Applicability of SWAT Model for Streamflow Simulation in a Highly Managed Agricultural Watershed

-Case Study: Yasu River Basin, Japan-

Abstract

  Modelling is inevitable as far as strategic planning and decision making are of concern. However, natural systems such as hydrology tend to be complex when it comes to modelling. Coupled with many variables and numerous uncertainties, hydrological modelling presents an enormous task especially on distributed or semi-distributed models. This study applies Soil Water Assessment Tool (SWAT) 2012 model for long term daily streamflow simulation in Yasu River Basin. Automatic irrigation from the reach is considered in paddy fields. Two reservoirs along the main channel are included in the model. Simulation period ranges from the year 1990 to 2009 inclusive of a two year warm up period. Sequential Uncertainty Fitting Algorithm (SUFI-2) is used as optimization program for model calibration, validation, parameter statistical significance and uncertainty analysis. Calibration is conducted from 1992 to 2000 whereas validation is from 2001 to 2009. The performance of the model is determined by coefficient of determination (R²) and Nash-Sutcliffe (NS). SWAT provided a suitable platform for hydrological modelling of Yasu River basin with relatively good performance for streamflow simulation.