Investigating the hydrological effects of land use change in catchment (Case study: Zanjanrood Basin)

Changes in land use can significantly influence the hydrological cycle and hence affect water resources. Understanding the impacts of land use changes on hydrology response at the watershed scale can facilitate development of sustainable water resources strategies. This paper investigates the hydrological effects of land use change in the Zanjanrood basin of Iran, during last 40 years. The study reveals how land use changes affected the hydrological regimes at the watershed scale. The water balance was simulated with the use of the Soil and Water Assessment Tool (SWAT2005). This is a hydrological model that requires the meteorological data, land use, soil and DEM of the inspected areas, in the form of a digital map. After calibrating and modeling accuracy determination, the effect of land use changes on hydrological responses was evaluated using, land use of 1967, 1994, 2007 years set as model input. The results indicated that land use change had significant impact on water yield and river discharge. The land use changes over the period 1967 to 2007 led to a 33% increase in the amount of surface runoff and a 22% decrease in the ground water storage. Furthermore, the area of subbasins that influenced by high annual group runoff (14-28 mm) increased about 16%