Can agri-environment initiatives control sediment loss in the context of extreme winter rainfall?

Soil erosion and sediment losses are likely to increase with projected climate change and increasing storm intensity, causing detrimental impacts to agriculture and the degradation of aquatic ecosystems. Agri-environment initiatives aim to mitigate these losses through farmer engagement and incentivisation for best practice. There is, however, limited evidence regarding the impacts of their delivery and their capacity to deliver resilience to extreme wet weather. As such, the aim of this study was to determine how fine-grained sediment provenance changes with flow condition in eight high priority English catchments targeted through a strategic agri-environment initiative and to compare the estimated sediment source proportions to the targeted advice being delivered to farmers. The provenance of fine-grained sediment was determined using sediment source finger-printing over low flow conditions and the winter of 2019–2020 which was characterised by severe flooding. Details on the advice delivered to farmers through the Catchment Sensitive Farming initiative were obtained from a delivery agency database and interviews with catchment officers. Dominant sediment sources varied considerably between catchments and were not easily predicted based upon their characteristics meaning that targeting on-farm advice effectively is challenging. Critically, however, changes in sediment sources rarely occurred with the extreme wet winter of 2019–2020. It is recommended that the greater availability of empirical catchment-specific evidence could significantly improve the delivery of such agri-environment initiatives. In the current absence of this evidence an assumption that riparian woodland is effective at preventing sediment losses and the targeting of advice to sediment sources proportionally based upon the area of the catchment they cover may improve the benefits of such initiatives.