A Thesis Submitted to Institute of Technology, School of Biosystems and Environmental

Abstract

The development of balanced plan for water resource utilization requires assessment of the water resources in terms of quality, quantity, spatial distribution and the land use land cover condition of the entire catchment area. This thesis work is aimed to characterize different aquifer systems and their hydrochemistry in Tikur Wuha River catchment which is located in South part of Ethiopia particularly in Sidama Zone. The catchment area of Tikur wuha River 625 km2. The area is located in central part of MER and generally characterized by two topographic features. which is the high land near the rift escarpment and the rift floor. The study area is covered by Recent lacustrine and alluvial deposits, scoria cones, rhyolitic lava flows and associated ignimbrites, tuffs and volcanic ash. The escarpment and the mountains of the eastern margin of the catchment are made up of Nazeret series, which is composed of ignimbrite, unwelded tuff, ash flow, rhyolitic flow, domes and trachyte. The low laying area which is the rift floor is covered with lacustrine and alluvial deposits. The hydrogeological classification is done using qualitative and quantitative approaches based on the hydrogeological characteristics of lithological unit and different data collected from different organization, based on this the study area is classified in to the following aquifer aquiclude system. Extensive and highly productive porous aquifer (T=110-2000 m2/day, K=5-400 m/day and Q= 17-70 l/s). Highly to moderately productive mixed porous and fissured aquifers (T=500-2700 m2/day, K=15-560 m/day and Q= 10-30 l/s). Extensive moderately productive fissured aquifer (T=10-110 m2/day, K=0.5-5 m/day and Q= 5-10 l/s). Extensive low to moderately productive mixed porous and fissured aquifer (T=10-55 m2/day, K=0.1-1 m/day and Q= 2.5-5 l/s). Low potential aquifers and aquicludes also cover some parts of the study area. Aquachem software has been employed to identify the different water types. From the analysis of hydrogeochemical data different water types are identified of which the majority of the cold springs, dug wells and boreholes from the highlands and escarpments are Ca-Mg-HCO3 type and Ca-Na-HCO3 type. The majority of waters from the rift floor boreholes and shallow wells; sodium is the dominant cation and the dominant anion is bicarbonate. These ground waters are Na–Ca-HCO3 and Na- HCO3 type.