A rainfall-runoff model called SWAT was used to study the Manimala River basin in Kerala. The model was calibrated using data from 2000 to 2007. Seven model parameters were adjusted to match observed data. The study found that surface runoff is affected by certain parameters like CN, ESCO, and SOL_AWC, while baseflow is influenced by GW_REVAP and ALPHA_BF. The model's accuracy was confirmed by comparing predicted and observed values.