Hydrologic models like SWAT can help manage water resources in semi-arid areas. Researchers in Tunisia used SWAT to simulate runoff in a catchment. They compared model predictions with actual measurements from 1990-2005. The model accurately predicted runoff, with key factors being curve number, soil evaporation, water depth, and slope. Results showed good agreement between simulated and observed data, with R^2 values over 0.75. SWAT is effective for predicting runoff in semi-arid regions.