Institute of Technology
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Item GROUNDWATER POTENTIAL ASSESSMENT USING GIS AND REMOTE SENSING: A CASE STUDY IN MANTHA WATERSHED, OMO-GIBE RIVER BASIN, ETHIOPIA(Hawassa University, 2023-05-27) ZERIHUN ZENEBE JEBULAIn the current study area, the demand for groundwater is increasing. Therefore, the ultimate purpose of this study was to map groundwater potential zones in Mantha watershed using geographic information system and remote sensing. Ten groundwater controlling factors (geology, rainfall, lineament, soil, land use/land cover, geomorphology, slope, and distance to river, elevation, and drainage density) were used to map the groundwater potential zones of the study watershed using remote sensing data. Among these, three layers (geology, geomorphology, and soil) of the study watershed were extracted from existing data, and five layers (slope, drainage density, elevation, lineament, and distance to river) were developed using DEM of 30m*30m spatial resolution. 20 years precipitation data obtained from National meteorology Agency of Ethiopia were converted into areal rainfall using inverse distance weight interpolation method integrated with ArcGIS 10.8 to develop rainfall layer of the study watershed. Landsat8 of the year 2020 was used to map the land use/land cover of the study watershed using supervised image classification with maximum likelihood algorism in ERDAS 2015. Then, all thematic layers were reclassified using literatures and Jenks methods and finally rated in analytical hierarchy process. The results of ten thematic layers data rated in in analytical hierarchy process indicated that the most dominant thematic layers that hold high weight relative to others were- geology (28%), rainfall (16.6%), lineament density (12.9%), and soil (10.3%). Groundwater potential map of the study watershed was obtained by using weights derived from AHP and overlay analysis conducted in arc GIS10.8_ platform. There were four groundwater potential zones mapped in the Mantha watershed, namely, very high, high, moderate, and low. The map result was verified by well data and the result showed strong agreement in each category with 85.7%, 83.33%, 90%, and 100% respectively. The finding of this study indicates that the geographic information system and remote sensing model approach are reliable and can be a reliable prospecting method of groundwater potential zoneItem IDENTIFICATION OF GROUNDWATER POTENTIAL ZONE BY USING GIS AND REMOTESENSING IN SUTEN TO TORA SUB-CATCHMENT, RIFT VALLEY LAKES BASIN, SOUTHERN ETHIOPIA(Hawassa Unversity, 2019-10-21) ASCHALEW GURMUThis study was aimed to mapping of Groundwater potential investigation of Suten-Tora sub catchment in the Rift Valley Lakes basin, Southern Ethiopia. Climate, hydro-geological, land use/land cover, soil, lithology, geomorphology and stratigraphic data were collected, analyzed and inferred. The aquifer characteristics from the well completion reports were used to map the Groundwater flow direction. A Groundwater level contour map; which developed from well completion report is revealed that the Groundwater flows from western towards the center and eastern part of the sub-catchment. The results also inferred from the geological formations show that the Suten-Tora Sub-catchment are mainly covered by partially welded pyroclastic flow, Gash Megal rhyolitic lava flows, Guraghe-Anchor basalt, Nazret welded pyroclastic, Lacustrine sediment, Mesozoic sediment, porphyritic rhyolitic lava domes, Wonji basalts, Precambrian basement complex and recent basalt flows. Moreover, there is also a Geological structure in the study area. The linear feature of these structures are characterized by three distinct interconnected fault trends systems are called in NW-SE, NE-SW and N-S which are more or less affect the availability of Groundwater potential. Among the above listed lithological formations lacustrine sediments, Wonji basalt with scoria deposit and pyroclastic are coincide with high Groundwater potential zone. Similarly a moderate Groundwater potential zone is covered by Geological formations; e.g. Chefe Donsa, un-welded to poorly weld pyroclastic and others small formations. In the other way low and very low potential zones are covered by depositions of Nazret pyroclastic, Gash Megal rhyolite and other similar lithological formations. For the delineation of Groundwater potential zones, the weight over analysis of different factors namely: lineament density, lithology, geomorphology, slope, soil texture, drainage density, rainfall and elevation have been analyzed through the Analytical Hierarchal process (AHP) and ArcGIS 10.3 software. The delineated Groundwater potential zone was categories into four classes namely high, moderate, low and very low potential zone. These delineated Groundwater potential zones class called high, Moderate, Low and very low potential zones are covers an area of around 50%, 20%, 16% and 14% of the total sub catchment area respectively. To conclude that; the center and southeastern parts of the sub catchment have high amounts of Groundwater potential. However the western part has les Groundwater potential. Depend on the validation of output accuracy level; the delineation of Groundwater potential zones by using GIS and remote sensing techniques is important method. Finally it has been recommend that ; the well drillers in this study area suggested to use this Groundwater potential zone map as informationItem 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.
