Establishing sediment budgets for two small lowland agricultural catchments in the UK

摘要: Sediment budgets have been established for two small (<4 km2), lowland, agricultural catchments, by using 137Cs measurements, sediment source fingerprinting and more traditional monitoring techniques to quantify the individual components of budget. The gross net erosion rates fields on catchment slopes were estimated measurements within selected fields, which encompassed a representative range slope angles, lengths land use. These estimates extrapolated over entire catchment, simple topographically driven soil model (Terrain-Based GIS, TBGIS) superimposed DEM, derive average rates. Suspended yields measured at outlets used establish relative contributions from surface, subsurface tile drains eroding channel banks yields. In-channel wetland storage quantified both direct measurements. catchments highlighted importance as pathway transfer, accounting ca. 60% 30% output catchments. Erosion contributed 10% 6% Although suspended these considered high UK standards (ca. 90 t km−2 year−1), delivery ratios ranged between 14% 27%, indicating that major proportion mobilised was stored In-field field-to-channel shown be similar magnitude, but in system associated wetlands relatively small, representing <5% annual yield.