Groundwater Potential Assessment and Characterization of Genale-Dawa River Basin

Kassahun, Nebiyou (2015) Groundwater Potential Assessment and Characterization of Genale-Dawa River Basin. Masters thesis, Addis Ababa University.

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Abstract

Genale-Dawa River Basin is one of the largest basins in Ethiopia. It is one of the most drought prone regions in Ethiopia. As a result a search for alternative source of water has always been a major issue in the region. This study therefore, aims at characterizing and evaluating the ground water potential resource of Genale-Dawa basin. The results of this research ultimately contribute to development of better water resources potential management. Delineation of the Genale-Dawa River basin was carried out first in order to define the problem domain of the model. This has resulted in 17860km2 area of the basin. This area was discretized to form a three dimensional. The discretized region has 19620 nodes, 17862 equilateral triangular elements of varying sizes with a maximum of 5km edge dimension and 2500km model thickness. The conceptualization of the model was done by grouping the discretized region in to 56 geological classes based on previous geological survey of the basin. The equivalent porous medium modeling approach was used to represent the different geological classes in the basin. Moreover, 23 rain gauge stations were used to determine the areal precipitation over the basin. The model takes perennial rivers as constant head boundaries, the side and bottom geometric boundaries of the model as no flow boundaries and the recharge due to precipitation as specified flow boundary. After conceptualization of the flow system was complete and numerical model developed, TAGSAC model manual calibration was done by seating hydraulic conductivity and percentage recharge as calibration parameters when calibration is complete. The result was evaluated quantitatively using average indicators (AM, RMS, MAE) and qualitatively by comparison of groundwater contour maps generated with recorded and simulated hydraulic head data. The calibration model was then used to determine monthly groundwater table fluctuation which eventually enabled the estimation of groundwater recharge potential of the basin. Additionally, base flow separation of perennial rivers was done to determine the monthly excess flux from the aquifer system. By adding these two values the total replenishable groundwater was estimated to be 2.78BMC. Hydro-geological map was also prepared based on hydraulic conductivity values obtained from model calibration. Identification of major groundwater recharge and discharge areas have also been done as an attempt towards basic groundwater flow system characterization.

Item Type:	Thesis (Masters)
Uncontrolled Keywords:	Ethiopia; Genale Dawa River Basin; Numerical Groundwater modeling; Replenishable Groundwater Potential; TAGSAC
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QE Geology T Technology > T Technology (General) T Technology > TA Engineering (General). Civil engineering (General) T Technology > TC Hydraulic engineering. Ocean engineering
Divisions:	Africana
Depositing User:	Andriamparany Edilbert RANOARIVONY
Date Deposited:	13 Jul 2018 11:23
Last Modified:	13 Jul 2018 11:23
URI:	http://thesisbank.jhia.ac.ke/id/eprint/7458

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