ethiopia. The study was mainly focused on assessing the available land and water resources potential for surface irrigation of Chemoga Watershed. This was done by using Geographic Information System (GIS)-based Multi Criteria Evaluation (MCE) tools, a hydrological Soil and Water Assessment Tool (SWAT) model, and a Crop Water and Irrigation Requirements Program of FAO (CROPWAT) model. GIS was used to map the land suitable for surface irrigation based on slope, soil, land use /land cover, and river proximity. SWAT model was used to estimate the water availability, and CROPWAT model calculate the reference crop evapotranspiration, effective rainfall, net and gross irrigation water requirement of crops. Potentially suitable land for surface irrigation development was evaluated by selecting six crops (barley, wheat, bean, maize, onion, and potato). The result of the overall weighted analysis for these factors gave about 25462.08 ha (71.4 %) of the Watershed land considered as high to moderately suitable whereas 10427.53 ha (28.6 %) were not suitable for surface irrigation. The SWAT model was calibrated and validated from the available hydro metrological and spatial data. Model performance result showed in between the observed and simulated stream flow with coefficient of determination (R2) and Nash-Sutcliffe efficiency (ENS) values 0.86 and 0.7 for calibration, and 0.74 and 0.63 for validation, respectively and indicated a good performance of the model in simulating the hydrology. The annual average simulated stream flow was evaluated and 36.2 m 3 /s. The water demand required by the selected crops was 228.18m3 /s/ha. From the total available suitable land, only 12376.03 ha can be irrigating with the available waterItem INSTITUTE OF TECHNOLOGY, FACULTY OF BIO-SYSTEMS AND WATER RESOURCES ENGINEERING, DEPARTMENT OF WATER RESOURCES AND HYDRAULIC ENGINEERING(Hawassa University, 2023-10-24) YONAS HAILU WASEThe goal of this study was to assess the groundwater potential zone in a Deme watershed area of the Omo-Gibe basin, Ethiopia, where data availability was poor. In this study, a number of data from a variety of sources have been used, including climate, stream flow, and spatial thematic layers including land use maps, soil maps, drainage density maps, geology maps, slope maps, lineament density maps, and geomorphology maps. In order to estimate the recharge amount and its spatio temporal fluctuation in the watershed, Soil and Water Assessment Tool model was utilized. At the Orata Alem location within the Deme watershed, several modeling techniques, sensitivity analysis, calibration beginning from 1991 to 2001, and validation 2002 to 2006 periods, were applied. As a result, the results of the calibration and validation phases showed that the model can accurately and reasonably reproduce the stream flow pattern and the various hydrograph responses, as indicated by the Nash-Sutcliffe efficiency(ENS) values of 0.78 and 0.74 and the coefficient of determination(R 2) values of 0.81 and 0.76, respectively. The watershed's mean annual recharge rate is estimated to be 214.5 mm/y, with the northern top section of the watershed experiencing a recharge rate of 233.77 mm/y, the middle of the watershed experiencing a recharge rate of 214.72 mm/y, and the lower part of the watershed experiencing a recharge rate of 194.51 mm/y. Analytical Hierarchical Process was used to rank the various layers based on a pair-wise comparison matrix in order to estimate the final normalized weights of thematic map layers. Groundwater flow direction was determined by the Surfer model. GIS-based Multi-Criteria Decision Analysis was applied for mapping of groundwater potential zones and its results were used to identify three Groundwater Potential Zone: low, moderate and high, with area coverage of 26.3664 Km2 ,744.1776 Km2 and 271.9179 Km2 correspondingly. Around 71.4% of the region has a moderate groundwater potential, and 26.084% has a high potential. Lastly, groundwater well inventory data for 35 wells dispersed around the region were used to validate the Groundwater Potential Zone map in order to evaluate the model's efficacy. The validation results confirmed that 84.44% the study Ground water potential zone match with ground water well points in the Deme watershed, so that the applied approach provides well reasonable results that can help in planning, management and sustainable utilization of the groundwater resources in this water-stressed area.Item Effects of land use land cover changes on soil erosion risk in Beshilo sub basin and the influence on Tebi dam, north eastern highlands of Ethiopia(Hawassa University, 2022-03-15) Andarge GetachewContinuous increase of world’s population and demand for food and staple production poses a major challenge for agriculture in the short