Contribution of remote sensing and GIS and the analytical hierarchical process approach to identifying groundwater recharge in the Abacha watershed, Chad

Groundwater is a major source of water supply for various areas. However, over the last ten years, demographic growth and other changes have contributed to an increase in water demand. It is therefore essential to map groundwater recharge areas in order to use them to meet local consumption needs. The aim of this study is to map groundwater recharge areas in the Abacha watershed in eastern Chad using a combination of GIS and AHP. Seven different factors were used in this study: altitude, lineament density, drainage density, precipitation, lithology, slope, and land use/land cover. Pairwise comparison matrices were then used to assess the degree of importance of each factor in relation to the others. Next, the raster calculator tool was used to map and identify groundwater recharge zones (GWRZ) by categorizing the Abacha watershed into three zones (high, medium, and low). The northeastern areas have low recharge potential. The medium class occupies a significant part of the central watershed, while the southern areas have acceptable recharge potential. Finally, the high class occupies the southern part of the watershed, which is characterized by good groundwater recharge. This approach, GIS and AHP, is important for groundwater resource decision-makers in determining the ideal sites for new water infrastructure projects in the Abacha watershed.