The study highlights the climatic water balance, drought assessment and agricultural potentiality of Uppar Odai sub-basin located in the Southern part of India, Tamil Nadu state. The average annual precipitation in the sub-basin is 625 mm, which is much lower than the state average rainfall (970 mm). It has been observed that the intensive agricultural practices and extensive groundwater mining lead to the groundwater decline in the sub-basin. Rainfall data were collected from 1971-2011 for five rain gauge stations.