From the source to the reservoir and beyond—tracking sediment particles with modeling tools under climate change predictions (Carpathian Mts.)

Abstract

Abstract Purpose The study tracks spatial and temporal distribution of sediment particles from their source to the deposition area in a dammed reservoir. This is particularly important due to the predicted future climate changes, which will increase the severity of problems with sediment transport, especially in catchments prone to erosion. Methods Analyses were performed with a monthly step for two mineral and one mineral/organic sediment fractions delivered from the Carpathian Mts. catchment (Raba River) to the drinking water reservoir (Dobczyce) by combining SWAT (Soil and Water Assessment Tool), and AdH/PTM (Adaptive Hydraulics Model/Particle Tracking Model) modules on the digital platform—Macromodel DNS (Discharge Nutrient Sea). To take into account future changes in this catchment, a variant scenario analysis including RCP (representative concentration pathways) 4.5 and 8.5, and land use change forecasts, was performed. Results The differences between the two analyzed hydrological units (catchment and reservoir) have been highlighted and showed a large variability of the sediment load between months. The predicted climate changes will cause a significant increase of mineral fraction loads (silt and clay) during months with high flows. Due to the location and natural arrangement of the reservoir, silt particles will mainly affect faster loss of the first two reservoir zones capacities. Conclusions The increased mobility of finer particles (clay) in the reservoir may be more problematic in the future, mainly due to their binding pollutant properties, and the possible negative impact on drinking water abstraction from the last reservoir zone. Moreover, the study shows that the monthly approach to forecasting the impact of climate change on sediment loads in the reservoir is recommended, instead of a seasonal one.