Design and application of a sediment and contaminant transport modelling system

A physically-based modelling system for water, sediment and contaminant transport at the river basin scale, called SHETRAN-UK, is presented which has particular relevance to environmental change impact studies. Based on the SHE hydrological modelling system, components have been developed for soil erosion and sediment yield, and for dissolved and particulate contaminant transport. Particular emphasis is placed on sediment and contaminant interactions and sediment transport by size fraction (including cohesive sediments) to account for the preferential sorption of contaminants by the finer sediment sizes. Three typical application areas are described: simulation of radionuclide dispersal in the biosphere as part of the establishment of the safety case for deep underground disposal of radioactive waste; modelling the impacts of likely changes in climate and land use on basin hydrology and soil erosion in a study of desertification in Mediterranean Europe; and development of forestry practice guidelines for minimizing soil erosion.