Authors: Dressler, S; Waygood, CG

Open access courtesy of:

DOI https://doi.org/10.36487/ACG_repo/2215_03

Cite As:
Dressler, S & Waygood, CG 2022, 'Understanding the limits of alluvial analogues: lessons from geomorphological design of mine rehabilitation in New South Wales, Australia', in AB Fourie, M Tibbett & G Boggs (eds), Mine Closure 2022: 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 93-100, https://doi.org/10.36487/ACG_repo/2215_03

Download citation as:   ris   bibtex   endnote   text   Zotero


Abstract:
A geomorphological approach to landform design aims to pattern constructed landforms in erodible materials on natural landforms. These natural landforms represent a mature geomorphic condition subject to a slow rate of evolution. Most commonly, stable alluvial landforms in the local environment are utilised as analogues. Unfortunately, few landforms constructed in mining overburden in New South Wales, Australia, have an overall geometry that allows for alluvial analogues to be directly applied; that is, the post mining landforms are frequently too steep. To address this challenge, approaches used internationally range from very sinuous drainage lines to flatten gradients, through to wide grassed drains to reduce velocities, and the use of rock armouring in drainage lines. Each of these approaches has some challenges. Overly sinuous designs move away from a dendritic drainage layout and are overly complex to construct. They are also vulnerable to piping failures. Wide grassed drains can develop preferential flow paths and can also impact unfavourably on the overall drainage density. Rock armouring is not generally favoured by geomorphologists since armouring represents a rigid conveyance system without self-healing capabilities. The strategy adopted by the authors is to design drains using a vegetated rock matrix approach. Effectively, a dendritic drainage layout is used at a desired drainage density, and the drain widths and/or longitudinal slopes adjusted to ensure that the drains have velocities below 3 m/s even for the design event (typically the 1:100-year event). These drains are wider and shallower than a typically optimised trapezoidal drain and, for frequent flood events, the rock is primarily required for the roughness it adds to the surface. With relatively low design velocities, sediment accumulates within the rock voids and revegetation of this material significantly increases the rock stability. The embedded rock and revegetated matrix are then able to withstand extreme flood events well above the original design event. This larger flood event is more in line with that expected for the required design life of these surfaces. It is noted that, because the rock size required is proportional to the velocities, increasing the drain perimeter by designing a flatter, wider drain does not necessarily increase the cost of the lining because smaller rock sizes result in reduced thicknesses of the rock lining.

Keywords: landform design, geomorphic approach, alluvial analogues, rock armouring

References:
Bugosh, N 2003, Stream Channel Design Reclamation – The Fluvial Geomorphic Approach to Hydrological Reclamation, workshop for Billings Land Reclamation Symposium and the Annual Meeting of the American Society of Mining and Reclamation.
Hancock, GH, Martín Duque, JF & Willgoose, G 2020, ‘Mining rehabilitation - using geomorphology to engineer ecologically sustainable landscapes for highly disturbed lands’, Ecological Engineering, vol. 155, p. 105836.
10.1016/j.ecoleng.2020.105836
Howard, E 2018, ‘Integrating erosion prediction into landform designs for rehabilitation and closure planning’, Proceedings of the 2nd International Congress on Planning for Closure of Mining Operations, Gecamin, Santiago.
Howard, EJ & Roddy, BP 2012, ‘Evaluation of the water erosion prediction project model – validation data from sites in Western Australia’, in AB Fourie & M Tibbett (eds), Mine Closure 2012: Proceedings of the Seventh International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 81–92,
Kelder, I, Waygood, CG & Willis, T 2016, ‘Integrating the use of natural analogues and erosion modelling in landform design for closure’, in AB Fourie & M Tibbett (eds), Mine Closure 2016: Proceedings of the 11th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 99–106,
Loch, R 2010, Sustainable Landscape Design for Coal Mine Rehabilitation, ACARP project C18024.
Martin Duque, JF, Tejedor, M, Martin-Moreno, C, Nicolau, JM & Zapico, I 2019, ‘Geomorphic rehabilitation in Europe: recognition as best available technology and its role in LIFE projects’, in AB Fourie & M Tibbett (eds), Mine Closure 2019: Proceedings of the 13th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 133–146,
Martin Duque, M, Zapico, I, Bugosh, N, Tejedor, M, Delgado, F, Martín-Moreno, C & Nicolau, JM 2021, ‘A Somolinos quarry land stewardship history: From ancient and recent land degradation to sensitive geomorphic-ecological restoration and its monitoring’, Ecological Engineering, vol. 170, p. 106359.
Rosgen, DL 1996, Applied River Morphology, Wildland Hydrology, Pagosa Springs.
Sawatsky, L & Beckstead, G 1996, ‘Geomorphic approach for design of sustainable drainage systems for mineland reclamation’, International Journal of Mining, Reclamation and the Environment, vol. 10, no. 3, pp. 127–129.
Sawatsky, L & Beersing, A 2014, ‘Configuring mine disturbed landforms for long-term sustainability’, Proceedings of Mine Closure Solutions, Infomine, Minas Gerais.
Slingerland, N & Dressler, S 2022, ‘Evaluating construction tolerances and tailings dam shape for closure using the CAESAR-Lisflood landscape evolution model’, in M Tibbett, AB Fourie & G Boggs (eds.), Mine Closure 2022: Proceedings of the 15th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1112–1125.
Witheridge, G 2009, Creeks and Catchments Publication. Report on the selection of Rock-sizing equations for use in the design of rock-lined channels, chutes and spillways,
20Rock%20Sizing%20Eqns-v1.pdf




© Copyright 2022, Australian Centre for Geomechanics (ACG), The University of Western Australia. All rights reserved.
Please direct any queries or error reports to repository-acg@uwa.edu.au