SWAT Modeling of Water Quantity and Quality in the Tennessee River Basin: Spatiotemporal Calibration and Validation
Gangsheng Wang1,2, Henriette I. Jager1,2, Latha M. Baskaran1, Tyler F. Baker3, and Craig C. Brandt41Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA 2Climate Change Science Institute, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA 3Tennessee Valley Authority, Knoxville, TN 37902 USA 4Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831 USA
Received: 21 Jan 2016 – Accepted for review: 22 Jan 2016 – Discussion started: 25 Jan 2016
Abstract. Model-data comparisons are always challenging, especially when working at a large spatial scale and evaluating multiple response variables. We implemented the Soil and Water Assessment Tool (SWAT) to simulate water quantity and quality for the Tennessee River Basin. We developed three innovations to overcome hurdles associated with limited data for model evaluation: 1) we implemented an auto-calibration approach to allow simultaneous calibration against multiple responses, including intermediate response variables, 2) we identified empirical spatiotemporal datasets to use in our comparison, and 3) we compared functional patterns in landuse-nutrient relationships between SWAT and empirical data. Comparing monthly SWAT-simulated runoff against USGS data produced satisfactory median Nash-Sutcliffe Efficiencies of 0.83 and 0.72 for calibration and validation periods, respectively. SWAT-simulated water quality responses (sediment, TP, TN, and inorganic N) reproduced the seasonal patterns found in LOADEST data. SWAT-simulated spatial TN loadings were significantly correlated with empirical SPARROW estimates. The spatial correlation analyses indicated that SWAT-modeled runoff was primarily controlled by precipitation; sedimentation was controlled by topography; and NO3 and soluble P were highly influenced by land management, particularly the proportion of agricultural lands in a subbasin
Wang, G., Jager, H. I., Baskaran, L. M., Baker, T. F., and Brandt, C. C.: SWAT Modeling of Water Quantity and Quality in the Tennessee River Basin: Spatiotemporal Calibration and Validation, Hydrol. Earth Syst. Sci. Discuss., doi:10.5194/hess-2016-34, 2016.