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Addis Ababa University Libraries Electronic Thesis and Dissertations: AAU-ETD! >
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Thesis - Hydraulics Engineering >
Please use this identifier to cite or link to this item:
http://hdl.handle.net/123456789/2308
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| Title: | Numerical Groundwater Flow Modeling of the Meki River Catchment, Central Ethiopia |
| Authors: | Dereje, Birhanu Mitiku |
| Advisors: | Prof. Tenalem Ayenew |
| Keywords: | groundwater management
Volcanic aquifer
Modflow
Modeling
Meki
Central Ethiopian |
| Copyright: | Oct-2011 |
| Date Added: | 3-May-2012 |
| Publisher: | AAU |
| Abstract: | The Meki river catchment aquifer is located in the central Ethiopian rift valley. This unconfined aquifer is
one of the most important groundwater reservoirs of the country. A total catchment of 2319 km 2 was
selected to study the groundwater flow system using a numerical groundwater flow model (Processing
Modflow Pro (Version 8.0.15)). A three dimensional steady-state finite difference groundwater flow
model is used to quantify the groundwater fluxes and analyze the subsurface hydrodynamics in the Meki
river catchment by giving emphasis to the well field that supplies water to the community. The area is
characterized by Quaternary volcanics covered with lacustrine, alluvial, talus, and pyroclastic deposits.
The model is calibrated using head observations from 95 wells. The simulation is made in a one layer
unconfined aquifer with spatially variable recharge and hydraulic conductivities under well-defined
boundary conditions. The calibrated model is used to forecast groundwater flow pattern, the interaction of
groundwater and surface water, and evaluate the behavior of the groundwater system under possible
future utilization scenarios . A sensitivity analysis conducted indicates that the model is more sensitive to
decrease in recharge and increase in hydraulic conductivity but less sensitive to increment or decrement
of pumpage.
The simulation result indicates that the groundwater flows from western escarpment to east directions
finally join Lake Ziway. Lakes and rivers play important role in recharging the aquifer. Simulations made
under different possible future utilization scenarios including increase in pumping rate results in
substantial regional groundwater level decline, which will lead to the drying of springs, and shallow hand
dug wells. It has also implications of reversal of flow from contaminated rivers in to productive aquifers
close to main river courses; decrease in recharge caused more inflow from Lakes as well as increase
stream flow but decrease drains, and disappearance of Lake Tuffa results in increased recharge and
groundwater outflow through springs. The sensitivity and scenario analysis provided important
information on the data gaps and the specific sites to be selected for monitoring that may be of great help
for transient model development. This study has laid the foundation for developing detailed predictive
groundwater model, which can be readily used for groundwater management practices. |
| URI: | http://hdl.handle.net/123456789/2308 |
| Appears in: | Thesis - Hydraulics Engineering
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| 69 | | 3.25 MB | Adobe PDF | View/Open |
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