| Title: | Diffuse phosphorus models in the United States and Europe: Their usages, scales, and uncertainties |
| Authors: | Radcliffe, D.E., J. Freer and O. Schoumans |
| Year: | 2009 |
| Journal: | Journal of Environmental Quality |
| Volume (Issue): | 38 |
| Pages: | 1956-1967 |
| Article ID: | |
| DOI: | 10.2134/jeq2008.0060 |
| URL (non-DOI journals): | |
| Model: | SWAT |
| Broad Application Category: | review/history |
| Primary Application Category: | model and/or data comparison |
| Secondary Application Category: | phosphorus cycling/loss and transport |
| Watershed Description: | None |
| Calibration Summary: | |
| Validation Summary: | |
| General Comments: | |
| Abstract: | Today there are many well-established computer models that
are being used at different spatial and temporal scales to describe
water, sediment, and P transport from diff use sources. In this
review, we describe how diffuse P models are commonly being
used in the United States and Europe, the challenge presented
by different temporal and spatial scales, and the uncertainty in
model predictions. In the United States, for water bodies that
do not meet water quality standards, a total maximum daily
load (TMDL) of the pollutant of concern must be set that
will restore water quality and a plan implemented to reduce
the pollutant load to meet the TMDL. Models are used to
estimate the current maximum daily and annual average load,
to estimate the contribution from different nonpoint sources,
and to develop scenarios for achieving the TMDL target. In
Europe, the EC-Water Framework Directive is the driving force
to improve water quality and models are playing a similar role
to that in the United States, but the models being used are not
the same. European models are more likely to take into account
leaching of P and the identification of critical source areas.
Scaling up to the watershed scale has led to overparameterized
models that cannot be used to test hypotheses regarding
nonpoint sources of P or transport processes using the
monitoring data that is typically available. There is a need for
more parsimonious models and monitoring data that takes
advantage of the technological improvements that allow nearly
continuous sampling for P and sediment. Tools for measuring
model uncertainty must become an integral part of models and
be readily available for model users. |
| Language: | English |
| Keywords: | |