Determination of Groundwater Vulnerability for Protection of the Drinking Water Basins: A Case Study From Türkiye, Kesikköprü Dam Lake Basin.

This study investigates the intrinsic groundwater vulnerability of the Kesikköprü Dam Lake Basin, a critical drinking water source for Ankara, Central Anatolia Türkiye. The DRASTIC model is applied within a Geographic Information Systems (GIS) framework, using seven hydrogeological parameters to generate a vulnerability map. Results indicate that most of the basin falls within "very low" and "low" vulnerability zones, with "medium" vulnerability observed in localized recharge-prone areas. Model validation is conducted using nitrate and total organic carbon concentrations, which represent pollution from agricultural and domestic wastewater sources. The spatial correlation between these indicators and DRASTIC output supports the model's reliability. Importantly, this research also integrates anthropogenic influences by evaluating the spatial distribution of agricultural, wastewater, and mining activities relative to vulnerability zones. While natural conditions suggest low contamination potential, the cumulative and long-term effects of these activities highlight significant risks in certain areas. To the best of the knowledge, this is the first study to validate a DRASTIC-based vulnerability map for the Kesikköprü Basin while addressing anthropogenic pressures. The findings offer a practical decision-making tool for land-use planning and sustainable groundwater management, both regionally and in similar hydrogeological contexts worldwide.