Integrated vulnerability assessment of surface and groundwater resources by combining two indices DRASTIC and WRASTIC

Today, human activities are one of the most important challenges in issues related to the quality of water resources, which is currently considered one of the management threats in the exploitation sector. This issue will require the identification and evaluation of water resources from different perspectives, of which the vulnerability of water resources is one. This study evaluates the vulnerability of water resources by combining two DRASTIC vulnerability indices in the aquifer sector and WRASTIC vulnerability index in the upland sector of Astana-Kuchsefahan region. In this study, after assessing the vulnerability with the relevant indicators, two methods of entropy and hierarchical analysis were used for scaling based on maximizing the correlation with nitrate concentration. The results showed that the most importance in both indices based on recalibrated weights include industrial use in the WRASTIC index and underground water depth in the DRASTIC index. The analysis of the calibration results showed that the correlation of nitrate with the DRASTIC vulnerability index using the AHP method was 0.61 and with the WRASTIC index was 0.58 using the Shannon entropy method. Also, the measurement results showed that the WRASTIC index ranges from 17 to 46 and the DRASTIC index ranges from 119 to 180. Based on the consolidated results in the western and eastern parts of the highlands, the level of vulnerability using the WRASTIC index is lower and there is a higher vulnerability in the western part of the aquifer compared to the eastern part.