The study aimed to map the runoff and curve numbers in Nowdeh watershed using a semi-distributed model in a GIS environment. The researchers ran the model for different time periods and found high accuracy in simulating runoff. They determined that the runoff curve numbers ranged from 73.5 to 84, with an average of 77.62 in the basin. The results suggest that measures to improve soil permeability are needed to prevent water loss in the area.