Summary of ground-water conditions in the Jaffna Peninsula, Republic of Sri Lanka, with a plan for investigating feasibility of ground-water development

Ground water in the Jaffna Peninsula of Sri Lanka, Ceylon, occurs within solution openings of the Jaffna Limestone of Miocene age. The freshwater forms a complex of lenses up to 25 meters thick overlying saline water derived from the sea. Salt-water intrusion and upconing of the salt water has occurred at several locations primarily along the coast. Recharge to the aquifer occurs during October-December. Discharge is primarily to wells and to springs along the north coast. Spring discharge is small compared to withdrawal from wells. Pumping from wells in an intensively studied 142-square-kilometer area of the Peninsula was 55.5 million cubic meters in 1976, whereas discharge to visible springs was an estimated 9.3 million cubic meters. Pumping during January-September removes water from storage causing heads to decline and the salt water-freshwater interface to rise. The storage is replenished as heads increase and the interface is depressed during the following October-December. Consequently, most of the recharge goes into storage rather than discharging to the sea. (Woodard-USGS)