AN EXAMINATION OF GROUNDWATER DISCHARGE PATTERNS A CASE STUDY OF WAK OYA AREA, SRI LANKA

Radon, is a natural radioactive element that can be found on water, soil and rock. Radon can be used to identify the ground and surface water system for protect the ground water recharge areas. Wak oya is one of the streams starts from Labugama-Kalatuwawa forest reserve which contribute the birth of many water ways. The main aim of this study is identifying the discharge difference between ground and surface water and study the changes in land use pattern in Wak oya catchment area to identify the changes in ground and surface water system in the area. These data can be used to protect the recharge area. Nine stream samples and five well water samples were analyzed for radon (222Rn) using RAD Aqua system, which transfer dissolve radon in the water samples to the air within the circuit. Land use changes of the study area analyze using remote sensing data, satellite images and land use data from Survey Department of SL. Radon concentration in the water samples studied varies between 1979 +/- 150,3260 +/- 150, and 7690 +/-160,15900 +/- 182 surface and ground water respectively. Measurements can be concluded that there is significant difference between radon concentrations of surface and well water. The differences in radon concentrations are used to detect interactions between surface water and ground water.

Keywords: Geology, Groundwater, Radon, Radioactivity,  Surface Water.