Mapping of Salinity Ingress Using Galdit Model for Sirkali Coastal Region: A Case Study

Abstract

A model is traced to evaluate and enumerate the significance of vulnerability to seawater intrusion due to excessive ground water withdrawals and some anthropogenic activities at coastal aquifers. So taking these issues into account few thematic maps which were influencing the saline water intrusion were prepared and overlaid using Geographical Information Systems (GIS). Based on GALDIT method, the groundwater vulnerability cartography has been assessed. To reckon the GALDIT index it requires six parameters like aquifer type, aquifer hydraulic conductivity, depth to groundwater level (AMSL), distance from the shore, impact of existing status of seawater intrusion and thickness of the aquifer. This GALDIT is the indicator scores and summing them and dividing by the total weight for determining the relative role of each one. Apart from this an identification of saltwater intruded area is done by using indicators of saltwater intrusion like Cl/(HCO 3 + CO 3 ) ratio and Na/Cl ratio. The vulnerability areas are classified as moderate with an area of 147.31 sq . km and low covering an area of 168.72 sq . km respectively based on the thematic maps. The final thematic map can be used for management of the coastal ground water resources.