After the Tsunami- Relief and Rehabilitation in Sri Lanka - restarting towards the future

Abstract

Groundwater quality and the water table behavior at Weligama Bay have been studied in the aftermath of the Tsunami. 90 affected shallow dug wells, situated on a 8 km coastal strip, were selected for the study. The wells are sunk into the permeable quaternary sand deposits overlying precambrian granite gneiss. The top quaternary sandy aquifer in the coastal margin at Weligama Bay is very permeable and hydro-geological conditions are very favorable for saltwater intrusion. The study helped to prepare the hydro-geological and the hydro-geo-chemical maps of the area. Prior to the Tsunami, water of these wells was non-saline and used by the people for drinking and other domestic purposes. The preliminary results of the study revealed that the electrical conductivity (EC) of wellwater in all wells situated in the Tsunami-affected region have become saline; the EC values, on average, increased from 300 to around 1300 μ Siemens/cm). Total dissolved solids of the wellwaters were around 1.000 mg/l. It can be concluded that the underground pressure wave which has likely developed due to the Tsunami may have disturbed the freshwater-saltwater equilibrium resulting in the mixing of fresh groundwater with saline water.