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

• Published in: Catena (Giessen) Vol. 47; no. 4; pp. 323 - 353
• Main Authors: Walling, D.E, Russell, M.A, Hodgkinson, R.A, Zhang, Y
• Format: Journal Article
• Language: English
• Published: Cremlingen-Destedt Elsevier B.V 31-05-2002; Catena
• Subjects: 137Cs; Bgi / Prodig; Catchments. Hydrological cycle; Earth sciences; Earth, ocean, space; Exact sciences and technology; Geomorphology, landform evolution; Hydrometeorology; Isotope geochemistry; Isotope geochemistry. Geochronology; Physical geography; Sediment budget; Sediment delivery ratio; Sediment storage; Surficial geology; Tile drains; England; United Kingdom; Great Britain; Derbyshire England; Western Europe; Derbyshire; British Isles; Sediment storage; Tile drains; Sediment delivery ratio; Sediment budget; 137Cs; drainage basins; sediment yield; sediment transport; balance; Europe; Cs-137; storage; soil erosion; sediments; Drainage; Bank erosion; Soil erosion; Watershed; Suspended load; Isotope analysis; Digital elevation model; Geographical information system; Cultivated land
• ISSN: 0341-8162; 1872-6887
• DOI: 10.1016/S0341-8162(01)00187-4

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