Alemu, Mesele (2017) Groundwater Dynamics and Aquifer Characterization of the Shallow Aquifers of Becho and Koka Area. Masters thesis, Addis Ababa University.
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PDF (Groundwater Dynamics and Aquifer Characterization of the Shallow Aquifers of Becho and Koka Area)
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Abstract
The present study area is located in upper Awash river basin, in central part of the country, which covers a total area of about 2780 Km2.The elevation ranges from 1519 to 2300 m.a.s.l. Becho and Koka areas were the focused areas for this specific research. The main objective of the present study was to provide detail information on the groundwater flow and characterize the shallow aquifers of Becho and Koka areas which will be vital information for future sustainable use of the groundwater resource. From long term mean monthly rainfall data, Becho and Koka areas receive 1141.6 and 914.4 mm mean annual rainfall respectively. Flow records at, Teji and Modjo river; Awash river at Hombole and Bello were selected for estimating recharge by BFS. Results from BFS by using excel spreadsheet program showed that the mean annual recharge for Becho and Koka areas were found to be 79 mm and 104.1 mm respectively. Based on groundwater level and TDS contour map the local groundwater flow direction in Becho area is tends to be the main Awash river. Whereas local groundwater flow direction in Koka area is tends to be towards lake koka. The average estimated soil field saturated hydraulic conductivity in Becho and Koka areas are 0.000421 and 0.00107 cm/sec respectively. In Becho area medium field saturated hydraulic conductivity values are come from due to the presence of alluvial deposits during the wet season, which covers the most upper parts of the soils. While in koka area the soil has medium to high field saturated hydraulic conductivity, since the area has primary porosity due to dominated by the lacustrine deposits. Hydrochemical study indicated the presence of two major water types in the study area. These are CaHCO3 and Na-HCO3. The Ca-HCO3 is dominant in Becho area, while Na-HCO3 is dominant in Koka area. Using SAR values in USDA (1954) groundwater classification, in Becho and Koka areas the shallow groundwater has been classified as excellent and good for irrigation purpose respectively. In both areas, the stable isotopes signature of the Hand dug well water characterized by depleted isotopic signature. From the result of isotopic signature, the recharge for depleted hand dug well water is from the precipitation. In Becho and Koka areas are estimated transmissivity values range from 0.03 to 19.70 m2/d and 0.97 to 57.27m2/d respectively. Because of the lacustrine deposits, Koka area has relatively high transmissivity values compared to Becho area.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Aquifer characterization, Field saturated hydraulic conductivity (Kfs), Groundwater dynamics, Hand dug well, Upper Awash basin |
| Subjects: | Q Science > Q Science (General) Q Science > QE Geology |
| Divisions: | Africana |
| Depositing User: | Selom Ghislain |
| Date Deposited: | 19 Jun 2018 13:25 |
| Last Modified: | 19 Jun 2018 13:25 |
| URI: | http://thesisbank.jhia.ac.ke/id/eprint/4672 |
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