Trends in relief design and construction in opencast mining reclamation

Nicolau J.

The aim of this study was to identify the mechanisms of runoff generation and routing and their controlling factors at the hillslope scale, on artificial slopes derived from surface coal mining reclamation in a Mediterranean–continental area. Rainfall and runoff at interrill and microcatchment scales were recorded for a year on two slopes with different substrata: topsoil cover and overburden cover. Runoff coefficient and runoff routing from interrill areas to microcatchment outlets were higher in the overburden substratum than in topsoil, and greater in the most developed rill network. Rainfall volume is the major parameter responsible for runoff response on overburden, suggesting that this substratum is very impermeable—at least during the main rainfall periods of the year (late spring and autumn) when the soil surface is sealed. In such conditions, most rainfall input is converted into runoff, regardless of its intensity. Results from artificial rainfall experiments, conducted 3 and 7 years after seeding, confirm the low infiltration capacity of overburden when sealed. The hydrological response shows great seasonal variability on the overburden slope in accordance with soil surface changes over the year. Rainfall volume and intensities (I30, I60) explain runoff at the interrill scale on the topsoil slope, where rainfall experiments demonstrated a typical Hortonian infiltration curve. However, no correlation was found at the microcatchment level, probably because of the loss of functionality of the only rill as ecological succession proceeded. The runoff generation mechanism on the topsoil slope is more homogeneous throughout the year. Runoff connectivity, defined as the ratio between runoff rates recorded at the rill network scale and those recorded at the interrill area scale in every rainfall event, was also greater on the rilled overburden slope, and in the most developed rill network. The dense rill networks of the overburden slope guarantee very effective runoff drainage, regardless of rainfall magnitude. Rills drain overland flow from interrill-sealed areas, reducing the opportunity of reinfiltration in areas not affected by siltation. Runoff generation and routing on topsoil slopes are controlled by grass cover and soil moisture content, whereas on overburden slopes rill network density and soil moisture content are the main controlling factors. Copyright © 2002 John Wiley & Sons, Ltd.

Siefert J., Mutz M.

Most surface waters of the post-mining landscape in Lusatia, Germany, are characterised by severe acidity (pH

Kapolka N.M., Dollhopf D.J.

The objectives of this study were to evaluate the effect of slope gradient and plant growth on soil loss on steep slopes, evaluate the effect of coversoil thickness on plant growth, and determine if the Revised Universal Soil Loss Equation (RUSLE) version 1.06 computer model could predict soil loss on steep slopes. Four slopes, with different gradients (25%, 33%, 40%, and 50%) were constructed. Each slope was divided into four plots with different coversoil thicknesses (0 cm, 15 cm, 30 cm, and 45 cm). Soil loss increased with slope gradients up to 40% and decreased as slope gradient increased to 50%. During the first two growing seasons, plant biomass was significantly correlated (r=0.65 and 0.70, respectively) to increases in coversoil thickness; however, increases in plant production did not reduce soil loss. Results from this study indicated that RUSLE v. 1.06 was an effective long-term planning tool to use on steep slopes.

Abel A., Michael A., Zartl A., Werner F.

 Acidification is the most common water quality problem in lakes created from previous open cast lignite mines. Aeration of aquifers and dump materials from mining activities causes pyrite oxidation. Pyrite oxidation products are stored in pore water, minerals and at the exchange complexes of the aquifers and dump sediments. Rainfall runoff transports sediments on the dump slope into the lakes. Elutriation of these sediments whithin the lakes releases either acid-producing or acid-neutralizing agents. At a test site south of Leipzig, the annual erosion rates were quantified by water erosion models (RUSLE, EROSION 2D, PEPP) and field measurements. They ranged from 300 up to 900 tons per hectare. Hydrogen ion equivalent release or binding at the sediment elutriation was computed from laboratory analysis of the pore-water quality, ion exchange complex and mineral composition of the sediment. Two of the three investigated sediments contained 3 mmol (eq) acidity per 100 g dry sediment and revealed saturation with respect to jarosite, jurbanite and gypsum. In the third sediment, 6 mmol (eq) alkalinity per 100 g dry sediment was obtained. The annual net acidity influx was calculated to be about 0.5 million mol (eq) for the lake of the test site.

Ehrenfeld J.G.

