 |
| Titel |
Mitigation scenario analysis: modelling the impacts of changes in agricultural management practices on surface water quality at the catchment scale |
| VerfasserIn |
Sam Taylor, Yi He, Kevin Hiscock |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090078
|
| Publikation (Nr.) |
 EGU/EGU2014-4294.pdf |
|
|
|
|
|
| Zusammenfassung |
| Increasing human pressures on the natural environment through the demand for
increased agricultural productivity have exacerbated and deteriorated water quality
conditions within many environments due to an unbalancing of the nutrient cycle.
As a consequence, increased agricultural diffuse water pollution has resulted in
elevated concentrations of nutrients within surface water and groundwater bodies. This
deterioration in water quality has direct consequences for the health of aquatic
ecosystems and biodiversity, human health, and the use of water as a resource for
public water supply and recreation. To mitigate these potential impacts and to meet
commitments under the EU Drinking Water and Water Framework Directives, there is a
need to improve our understanding of the impacts that agricultural land use and
management practices have on water quality. Water quality models are one of the tools
available which can be used to facilitate this aim. These simplified representations
of the physical environment allow a variety of changes to be simulated within a
catchment, including for example changes in agricultural land use and management
practices, allowing for predictions of the impacts of those measures on water quality to
be developed and an assessment to be made of their effectiveness in improving
conditions.
The aim of this research is to apply the water quality model SWAT (Soil and
Water Assessment Tool) to the Wensum catchment (area 650 km2), situated in
the East of England, to predict the impacts of potential changes in land use and
land management practices on water quality as part of a process to select those
measures that in combination will have the greatest potential to improve water
quality.
Model calibration and validation is conducted at three sites within the catchment against
observations of river discharge and nitrate and total phosphorus loads at a monthly time-step
using the optimisation algorithm SUFI-2 (Sequential Uncertainty Fitting Version 2) within
the program SWAT-CUP (SWAT Calibration and Uncertainty Programs). Model performance
is assessed against a variety of statistical measures including the Nash-Sutcliffe efficiency
coefficient (NSE) and percentage bias (PBIAS).
Various mitigation scenarios are modelled within the catchment, including changes in
fertiliser application rates and timing and the introduction of different tillage techniques and
cover-crop regimes. The effects of the applied measures on water quality are examined and
recommendations made on which measures have the greatest potential to be applied within
the catchment to improve water quality. This study reports the findings of that analysis and
presents techniques by which diffuse agricultural pollution can be reduced within catchments
through the implementation of multiple on-farm measures. The methodology presented has
the potential to be applied within other catchments, allowing tailored mitigation
strategies to be developed. Ultimately, this research provides ‘tested’ mitigation options
that can be applied within the Wensum and similar catchments to improve water
quality and to ensure that certain obligatory water quality standards are achieved. |
|
|
|
|
|
|