Modelling solute and sediment transport at different spatial and temporal scales

摘要

A concept for continuous modelling of solute and sediment transport at the catchment scale for a period of 50 years is presented. The simulation is based on the application of the OPUS model system, which is designed fro long-term simulations of agricultural processes. As OPUS is a hillslope model, the catchment is discretized into numerous slopes. Modifications and enhancements of the OPUS model were made in order to simulate interflow induced by macropores. The simulation results are compared with measurements at different spatial and temporal scales of a meso-scale catchment used for drinking water supply. Five small subcatchments of 22 to 29 ha are used to validate the model at the local scale. The modified and validated model is then applied to the Wahnbach catchment with an area of about 54 km~2. Simulations at the local and the catchment scales are presented and compared with measurements. To model the long-term behaviour of solute and sediment transport with a deterministic model, a complete set of climate and land-use data is necessary. In this case study a method was developed to overcome the lack of data by using a weather generator. The long-term catchment simulations are validated by determining the mass of sediments trapped in the drinking-water reservoir. The results confirm that the model concept is applicable to a large range of scales from single events to decades and from single slopes to meso-scale catchments. By using these methods it is conceivable to make forecast simulations of the future solute and sediment discharge using land-use scenarios.