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UNESCO-IHE Institute for Water Education, Delft (2021)

Groundwater model development and optimization of pumping in Akaki catchment, Ethiopia

Tiruneh, Dereje Endalkachew

Titre : Groundwater model development and optimization of pumping in Akaki catchment, Ethiopia

Auteur : Tiruneh, Dereje Endalkachew

Université de soutenance : UNESCO-IHE Institute for Water Education, Delft

Grade : Master of Science (MS) 2021

Résumé
As a result of rapid population increase, urban growth, and aging infrastructure of surface water supply system the city government of Addis Ababa is forced to serve 70 percent of the city water supply from groundwater. After the Akaki Phase I shallow groundwater well development was put into operation in 2001 an additional 178 deep groundwater wells in a different part of the catchment area have been drilled to satisfy the city water demand. The declining water level caused by withdrawals of water from wells for the last two decades and the plan of excavating new wells in the whole of the Akaki river catchment has raised concern concerning the ability of the aquifer system to sustain production. The Akaki well field in particular is heavily used in this area. The purpose of this research is to develop a groundwater model that can be coupled with optimization models to suggest optimal management strategies to reduce groundwater depletion and increase the sustainability of this resource. In the first stage of the study, a groundwater model has been developed for the area and calibrated using available data. Afterward, the model was applied to simulate the present and future condition of the system. In the last step, the model was combined with GWM (Groundwater Management) - optimization groundwater management model to produce optimal pumping rates under different strategies of saturated thickness reduction, which could be implemented when new wells are developed to meet the demand of the city in 2030. Four strategies were set to understand the effect of change in the saturated thickness of the aquifer and the results of the simulation-optimization show that the excessive pumping of 160,111 m3/day to meet the future demand will lead up to a 20% reduction of saturated thickness from the existing groundwater level with some optimal pumping strategies identified. This study presents optimal pumping rates under different strategies to make a better decision by the city water supply authorities to protect long-term water-level decline. Further studies are needed to improve the accuracy of the developed model, including collecting sufficient observation data for calibration.

Sujets  : groundwater modelling Ethiopia groundwater management numerical modelling simulation modelling optimization models

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Page publiée le 8 novembre 2022