Evaluation of the water erosion prediction project model – validation data from sites in Western Australia

Howard, Evan; Roddy, Brendan

doi:10.36487/acg_rep/1208_09_howard

Cited by 3 publications

(3 citation statements)

References 8 publications

(10 reference statements)

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“…WEPP is capable of predicting erosion in a mine setting, provided the model is well calibrated. Howard and Roddy (2012) give an evaluation of the WEPP model and provide validation data for 11 mine site batters ( Figure 7).…”

Section: Assumption #1: Erosion Rate Increases With Slope Lengthmentioning

confidence: 99%

Hydrological function of berms within a waste landform design

Roddy¹,

Howard²

2016

Proceedings of the International Conference on Mine Closure

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Berms remain a persistent feature in waste dump landform designs as they are perceived to provide the benefits of reduced slope length, protection against future batter erosion by partitioning the slope with level or backsloping berms, and reduced flow velocity. Underpinning this rationale is the belief that the berms will be a permanent and unchanging feature that controls erosion over the long term. These assumptions are not true. Berms begin to evolve immediately after their construction by trapping sediment and having a beneficial effect over the short to medium term. Longer term, berms fill with sediment and overtop. The time it takes to overtop depends on the material, the size of the berm, and the climate. Once a berm is breached, previously hydraulically disconnected batter sections become a connected flow network that delivers large volumes of runoff from upper slopes to lower slopes that were never designed to withstand them. This process can be caused, or contributed to, by poor quality construction techniques.

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Section: Assumption #1: Erosion Rate Increases With Slope Lengthmentioning

confidence: 99%

Hydrological function of berms within a waste landform design

Roddy¹,

Howard²

2016

Proceedings of the International Conference on Mine Closure

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“…Consequently, the 'conventional approach' to land restoration using constant gradients, terraces and contour banks has evolved in many instances. Non-linear designs could include concave slopes based on material's erodibility analyses (Howard & Roddy 2012) through to more complex natural landforms with examples in the United States (Bugosh 2003), Canada (Sawatsky & Beckstead 1996), Spain (Martin Duque et al 2019Duque et al , 2021 and Australia (Kelder et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Understanding the limits of alluvial analogues: lessons from geomorphological design of mine rehabilitation in New South Wales, Australia

Dressler¹,

Waygood²

2022

Mine Closure 2022: 15th Conference on Mine Closure

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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.

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“…The BIF-sheeted batter design was previously modelled using both the Water Erosion Prediction Project (WEPP) erosion model and the SIBERIA landform evolution model. These models were calibrated using laboratory-based methods shown to produce accurate erosion predictions (Howard & Roddy 2012;Howard 2018).…”

Section: Introductionmentioning

confidence: 99%

Selection of a representative dolerite waste sample for use in erosion assessments using remote sensing techniques

Howard¹,

Bettison²

2019

Proceedings of the International Conference on Mine Closure

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Rehabilitation of the W39 Overburden Storage Area (OSA) is currently being planned by BHP. The W39 OSA is located at the Mt Whaleback iron ore mine site in the Pilbara region of Western Australia. The proposed OSA batter design utilises Banded Iron Formation (BIF) waste to sheet the majority of the batter slopes except for a 20 m high section that is to be sheeted with durable, competent dolerite waste rock currently stockpiled on an adjacent OSA. The stockpile is 25 ha in size and contains dolerite with a range of particle sizes. Key to the erosion stability of the rehabilitation design is the erosion resistance of the dolerite, which in turn is largely a function of the dolerite's particle size distribution. It is therefore critical that the materials selected for erosion testing from the 25 ha stockpile are representative of the material as a whole. In order to select a representative waste sample, a combination of remote sensing techniques was employed. Ortho-rectified imagery was sourced from a drone survey. The drone image was then divided into smaller 1-ha cells, and digital photographic techniques were used to determine the particle size distribution and mean rock size for each of the cells. The information for each cell was then combined to produce a map of changing mean rock size over the entire stockpile. From that mapping, representative locations were selected for testing, and areas of finer particle size were identified for exclusion from future rehabilitation works. This paper outlines the importance of selecting representative samples, details the methods used to select a representative dolerite waste sample, and provides results of the study.

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Evaluation of the water erosion prediction project model – validation data from sites in Western Australia

Cited by 3 publications

References 8 publications

Hydrological function of berms within a waste landform design

Hydrological function of berms within a waste landform design

Understanding the limits of alluvial analogues: lessons from geomorphological design of mine rehabilitation in New South Wales, Australia

Selection of a representative dolerite waste sample for use in erosion assessments using remote sensing techniques

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