Off‐site impacts of soil erosion and runoff: Why connectivity is more important than erosion rates

• Published in: Soil use and management Vol. 35; no. 2; pp. 245 - 256
• Main Authors: Boardman, John, Vandaele, Karel, Evans, Robert, Foster, Ian D. L., Aitkenhead, Matt
• Format: Journal Article
• Language: English
• Published: Bedfordshire Wiley Subscription Services, Inc 01.06.2019
• Subjects: Agricultural land; Agricultural management; Agricultural runoff; Anthropogenic factors; Arable land; connectivity; Culverts; Design modifications; Digital mapping; Ditches; Economics; environmental impact; Erosion rates; field mapping; Flooding; Human influences; Mapping; Mitigation; off‐site impacts; Paths; Pollutants; Remote observing; Remote sensing; Rivers; roads; Runoff; runoff and sediment flux; Sedimentation; sediments; soil; Soil erosion; Soil permeability; Watercourses; Western European region; Western European region
• ISSN: 0266-0032; 1475-2743
• DOI: 10.1111/sum.12496

Off‐site impacts of soil erosion are of greater social and economic concern in Western Europe than on‐site impacts. They fall into two related categories: muddy flooding of properties and ecological impacts on watercourses because of excessive sedimentation and associated pollutants. Critical to these impacts is the connectedness of the runoff and sediment system between agricultural fields and the river system. We argue that well‐connected systems causing off‐site damage are not necessarily related to areas of high erosion rates; emphasis should therefore be on the way in which connections occur. In temperate, arable systems, important elements of connectivity are anthropogenic in origin: roads, tracks, sunken lanes, field drains, ditches, culverts and permeable field boundaries. Mapping these features allows us to understand how they affect runoff and modify its impacts, to design appropriate mitigation measures and to better validate model predictions. Published maps (digital and paper) do not, by themselves, give sufficient information. Field mapping and observation, aided by remote sensing, are also necessary.