Assessing soil redistribution in sinkholes using fly ash fallout: a case study in the Perm Region, Russia

摘要

The assessment of soil matter lateral transport in five different sinkholes is the focus of this study. Fly ash (the particular component of the smoke produced by steam locomotive) was used to assess the erosion amount and rate. The objectives include to calculate the erosion, transport and deposition rates on the side slopes of sinkholes, to assess the amount of soil matter loss from sinkholes to cavities, and to evaluate the relationship between the volume of the lateral soil matter transport and soil properties. The soils of the sinkholes are more exposed to erosion than to deposition, the accumulation of soil matter occurs only on the lower parts of the sinkhole side slopes and only the material of the humus horizon is involved in lateral transport. Over 20% of the soil matter involved in soil redistribution was lost from the sinkholes with ponor to underground cavities over the last 100 years. The mean erosion rate is 8 t ha(- 1) year(- 1) for loamy soils (45% slope inclination) and 13 t ha(- 1) year(- 1) for skeletic sandy loam soils (63% slope inclination). Soil matter movement plays a critical role in the formation of sinkhole soilscapes; it causes the increase of the humus horizon thickness and the decrease of the soil property variability from the top to the bottom of the sinkholes.