Comparative analysis of DRASTIC and GOD model for groundwater vulnerability assessment

Groundwater is one of the world's most important water resources, with varying quality and quantity. It is extremely difficult to recycle contaminated groundwater. As a result, protecting groundwater from contamination is critical. Climate change has made effective groundwater resource management a pressing concern, particularly in regions where water is in great demand for industrial and agricultural activity. The quality of the groundwater in the coastal area of Surat district is steadily reduced as a result of climate change, the usage of pesticides and fertilizers, and the increased sea level rise. The groundwater quality vulnerability presented in this study was simulated using a hybrid model that combined several parameter maps and a geographic information system. Government data are employed as the primary data in this study, and these data are reframed into the appropriate structure in GIS software. Groundwater Quality vulnerability is found by the effective factors and the parameter maps which are used as secondary data. In order to achieve this, a model was trained, optimized, and tested in the Arc-GIS Software. To run the model and to prepare the maps of the parameters Arc-GIS software was used. The primary benefit of GIS is how effectively it can combine data layers and modify the parameters used to classify vulnerabilities. Depth of water, Net recharge, Aquifer, Soil, Topography, Impact of the vadose zone, Hydraulic conductivity, land use, and land cover are the parameters to be considered for assessing the vulnerability using DRASTIC and modified DRASTIC model for the same. In the DRASTIC and Modified DRASTIC model all the parameters are weighted by the conventional weights. In the DRASTIC-AHP model, the weights of the DRASTIC parameters are modified using the Analytic Hierarchy Process. After employing all the models, the DRASTIC-AHP model gives the best results compared to all other models. Based on the study it is observed that the depth to the water table, net recharge, impact of the vadose zone, and aquifer media are the effective parameters that affect groundwater vulnerability. Vulnerability results are validated using the past year chloride concentration data. Based on the validation results from the DRASTIC-AHP model gives the best correlation. So, The DRASTIC-AHP model gives the best and most accurate results for the study area. According to the current situation of groundwater vulnerability and its quality, this research helps land use regulations and norms for activities related to recharge and seepage by describing the groundwater vulnerability in the studied region. So, this study helps policymakers and local authorities in taking protective measures for groundwater quality.