Groundwater Modelling to Predict Management Options for Kayts in Northern Sri Lanka

Abstract

Kayts is one of several islands which lie off the western end of the Jaffna Peninsula in the northern- most part of Sri Lanka. A low salinity groundwater lens is the only promising source of fresh water on the island. The return of refugees in the post conflict period has raised concerns for the quantity and quality of groundwater available for drinking and agriculture and on increased risk of seawater intrusion and upcoming from unsustainably high extraction rates. The groundwater flow model MODFLOW, mass transport model MT3DMS, and salinity intrusion model SEAWAT were used to model the regional flow system and the interface separating the freshwater and saltwater flow systems, and for pumping and rainfall recharge scenarios. The water balance for the sand dune area in Kayts, found the available water from this region is 266 m3 /d. Preserving the sand dunes which are the only reliable source of potable water for Kayts remains a priority.