The design of post‐mining landscapes using geomorphic principles

Abstract

Nature can provide analogues for post-mining landscapes in terms of landscape stability and also in terms of the rehabilitated structure 'blending in' with the surrounding undisturbed landscape. In soil-mantled landscapes, hillslopes typically have a characteristic profile that has a convex upper hillslope profile with a concave profile lower down the slope. In this paper hillslope characteristic form is derived using the area-slope relationship from pre-mining topography at two sites in Western Australia. Using this relationship, concave hillslope profiles are constructed and compared to linear hillslopes in terms of sediment loss using the SIBERIA erosion model. It is found that concave hillslopes can reduce sediment loss by up to five times that of linear slopes. Concave slopes can therefore provide an alternative method for the construction of post-mining landscapes. An understanding of landscape geomorphological properties and the use of erosion models can greatly assist in the design of post-mining landscapes.

Slope shape effect on runoff and soil erosion under natural rainfall conditions

“…Meyer & Kramer (1969) hypothesized that concave profile would erode less and produce less sediment than common uniform, convex, or complex slopes. Hancock et al (2003) demonstrated that concave hillslopes can reduce sediment loss by up to five times that of linear slopes. These findings are partly supported by the results of our study.…”

“…Similarly, Römkens et al (2001) reported that the uniform slope yielded a significantly larger amount of total soil loss than the concave slope. Hancock et al (2003) also stated that concave slopes can reduce sediment loss by at least half the amount of the linear slope.…”

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

“…However, 'very few linear slopes with benches are observed in nature' (Hancock et al, 2003(Hancock et al, , p. 1097. Reclamation land forms built using conventional methods 'depart considerably from the stable natural landforms surrounding them, both in performance and appearance' (Bugosh, 2006a, p. 156).…”

“…In the long term, many of the geometric slopes are prone to severe erosion, and once this failure has occurred, they channel water in concentrated flow paths, leading to severe gullying (Hancock et al, 2003;Sanz et al, 2008). Sawatsky and Tuttle (1996) suggested that gully erosion can be used as an indicator of the performance and sustainability of mining reclamation.…”

“…In this framework, where geometric designs dominate, many authors have argued in favour of geomorphic approaches: 'nature can provide analogues for post-mining landscapes in terms of landscape stability and also in terms of the rehabili tated structure blending in with the surrounding undisturbed landscape' (Hancock et al, 2003(Hancock et al, , p. 1097; designing slopes and landforms based on natural ones can achieve the dual goal of being more visually attractive and being more func tional and cost effective (Schor and Gray, 2007); landform design in mining reclamation should make the final landform hydrologically, geomorphologically and visually compatible with the surrounding area and remain stable for the long term (Hancock et al, 2003); the design of mature landforms 'serves to improve the aesthetic appearance, provide a wider range of habitats for wildlife and avoid the large surface-flow rates typical of long, straight slopes' (Sawatsky et al, 2000, p. 28). Sustainable reclaimed mined landscapes over the long term can be achieved through attention to geomorphic parameters (Table I) (Riley, 1995;Keys et al, 1995).…”