Restoring earth surface processes through landform design. A 13‐year monitoring of a geomorphic reclamation model for quarries on slopes

TLDR

Geomorphic principles have been applied to surface‑mining reclamation since the mid‑1990s, yet contour mining and slope quarries remain problematic because steep gradients promote mass movement and water erosion. The study proposes a geomorphic model to simultaneously address these reclamation problems on mined slopes. The highwall–trench–concave slope model, first used in 1995 at La Revilla, divides the area into a highwall–trench sector that allows natural erosion and debris accommodation, and a concave‑slope sector that promotes soil formation and ecosystem establishment while shielding against sedimentation. Thirteen years of monitoring confirm the model’s effectiveness: the highwall backwastes, the trench fills with debris, and soils and vegetation recover on the concave slope, but the trench fills faster than planned, risking runoff and sedimentation unless a three‑dimensional drainage strategy is adopted. © 2010 John Wiley & Sons, Ltd.

Abstract

Abstract The application of geomorphic principles to land reclamation after surface mining has been reported in the literature since the mid‐1990s, mostly from Australia, Canada and the USA. This paper discusses the reclamation problems of contour mining and quarries on slopes, where steep gradients are prone to both mass movement and water erosion. To address these problems simultaneously, a geomorphic model for reclaiming surface mined slopes is described. Called the ‘highwall–trench–concave slope’ model, it was first applied in the 1995 reclamation of a quarry on a slope (La Revilla) in Central Spain. The geomorphic model does not reproduce the original topography, but has two very different sectors and objectives: (i) the highwall–trench sector allows the former quarry face to evolve naturally by erosion, accommodating fallen debris by means of a trench constructed at the toe of the highwall; (ii) the concave‐slope base sector, mimicking the landforms of the surrounding undisturbed landscape, promotes soil formation and the establishment of self‐sustaining, functional ecosystems in the area protected from sedimentation by the trench. The model improves upon simple topographic reconstruction, because it rebuilds the surficial geology architecture and facilitates re‐establishment of equilibrium slopes through the management and control of geomorphic processes. Thirteen years of monitoring of the geomorphic and edaphic evolution of La Revilla reclaimed quarry confirms that the area is functioning as intended: the highwall is backwasting and material is accumulating at the trench, permitting the recovery of soils and vegetation on the concave slope. However, the trench is filling faster than planned, which may lead to run‐off and sedimentation on the concave slope once the trench is full. The lesson learned for other scenarios is that the model works well in a two‐dimensional scheme, but requires a three‐dimensional drainage management, breaking the reclaimed area into several watersheds with stream channels. Copyright © 2010 John Wiley & Sons, Ltd.