249-9 Integrated Assessment of Coastal Groundwater Vulnerability: A Study in Indian Sundarbans

Session: Emerging Contaminants: Geochemical Insights and Impacts on Human and Environmental Health

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Abstract:

Groundwater is the primary source of drinking water in the Sundarbans, India-a UNESCO heritage site highly vulnerable to both natural and anthropogenic factors (e.g., sea level rise, over-extraction, high population density). This study integrates geospatial and hydrochemical approaches to assess the current state of groundwater resources. A vertical vulnerability model using the DRASTIC-LU method and a horizontal vulnerability model using GALDIT (targeting seawater intrusion) have been developed. To minimize subjectivity in parameter weighting, the Analytical Hierarchy Process (AHP), resulting in AHP-DRASTICLU and AHP-GALDIT models. Model validation used nitrate (NO₃⁻) concentrations for AHP-DRASTIC-LU and multiple geochemical indices Groundwater Quality Index for Seawater Intrusion (GQI_SWI). High nitrate levels aligned with zones of high vulnerability likely due to anthropogenic activity. Spatial distribution revealed seawater influence in the northeastern and southeastern zones and anthropogenic impact in the northwest. GQI_SWI indicating mixed water in ~81.3% of samples, and 16% exhibiting saline groundwater. GQI_SWI also showed strong correlation with electrical conductivity, indicating seawater intrusion. The integrated vulnerability model revealed that 42% of the area is highly vulnerable, 33% moderately vulnerable, 25%  low  to very low vulnerable.  Vulnerability zones matched pollution load maps, affirming model accuracy. Therefore, this framework serves as an effective decision-support tool for sustainable groundwater management in coastal regions.

Keywords: Groundwater Vulnerability; Coastal Aquifers; DRASTIC, GALDIT; AHP; LULC; Seawater Intrusion; Indian Sundarbans

Geological Society of America Abstracts with Program. Vol. 57, No. 6, 2025

doi: 10.1130/abs/2025AM-8414

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