The potential impact of projected change in farming by 2015 on the importance of the agricultural sector as a sediment source in England and Wales.

摘要

In association with a major initiative aimed at identifying policy packages for inclusion in the Programmes of Measures (POM's) comprising EU Water Framework Directive (WFD) River Basin Management Plans (RBMP's), recent work has evaluated the gap between current and compliant suspended sediment losses due to farming across England and Wales. The work required national scale sediment source apportionment to assess the current contributions of diffuse agricultural and urban sector losses, channel bank erosion and point source discharges to the total suspended sediment loads delivered to all rivers. Results suggested that the agricultural sector dominates present day (year 2000) sediment inputs to rivers (1929 kt=76%) compared to eroding channel banks (394 kt=15%), diffuse urban sources (147 kt=6%) and point source discharges (76 kt=3%). Projected change in farming by 2015, represented by the Business as Usual forecast of structural developments and predicted uptake of sediment mitigation methods, suggested an overall 9% reduction in sediment loss from the agricultural sector across England and Wales. The projected reduction is unlikely to deliver sediment compliance in all catchments. Key limitations of the integrated modelling approach are discussed.