Sediment and Suspended Sediment Tracing in a Small Upland Catchment in North Cornwall

Suspended sediment is increasingly viewed as a pollutant in river systems. Information on the source of the sediment transported by water systems is an important requirement for designing sediment control strategies. This paper describes an investigation aimed at identifying the primary sediment and suspended sediment sources of the Upper River Tamar in a small upland agricultural catchment in North Cornwall. The source fingerprint approach was used to establish suspended sediment and sediment sources in the catchment. Representative samples of bed materials, suspended sediment, soils and banks were collected in order to evaluate sediment storage, sediment and suspended sediment quality, and finally to determine sediment and suspended sediment sources. Sediment storage was shown to be homogeneous, and the different tributaries seem to contribute little to sediment delivery. The suspended sediment total phosphorus (TP) and metal concentrations were shown to be highly enriched at the outlet of the basin. Runoff from the surrounding fields and from tributary eroded banks was found to be a significant source of suspended sediment delivery to the main channel. Remobilisation of bed sediment and bank materials only appeared to be a marginal source of sediment and suspended sediment.Faculty of Scienc