Some sampling considerations in the design of effective strategies for monitoring sediment associated transport

The sediment-associated component frequently accounts for a major proportion of the load of many substances transported by rivers, such as nutrients, heavy metals and radionuclides. However, many monitoring programmes which aim to assess river loads are based on traditional approaches to water quality monitoring and fail to take account of existing knowledge regarding the behaviour of suspended sediment in rivers and the problems of measuring suspended sediment loads. In consequence, the resultant load estimates may be unreliable. Data obtained from the River Exe in Devon, UK are used to demonstrate some of the considerations which need to be taken into account in obtaining reliable assessments of the loads of sediment-associated substances and to emphasise the need for greater interaction between water quality and sediment monitoring programmes.