and medium period. In the current study area, soil loss information and evaluation of risk of potential of soil erosion was not assessed. So, the aim of these study is to assess and analyze the impact of land use land cover change on soil erosion risk using remote sensing and GIS techniques in the upper bushilo sub-basin northern-eastern highland of Ethiopia between 1990 and 2020. Primary materials and tools used are ArcGIS 10.8 software, ENVI 5.3 software, Landsat satellite image of 1990, 2000, 2010, and 2020, ASTER DEM /DEM 30X30 was downloaded from USGS earth explore, Google earth pro as use for base map that also were downloaded for the four study periods. GPS, Camera, Internet access, and computer software were used for data processing and GIS analysis. the watershed’s computed soil loss ranged from zero in plain areas and water courses to large over 68.7t ha-1 yr -1 . In very degraded sloping regions and at specific spots of steep slopes of the watershed, gross soil loss rate ranged to 79.65 t/ha. It shows a larger spatial variation of soil loss over the watershed. It is mainly caused by the difference in soil, rainfall, slope, land cover, and improper land management. The estimated mean annual gross soil loss from 1990-2020 under the entire watershed is about a 9.94 t/ha/yr. Within the study period (1990-2020), 41723.8 ton soil has transported to Tebi dam. The GIS-based RUSLE model can assist decision-makers in effective planning for erosion control studies on risky areasItem GIS-BASED SURFACE IRRIGATION POTENTIAL ASSESSMENT: A CASE STUDY IN BILATE RIVER WATERSHED, SOUTH-WESTERN, ETHIOPIA(Hawassa University, 2021-04-26) ALELU MANAMO MERASAThe major problem associated with rainfall-dependent agriculture in Ethiopia is the high degree of rainfall variability and unreliability. As a consequence, food insecurity often turns into famine. Irrigation development is one of the key strategies to increase agricultural production and alleviate poverty. This study, therefore, aimed to assess the surface irrigation potential and land resources potential of the Bilate River Watershed for irrigation expansion. Watershed delineation, identification of potentially irrigable land, and estimation of irrigation water requirement and surface water resources availability of the study area were the steps followed to evaluate this irrigation potential. Irrigation potential was mapped by using GIS of the watershed; Arc SWAT model was used to estimate the water resources availability in the watershed; Analytical hierarchy process (AHP) comparison was used to conduct land suitability assessment and a CROPWAT 8.0 model was used to determine the crop water requirement for major crops of the study area. To identify potentially irrigable land, irrigation suitability factors such as soil physical properties, slope, land use/ land cover, and distances from the water supply (sources) are taken into account. The final results of the overall weighted overlay analysis of irrigation land suitability indicate that 317,841ha (64%) are highly suitable (S1), 153,459ha (30.91%) are moderately suitable (S2), whereas 25,039ha (5.044%) are not suitable (N) for surface irrigation development. The SWAT model was calibrated and validated. The observed monthly streamflow values have a coefficient of determination (R2 ) and Nash-Sutcliffe Coefficient (NSE) of 0.77 and 0.66 respectively for the calibration period and 0.81 and 0.64 for the validation period. The irrigation water demand required by five major selected crops which are grown in the study area throughout the growing season was found to be 663.04 m 3 /s. The annual dependably simulated streamflow was 225.14 m 3 /s. The estimated dependably available flow can potentially irrigate only an area of 53,645.77 ha for highly suitable areas. The result showed that the water demand of the crops was greater than the available dependably flow of the watershed. Therefore to increase the irrigation potential of the watershed sprinkler or drip irrigation methods can be usedItem EVALUATION OF SMALL SCALE HYDROPOWER WITH DIFFERENT DEVELOPMENT APPROACH AT UPSTREAM OF GIDABO RIVER FOR RURAL ELECTRIFICATION(Hawassa University, 2023-12-07) HABTAMU HAILUHydropower is considered as one of the most desirable source of electrical energy due to its environmental friendly and extensive potential available throughout the world. The main objective of this study has to evaluate the small scale hydropower potential for rural electrification of Gidabo river, estimation of discharge to power generation for each selected sites, study energy demand for rural community and finally to prioritize and rank the best suitable site based on multi criteria decision analysis. The materials such as, RET Screen model with the objective to make complete pre-feasibility