Integrated approaches to phosphorus management in the Watton Brook
Knightbridge, J.1 and Edevane, J.2, 1Mott MacDonald, 2Anglian Water, UK
(free)
Phosphorus enrichment in waterbodies can increase the risk of eutrophication and can be detrimental to ecosystem health of the waterbody. Phosphorus is a common reason for waterbody failure to meet ‘Good’ status under the Water Framework Directive (WFD). The Watton Brook, a tributary of the River Wissey in Norfolk, has an overall ‘Moderate’ Water Framework Directive status and ‘Poor’ status for phosphate (2016). Source apportionment modelling estimates that over 70% of the phosphate derives from water recycling centre (WRC) discharges; this was confirmed by an enhanced treatment trial at the largest WRC in the catchment, Watton.
The trial was successful in meeting targets, however further reductions in phosphate are required to achieve ‘Good’ status. Given the significance of agricultural sources of phosphorus, and the cost of installing additional treatment, or optimising existing treatment, this study explores alternative integrated catchment-based solutions by taking a stakeholder and ecosystem services-led approach. The feasibility for holistic catchment approaches built on a detailed environmental conceptualisation and ground-truthing of phosphorus source apportionment before investigating the likely cost and environmental benefit of these. By combining natural capital mapping and phosphorus modelling the study spatially targets solutions to reduce phosphorus loadings and deliver multiple environmental and social benefits.
Keywords: Agriculture, Catchment management, Integrated solutions, Modelling, Natural capital, Phosphorus balancing, Stakeholder engagement, Water recycling.
