Delineation of the groundwater potential zones of upper Tigris Diyarbakır Sub-basin in Turkey using GIS and Analytical Hierarchical Process (AHP) techniques

With its water resources and agricultural activities, the Diyarbakir basin is considered as an important field not only in Turkey but also in the Middle East. Since the irrigation project has not been completed yet, there is a wide use of groundwater for irrigation. For this reason, the determination of groundwater potential should be evaluated properly. Instead of determining the Groundwater potential of the region with observation wells, which is an expensive method, this study opted for evaluating the groundwater potential of the basin by the GIS-based Multi-Criteria Decision Making (MCDM) method by means of essential factors affecting groundwater formation. For the delineation of the groundwater potential zones of Upper Tigris Basin, the AHP method and ArcGIS 10.2.1 program were used. 8 key criteria were properly taken into consideration; Geomorphology, Geology, Line Density, Drainage Density, Slope, Land use, Rainfall, and Soil Type. Weights of all criteria were assessed via the AHP technique. Finally, considering the weights of all the parameters through the Overlay Weighted Sum method, the Groundwater Potential Index (GWPI) was obtained. The potential was classified into five stages for the sub-basin as 1447 km2 (13.8%) portion of the basin is very poor potential, 3758 km2 (35.8%) portion of the basin is poor potential, 3267 km2 (31.1%) portion of the basin is moderate potential, 1443 km2 (13.7%) portion of the basin is good potential, 585 km2 (5.6%) portion of the basin is very good potential.