Evans K.G.

Erosion of rehabilitated mines may result in landform instability, which in turn may result in exposure of encapsulated contaminants, elevated sediment delivery at catchment outlets, and subsequent degradation of downstream water quality. Rehabilitation design can be assessed using erosion and hydrology models calibrated to mine site conditions. Incision rates in containment structures can be quantified using 3-dimensional landform evolution simulation techniques. Sediment delivery at catchment outlets for various landform amelioration techniques can be predicted using process-based and empirical erosion-prediction models and sediment delivery ratios. The predicted sediment delivery can be used to estimate an average annual stream sediment load that can, in turn, be used to assess water quality impacts. Application of these techniques is demonstrated through a case study applied to a proposed rehabilitation design option for the Energy Resources of Australia Ltd (ERA) Ranger Mine in the Northern Territory of Australia.

Hancock G.R., Evans K.G., Willgoose G.R., Moliere D.R., Saynor M.J., Loch R.J.

This study forms part of a collaborative project designed to validate the long-term erosion predictions of the SIBERIA landform evolution model on rehabilitated mine sites. The SIBERIA catchment evolution model can simulate the evolution of landforms resulting from runoff and erosion over many years. SIBERIA needs to be calibrated before evaluating whether it correctly models the observed evolution of rehabilitated mine landforms. A field study to collect data to calibrate SIBERIA was conducted at the abandoned Scinto 6 uranium mine located in the Kakadu Region, Northern Territory, Australia. The data were used to fit parameter values to a sediment loss model and a rainfall–runoff model. The derived runoff and erosion model parameter values were used in SIBERIA to simulate 50 years of erosion by concentrated flow on the batters of the abandoned site. The SIBERIA runs correctly simulated the geomorphic development of the gullies on the man-made batters of the waste rock dump. The observed gully position, depth, volume, and morphology on the waste rock dump were quantitatively compared with the SIBERIA simulations. The close similarities between the observed and simulated gully features indicate that SIBERIA can accurately predict the rate of gully development on a man-made post-mining landscape over periods of up to 50 years. SIBERIA is an appropriate model for assessment of erosional stability of rehabilitated mine sites over time spans of around 50 years.

Weltz M.A., Kidwell M.R., Fox H.D.

Willgoose G., Riley S.

There is a need to assess the long-term stability of engineered landforms associated with the rehabilitation of Ranger Uranium Mine, Northern Territory, Australia, as it is a requirement that mill tailings must be contained for periods in excess of 1000 years. The geomorphic model, SIBERIA, is calibrated on hydrologic and erosion data collected by a combination of monitoring and rainfall simulation experiments on the waste rock dumps of Ranger. Preliminary analysis of Ranger's preferred above-grade option suggests that erosion of the order of 7 to 8 m will occur on the structure in a period of 1000 years. This depth of erosion may be sufficient to compromise the integrity of containment. It is shown that SIBERIA has significant advantages over steady-state erosion models. Suggestions are made for the design that will enhance the stability of the structure and extend the structural life of the containment. © 1998 John Wiley & Sons, Ltd.

Evans K.G., Loch R.J.

Observable differences in particle size, smoothness and compaction between cap site (slope 2·8 per cent) and batter site (slope 20·7 per cent) surfaces on the waste rock dump at Ranger Uranium Mine were quantified in terms of revised universal soil loss equation (RUSLE) parameter values. Cap site surface material had a Km (erodibility corrected for sediment density) of 0·030 and batter site surface material had a Km of 0·0056. Using these Km values (derived from particle size distributions), slope length and steepness (LS) factors of 0·36 for the cap site and 3·66 for the batter site, and a cover (C) factor of 0·45 for the cap site and 0·16 for the batter site, the RUSLE predicts an erosion rate from the cap site that is 1·9 times greater than erosion from the much steeper batter site. The RUSLE indicates that the finer particle size and blocky soil structure of the cap site (D50 = 0·91 mm) compared with the looser granular structure of the batter site (D50 = 1·74 mm) strongly influence erosion. The predictions are similar to observed soil losses from erosion plots on these sites under rainfall simulation events, for which the measured erosion rate from the cap site was approximately twice that from the batter site. For the RUSLE to predict the observed erosion rates, the support practice (P) factor for the cap site would have to be approximately 30 per cent greater than the P factor for the batter site. The higher cap site P factor probably results from smoothing and compaction caused by vehicle movement across the surface. Compaction is considered to have greatly reduced infiltration capacity, thus increasing the erodibility of the cap site. Vehicles probably also crushed the surface material at the cap site, creating the observed finer particle size distribution and further increasing the erodibility. Compaction, through its effects on erodibility (Km) and surface roughness (P), is concluded to be the major cause of higher erosion from the cap site, even though the slope steepness is 10 times less. Parameterisation of the RUSLE quantifies the differences between sites and explains the unexpected erosion rates observed. The results highlight the need for careful management of rehabilitated sites to avoid increases in erosion which may arise from compaction by machinery.

