USING ENVIRONMENTAL RADIONUCLIDES TO TRACE SEDIMENT MOBILISATION AND DELIVERY IN RIVER BASINS AS AN AID TO CATCHMENT MANAGEMENT

摘要

Although sediment problems have long been recognised in those areas of the world with high rates of soil loss and high specific sediment yields, recent years have seen a growing recognition of the wider significance of fine sediment as an environmental problem. This has resulted in a growing need to incorporate sediment control strategies into catchment management programmes. The design of effective sediment control strategies is, however, heavily dependent upon a sound understanding and knowledge of sediment mobilisation and delivery within the catchment system and thus the overall sediment budget. Traditional monitoring techniques are generally unable to provide information on the internal functioning of the sediment budget. Against this background, there is a need for new approaches to data collection and tracing techniques are being increasingly used. Environmental radionuclides provide a particularly useful tool for tracing sediment mobilisation and delivery and this paper provides further information on the basis for their use and on their potential applications. Selected examples of then - application to documenting rates of soil loss and sediment delivery from cultivated fields, sediment source tracing, and documenting rates of floodplain sedimentation and longer-term changes in suspended sediment properties are provided.