Hancock, G & Martín Duque, JF 2022, 'Assessing the stability of a geomorphically reconstructed post-mining landscape: a case study of the Santa Engracia mine, Spain', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 127-142, https://doi.org/10.36487/ACG_repo/2215_06 (https://papers.acg.uwa.edu.au/p/2215_06_Hancock/) Abstract: New technology allows for the reconstruction of post-mining landforms using geomorphic design principles. It is important that such designs be evaluated and, if needed, be reshaped so that soil loss is minimised and they geomorphologically and ecologically integrate with the surrounding landscape. One method to assess geomorphic landform designs is to use a computer-based landscape evolution model. Landscape evolution models allow different designs to be input and will highlight where erosion will occur and the type of erosion (i.e. sheetwash, rilling, gullying) as well as erosion rate. At the Santa Engracia abandoned mine (East-Central Spain), post-mining landscapes were designed and constructed using geomorphic principles (GeoFluv method and Natural Regrade software). In this design process, the SIBERIA landscape evolution model has been used to assess the erosional behaviour of these landscapes. Results demonstrate that some gullying is inevitable. Using suitable topsoil, vegetation and an organic blanket will dramatically reduce erosion, and if vegetation can be established, the modelling demonstrates that the landscapes will have minimal erosion. The erosion forecast is 5.3–15.2 t ha-1 yr-1, an order of magnitude less than the initial erosion rate (~350 t ha-1 yr-1) using conventional (terraced) mine restoration. Further, the erosion rates and localised gullying approximate the unmined (natural) Alto Tajo environment. Importantly, with the ability to spatially forecast gully location, erosion reduction measures can be undertaken. Consequently, the method described here provides a robust assessment procedure that can be used at other sites and highlights the potential strengths and weakness of a design process, therefore supporting lower cost with a higher chance of restoration success. The combination of geomorphic landform design and assessment using a landscape evolution at this project presents a new standard for mine rehabilitation in Europe. Keywords: geomorphic landform design, geomorphic restoration, GeoFluv, SIBERIA, gully