Rainfall being the predominant from of precipitation causing stream flow, especially the flood flow in a majority of rivers in India. In the present study, an attempt has been made to assessment the rainfall variation and monitoring with respect to spatial distribution in Thirumanimuttar River Sub Basin of Cauvery River, South India. To achieve the aim of rainfall variations during Winter (Jan. & Feb.), Summer (Mar. to May), Southwest Monsoon (Jun. to Sep.) and Northeast Monsoon (Oct. to Dec.) were analyzed for a period of 12 years from 2000 to 2011. These results were taken into platform to prepare the spatial distribution maps. The spatial distribution maps of Southwest- and Northeast monsoon season showed that 1802.78 km2 and 2033.28 km2 of the study area received high rainfall during the respective monsoon seasons. Annual average rainfall spatial distribution map for the years 2000-2011 revealed that 74.43 km2 fell under high rainfall zone in the study area. The results suggest that the model reproduces the number and spatial distribution maps of rainfall extremes with some accuracy, but that mean rainfall and rainfall variability is estimated over dry regions of Thirumanimuttar River Basin, Cauvery River, South India