studies, GPS also used to estimate elevations at different points and ArcGIS was used to delineate watersheds and to determine heads by developing contours. The study method, conducted by reviewed different literatures related with power potential assessment and the collection of hydrological and meteorological data after collected those data, then analyzing data’s by using different software models, after analyzed the data making prefeasibility study for site selection, and transferred flow data for ungauged sites by using area ratio method then calculated power produce potential for each sites then develop flow and power duration curves to select design flows and ranked potential sites based on multi criteria decision analysis to select best suitable sites ,finally energy demand forecasted by using end use method. There was six (6) potential study sites had been selected by using Geographical Positioning System (GPS) of field surveying along the river and represented each site by code with respect to the discharge, power, head, nearest town and road accessibility. Analytical hierarchy process was chosen in combination with GIS as a method of multi criteria decision making to prioritize and select best hydropower site. ArcGIS, MCDA, GPS and Google earth were used for visualization, data analysis and interpretation. Based on multi criteria decision analysis of suitability index value (SI)the site code A@D$ become first choice and site code A@C$ become the last . The total annually energy potential of the selected site code A@D$ was estimated about 33146.0 MWh, 24076.16MWh and 5263.18 MWh for 30 %, 50 % and 90 % of time exceedance respectively. All six potential sites in the study area are classified as small scales hydropower based on installed capacity and also medium based on head. Finally, the forecasted of energy demand for community and load analysis was performed by using end-use method, for this study consider residential, Community and commercial load analysis to energy demand forecasting and evaluation. Generally, this research will give a piece of information about the study area for those concerned body for future work also additional works and for the implementation of SHP PlantsItem Estimation of Groundwater Recharge Using GIS Based Wetspass-M Model: The Case of Dedaba Watershed, Rift Valley Lakes Basin, Ethiopia(Hawassa University, 2024-10-18) JIBRIL WAKEYO WARIOThe Dedaba watershed, located within the Rift Valley Lakes Basin in Oromia, Ethiopia, is experiencing significant changes driven by agricultural expansion, land use and land cover (LULC) changes, and a growing population. These dynamics, combined with insufficient watershed management, have resulted in water resource depletion, pollution, and environmental degradation. The escalating demand for groundwater, driven by the population increase, present a considerable challenge in this region. This study utilized the WetSpass-M (Water and Energy Transfer between Soil, Plants, and Atmosphere under quasi Steady State – Monthly) model, a spatially-distributed water balance model, to assess seasonal and annual groundwater recharge, actual evapotranspiration, and surface runoff in the Dedaba watershed. The model integrates spatially distributed data on precipitation, potential evapotranspiration, temperature, wind speed, soil types, LULC, and topography. These datasets, processed using GIS techniques, allowed for the generation of detailed spatial water balance components. Calibration and validation of the model were conducted using observed groundwater levels and streamflow data, ensuring accurate simulations. The calibrated WetSpass-M model revealed groundwater recharge estimates ranging from 0.46 to 65.4 mm/year, with an average of 37.47 mm/year, representing 3.4% of the total recharge. To understand the impacts of LULC changes on groundwater recharge, the model was applied using LULC data from 1990 and 2020. Results indicated a continuous decline in recharge rates over this period, underscoring the significant influence of LULC on groundwater resources. Specifically, the model estimated recharge at 3.29 mm in January 1990, peaking at 6.03 mm in September, and dropping to 0.13 mm in December. By 2005, these values had decreased, with January at 2.84 mm, September at 5.2 mm, and December at 0.12 mm. The downward trend persisted into 2020, with recharge starting at 2.61 mm in January, peaking at 4.52 mm in September, and reaching 0.12 mm in December. The study highlights the critical need to consider temporal variability and long-term trends in groundwater recharge for sustainable water management in the Dedaba watershed. The analysis of LULC changes shows a rapid urban expansion, reduction of forests and grasslands, and consequent threats to groundwater recharge. Mitigating these