Riley S.J.

The geomorphic stability of the cover (cap) over the pit of Nabarlek Uranium Mine in Arnhem Land, Northern Australia, is important because radon gas and other long-lived radio-nuclides arising from mill tailings must be contained for long periods. The primary agents of denudation in the region's seasonally wet tropical environment of low relief are rainwash, overland flow, rilling and gullying. Other agents of erosion are of less concern, although biogenic agents of erosion (e.g. termites and windthrow) may enhance fluvial activity. A combination of modelling, using the Universal Soil Loss Equation, and analogue estimates of denudation and thresholds of rilling and gullying from areas with similar geology, topography and climate are used to estimate the stability of the Nabarlek cover. Denudation rates are conservatively estimated at less than 100mm ky−1. It is suggested that with some minor design modifications the cover will retain its integrity for several thousand years.

Haigh M.J.

Large tracts of land in South Wales, officially listed as “reclaimed” from former mineral workings, are in very poor condition. Problems include gullying, accelerated runoff, poor vegetation cover, erosion and poor soil structure. Some of these problems are due to low quality engineering and poor land husbandry but they are magnified by natural processes. Some minespoils/soils include a high proportion of friable shales. These break down rapidly, when exposed to disturbance/weathering, releasing clays which clog up soil pores and impede the infiltration of water. This causes a progressive deterioration of the land with symptoms that may include waterlogging, replacement of grass by moss/lichen/bare ground, dieback of soil microbiota, increases in soil bulk density, and decreases in soil aggregate stability. Remedies proposed include developing a large/active soil microbiota capable of incorporating clay domains in water-stable soil aggregates.

Bell J.C., Daniels W.L., Zipper C.E.

Surface mining for coal disturbed hundreds of thousands of hectares in the Appalachians by the mid-1970s. The mined landscape created by typical “shoot-and-shove” mining methods during this era led to severe water-quality and land-use problems. Enacted in 1977, the Surface Mining Control and Reclamation Act (SMCRA) required that all mining spoil be stabilized and returned to “approximate original contour” (AOC) wherever possible. This requirement is controversial in the steeply sloping Appalachian (U.S.A.) mining region. The major goal of this research was to objectively evaluate the long-term slope stability and potential erosivity of central Appalachian AOC landforms. Many AOC backfills in this region face long-term stability problems. The major factors leading to backfill instability are: (1) excessively steep and/or convex fill configurations; (2) excessive seepage leading to loss of fill strength; and (3) inaccurate estimation of spoil shear strength parameters and fill safety factors. Slope failures may occur both within and beyond the five-year bond release period mandated by SMCRA. Steeply sloping siltstone spoils are particularly prone to erosion losses, and rapid revegetation is essential for the stabilization of AOC slopes. Widespread implementation of alternative landforms which utilize hollow fills for excess spoil disposal while still eliminating the highwall would greatly reduce the potential for slope failures and erosion by reducing total backfill slope areas and lengths.

Sanchez C.E., Karl Wood M.

