Assessment of effects of changes in landuse on the water balance components using SWAT (Case study: Doroudzan dam basin)

In this study, to investigate the effects of land use changes on hydrological components of the Doroudzan Dam basin for the three periods of 1979 to 1990, from 1987 to 1999, and from 1997 to 2006, three land use maps for the years 1986, 1996 and 2005 were prepared. Then, using the semi-distributed SWAT model, the basin hydrology processes were simulated. After calibration to validate the model, validation was performed for each period. The Nash-Sutcliffe coefficient in calibration and validation of the first period was 0.74 and 0.52, in the second period was 0.88 and 0.61, and in the third period was 0.83 and 0.8, respectively. Also, three scenarios were defined to determine the effect of each land use management application in the study time step (1979 to 2006). All the scenarios were simulated under the same conditions for rainfall and temperature and  different land use maps. The impact of land use change under these scenarios is well observed, with the latter having a 27.7% decrease in surface runoff compared to the control scenario, as rangeland, forest, agricultural cover increased, wasteland decreased. Has found. In the third scenario, surface runoff decreased by 13.5% compared to the control scenario, but increased compared to the second scenario, as rangeland cover decreased and wasteland increased.