Groundwater Potential Mapping Using Geospatial Approaches Combined with Electrical Resistivity Tomography in Bazian Basin, Sulaymaniyah Governorate, Iraqi Kurdistan Region

In the Bazian basin in northern Iraq, groundwater plays a crucial role in agriculture and other activities. Unfortunately, excessive legal and illegal well extraction over the past three decades has led to a significant decline in the water table. To address this challenge, the study combined geographic information system (GIS) data with Electrical Resistivity Tomography (ERT). The objective is to create a geospatial model for groundwater potential zoning using multi-criteria analysis techniques, supported by geophysical approaches. This study used seven thematic layers, including geology, rainfall, slope, lineament density, drainage density, land use/land cover, and runoff, and finally combined them with remote sensing data, Google Earth Engine, and conventional information within the GIS environment. Thematic layers were ranked based on their importance for groundwater potential and weighted using the multi-criteria decision analysis and Analytical Hierarchy Process (MCDA-AHP). Two-dimensional (2D) electrical resistivity tomography was conducted using the SYSCAL R1 PLUS along three profile lines distributed over the study area. The data were recorded using the Wenner – Schlumberger array, and the raw data were subsequently processed using the Res2dinv software. The resulting groundwater potential zones for the total area (362) km2 (GWPZs) were categorized into five zones: very low, low, moderate, high, and very high. The covered area for each level was 4.4%, 8.9%, 34.3%, 32.7%, and 19.7%, respectively. Electrical resistivity tomography (ERT) and well extraction rates are used to validate groundwater potential zones (GWPZs). The results from three ERT profiles align with the potential zone map. Additionally, a second validation using extraction rates from 40 wells was used to confirm these findings.