Assessment of groundwater vulnerability using modified DRASTIC-Analytical Hierarchy Process model in Bucak Basin, Turkey

This study includes hydrogeological studies covering the Bucak Basin located in the feeding area of Kırkgöz Springs, which is the drinking water source of Antalya. Hydrogeological data has been evaluated based on Geographic Information Systems with modified DRASTIC-Analytic Hierarchy Process methods. The aim of the study is to present groundwater vulnerability in order to evaluate the pollution potential of groundwater in the Bucak Basin. For this purpose, the DRASTIC method, which includes 7 different parameters, was used to determine the vulnerability of groundwater. The method has been modified via Analytic Hierarchy Process during the weighting of the DRASTIC parameters. In the preparation of thematic maps of weighted parameters, Geographic Information Systems was utilized. Two different basin-based groundwater vulnerability maps were obtained with the calculation of the DRASTIC index and modified DRASTIC-Analytic Hierarchy Process index values. While on the DRASTIC index vulnerability map, 29.7% of the study area has high, 53.4% has medium, and 16.9% has low groundwater vulnerability; on the modified DRASTIC-Analytic Hierarchy Process index vulnerability map, 10% of the study area has very high, 26.3% has high, 60% has a medium, and 3.7% has a low vulnerability. On both groundwater vulnerability maps, the environment with the highest pollution vulnerability has been found to be the alluvium aquifer in which agricultural activities are carried out. As a result of the study, it has been concluded that the pollution sources of agricultural origin are the important pollution factors in terms of groundwater vulnerability in the Bucak Basin. It has been established that the DRASTIC method alone cannot represent the features of the application area, therefore by adding the lineament and land use parameters and weighting the parameters again with Analytic Hierarchy Process, more sensitive and accurate results have been obtained. Geographic Information Systems-based modified DRASTIC-Analytic Hierarchy Process integration has been demonstrated to be an effective tool for the assessment of groundwater pollution vulnerability and water resources management in the Bucak Basin. The results of the study are thought to become an important source in the decisions of local authorities on water resources management.