GIS –BASED GROUNDWATER POTENTIAL ZONE MAPPING OF BURJIE WATERSHED, ABAY BASIN, ETHIOPIA.

Abstract

Groundwater is a hidden natural resource which plays a crucial role in all the environmental and biological processes with a greater significance on socio-economic activities. A case study with an aerial extent of 523.1 km2 was carried out to determine the groundwater potential zones in the Burje watershed, Abay basin, Ethiopia. A total of seven thematic layers including geology, lineament density, slope, soil, Land use/Land cover, rainfall, and drainage density were used to map the groundwater potential zones of Burje catchment. The methods to assess the identification of groundwater potential zone mapping was using weight overlay analysis and Analytical Hierarchy Process (AHP) algorithm. Finally, groundwater potential zones are classified into three categories namely low, moderate, and high zone. It is observed that 32.7% (171.05 km2 ) of the study area falls under ‘low’ groundwater potential zone. Approximately 155.94 km2 area accounting for 29.8% of the study area falls under ‘moderate’ category and ‘high’ groundwater potential zone encompasses an area of 196.11 km2 accounting for 37.5 % of the total study area. The geographical information system method output results were validated by conducting field survey by randomly selecting wells in different places using Geographical positioning System (GPS) instruments. About 27 bore wells yield data had been collected to quantify the yield from groundwater potential zone map derived from geo-informatics. The produced result was verified by comparing with the existing groundwater borehole databases and the results show that there is good agreement between the predicted groundwater potential map and the existing groundwater borehole database. From the 7 wells 4 falls on high zone (57.14%). Out of 11 wells yields data ,7 wells (63.63%) of them were fallen on the moderate zone whereas out of the 9 wells yield data ,7 wells and springs data (77.77 %) was fallen on the zone classified as low.