Groundwater–Surface Water Interaction and Analysis of Recent Changes in Hydrologic Environment of Lake Ziway Catchment

Alemu, Dribssa (2006) Groundwater–Surface Water Interaction and Analysis of Recent Changes in Hydrologic Environment of Lake Ziway Catchment. Masters thesis, Addis Ababa University.

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Abstract

The study area is northern part of the Central Main Ethiopian rift valley bounded in west and north by Awash basin; and in east by Wabi shebele catchment. Meki and Katar are the main rivers draining western and eastern part of the catchment respectively and both feed Lake Ziway before outflow to Bulbula River in south west. The area has mean annual precipitation, potential evapotranspiration and actual evapotranspiration of 887mm, 1284mm and 856mm respectively. Direct groundwater recharge of the catchment was estimated using empirical formula, soil moisture budgeting and groundwater balance methods. The empirical formula gives 67mm; while the results of soil moisture balance and groundwater balance are 57mm and 83mm respectively. Groundwater and surface water interaction in the area have been analyzed using groundwater table contour, field base river discharge measurements, channel water balance and hydrographic analysis. The analysis result shows that Meki River in volcano-lacustrine deposit of rift floor and Katar River in Upper and Central Wonji Fault Belt are loosing reaches. In the rest of the catchment areas, the rivers and streams are gaining reaches. Annual and monthly lake water balances have been conducted by incorporating available and necessary parameters. In annual basis groundwater outflow is greater than groundwater inflow. The recession in groundwater inflow over outflow is higher in the months of July and August due to time lag between commencement of surface moisture and contribution of groundwater to the lake on one hand and the increase in groundwater outflow due to rising lake level on the other hand. Assessment of recent changes in hydrologic environment has been analyzed by trends in short and long term precipitation, evaporation, abstraction, rivers discharge, lake level and direct groundwater recharge. All these parameters reveal changes of hydrologic environment; attributed both to climate change and human interference.

Item Type: Thesis (Masters)
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
Q Science > Q Science (General)
Q Science > QE Geology
Divisions: Africana
Depositing User: Selom Ghislain
Date Deposited: 19 Jun 2018 13:30
Last Modified: 19 Jun 2018 13:30
URI: http://thesisbank.jhia.ac.ke/id/eprint/4667

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