Abstract
Abstract
Complex hydrological processes can be modeled using the Soil and Water Assessment Tool (SWAT). However, poor quality inputs, lack of observation and high number of input parameters make the modeling challenging and complicate the calibration process. The main aim of this study is to assess the parameters uncertainty and suitability of discharge and remotely sensed ET data to calibrate the SWAT model and explore the possibility of using MODIS satellite imagery for direct calibration in ungauged study areas. Different techniques are adopted to acquire accurate land use map and remotely sensed evapotranspiration derived from Sentinel-2 and MODIS satellite imagery. Sobol’ sensitivity analysis is used to effectively identify the key parameters and provides crucial information on how they influence the model outputs. To address model equifinality and uncertainty, the model of the Ilam Dam Basin in Iran is calibrated and validated using a multi-criteria performance evaluation approach that considers all performance criteria concurrently. The discharge predictions at the Sarjoy station showed good discharge predictions during 12 years of calibration (NSE = 0.6, KGE = 0.79, PBIAS = 3.7 and \({R}^{2}\)= 0.64) and 5 years of validation (NSE = 0.5, KGE = 0.76, PBIAS = -0.3 and \({R}^{2}\) = 0.58). ET predictions at the selected HRU also demonstrated acceptable results for calibration (NSE = 0.37, KGE = 0.69, PBIAS = -0.9 and \({R}^{2}\) = 0.47) and validation periods (NSE = 0.47, KGE = 0.73, PBIAS = 0.4 and \({R}^{2}\) = 0.54). The sensitivity analysis shows that while key parameters in both the discharge and ET models exhibited similarity, their varying levels of influence are notable. Furthermore, the direct calibration of the SWAT model yields acceptable performance criteria (NSE = 0.43, KGE = 0.66, PBIAS = -18 and \({R}^{2}\) = 0.61), making it a valuable approach in data-scarce regions.
Publisher
Research Square Platform LLC