Runoff simulation in Kwan Phayao watershed based on the SWAT model

The aims of this study were: 1) to study the simulation of runoff in Kwan Phayao watershed based on SWAT model and 2) to evaluate the appropriate parameters coefficients of SWAT model suitable for Kwan Phayao Watershed. This simulation runoff in the monthly time step. The Digital Elevation Model (DEM), land use, soil and meteorological data were addressed to evaluate the runoff. Then, the runoff values obtained from the model were calibrated and validated was compared with the runoff values obtained from the I.17 station for determine the sensitivity of the parameters to the runoff of the watershed area. Using the SWAT-CUP program, the parameters were adjusted. According the results, the effective parameters were composed of: 1) ALPHA_BF.gw (Base flow alpha factor), 2) GWQMN.gw (Threshold depth of water in the shallow aquifer required for return flow to occur), 3) GW_REVAP.gw (Groundwater "revap" coefficient), 4) GW_REVAP.gw (Groundwater delay), and 5) REVAPMN.gw (Threshold depth of water in the shallow aquifer for "revap"). using the R
²
, NS, and PBIAS values as the basis for determining the reliability. The statistical outcomes showed the calibration was R
²
= 0.58, NS = 0.58, and PBIAS = 2.2. As for the validation results was R
²
= 0.66, NS = 0.57, and PBIAS = -2.0. It shown the relationship between runoff value from the model and runoff value from station 1.17 and reliability is acceptable. It demonstrated that these the parameter set can be used in the Kwan Phayao watershed as well.