Designing, building and assessing a geomorphically reconstructed postmining landscape: A case study of the Santa Engracia mine, Spain

Abstract

New technology allows the reconstruction of postmining landforms using geomorphic design principles. It is important that such designs be evaluated and if needed, redesigned or reshaped so that soil loss is minimised and to ensure the landscape is geomorphically and ecologically integrated with the surrounding landscape. One tool to assess geomorphic landforms is to use a computer-based landscape evolution model (LEM). LEMs allow different designs to be input and will highlight where erosion will occur and type of erosion (i.e. sheetwash, riling, gullying) as well as erosion rate. At the Santa Engracia abandoned mine (East-Central Spain), postmining landscapes were designed using geomorphic principles (GeoFluv method and Natural Regrade software) and later constructed. The SIBERIA LEM was used to assess the erosional behaviour of these landscapes. Using suitable topsoil, vegetation and an organic blanket reduces erosion, and if vegetation can be established, the modelling demonstrates minimal gully erosion. The erosion forecast (5.3 to 6.3 t ha⁻¹ year⁻¹) is significantly lower than the initial surface (~350 t ha⁻¹ year⁻¹) using conventional (terraced) mine restoration. The predicted erosion rates and gullying are less than for the unmined (natural) Alto Tajo environment. Importantly, with the ability to spatially forecast gully location, erosion reduction measures can be undertaken. The method described here provides a robust assessment procedure and highlights the potential strengths and weakness of a design therefore supporting lower cost construction and repair with a higher chance of restoration success. The combination of geomorphic landform design and assessment using a LEM for this project (LIFE RIBERMINE) presents a new standard for mine rehabilitation in Europe.