Identification of Groundwater Potential Zone using Remote Sensing and GIS Techniques in Sede River Watershed in Hulet Eju Enesie District: Blue Nile Basin, Ethiopia

Abstract

Water plays a vital role in the development of activities in an area. Despite Blue Nile Basin, water supply is largely obtained from surface water, which is highly dependent on the seasonal inputs from rainfall. Due to this case it is inadequate to fulfill the water demand. Productivity through groundwater is quite high as compared to surface water, but groundwater resources have not yet been properly exploited. Keeping this view the present study attempts to identify groundwater potential zones in the Sede River Watershed of the Blue Nile Basin using remote sensing and GIS techniques. Integrated remote sensing and GIS have been used in the present study to prepare thematic maps such as lithology, topography/elevation, drainage density, lineament density, rainfall, soil type, slope and land use/ land cover. On the basis of relative contribution of each of these maps towards groundwater potential, the weight of each thematic map has been assigned based on the Saaty's analytical hierarchy process. These weights were assigned each thematic map to obtain a unified weight map. The thematic layers were finally integrated using weighted overlay analysis method in GIS software to delineate groundwater potential map of the study area. Thus from the present study it is observed that an integrated approach involving remote sensing and GIS technique can be successfully used in identifying potential groundwater zones in the study area. Five categories of groundwater potential zones, namely very good, good, moderate, fair and poor zones have been demarcated. The very good groundwater potential zones correspond to quaternary alluvial, it is residual and transported soils occupying flat lying and gentle topography area covered by grass land. It is occurred in central part of the area, which is the nearest to the intersection of Ayibar river and Sede River, Addis Alem, Debre Selam and Abiyote Selam kebele administration. The good potential zone are concentrated along the lineament line having high density area and covered in spares vegetation area. Moderate zone is covered largest area, it is present on the steep slope area which is occupied by sparse forest, shrub land and bare land area. It is highly dominated on the north and south part of the study area. Fair zones are available on the cultivated land throughout the study area. The area is dominated by gentle topography and far from lineament. Poor zone mainly presented on mountains and escarpments with steep cliff, where the area have high run-off. Finally, the resulted groundwater potential zoning map validated based on NDWI, NDMI and existing borehole data of the study area.