Water erosion and characteristics of sediment load in the Kopaninský stream basin

In May 2005, a major part of the Czech Republic was hit by an extreme rainstorm resulting in both soil erosion and flood events. We surveyed the erosion rills and soil material deposits produced by this rainstorm in the most damaged field of the experimental catchment Kopaninsky stream in the Bohemo-Moravian Highland. We measured the volume of the deposited sediment, its texture, bulk density, and other properties. The sediment consisted of two layers with a fuzzy boundary between them. The lower layer contained more fine particles, while the upper layer was mainly formed by a coarser material. The sediment generally contained lower amounts of Cox and available nutrients than the original soil from which it was eroded. The results of the measurements were put into a broader context by using an event-based erosion prediction model ERCN, based on the curve-number method and on the Universal Soil Loss Equation. It was demonstrated that a 75 m wide riparian grassland strip in the study area was able to detain about 70% of the soil material eroded from the uphill ploughed land during the extreme rainfall-runoff event of 23rd May 2005. It was confirmed that grassland and other vegetation strips along water courses are highly efficient in reducing the surface water pollution during extreme erosion events.