Groundwater Recharge Estimation and Water Suitability Evaluation Case Study of Upper Fafem Sub Catchment in Somali Regional State of Eastern Ethiopia
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Date
2021-05-22
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Addis Ababa University
Abstract
This study was conducted in upper Fafem sub catchment in Somali region which has an area of 1,300km2. Estimation of groundwater recharge and water quality for domestic and irrigation purposes of an area is very important for groundwater planning and management. There are number of methods used to estimate groundwater recharge. Wetspass model is one of the recharge estimation methods, this model simulates the recharge, run off and evapotranspiration in an annual and season bases. For estimating the recharge using wetspass, inputs of the model should be prepared in the form of digital maps using ArcGIS. The inputs of the model are long term meteorological data (precipitation, temperature, wind and potential evapotranspiration) and physical characteristics of the catchment such as soil type, slope, land use/land cover, elevation and groundwater depth. For this study, long term average annual rainfall of 660.46 mm was distributed as 616 mm (93%) of actual evapotranspiration, 23 mm (4%) of groundwater recharge and 20 mm (3%) of surface run off. Groundwater potential zones of upper Fafem sub basin were also identified using Remote sensing and GIS, the groundwater potential zones were classified as; low groundwater potential zone, moderate groundwater potential zone, high groundwater potential zone and very high groundwater potential zone. Most of the area is characterized by moderate groundwater potential, almost 52% of the area is characterized as moderate groundwater potential. For evaluating groundwater suitability for drinking and irrigation purposes, eight water samples were collected from the boreholes in the study area. The laboratory result of the water samples was compared to the WHO and MoW&I standards. As a result, the groundwater of this catchment is suitable for drinking and irrigation purposes according to the laboratory results.
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Upper Fafem Sub Catchment, Groundwater Recharge Estimation, Wetspass Model, Water Suitability Evaluation, Groundwater Potential Zones, Soil Water Balance