Determining the relationship between rainfall and runoff for a basin is one of the most important issues that hydrological engineers are facing. Hydrologists need to investigate the relationships between rainfall and runoff, which are usually nonlinear and complex, to design and manage. The climatic factors include the type, severity and duration of precipitation, and the spatial distribution of rainfall, as well as the movement of rain mass and other factors such as evapotrairation. Physiographic and hydrologic parameters include land use, soil, basin area, basin shape, elevation, slope, direction and type of drainage network, soil moisture and groundwater table. All of these factors are effective in both surface runoff and peak discharge. In this research, the HEC-HMS model was used to investigate the effects of climate and hydrological changes, as well as calibration and sensitivity analysis. One of the other objectives of this research is to predict the runoff of the upstream basin of Zayandehrud Dam based on predicted values of climate data in different scenarios and future hydrological parameters. Also, the study of land use change in the future and its effects on the amount of runoff and the comparison of the amount of runoff resulting from this change with the predicted lubricant volume for the future in different climate scenarios has been addressed. In the runoff-run simulation with HEC-HMS model, the results of calibration and validation show the acceptable performance of this model in estimating runoff in the study area. In the calibration stage, the coefficient of estimation R2 for the sub-basin of upstream of Qaleh Shahrokh and Eskandari stations was 0.54 and 0.51, respectively, and 0.73 and 0.44, respectively, and NSE for calibration, respectively 0.44 and 0.42 respectively and in the validation phase, respectively, 0.62 and 0.88, respectively, and the fitting index d for calibration was 0.84 and 0.81, respectively, and in the verification step respectively, 0.93 and 0.91 respectively.
