Using Rainfall Simulators to Design and Assess the Post-Mining Erosional Stability

The mining industry is crucial for global economic growth but faces environmental challenges, especially in designing stable rehabilitated landforms. To tackle these issues, rainfall simulators have been recognized for their value in providing data for erosion modeling and analysis, aiding the development of effective land cover systems for long-term stability. This chapter provides an overview of the theory, specifications, and design principles of rainfall simulators. It explores the detailed design and construction of a well-known model, along with its calibration process ensuring accurate rainfall production and distribution. The chapter also discusses raindrop size distribution and associated kinetic energy calculations. Calibration results demonstrate satisfactory outcomes with Christiansen’s uniformity coefficient exceeding 85% and a median raindrop size of 2.15 mm. The device successfully generates desired kinetic energy for simulated rainstorms, crucial for studying soil erosion. Examples highlight the application of rainfall simulators in evaluating erosion stability in Queensland mines. Efforts to construct a soil erosion database for 34 open-cut mines in Queensland using a similar portable rainfall simulator are highlighted. This database contributes to developing user-friendly MINErosion models, providing estimates of soil erosion/deposition at different scales to support the Australian mining sector

The relationship between leaf water potential and stem diameter in sorghum

Leaf water potential (psi (l)) represents a good indicator of the water status of plants, and continuous monitoring of it can be useful in research and field applications such as scheduling irrigation. Changes in stem diameter (Sd) were used for monitoring psi (l) of pot-grown sorghum [Sorghum bicolor (L.) Moench] plants in a glasshouse. This method requires occasional calibration of S-d values against psi (l). Predicted values of psi (l), based on a single calibration show a good correlation with measured psi (l), values over a period of 13 d before and after the calibration. The correlation can further be improved with shorter time intervals

Effects of long-term combined application of organic and mineral fertilizers on microbial biomass, soil enzyme activities and soil fertility

Soil health is important for the sustainable development of terrestrial ecosystem. In this paper, we studied the relationship between soil quality and soil microbial properties such as soil microbial biomass and soil enzyme activities in order to illustrate the function of soil microbial properties as bio-indicators of soil health. In this study, microbial biomass C and N contents (Cmic & Nmic). soil enzyme activities, and soil fertility with different fertilizer regimes were carried out based on a 15-year long-term fertilizer experiment in Drab Fluvo-aquic soil in Changping County, Beijing, China. At this site, 7 different treatments were established in 1991. They were in a wheat-maize rotation receiving either no fertilizer (CK). mineral fertilizers (NPK). mineral fertilizers with wheat straw incorporated (NPKW+), mineral fertilizers with incremental wheat straw incorporated (NPKW+), mineral fertilizers plus swine manure (NPKM), mineral fertilizers plus incremental swine manure (NPKM+) or mineral fertilizers with maize straw incorporated (NPKS). In different fertilization treatments Cmic changed from 96.49 to 500.12 mg kg, and Nmic changed from 35.89 to 101.82 mg kg. Compared with CK, the other treatments increased Cmic & Nmic, Cmic/Corg (organic C) ratios, Cmic/Nmic, urease activity, soil organic matter (SOM). soil total nitrogen (STN), and soil total phosphorus (STP). All these properties in treatment with fertilizers input NPKM+ were the highest. Meantime, long-term combined application of mineral fertilizers with organic manure or crop straw could significantly decrease the soil pH in Fluvo-aquic soil (the pH around 8.00 in this experimental soil). Some of soil microbial properties (Cmic/Nmic. urease activity) were positively correlated with soil nutrients. Cmic/Nmic was significantly correlated with SOM and STN contents. The correlation between catalase activity and soil nutrients was not significant. In addition, except of catalase activity, the soil pH in this experiment was negatively correlated with soil microbial properties. In conclusion, soil microbial properties reflect changes of soil quality and thus can be used as bio-indicators of soil health

MINErosion 4: Using measurements from a tilting flume-rainfall simulator facility to predict erosion rates from post-mining catchments/landscapes in Central Queensland, Australia

The use of draglines to remove overburden in Queensland opencut mines, results in landscapes that consist of long parallel tertiary overburden spoil-piles that are generally highly saline, dispersive, and highly erodible. The height of these spoil-piles may exceed 50–60 m above the original landscapes and the slopes are at the angle of repose of around 75% or 37°. Legislation and public opinion require that these highly disturbed open-cut post-mining landscapes should be satisfactorily rehabilitated into an approved post-mining land use with acceptable erosion rates. Therefore, these slopes must be reduced before the landscape can be rehabilitated. The most expensive component of the rehabilitation process is the re-shaping and preparation of the overburden to create a suitable landscape for vegetation growth. As soils and overburden varies greatly in their erodibilities, the extent and cost of earthworks can be minimized, and rehabilitation failures avoided, if soil erosion from designed landscapes can be predicted using laboratory-based parameters prior to construction of these landscapes. This paper describes the development of a model for that purpose.A catchment or landscape erosion model MINErosion 4 was developed by upscaling the existing hillslope model MINErosion 3 (So, et al., 2018) and integrate it with both ESRI ArcGIS 10.3 or QGIS 3.16 (freeware), to predict event based and mean annual erosion rate from a postmining catchment or landscape. MINErosion 3 is a model that can be used to predict event and annual erosion rates from field scale hillslopes using laboratory measured erodibility parameters or routinely measured soil physical and chemical properties, and to derive suitable landscape design parameters (slope gradient, slope length and vegetation cover) that will result in acceptable erosion rates. But it cannot be used to predict the sediment delivery from catchments or landscapes. MINErosion 4 was validated against data collected on three instrumented catchments (up to 0.91 ha in size) on the Curragh mine site in Central Queensland. The agreement between predicted (Y) and measured (X) values were very good with the regression equation of Y = 0.92X and an R2 value of 0.81 for individual storm events, and Y = 1.47X and an R2 value of 0.73 for the average annual soil loss. This is probably the first time that a catchment scale erosion is successfully predicted from laboratory measured erodibility parameters

The selected storm events for spoil’s covered plots used to validate MINErosion 3.1.

<p>[<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194230#pone.0194230.ref025" target="_blank">25</a>]. Treatments were SpBa: Bare plots covered with spoil; SpTr: Plots covered with spoil and with trees as a vegetation cover; SpPa: Plots covered with spoil and with pastures as a vegetation cover, S %: Slope %.</p

Comparison of predicted and measured annual soil loss using MINErosion 3 from three field trials in Central Queensland.

<p>Data for Curragh is an average of 6 years and Oakey Creek is an average of 4 years [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194230#pone.0194230.ref003" target="_blank">3</a>] and the data for Kidston is for one year only (bare soil and vegetated plots of 3 and 9 years).</p

On the left is a typical long parallel overburden spoil piles produced by dragline operation in a Central Queensland open cut coal mine[2] and a close-up view of the spoil-piles that can reach 50 to 60 m high [1].

<p>Note that the working pit (left photo) is flanked by the high wall on one side and fresh spoil piles on the other side.</p

Relative soil loss as affected by vegetation type (tussocky Rhodes vs stoloniferous Sabi grasses) [13].

<p>Relative soil loss as affected by vegetation type (tussocky Rhodes vs stoloniferous Sabi grasses) [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0194230#pone.0194230.ref013" target="_blank">13</a>].</p

Predicted annual erosion rates for a rehabilitated and vegetated postmining hillslope covered with Curragh soil.

<p>Vegetation options are tussocky or stoloniferous grasses. Shaded cells have less than 12.5 t/ha/y.</p