Salinity Mapping of Coastal Aquifers Using GIS and GALDIT

Abstract

Aquifers are vulnerable to saltwater intrusion, making the groundwater pumped from these aquifers unfit for consumption. The vulnerability of aquifers to saltwater intrusion can be assessed by GALDIT, an index based method. GALDIT measures the vulnerability in terms of six parameters Groundwater occurrence, Aquifer conductivity, Level above mean sea level, Distance from the shore, Existing impact, and Thickness of the aquifer. This study aims to find the vulnerability of aquifers in the coastal areas of Ernakulam district in Kerala to saltwater intrusion. The study area includes the taluks of Kanayannur and Kochi. GALDIT method is applied to each aquifer to get the vulnerability in terms of low, moderate, and highly vulnerable. This classification can be used for assessing the vulnerable areas for timely intervention measures. The data for the aquifers was collected from IWRIS (Indian Water Resource Information System) website and CGWB (Central Ground Water Board). Then using the data compiled from the GALDIT method, vulnerability maps were prepared in ArcGIS. Kriging Interpolation method was used to prepare maps for the influence of the six parameters of GALDIT on saltwater intrusion and then weighted overlay analysis was used to classify the vulnerable zones of the study area into low, moderate, and highly vulnerable.