The study area, upper Gadilam River basin, is located in Vizhupuram district of Tamil Nadu. The number of energized wells in this area has increased manifold due to free supply of electric power until recently by the government of Tamil Nadu, which has resulted in a regional decline in groundwater piezometric heads in this water table aquifer. A hydrogeological study was carried out in the study area. This paper deals with aquifer parameters estimation based on the pumping test data generated in the field. Water level observations in the area indicated that aquifer has undergone less stress condition within the course of time from the yesteryears or early 1995 to June 2004. Transmissivity computed by Theis (1935) method ranges from 301.82 gpd/sq. ft at Ponniyandal to 19,910.14 gpd/sq. ft in Pallavadi towards south central part of the study area. The specific capacity has a range of 0.906 gpm/ ft. of dd in Ponniyandal to 121.91 gpm/ft of dd at Kottaiyampalayam in the eastern central part of the study area. Groundwater level in the basin by rainfall recharge and hydrodynamic method is estimated as 69 million cu.m of recharge and 33 million cu. m of groundwater storage.

The upper Gadilam river basin is located in Vizhupuram district of Tamil Nadu. The number of energized wells in this area has increased manifold due to free supply of electric power until recently by the government of Tamil Nadu. This has resulted in large-scale groundwater abstraction causing an overall decline in regional piezometric heads in this water table aquifer. A regional hydrogeological study was attempted for a quantitative understanding of the regional aquifer parameter of the study area. The status of hydrogeological conditions of the study area is discussed in this paper.

Earth Sciences Journal, Palaeoenvironmental Studies, Rajapuram and Somanapally Sandstones, Palaeocurrent Analysis, Crossbedding, Proterozoic Rocks, Godavari Valley, Pakhal Sandstones, Polycrystalline Grains, Precambrian Sediments, Bimodal System.