Large quantities of coal are extracted in New Mexico by surface mining that results in large areas of surface disturbance. Some goals of reclaiming these disturbances are to control erosion and consequent sediment yields by recontouring and revegetation. This study investigates the rates of infiltration and sediment removal on successfully reclaimed coal mine areas, and their relationship with analogous undisturbed rangeland. Reclaimed areas that had been revegetated for one, three and five years, and a nearby natural rangeland, were subjected to simulated rainfall. Ponding time and runoff time were similar between the non-disturbed lands and the areas reclaimed one and five years before for both dry and wet soil moisture scenarios. The area revegetated three years before required substantially longer time to pond and yield runoff than the rangeland. The reclaimed areas with three and five growing seasons displayed greater infiltration rates than the rangeland area on dry soils and wet soils. Infiltration rates for the reclaimed area with one growing season were similar to the natural rangeland area for both soil moisture conditions. Sediment production and concentrations on the newly reclaimed areas were equal to, or greater than, that for the rangeland on dry and wet soils, respectively. The reclaimed area with the most established vegetation yielded the least sediment of all the reclaimed sites, and significantly less than the rangeland site, regardless of soil moisture situations. Various vegetation, rock, soil, and surface roughness variables were found to influence ponding and runoff times, infiltration rates, sediment production, and sediment concentration. These variables include, in decreasing importance: foliar grass cover, grass production, bulk density, foliar shrub cover, shrub production, horizontal roughness, litter cover, vertical roughness, rock cover and organic matter content.

Khanbilvardi R.M., Rogowski A.S.

Mathematical simulation of erosion on upland areas is described. The erosion process is divided into rill and interill components according to the source of eroded sediment. The model provides estimates of sediment yield, predicts patterns of flow, delineates partial contributing areas and shows principal zones of deposition. Predicted values of sediment yield for individual storms over a 10-year period agreed well with experimental data for two agricultural watersheds. No concurrent data exist to verify the extent of deposition, or rill scour also predicted by the model.

Lenart J., Kašing M., Schuchová K., Tichavský R.

Frouz J., Oppong J.C., Bartuška M., Šanda M., Lišková K., Gerwin W., Nenov R., Červenka J., Houška J., Kubát J.-., Vitvar T., Dušek J.

Pawlik M., Rudolph T., Bernsdorf B.

Abstract Mining processes have a significant impact on the surrounding environment even after the exploitation has ceased. Today a continuous monitoring of post-mining processes in the areas of water management, vegetation and air pollution is important. In the project “Digital Twin – Integrated Geomonitoring” funded by the RAG Stiftung (no.20-0013) and carried out in cooperation with the Geological Survey of North-Rhine Westphalia, scientists are investigating the possibilities of integrating and fusing data from multiple sources (mining and geological maps, in-situ measurements, drone flights and satellite missions). The goal is to understand the causes and phenomena occurring on the Earth’s surface and thus to generate a process understanding. The key issue of this project is geo-monitoring of the environment in mining areas using vegetation indicators. This paper presents an analysis of the vegetation health of the cover for the period 1984-2021 using selected remote sensing indicators: NDVI, GNDVI, SAVI, MSAVI, NDWI and MNDWI. The studies indicate the possibility of long-term spatial-temporal observations of a selected test area in order to observe the impact of post-mining processes in the area of the closed Prosper-Haniel mine.

Jahandari S., Tao Z., Chen Z., Osborne D., Rahme M.

Stephan K., Hubbart J.A.

With globally more than 100,000 km2 impacted by surface mining at present, and with increasing demand for surface-mined products, land managers are challenged to address landscape degradation of decommissioned quarries, especially in urban areas. In this study, soil, microclimate, and vegetation community data were collected from geomorphologically distinct locations (quarry floor, platform with pond, quarry top, highwall edge) within an urban limestone quarry abandoned 70 years ago without reclamation in central Missouri, USA. Results were compared with two nearby reference sites to bookend conditions in the abandoned quarry, including a recently closed quarry and an urban forest. Results of this study showed that abiotic mining legacies gave rise to distinct vegetation communities comprising 74 native species but also 21 non-native species. Species richness was increased near persistent edges (cliff edge, pond edge) and approached the lower range of species richness found in natural areas in the region. The results of this case study are congruent with the growing body of studies about spontaneous succession on abandoned surface mines worldwide in that spontaneous (vs. managed) revegetation can lead to species-rich, near-natural communities. This finding may justify revision of current legislation requiring technical reclamation of surface mines, especially where favorable substrate, such as limestone, is conducive to swift onset of revegetation. To improve the ecological value of such areas, the provision of funding for long-term invasive species management should also be considered.

Vicente E., Moreno-de las Heras M., Merino-Martín L., Nicolau J.M., Espigares T.

