The Soil and Water Assessment Tool (SWAT) was used to simulate water balances in different cropping patterns under current and future climates in West Seti river Sub-basin, which is located in the far western region of Nepal. The results show that total precipitation over rice, maize, millet, wheat and barley fields were 1002, 818, 788, 186 and 169 mm respectively, whereas total simulated actual evapo transpiration (ET) are 534, 452, 322, 138 and 177 mm respectively under current climate. Actual ET will change by-1.9% in rice, -1.1% in maize, -2.0% in millet, +6.7% in wheat and +5.4% in barley under future climate projections. Results show that yield of maize and millet will decrease by 5.9% and 8.0% whereas yield of rice, wheat and barley will increase by 1.2%, 6.6% and 7.0% respectively. Therefore, the impact of climate change shows that summer crop yields will decrease except of rice and winter crop yields will increase. In general, a result of watersheds interventions shows that the crop yields will increase after the watershed interventions.