IDENTIFICATION OF GROUNDWATER POTENTIAL ZONE BY USING GIS AND ELECTRICAL RESISTIVITY TECHNIQUES IN AND AROUND THE WELLINGTON RESERVOIR, CUDDALORE DISTRICT, TAMILNADU, INDIA

We have attempted to investigate groundwater for irrigation purpose at the time of monsoon failure which would serve as a key element in both short and long-term perspective in and around the Wellington reservoir of Vellar basin by assessing the subsurface geology and groundwater potential zones. An attempt had been made to identify the subsurface lithology and aquifer zones by geoelectrical resistivity method in part of Tittagudi, Nallur and Vriddhachalam block of Cuddalore District. This method is useful to delineate the subsurface formations, weathered zone and fracture pattern, etc. The study area consists of major subsurface litho units like sand, Silt, Clay, Charnockite, Migmatite rocks and Fissile hornblende biotite gneiss. In order to explore the groundwater resources of the study area with an aerial extent of 495.3 km2. Electrical soundings have been conducted at every 5 Km intervals in grid pattern by adopting Schlumberger technique in 30 locations. Each location measuring 100m extent with an electrode spacing of 10m,20m, 30m, 40m, 50m, 60m, 80m, 100m spacing. Which have been qualitatively and quantitatively interpreted using software. Pseudo sections have been generated by IPI2 WIN ver.3.1 and isoresistivity maps were prepared by using software MapInfo 8.5 Considering the geological, geomorphology and hydrogeological conditions the VES interpretation was done. From the interpretation result the VES no. 4 (Alambadi) and VES no 30 (Devangudi) is found to be prospective for groundwater. This information not only helps to understand the hydrogeology of the area but also provides improved task for groundwater exploration and management as well.