Book Description

The Soil and Water Assessment Tool (SWAT) was evaluated for its ability to simulate and analyze the hydrology of the 85,560 km2 Wabash watershed that is shared by the states of Ohio, Indiana, Illinois, and Kentucky in the Midwest region of the United States. The data employed in the analysis are available to the public from trusted organizations, e.g., the USGS, MRLC, etc. The purpose of this study is to 1) create a hydrological model for the Wabash watershed, and 2) to conduct detailed analyses of the output data, especially during the spring season, to study potential spring season flooding. The data used for these analyses are precipitation, temperature, Soil Water Yield, surface runoff, and snow melt. The basin was divided into 516 subbasins based on the DEM data and a threshold area of 9,000 ha. A total number of 2,803 Hydrologic Response Units (HRU) that represent the different soil types and land use was generated, according to the soil, land use maps and slope with threshold values of 20%, 10%, and 20%, respectively. The first five years were used as the warm-up period to mitigate the effect of initial conditions. The calibration was carried out at daily time steps using flow data from January 2003 to December 2009. The years from 2010 to 2013 were used for validation. SWAT-CUP (a calibration/uncertainty or sensitivity program interface for SWAT) was used. In this study, the sequential uncertainty fitting algorithm (SUFI-2) procedure was used for parameter optimization and uncertainty propagation analysis. The main findings of this study are: 1) The areas adjacent to the main channel are the most affected, with higher concentrations downstream, 2) Differences in Land Use and Land Cover type (LULC) do not have a significant influence on the results, and 3) high peak precipitation events did not have a significant contribution to flooding due to an increase in temperatures during the same times those peaks occurred.