SWAT hydrological models are one of the methods of estimating runoff obtained from rainfall at points without hydrometric stations. In other words, by simulating the process of converting precipitation into runoff, these models are able to estimate the amount of runoff in watersheds without measuring stations with the least possible time and cost.

Based on this, the current study has been conducted with the aim of evaluating the power of the SWAT hydrological model in climatic conditions and simulating the outflow of rivers in the Tajen watershed and comparing it with observations. The most important data used in the research include vegetation, altitude classes, slope, climate data (wind, rain, maximum temperature, minimum temperature), climate changes and climate change conditions, etc.

The results of this study show that the error rate of the LARS-WG hydrological model in climate conditions and in the simulation of runoff and average daily discharge was very low, so that the Nash-Sutcliffe coefficient of the simulated daily discharge compared to the observed discharge in the period from 1998 to 2014, during calibration, was more than 0.50, which after re-optimization Soil parameters, this coefficient was obtained in the validation stage (2018-2014) above 0.74 for daily discharge. And this is an indication of the low level of model error in simulating the outflow of the watershed.



Keywords: SWAT hydrological model, climatic conditions, Tajen watershed.