Groundwater potential mapping at northeastern Wasit and Missan governorates, Iraq using a data-driven weights of evidence technique in framework of GIS

Abstract

In this study, a data-driven weights of evidence (WOE) technique was used to demarcate groundwater potential zones at northeastern Missan and Wasit governorates, Iraq using geographic information system (GIS) platform. In the first step, borehole location inventory map consisting of 143 with relatively high yield (>8 L/s) was prepared. Then, eight influencing groundwater factors, namely altitude, slope, geology, land use/land cover, distance to roads, distance to faults, aquifer type, and depth of wells were prepared and integrated into spatial database. The spatial association between borehole locations and each influencing groundwater factors were analyzed and discussed. For the analysis of groundwater productivity, the studentised contrast C/S(C) of each groundwater factors were spatially overlaid and weighted summed to produce groundwater potential index (GWPI) map. The resulting map was classified into four categories: low, moderate, high, and very high according to natural break classification scheme. The low GWPI zone covers 30 % (2,215 km2). The moderate, high, and very high cover 32 % (2,349 km2), 23 % (1,649 km2), and 15 % (1,075 km2) of the total study area, respectively. The high and very high zones cover approximately 40 % of the study area indicating moderate productivity of the aquifer system in the study area. The results of the analysis were validated using receiver operating characteristic (ROC) technique. The areas under the ROC curve (AUC) for success and prediction rates were 0.81 and 0.80, respectively, indicating the high capability of WOE for modeling groundwater potentiality in the study area. Result of this study could be used as guide to manage aquifers in these areas and serve as indicator for sustainable management of aquifer systems.