The effects of surface heterogeneity on erosion and sedimentation and their implications for of soil properties at postmining sites

Erosion is often mentioned as a serious problem namely in vegetation free areas such as post mining soils. Much less attention has been paid to the role of erosion and deposition on habitat formation. Study describes the effect of erosion and deposition on soil chemical and physical properties in sites with various topography using an array of artificial postmining catchments located near Sokolov (Czech Republic). All the study sites are formed by the deposition of postmining overburden consisting of clays impregnated with carbonates. Falcon was established in 2019 and allows a detailed assessment of the first stages of ecosystem development. It consists of four parallel catchments (0.25 ha each); two are rehabilitated, and two are not. The reclaimed areas are leveled and planted with alders, whereas the unreclaimed sites created longitudinal terrain waves to mimic the situation after heaping. Detailed surface change studies by means of erosion pins and 3D terrain models created with the help of drones revealed that the surface elevation rises in the flat catchments and decreased in the wave-like catchments. In contrast, sediment loss through surface runoff shows no difference between the flat and wave-like areas. Considerable heterogeneity in the erosion process is observed in wave-like areas; the upper part of the terrain waves is heavily eroded, while eroded material accumulates in the depression. The depressions contain more silt and clay material and have higher water retention rates and lower infiltration rates, whereas the opposite is true for elevated wave tops. Study show that erosion and deposition play key role in microhabitat formation, which can be crucial in future ecosystem development.