The assessment of changes in rainfall over a regional scale has become essential to manage future planning and policy development. The changes in precipitation over the Cauvery river basin are studied using the general circulation models output and observed datasets. Future scenarios and historical model outputs from the CNRM-CM5 model are used in this study .The historical observed precipitation data is used to project future precipitation by comparing historical and future model simulation. The change assessment shows significant increase in rainfall throughout the basin with an increase in future time scale. The quantile delta mapping handles the bias in the general circulation models better than the traditional quantile mapping bias correction technique. The quantile delta method is simple, easy to apply and requires less computational power. The increase in future precipitation compared to observed statistics ranges from 20 to 100 % especially during the monsoon seasons. The Representative Concentration Pathways (RCP) 2.6 and RCP 8.5 scenarios show very high changes in precipitation with an increase in future time scale and the RCP 4.5 scenario shows moderate changes compared to other scenarios. Tracking the precipitation rate and forecasting future conditions will help the planning of actions and development at a regional scale. © 2020 Ecological Society of India. All rights reserved.