Investigation of the Effect of Land Use Change on Runoff of Qarachai River Basin Using HEC-HMS Models

In recent decades, land use change under the influence of environmental and human factors has caused serious effects on the environment, economy and society. Hydrological models are a simplified representation of the actual hydrological system that studies the operation of the basin, so model selection requires recognizing the capabilities and limitations of hydrological models in the basin. In the present study, the analysis of land use changes and its effect on runoff in Qara-Chay basin was performed using HEC-HMS models. In order to investigate land use changes on the impact on basin runoff changes, the 2020 annual rainfall of the basin with 2001 land use characteristics was introduced to the model. The results related to land use changes show that the most changes in land use include changes related to land without vegetation in a decreasing manner and a mixture of irrigated and rainfed agriculture in an increasing manner. In the simulation of Gharachai catchment basin in HEC-HMS model, calibration of the basin in six sub-basins based on runoff peak, runoff height and runoff volume was examined. 94% and in the runoff peak element with 95.12% and in the runoff volume element with 97.5% show the correct implementation of the model on the basin. Therefore, it can be said that land use change in Qarachai catchment has increased the peak and volume of runoff and ultimately has led to an increase in runoff in this basin.