Erosion rates estimates on a post-mining site

Mining waste serves as a significant example illustrating the transport of contaminants in association with rainfall, runoff, and erosion. Due to past or ongoing metal extraction activities, mining waste deposits are widespread across numerous countries. Rainfall events affecting these areas can lead to environmental concerns due to both liquid and particulate transfers. Acid mine drainage has been extensively researched in this context, illustrating the transfers linked to the liquid phase. Furthermore, rock crushing and high metal concentrations in the waste create materials with minimal cohesion and little vegetation cover, making them highly susceptible to surface erosion. As a result, mine wastes may also be particularly prone to contaminant transport in the particulate phase, although such transfers have received comparatively less attention than liquid transfers. Assessments of surface erosion caused by rainfall and runoff are still lacking in literature, which limits our comprehension and ability to model these processes in these unique environments.

We propose estimating erosion rates on a 3.8-hectare post-mining site located in central France. Given the high erosion rates, we opted to combine two distinct methodologies based on elevation differences: i) erosion pins for simple and reliable but localized estimates of erosion rates, and ii) differences in Digital Elevation Models (DEMs). In this study, the DEM was obtained using a novel handheld laser scanner. Both methods yielded results within the same range, indicating substantial erosion rates and thereby highlighting the significance of particulate transport. Depending on the local circumstances (e.g., tailings characteristics, tailing-to-stream connectivity), future studies should consider both liquid and particulate transport from post-mining sites to develop relevant mitigation strategies.