SIMULATION OF SALTWATER INTRUSION IN THE PAVANJE-GURPUR BASINS OF KARNATAKA

Abstract

ABSTRACT The development and management of fresh groundwater resources in coastal aquifers are seriously constrained by the saltwater intrusion. The Dakshina Kannada district is one of the rapidly developing districts of Karnataka. Due to the increase in population, urbanization and industrialization, the district is facing severe shortage of freshwater resources during the summer period. Also, the rivers of the district are being seasonal and tidal in nature, saltwater intrusion into the adjoining aquifers during the non-monsoon period is greatly felt up to several kilometers inland along and around the river courses. Hence the present work is aimed at simulation of saltwater intrusion in the Gurpur and Pavanje river basin aquifers using Saturated-Unsaturated Transport (SUTRA) model and comparing it with the field observations. The model is also used to predict the impact of increasing stress on freshwater aquifers due to the developmental activities. The results from the investigation indicate that the model prediction agrees well with the observed salinity levels in the study area. As such, the saltwater intrusion is not a severe problem in the region except a few pockets. The study also includes the evaluation of the basin characteristics through field tests and water quality/level observations through a network of wells. The coastal aquifers are predominantly shallow unconfined aquifers with transmissivity and specific yield values ranging from 49.2–461.4 m2/day and 0.00058–0.2805 respectively. The aquifers along the river courses are getting contaminated during the summer months only and region in the proximity of the sea is affected throughout the year. The optimal pumping rates have also been worked out for the region with potential groundwater development to avoid the problem of saltwater intrusion. The results from the study would be useful in the sustainable groundwater development in the region.