The use of ecohydrologically suitable microsites, such as sink patches (i.e. zones intercepting and infiltrating runoff) and nurse shrubs, have largely been proposed as tools to improve the establishment of late-successional trees in Mediterranean reclaimed landscapes. Nonetheless, this technique needs to be accurately tested along with the influence of seedling water-use strategy. To that purpose, we monitored the short- and mid-term (i.e. 4 and 8 years, respectively) influence of sink patches and nurse shrubs ( Genista scorpius ) on seedlings of two species with contrasted water-use strategies, Pinus nigra , a more drought avoider and isohydric species, and Quercus ilex , a more drought tolerant and anisohydric species. In the short term, G. scorpius shrubs enhanced the establishment of seedlings planted in shaded spots under its canopy. This positive interaction was more relevant for Q. ilex in drier years, while P. nigra was more facilitated in wetter years. Sink patches ameliorated the survival of both species, but only promoted greater growth during wetter years. P. nigra seedlings showed a high sensitivity to precipitation reduction. Their survival and growth were strongly constrained in dry years, resulting in a very high cumulative mortality at the end of the 8-year study period regardless of the microsite the seedlings were planted in. Q. ilex showed better seedling performance than P. nigra in the mid-term, keeping also the positive effects of suitable microsites on plant survival in the mid-term, after 8 years of plantation. Our results support the use of suitable microsites that ameliorate ecohydrological conditions as key spots for enhancing ecological succession in reclaimed mining sites, particularly the use of G. scorpius as nurse shrub for improving Q. ilex seedling establishment and growth. Our results also suggest that seedling functional strategy to cope with drought is a critical factor conditioning the overall plantation performance in the mid-term. Thus, seedling water-use strategy should constitute a key species selection criteria in future restoration programs focused on Mediterranean ecosystems, especially under climate change. • Short- (4 years) and mid- (8 years) term analysis • Effects of suitable microsites were modulated by seedlings' functional strategy. • Nurse shrubs only facilitated Q.ilex in shaded spots under their canopy. • Sinks only enhanced seedling growth during wet years. • P.nigra was far more sensitive to precipitation reduction than Q.ilex .

Duchnowska M.

The article presents a detailed description of the transformation of the terrain relief due to long-lasting underground and surface mining activity in the Wielka Kopa massif at Rudawy Janowickie (the Western Sudetes mountains). It includes both the anthropogenic forms and secondary transformations of these forms due to natural land-shaping processes, ongoing after mining had been discontinued. The location deserves special attention, as it shows particularly significant mining-induced relief transformations, whose scale can be compared to those of the Walbrzych hard coal basin and the Turoszow lignite basin. The presented object is also an important historical heritage and deserves special attention due to its high research, didactic and tourism potential. The article offers a description of the characteristics and a classification of the anthropogenic forms in the area of Wielka Kopa, which are hoped to serve as an aid in planning future actions related to the revitalization of the area and also as an example for future descriptions of other closed mining facilities.

Hooke R.L., Martín Duque J.F.

In the half-dozen decades following World War II, Earth’s human population tripled and the global gross domestic product increased nine fold. The disparity in these figures reflects an unsustainable increase in the rate of consumption of Earth’s natural resources—an increase that has been dubbed The Great Acceleration. Humans are using renewable resources faster than they are renewed, using non-renewable resources faster than substitutes can be found, and discarding waste faster than it can be absorbed by the natural environment. The increase in the mass of earth moved as a direct or indirect result of this exploitation of earth resources has rendered humans the premier geomorphic agent currently sculpting Earth’s surface. Mitigation efforts such as transitioning to renewable energy sources, reforestation and afforestation, restoration of ecosystems in disturbed landscapes, and recycling are constructive but insufficient. Attainment of a completely circular economy might suffice, but unless we submit to a significant decrease in our standard of living, this is likely impossible with the population increasing as it is. Lowering fertility below the replacement level of 2.1 children per woman, and thus initiating a gradual long-term decrease in global population is the most promising solution.

Mossa J., James L.A.

