http://ir.bdu.edu.et/handle/123456789/14130 2001-01-13T05:51:03Z http://ir.bdu.edu.et/handle/123456789/15143 Hydrogeochemical Studies and Water Quality Analysis of Lower Bilate River Catchment, Southern Rift Valley of Ethiopia Ali Eissa The study area is found in the main rift valley of Ethiopia in which surface and groundwater are the main source for domestic and agricultur al purposes. The main objective of the study is to investigate the hydrochemistry and water quality of the area using graphical, multivariate and water quality analysis techniques. The spatial distribution of major cation and anions ions reveals in order of Na + > Ca 2+ and HCO 3 - > Cl - > SO 4 2- > F - > NO 3 - respectively. Na-HCO is the main hydrogeochemical facies resulting from deep rock-water interactions and long residence time. The principal component analysis shows that the first 3 factors explain 82.02% of the total variance of the hydrochemistry that shows hydrolysis of silicate minerals and to some extent, anthropogenic effects are the main factors that control groundwater chemistry. Water quality index values show the majority of the samples comprised very poor water (34.2%), distributed in the south-eastern parts of the study area, followed by excellent water (15.77%) in the western and good water (21.05%) in north western, north eastern and southern parts of the study area. The poor water types covers 21.05% and the remaing 8.10% is unfit water. The study result shows that the major drinking water quality problems in the area is fluorides concentration in which the values exceed the WHO standards with the average value of 8.3 mg/l . This water quality problem is high towards the discharge area with a parallel enrichment of F. In terms of irrigation water quality, the Sodium Absorption Ratio shows that the surface waters (Rivers) samples (SAR=2.57) were highly suitable for irrigation compare to groundwater with SAR value 22.4 . The sodium hazard versus salinity hazard of the entire surface water sample fall into category C 1 3 -S and shows very low electrical conductivity and sodium hazard index which is suitable for irrigation purpose The study result will be helpful for water managers and government offices to protect the local people from water quality problems,bone fluorosis and tooth decay on bones which is common in the area. Furthermore, This study, helps local farmers and agricultural activities in the extended rift valley farmlands 2022-08-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/15142 Hydrogeological Characterization of Basement Rock in Assosa Area, Benishangul-Gumuz Regional State, Western Ethiopia Mulutsega Mesfin This thesis presents the hydrogeological characterization of basement Aquifers in the Assosa area, Benishangul-Gumuz Regional State, Western Ethiopia. The study area covers 863 Sqkm of Hoha and Selga rivers and is mostly covered by crystalline basement rocks (hard rocks) which are regionally known to be called aquicludes. Recent well drilling in the area shows that the well yield varies significantly (from abandoned to high discharge well). Currently, the water demand in the area is highly rising. However, limited groundwater investigation in the area causes well abandonment. To avoid the problem, combined geological, geophysical (electrical resistivity and magnetic methods), and pumping test methods, were carried out to investigate the hydrogeological system of the area. The study aims to characterize the expected aquifer zone / water-bearing units and map surface and buried geologic structures and weak zones. Twenty-one (21) VES data points and seven (7) 2D ERI survey data points with Schlumberger and Wenner configuration were conducted along Hoha and Selga river structures identified by satellite gravity and 364 magnetic data. The magnetic data and gravity data were processed using Oasis montaji 6.4.2 whereas IPI2win and Surfer were used for preparing pseudo-depth,geoelectric sections, and 2D ERI. According to this research work, the hydrogeological set up of the area is highly heterogeneous and mainly controlled by geological structures, weathering, and fracturing intensity.The aquifer is both intergranular and weathered / fractured volcanic and basement aquifer with secondary porosity. The study area has a localized shallow and deep confined and unconfined aquifer nature. Accordingly, the aquifer area is highly heterogeneous and mainly controlled by geological structures, weathering, and fracturing intensity for hard rock aquifers, however, granular porosity is dominant in the shallow alluvial aquifers. The transmissivity varies from 3.94 to 76.6m2/d, hydraulic conductivity ranges from 0.17 to 2.24 m/d. Secondary porosity and permeability that develop from secondary processes mainly control the aquifer productivity of the area. 2022-08-01T00:00:00Z http://ir.bdu.edu.et/handle/123456789/15141 “Petrology and Geochemistry of Volcanic Rocks at Mertule Maryam Area, Northwestern Ethiopian Plateau: Implications for Source Characterization” Bayelign Tewachew The study is conducted on the Mertule Maryam volcanic section which is located in the northwestern Ethiopian Plateau (EP). The aim of the study is to understand the petrogenesis of volcanic rocks based on their petrological and geochemical signatures. To achieve the aim of the study: geological mapping, petrographic and geochemical studies of the volcanic rocks by comparing and contrasting with the regional studied datasets have been conducted. As a result, the study area contains volcanic rocks varying in composition from basaltic rocks at the lower part through intermediate rocks (alkali feldspar-phyric trachyandesitic pyroclast and porphyritic trachyandesitic to phonolite) at the middle part to pyroxene-rich tephrite at the upper part. Petrographically, the texture of the basalts vary from aphyric through olivine-clinopyroxeneplagioclase-phyric to plagioclase-phyric up section. The texture of the intermediate rocks vary from alkali-feldspar-phyric to alkali-feldspar-hornblende-aegirine-phyric. On the other hand, the pyroxene-rich tephrites are characterized by having a texture varying from clinopyroxene-phyric to clinopyroxene-glomeroporphyritic up section. Based on geochemical analysis, the basalts are transitional; while the intermediate rocks and pyroxene-rich tephrites are alkaline in composition. Different degree of partial melting at different depths and in some cases crustal contamination were responsible for the compositional variation of the basaltic rocks; whereas both fractional crystallization and partial melting processes, without crustal contamination, were responsible for the compositional variation of the pyroxene-rich tephrites. The intermediate volcanic rocks were affected by assimilation fractional crystallization (AFC) process in their genesis. The basaltic and intermediate magmas were generated from spinel dominated amphibole-bearing spinel-garnet asthenospheric mantle sources with some interaction of the lithospheric and crustal materials. While the basanite magmas were generated from garnet dominated spinel-garnet asthenospheric mantle source. 2022-08-01T00:00:00Z