Use of Swat Model for Hydrological Simulation in Lam Takhong Watershed in Thailand

Abstract

The flow stream in Lam Takhong river has been gradually decreasing in recent years, which is one of the causes affecting the water quality in the river. Therefore, it is necessary to simulate and forecast the flow in the river and this helps environmental agencies to control and make appropriate decisions on water resources management. In Thailand, the application of models in environmental and hydrological simulation is widely applied and appreciated. However, previous studies have not auto-calibrated parameters by SWAT-CUP in Lam Takhong watershed. The environmental parameters estimation impacting streamflow in Lam Takhong watershed uses the calibrated results of the SWAT model. The calibration used the traditional weather data in Nakhon Ratchasima from 1990 to 2014 and from 2015 to 2017 for validation. The study has applied 11 the parameters for the streamflow calibration and the sensitive analysis gave the main initial SCS CN II value and groundwater delay parameters affecting the flow simulation process. In general, the weather data is one of good additions to the dataset for hydrological modeling in the Lam Takhong watershed and the modified values for SWAT give the R2 value 0.85 in upstream and 0.70 in downstream for monthly total flows is good. The flow from the simulation shows that the SWAT model is suitable for stream flow in Lam Takhong river in Thailand. In addition, these results can be integrated water quality model to forecast water quality and allocate the Nitrogen loading in Lam Takhong river.