Restoring earth surface processes throughudlandform design. A 13-year monitoringudof a geomorphic reclamation model forudquarries on slopes

摘要

The application of geomorphic principles to land reclamation after surface mining has been reported in the literatureudsince the mid-1990s, mostly from Australia, Canada and the USA. This paper discusses the reclamation problems of contourudmining and quarries on slopes, where steep gradients are prone to both mass movement and water erosion. To address theseudproblems simultaneously, a geomorphic model for reclaiming surface mined slopes is described. Called the ‘highwall–trench–udconcave slope’ model, it was fi rst applied in the 1995 reclamation of a quarry on a slope (La Revilla) in Central Spain.udThe geomorphic model does not reproduce the original topography, but has two very different sectors and objectives: (i) theudhighwall–trench sector allows the former quarry face to evolve naturally by erosion, accommodating fallen debris by means of audtrench constructed at the toe of the highwall; (ii) the concave-slope base sector, mimicking the landforms of the surroundingudundisturbed landscape, promotes soil formation and the establishment of self-sustaining, functional ecosystems in the areaudprotected from sedimentation by the trench. The model improves upon simple topographic reconstruction, because it rebuildsudthe surfi cial geology architecture and facilitates re-establishment of equilibrium slopes through the management and control ofudgeomorphic processes.udThirteen years of monitoring of the geomorphic and edaphic evolution of La Revilla reclaimed quarry confi rms that the area isudfunctioning as intended: the highwall is backwasting and material is accumulating at the trench, permitting the recovery of soilsudand vegetation on the concave slope. However, the trench is fi lling faster than planned, which may lead to run-off and sedimentationudon the concave slope once the trench is full. The lesson learned for other scenarios is that the model works well in a twodimensionaludscheme, but requires a three-dimensional drainage management, breaking the reclaimed area into several watershedsudwith stream channels.