Climate variability caused by global warming affects the inflow, outflow, and water discharge in the dam and ultimately affecting the crop production. Water supplies are substantially impacted by climate change and hydrological conditions of different regions, particularly the river basins. The Papanasam dam had an inflow of 5114 to 9330 m3/s in normal rainfall years and 7491 to 9523 m3/s during the excess rainfall years. The water released during the normal and excess rainfall years ranged from 113 to 167 days. In Manimuthar dam, water release days varied from 133 to 144 days during excess years. In deficit years, the water release days ranged from 55 to 90 days. In the normal years, Manimuthar dam had an inflow of 4092 to 7413 m3/s, 6764 to 7822 m3/s in the excess years and 3621 to 4497 m3/s in the deficit years. To conclude that, the best rice-based cropping system under excess rainfall situation is rice –rice followed by rice-maize and rice-pearl millet. During deficit years, pulse crops perform better than other crops. In normal rainfall years, the performance of rice-based cropping system follows the order of rice-rice, rice-maize, rice-pearl millet, rice-sorghum and rice-pulses.