Effect of Land Use Changes on Watershed Hydrologic Behavior (Case Study: Qaleshahrokh Watershed)

Qaleshahrokh watershed with an area of 150980.1 hectares was selected for investigating the relation between land use changes and watershed hydrologic behavior. From satellite data, land use, curve number maps and runoff coefficients were obtained for 1975, 1990 and 2002. Results show that most of the land use changes occurred through converting rangelands to dry lands and irrigated agriculture. Weighted means of CN and C was 85.9 and 0.55, 87 and 0.58, 87.24 and 0.6, in 1975 to 2002 respectively. Also runoff depth increased 0.25 mm per year between 1975-1990 and 0.075 mm/year between 1990-2002.