The goal of the study was to use a GIS-based model to estimate runoff in an agricultural-forest watershed in Thailand. The researchers combined the Soil Conservation Service Curve Number method with GIS to simulate runoff during the monsoon seasons of 2011 and 2012. The model was calibrated and validated using observed data from two stations in the watershed. The results showed that the model accurately estimated runoff at both stations, indicating that the GIS-based curve number method is effective for predicting runoff in the study area.