Water Resource Engineering

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Browsing Water Resource Engineering by Subject "Contamination"

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    Assessment of Vulnerability of Alluvial Aquifers of Transition Zone to Contamination: The Case of Danakil Basin, Northeastern Ethiopia
    (Addis Ababa University, 2022-06) Kumneger, Mollalegn; Taye, Alemayehun (PhD)
    Groundwater is indispensable to humankind, but with the increasing load over this precious resource, it has become necessary to study it in detail with geological as well as hydrogeological aspects to understand the nature of the groundwater resource of a Danakil basin to manage it well and use it sustainably, vulnerability assessment of the resource is conducted to highlight the areas which are more susceptible to contamination. In the present study, an attempt has been made to account for the groundwater vulnerability using an overlay index method, DRASTIC, which is used to prepare a vulnerability map using GIS, of the study area, Danakil basin. The DRASTIC Vulnerability index (DVI) is calculated as the sum of the product of ratings and weights assigned to each of the parameters on a scale of 1 to 10 and 1 to 5 respectively. And a 2D finite element groundwater flow and solute transport model were developed to simulate the spatial and temporal variations of the salinity intrusion in the alluvial aquifer of the Danakil basin taking into account the transition zone between freshwater and saltwater. The available historical records of water table levels were used to calibrate the developed model. Emphasis was devoted to the response of the transition zone to different pumping scenarios in the study area. The vulnerability index ranges from 50-149 and is classified into three classes it reduced approximately 20%, 50% and 30% of the area lies in low, medium, and high vulnerability zones. Results from the solute transport model also indicated that the saltwater intrusion problem has evolved during over-abstraction (pumping). Unlike previous investigations, this study presents the most qualitative assessment of the available groundwater in the alluvial aquifer under different pumping scenarios. In conclusion, Danakil basin alluvial aquifer is vulnerable to geogenic sources of salt intrusion due to over abstraction. Results can be an important input for policymakers in the development of sustainable groundwater protection and abstraction strategies for the region.