The vulnerability assessment of the aquifer of Dehgolan plain using Different Methods Based on Vegetation Changes

Vulnerability assessment of the groundwater pollution due to increasing effects of human activities and related risks for human health, economy and environment has become more important worldwide. Groundwater vulnerability estimation is done according to the variety of known methods based on hydrogeological parameters. The results of different methods are analyzed and compared with each other in order to identify the best approach in hydrogeological conditions and reference scale. According to such a view, this research was evaluated using four methods DRASTIC, SINTACS, DAC and COP based on vulnerability index and their comparison for the alluvial aquifer of Dehgolan Plain. Comparison of the methods was done using the values of nitrate data ​​and normalized groundwater vulnerability index (NGVI). In order to calculate the vegetation percentage of the study area for the COP method, NDVI 5.3 software was used from satellite images (LIO-TM) on May 23, 2024. It was observed that the aquifer area is divided into three levels including aqueous (0.5%), medium and poor coverage (2.5%) and agricultural (97%). The results of the vulnerability maps indicate more pollution in areas with low groundwater levels. Also, in all four methods, the southern part of the study area has been exposed to extreme vulnerability. The percentage of vulnerability level in the very high layer of Dehgolan aquifer was obtained by DRASTIC, SINTACS, DAC and COP vulnerability methods as 0, 83.8, 2 and 0 respectively. According to the comparison of four vulnerability methods using the NGVI index, it was observed that the COP method is better than the other three methods in the region.