Mining is of interest to geomorphologists because of the unique types of excavated and accumulated landforms and landscapes that are vulnerable to geomorphic hazards. Mining is extensive worldwide. It produces more sediment than paved road construction, house construction or agriculture. Mining is associated with increasing vulnerability to slope failures, erosion, floods, sedimentation, subsidence, and other geomorphic hazards. Understanding and effectively applying geomorphic principles are important for preventing or minimizing the negative effects of mining. This chapter discusses the types and history of mining operations and associated geomorphic impacts that may result in characteristic landforms and landscapes. It then describes mining-related geomorphic hazards and the nascent fields of sustainable mining and mined-land reclamation. We have much still to learn from the study of mining landscapes, with potential applications in landscape evolution, models of geomorphic hazards, reclamation, and Quaternary geology and geomorphology. Given a growing global population and expanding demands for mineral resources, the need for sustainable practices will increase and wise application of geomorphic knowledge in mined landscapes will become increasingly important.

Martín Duque J.F., Zapico I., Bugosh N., Tejedor M., Delgado F., Martín-Moreno C., Nicolau J.M.

This research documents the successful application of a novel holistic approach to return land degraded over thousands of years of use to full ecological function. The surroundings of the Somolinos hamlet in Central Spain illustrate a millennial history of land transformation and degradation by agrarian and extractive activities exacerbated at the second half of the 20th century by mechanized mining. This land stewardship history was culminated by a recent intervention of geomorphic-based ecological restoration and its monitoring. Historic anthropogenic processes which triggered gully erosion were intense deforestation for agriculture and grazing, and construction materials quarrying. From 1963 to 2006 mechanized quarrying operated over ancient extractive landforms. In 2007, a conventional rehabilitation mitigated risks but failed at controlling erosion and promoting soil and vegetation reestablishment. A geomorphic-based ecological restoration was accomplished since 2011. The GeoFluv-Natural Regrade CAD software was used for geomorphic landform design, and construction was completed with a carbonatic colluvium topdressing supplemented with a manure-amended soil, that was seeded with grasses. The whole process was a truly complete application of ecological engineering. One of the main purposes of this research was to carefully scrutinize the completed project, to evaluate its effectiveness and, if any deficiencies were found, to analyze their causes, so that they could be avoided in the future. Therefore, the landscape evolution and erosional behaviour of the restored area has been monitored from 2011 to 2020 through a time-lapse sequence of several oblique aerial photos, and by comparing topographies through Digital Elevation Models (DEMs) of Difference (DoDs). Those topographies were surveyed with differential GPS (DGPS) and with Structure from Motion (SfM) combined with Unmanned Aerial Vehicles (UAVs). This monitoring revealed: (a) landscape healing and diversification of the vegetation community composition and structure, as a result of the environmental heterogeneity of the geomorphic design; and (b) absence of hillslope and channel erosion for 99.8% of the area with limited surface erosion zones in 0.2% of the restored area. Our analysis attributed those limited erosion zones to a combination of: (a) minor design oversights; (b) slight construction deviation from the design grade; and (c) excessive runoff entering the repaired area that exceeded the design discharge. These erosion zones started to stabilize five years after initial restoration and achieved steady-state stability at nine years. The main lesson learnt from these minor deficiencies is that such erosion zones can be avoided at the design phase within GeoFluv-Natural Regrade by checking proper convex-concave slopes and concave channel profiles and by carefully considering any adjacent runoff entering the designed areas, which influence the channel's tractive forces. The use of Landscape Evolution Models, such as SIBERIA, can also identify design anomalies subject to erosion. Then, after rigorously inspecting the design, it is imperative that the construction is completed true to the design by defining and following construction tolerances. • Two millennial of land transformation, degradation and healing in Somolinos (Spain) • A holistic ecological restoration design and monitoring in Somolinos (Spain) • A geomorphic-based ecological restoration, 9-yr monitored, performed successfully. • GeoFluv key findings are reported to address those issues in future work.

Martín Duque J.F., Tejedor M., Martín Moreno C., Nicolau J.M., Sanz Santos M.A., Sánchez Donoso R., Gómez Díaz J.M.

Geomorphic-based mine restoration of clay quarries in Tortosa (Catalonia) was co-funded by the European Union’s LIFE programme. The landform design was made with GeoFluv-Natural Regrade. Their buil...

Hancock G.R., Duque J.F., Willgoose G.R.

