Title: | Evaluation of the TBET Model for potential improvement of Southern P Indices |
Authors: | Forsberg, A., D.E. Radcliffe, C.H. Bolster, A. Mittelstet, D.E. Storm and D. Osmond |
Year: | 2017 |
Journal: | Journal of Environmental Quality |
Volume (Issue): | 46(6) |
Pages: | 1341-1348 |
Article ID: | |
DOI: | 10.2134/jeq2016.06.0210 |
URL (non-DOI journals): | |
Model: | SWAT |
Broad Application Category: | pollutant only |
Primary Application Category: | GIS interface, GIS utility, or other type of interface/utility |
Secondary Application Category: | phosphorus cycling/loss and transport |
Watershed Description: | 18 total field sites located in Washington County, Arkansas, Putnam county, Georgia, or Henderson County, North Carolina, U.S. |
Calibration Summary: | |
Validation Summary: | |
General Comments: | The authors describe testing of the "TBET model" in this study, but TBET is really an interface based on output from underlying SWAT simulations, and thus SWAT is identified as the model for this study. |
Abstract: | Due to a shortage of available phosphorus (P)-loss datasets,
simulated data from an accurate quantitative P transport model
could be used to evaluate a P Index. The objective of this study
was to compare predictions from the Texas Best Management
Practice Evaluation Tool (TBET) against measured P-loss data
to determine whether the model could be used to improve
P Indices in the southern region. Measured P-loss data from
field-scale study sites in Arkansas, Georgia, and North Carolina
were used to assess the accuracy of TBET for predicting fieldscale
loss of P. We found that event-based predictions using an
uncalibrated model were generally poor. Calibration improved
runoff predictions and produced scatterplot regression lines that
had slopes near one and intercepts near zero. However, TBET
predictions of runoff met the performance criteria (Nash–Sutcliffe
efficiency ³ 0.3, percent bias £ 35%, and mean absolute error
£ 10 mm) in only one out of six comparisons: North Carolina
during calibration. Sediment predictions were imprecise, and
dissolved P predictions underestimated measured losses. In
North Carolina, total P-loss predictions were reasonably accurate
because TBET did a slightly better job of predicting sediment
losses from cultivated land. In Arkansas and Georgia, where the
experimental sites were in forage production, the underprediction
of dissolved P led directly to the underpredictions of total P.
We conclude that TBET cannot be used to improve southern P
Indices, but a curve number approach could be incorporated into
P Indices to improve runoff predictions. |
Language: | English |
Keywords: | |