108. Sediment Transport in Agricultural Catchments – The Need for Methods to Trace Sediment Sources

In the Agricultural Environmental Monitor ing Programme (JOVA) runoff, losses of suspended solids and nutrients are measured. In the Skuterud (680 ha) and Mordre (450 ha) catchments, soil erosion from agricultural land is considered to be the major source of particles. Information about agricultural practices on each field is collected to relate losses of particles to e.g. the area ploughed at the time of runoff. In spite of there being less area tilled than normal in the autumn 2000, soil losses were 5–6 higher than mean values for the 10-year monitoring period (1991/1993–2001). Autumn precipitation was 2–3 times higher and runoff 3–5 times higher than normal. A field inventory documented that not only tillage contributed to soil losses, but also preferential flow, erosion around hydrotechnical installations and especially bank erosion. It illustrates the need to have methods for tracing all sources of sediment for the planning of conservation measures.