Watershed

Oral

394296 - Evaluation of Ensemble Precipitation Data for Uncertainty Analysis in SWAT Water Quality Simulation

Thursday, June 7
8:30 AM - 10:00 AM
Location: Greenway IJ
Co-Authors: Ashok Mishra, Clemson, SC – Clemson University; Abdul Khan, Clemson, SC – Clemson University

The Critical Source Areas (CSAs) have been recognized as optimal locations for the control of nonpoint source (NPS) pollution and implementation of best management practices (BMPs). In previous studies, CSAs were identified based on factors such as pollutant concentration, load, and yield at the levels of subbasins and/or hydrologic response unit (HRU); however, the previous studies did not consider the influence of the temporal and spatial uncertainties of precipitation data, which triggers most of the NPS pollution. The objective of this study was to assess the impact of using different precipitation datasets on identifying CSAs at the subbasins level. This study used 15 years (2000–2015) of daily precipitation data from five datasets, including RG (Rain gauges), IDW (Inverse Distance Weighting data), Prism (Parameter-elevation Relationships on Independent Slopes Model), CFSR (Climate Forecast System Reanalysis) and TRMM (Tropical Rainfall Measuring Mission). The Soil and Water Assessment Tool (SWAT) was calibrated against measured streamflow, total nitrogen, (TN) and total phosphorus (TP) in Seneca Watershed at four different locations to identify CSAs. For each precipitation dataset, the best performing parameter and prediction uncertainties were determined using the Sequential Uncertainty Fitting Procedure. Satisfactory simulations were achieved for streamflow, TP, and TN using the five different precipitation datasets; however, the parameters uncertainty, especially for TN and TP simulations, varied significantly using different precipitation models. This study concluded that using multiple precipitation inputs can increase the level of confidence in simulation results, particularly in water quality modeling.

Ali Alnahit

Graduate Research Assistance
Clemson University

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394296 - Evaluation of Ensemble Precipitation Data for Uncertainty Analysis in SWAT Water Quality Simulation



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