Mine rehabilitation landform design: What is GeoFluv™ and how is it different to the conventional approach?

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Traditionally, mine rehabilitation success has been based on creating simplistic, safe and stable landforms which grow some form of vegetation such as pasture, native grasses, trees or even forestry trials. Now there is a relatively new approach that creates complex landforms that mimic nature, and it is fast becoming a requirement in modern mining development consents (particularly in New South Wales). The well-regarded approach is called natural land from design which is predominately GeoFluv™ (natural landform design), and it is taking mine restoration to new heights in a way that stakeholders and communities can be proud of, writes Atlantech Senior Environmental Consultant Dean Woods.

What is GeoFluv™?

GeoFluv™ is a patented approach to land rehabilitation which recognises the importance of “natural” landform and erosion patterns in the successful rehabilitation of highly disturbed land.

The natural landform design (GeoFluv™) is a lot closer at resembling what we see in nature, when compared to traditional 10 degree-sloped landforms with flat tops. I think the new approach to landform design is far more aesthetically pleasing which should leave a legacy favourable to the community, governments and future ecosystems.

See image of traditional vs GeoFluv™ approach below (courtesy of the GeoFluv™ website):

Traditional vs GeoFluv™ approach, courtesy of the GeoFluv™ website

I know I am not alone when I say that when driving past modern designed landforms it is much harder to distinguish between what is mine rehabilitation and what is naturally occurring, and that is the ultimate outcome. Such areas are a legacy for future generations and the standard to strive for.

A more detailed insight: GeoFluv™ vs conventional landform design

Landform design is a key challenge faced by the mining industry and design approaches have evolved over time.

Conventional mine landforms have typically consisted of linear batters separated by flat or back sloping benches with contour banks and engineered rock structures which are designed to capture runoff and reduce erosion potential. Water from the top of the dump is typically conveyed to the toe of the dump using rock drains (Howard et al, 2011).

In response to the suboptimal performance of these landforms the industry has looked at other approaches that consider geomorphic design principles to improve landform performance. In recent years, software such as GeoFluv™ has been developed to undertake geomorphic design.

GeoFluv™ is a geomorphic method for land rehabilitation design that is able to reproduce the complexity of natural landforms and drainage networks within catchments. Specifically, it designs mature and stable stages of catchments — those which would naturally form by erosional processes for the materials, climate, and physiographic conditions at the site. Its implementation is sought after to achieve long-term erosional stability, reduced maintenance and increased biodiversity on rehabilitation landforms as compared to traditional approaches to mine rehabilitation landforms (Hancock et al., 2019).

Figure 1 - Scheme for a geomorphic landform in comparison to current conventional form (Lacy, HWB 2019).

How can geomorphic design be assessed by LEM?

The GeoFluv™ design can be assessed using Landform Evolution Models (LEM) to assess erosional stability. The LEM uses a digital elevation model (DEM), hydrology, sediment transport data and climate to achieve this.

Figure 2- Geomorphic design method using the GeoFluv™ approach (NSW Resources Regulator, 2021)

Evaluation

The problems associated with conventional landform design is well documented and acknowledged throughout the industry. The benefits of a transition to the use of geomorphic design and software applications such as GeoFluv™ are now also well documented and represent leading practice.

A paper published in 2019 (Bugosh and Epp, 2019) was able to conclude that rehabilitated subwatersheds designed using the GeoFluv™ method and constructed to the design had measured sediment yields that were equal to or lower than the adjacent un-disturbed native subwatershed. The San Juan Coal Company, at its La Plata Mine, began implementing a research study to quantify the sediment production rate from rehabilitated landforms using the GeoFluv™ design method and surrounding undisturbed native lands. The paper concluded that study results quantitatively support qualitative observations that the new fluvial geomorphic-based alternative to traditional rehabilitation practices can provide sediment yield that meets rehabilitated erosion control and water quality goals.

Examples

Australia has many examples of GeoFluv™ landform design leading the way, including Glencore’s Mangoola Coal mine in New South Wales which was the first site nationally to adopt the natural rehabilitation technique.

There are interesting points to note for the Mangoola example, including that most of the seed for the rehabilitation has come from within 10 kilometres from the site, the rehabilitation includes planned wetland areas, nest boxes have been made from a local Men’s Shed, and areas are seeded by hand to ensure appropriateness to the landscape. Technology is leveraged to monitor pests, and the progress of flora and fauna. The aim is to establish a long term sustainable eco system.

To learn more about Mangoola Coal’s project and other landform design that is leading the way visit:

My view

The future of mine landform design and rehabilitation is heading in the right direction. Several trials have shown that when rehabilitation is done well it can provide valuable post-mining land uses such as grazing areas, forestry, solar farms, hydrological energy, and ecological significant habitats. I believe the future is likely to see rehabilitation areas be accepted by the State Government as applicable biodiversity offset areas, mine sites be certified/signed off sooner after the end of mine life due to proactive techniques while the site is operational as well as beneficial re-use of mine voids (Muswellbrook Coal hydro set-up is an example).

Are you using GeoFluv™ to design your landforms?

For assistance integrating the GeoFluv™ design approach into your rehabilitation management and construction teams, please contact Atlantech on 0448 077 270.

Sources:

Bugosh, N & Epp, E 2019, ‘Evaluating sediment production from native and fluvial geomorphic reclamation watersheds at La Plata Mine’, Catena, vol. 174, pp. 383–398.
https://www.landforma.com/wp-content/uploads/2019/02/9-Bugosh-and-Epp_Evaluating-sediment-production-2019_CATENA_Compressed-1.pdf
Hancock, G.R.,Martín Duque, J.F.and Willgoose, G.R., 2018. Geomorphic design and modelling at catchment scale for best mine rehabilitation–The Drayton mine example (New South Wales, Australia), Environmental Modelling and Software 114 (2019) 140–151. https://www.sciencedirect.com/science/article/abs/pii/S1364815218301245?via%3Dihub
Howard, EJ, Loch, RJ, Vacher, CA (2011). ‘Evolution of landform design concepts’, Trans. Inst. Mining and Metallurgy, 120:112–117
Lacy, HWB 2019, 'Mine landforms in Western Australia from dump to landform design: review, reflect and a future direction', in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 371-384, https://papers.acg.uwa.edu.au/p/1915_30_Lacy/
NSW Resources Regulator, 2021, ‘Landform Evolition Modelling and geomorphic Design Principles for Mine Rehabilitation Landforms: Questions and answers’, NSW Government, https://www.resourcesregulator.nsw.gov.au/sites/default/files/documents/q-and-a-landform-evolution-modelling-and-geomorphic-design-principles-for-mine-rehabilitation-landforms_f_9feb2021.pdf