Managed Aquifer Recharge Suitability Mapping in the Akaki Catchment, Central Ethiopia
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Date
2022-12
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Addis Ababa University
Abstract
Groundwater resources in Akaki catchment are under increasing stress due to excessive use and a variety of anthropogenic influences such as population growth, urbanization, and pollution. The intense pumping has caused the water table level to drop quickly. For groundwater resources to be utilized in a sustainable manner, artificial recharge techniques and effective management methods are essential. Managed Aquifer Recharge is an artificial method for replenishing subsurface aquifers utilizing excess surface water, treated wastewater, and stormwater. It could be used as a method to increase freshwater availability and prepare for climate change. Creating a MAR suitability map may be one of the steps to be taken to reach sustainable groundwater management.
The present study used GIS multi-criteria decision analysis commonly known as GIS-MCDA method to identify suitable sites for implementing MAR. Utilizing a web-based application called INOWAS, the available MAR techniques are summarized based on the hydrogeologic parameter and the study area's objectives. To create the MAR suitability map, seven contributing factors were employed as criteria: drainage density, land use, slope, soil, geology, water level and rainfall. They were selected based on the objective and the available data. Three steps are performed in order to identify suitable sites for MAR: problem definition, suitability mapping, and sensitivity analysis. Among different criterions, step-wise function was used for standardization, pairwise comparison was used for criterion weighing as well as weighted overlay analysis was used as decision rules. The suitability map divided the study area into highly suitable, suitable, moderately suitable, low suitability, and unsuitable classes. The results show that 71.54% of the area is moderately suitable for implementing MAR. The suitable areas locate in the northern part of the catchment. The majority of areas are moderately suitable and are scattered throughout the watershed. The areas with low suitability are mainly in southern parts of the area. The first MAR suitability map for the Akaki watershed can be used as a guide and screening tool to target site-specific research for MAR implementation in highly suitable regions.
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Managed Aquifer Recharge (MAR), GIS, Suitability Mapping, Multi-Criteria Decision Analysis, Akaki Catchment