Assessment of Aquifer Vulnerability Using GALDIT Model — A Case Study

With the increasing urbanization, agriculture, industrial activities along the coastal stretches of India, more and more people depend on ground water due to which there are cases of large scale decline in both quantity and quality. One of the State which is facing a critical change in its geomorphology and land use/land cover is Goa which is known for its tourism industry. Therefore, the water management will be a major issue in the years to come. A field survey conducted in parts of north Goa coast to understand the ground water availability status, quality issues and salinity conditions of ground water due to sea water intrusion. Accordingly, an attempt was made to understand the extent of seawater mixing with ground water using a model known as GALDIT Model. GALDIT is an indicator based model which assess and quantifies the significance of vulnerability to seawater intrusion due to excessive groundwater withdrawals. The system contains three significant parts: weights, ranges, and ratings. Each GALDIT factor has been evaluated with respect to the other to determine the relative importance of each factor. Accordingly indices were calculated for the selected wells (wells were selected along the coast and also perpendicular to the coast). Results obtained by GALDIT model showed that about 42% of the wells in the study area are low vulnerable and 58% of the wells are moderately vulnerable to sea water intrusion.