risks requires collaborative efforts, including promoting afforestation, water-conserving urban farming, sustainable agricultural practices, and artificial recharge techniques. Future research should incorporate climate change projections to enhance groundwater recharge predictions and improve water resource management strategies.Item FLOODPLAIN MODELING AND MAPPING USING GIS & HEC-RAS ON DOWNSTREAM REACH OF DIJO RIVER, ALAGE, ETHIOPIA(Hawassa University, 2022-10-08) MEKA TIRA WUDAFlood is the most dominant common, continuously frequent and destructive natural disaster in the world. It causes loss of life and property, displacement of people, breaking of socio-economic activities and loss of fertile agricultural lands. Dijo River flood affects Alage ATVET Collage during rain seasons. The main objective of this research is to map the flood inundation area on downstream reach (Alage ATVET collage) of Dijo River. GIS 10.3, HEC-Geo RAS, HEC- RAS 5.0.6, excel 2016 and easy fit 5.5 software’s are used for this research. primary data’s (total station surveying data, field observation) and secondary data (Dijo and furfuro stream flow data and Manning’s n value) are used to conduct the research. Flood frequency analysis, pre-processing, processing/model execution and post-processing methods are used and got 101.22m3 /s, 164.6 m3 /s, 175.8 m 3 /s, 207.58 m3 /s and 227.83m 3 /s peak discharge for 2, 10, 25, 50 and 100- years return period respectively. 27 x-section cut lines are drawn on 4km river reach geometry, among these 55.6 % of the x-sections are severely flood venerable x- sections from all return period peak flood discharges and to both side of the river reach. The flood inundation area of 2, 10, 25, 50 and 100 years return periods were 5702, 8154.71, 8499.96, 9271.9 and 9851.84m2 respectively. This area includes both Alage ATVET collage and neighboring kebeles of the collage. Therefore, the responsible body makes remedial measures to control the flood like repair and increase the height of the exiting earthen dykes at upstream of alage Bera Bridge, construction of new dykes and levees at the chefe agricultural area, grassland area and desilting siltation-filled x-section, afforestation from upper watershed of the riverItem GROUNDWATER POTENTIAL MAPPING USING SWAT MODEL AND GIS BASED MULTI-CRITERIA DECISION ANALYSIS: A CASE STUDY IN GIDABO WATERSHED, RIFT VALLEY LAKES BASIN, ETHIOPIA(Hawassa University, 2022-07-08) BIRUK TAMIRU TADELEGroundwater is the water that is located in the subsurface and saturates the rocks and soil beneath the ground surface. Groundwater is the most valuable natural resources for mankind for drinking, industrialization and irrigation in present day, but the availability is reduced gradually due to over exploitation and lack of management. However, identifying the groundwater potential zones in certain areas of Ethiopia is still challenging in terms of time and cost for resolving water scarcity problems and the management system of groundwater. A systematic assessment and identification of groundwater is essential for proper utilization and management of this precious natural resource. In recent years, Geographic information system based studies have gained much prominence in groundwater exploration, because it is rapid and will provide first-hand information on the resource for further developments. Therefore, the present study was conducted with an objective to identify the groundwater potential of Gidabo catchment, Rift Valley Lakes Basin of Ethiopia using SWAT and GIS-based MCDA techniques. Thematic maps were developed, for ten major parameters (recharge, soil, lineament density, lithology, land-us/ land-cover, geomorphology, slope, drainage density, Roughness and Topographic wetness index (TWI)) that affect the occurrence and movements of groundwater. Recharge was simulated by using SWAT model, the rest thematic layers were developed using ArcGIS 10.4 and Weights assigned to each thematic maps were based on their characteristics and water potential capacity through analytic hierarchy approach (AHP). The thematic layers were subjected to weight sum overlay in ArcGIS spatial analysis tool box, to delineate groundwater potential zone map. The resulted groundwater potential zone was categories in to four classes, namely high, moderate, low and very low. Generally Low and very low groundwater potential zones were found around highland area which coincide with structural hills, peak of the mountain and hard geological formation. The accuracy of the output was cross-validated with information on groundwater prospects of the catchment. Finally, it can be concluded that SWAT and GIS-based MCDA-AHP techniques is very effective and useful for the delineation and identification of groundwater potential zones in the study area.