Performance Comparison of DRASTIC, GOD, and AVI Models for Groundwater Vulnerability Assessment in Asadabad Aquifer, West Iran

Groundwater is highly vulnerable to pollution resulting from human activities. Preparing vulnerability maps is considered as a key tools in groundwater resource management. Asadabad Plain placed in Hamadan Province is a region with significant industrial and agricultural activities. The infiltration of urban and agricultural wastewater into the groundwater of this plain has posed environmental threats to both water and soil resources. The objevtive of this study was to assess the vulnerability of Asadabad Plain aquifer to nitrate pollution using three models: DRASTIC, GOD, and AVI. Ground water samples were collected from 23 shallow and deep wells with appropriate spatial distribution across the plain on October 2020, Hydrochemical analysis was performed for determining of pH, EC and nitrate concentration. Groundwater vulnerability maps were prepared using three models to saticfying high vulnerability regions with elevated nitrate concentrations. The results indicated that, according to DRASTIC model, 46.6% of groundwater resources fell into low vulnerability range, and 53.4% within the moderate range. In the GOD models, spatial zoning map based on GOD model showed that 61.1% of groundwater resources have low vulnerability and 38.9%, have moderate vulnerability. Spatial zoning using of AVI models, indicated that 68.3% and 31.7%,. Of groundwater resources fell into low and moderate vulnerability, respectively.To improve the future outlook of vulnerability maps, it is essential to validate these studies using physical models as well. Since DRASTIC simultaneously considers various indicators such as water table depth, soil permeability, soil/rock texture, and slope, it therefore well reflects the actual state of the aquifer.