This project was a collaboration funded by Southern Water that considered how low-cost catchment modelling approaches (e.g. ArcSWAT) can help to predict where and when water quality issues are most likely to arise.
Since its inception in 2000, the EU Water Framework Directive (WFD) has fostered a transformation in river basin management. In order to meet the Directive's need for holistic River Basin Management Plans (RBMP), hydrological catchment models are increasingly used to predict the impact of environmental change on the flow characteristics and water quality of European rivers.
The WFD seeks to prevent the deterioration of ground and surface water bodies, and achieve good ecological and chemical status in water courses. This requires the management of a range of chemical contaminants, including pesticides, and their supply to water courses. Metaldehyde (a synthetic aldehyde pesticide used globally in agriculture) has been identified as an emerging contaminant of concern. Metaldehyde is a particular problem because it is highly stable in water, can be very mobile in the environment, and is ineffectively removed by drinking water treatment processes.
As part of Southern Water’s development of new strategic approaches, such as Integrated Water Cycle Management (IWCM), there is also a need to develop capability in advanced catchment modelling. Current exemplars of best practice in catchment modelling produce static risk assessment at a relatively high geographical level. The predictive catchment modelling approach proposed here allowed Southern Water to predict and build scenarios of pollutant risk in specific catchments. The development of this predictive modelling capability provided opportunities for stakeholder engagement and facilitated development of catchment-specific solutions, particularly with regard to emerging higher water quality standards for diffuse contaminants.