Mining is essential to the human economy and has been conducted for millennia. In the past ~60 years, the scale of disturbance created by mining has grown larger in response to economic demands and technology capacity. However the scale of disturbance from mining is dwarfed by that of urban expansion and agriculture. Nevertheless, it is well recognised that mine sites have radically disturbed abiotic and biotic system components that, post-mining need to restore new land uses and ecosystem goods and services. In many cases, such aims demand a geomorphic integration with the surrounding undisturbed landscape. Erosional stability based on geomorphic principles is the first and most important part of the process. Without erosional stability, vegetation will be difficult to establish and maintain and soil and nutrients will be lost from the site. In this review we outline this process and methods by which a geomorphic and integrative landscape can be established. We also examine the issue of establishing a self-sustaining landscape that is similar to that of the prior undisturbed landscape. Here we argue that this is not possible in almost all situations, however the development of a new and ecologically successful, albeit different landscape is. The community needs to accept that mining, like agriculture, is essential to the modern economy and that a past landscape cannot be replaced with the same, but a new, functional and productive one can be developed. However, the ability to do this and ensure long-term ecological sustainability is questionable for many sites and considerable effort needs to be made to develop the technology to ensure that this will occur. We outline a way forward, based on geomorphic design and modelling.

Vidal-Macua J.J., Nicolau J.M., Vicente E., Moreno-de las Heras M.

Opencast mining is an activity that caters to many economic sectors; however, it has a large impact on society and the environment. After mining, the major concern is to restore the previous land cover, which was generally a natural vegetation cover. Establishing permanent vegetation cover can restore landscape connectivity and previous ecosystem functions, enhance aesthetic values and prevent off-side effects associated with post-mining landscapes. Opencast mining reclamation deals with these issues with several strategies that aim to develop a vegetation cover after mining activity has stopped. However, not all reclamation actions are effective, and assessing their efficiency by monitoring vegetation development at reclaimed sites is a time-consuming task because it usually involves extensive field work. In this study, we present a semi-automatic approach based on analysing satellite data (Landsat) time series and using a machine learning technique to identify suitable conditions for vegetation development at reclaimed opencast mines. We analysed the Teruel coalfield (Aragón, central-eastern Spain). This area is a representative Mediterranean-Continental region that is of particular interest due the diversity of reclamation actions that have been applied and the increase in drier conditions during the last decades. Conditions were described with topography derived variables, technical reclamation features and drought-occurrence variables as potential explanatory factors. The implemented approach allowed us to identify the main abiotic filters for vegetation of this geographic region: the water availability and soil retention (both controlled by the topographic slope), and the proximity to seed sources. The analysis evidenced the negative influence of drought occurrence on vegetation development, and different responses were found depending on the timescale at which drought is calculated. Our results indicate that the reclamation landform model is the main key factor influencing vegetation development. A model such as the smooth berm-slope increases water availability and controls soil erosion, and hence, improves vegetation development. In addition, we found that further than 500-600 m from the mine, the effect of seed source declines dramatically. Therefore, all these issues should be considered in future reclamation designs in a Mediterranean-Continental environment. Our methodology could be adapted to other geographic regions where spatial environmental data are available.

Reed M., Kite S.

DePriest N., Hopkinson L., Quaranta J.

Geomorphic reclaimed landforms aim to improve groundwater movement and diminish contaminant transport through increased runoff and reduced groundwater infiltration. The objective of this research was to determine if geomorphic reclamation techniques result in improved selenium concentrations of discharge water as compared to conventional reclamation for valley-fills constructed of blasted rock. Comparisons investigated if groundwater and contaminant desorption could be improved by altering valley-fill construction. Three-dimensional finite-element groundwater modelling was performed on two valley-fill geometries and was coupled with laboratory testing of selenium leaching from blasted-rock overburden. Selenium desorption characteristics and distributions were compared. Lower water volumes and shorter contact times with overburden fill resulted in lower masses of selenium desorbed from geomorphic fills as compared to conventional techniques. When results were normalized by varying fill areas and volumes, the geomorphic valley-fill exhibited 23% lower surface infiltration, 27% lower discharge volumes and 39% lower selenium discharge loads as compared to the conventional reclamation. To achieve these advantages in geomorphic reclamation, infiltration must be reduced through both the construction of curvilinear slopes of the fill surface and the creation of a low infiltration-capacity reclaimed stream.