Erosion characteristics of different reclaimed substrates on iron tailings slopes under simulated rainfall

Abstract

Water-induced erosion of iron tailings is a serious problem affecting ecological restoration, but, little is known about how the occurrence of erosion on tailings slopes and types of reclaimed substrates that are beneficial to reducing slope erosion. This study measured the slope erosion characteristics of six reclaimed substrates including loose tailings (Lt), crusty tailings (ct), tailings incorporating mushroom residues (tM), tailings incorporating soil (tS), tailings incorporating soil and mushroom residues (TSM) and soil (S) in experimental soil flumes under three simulated intermittent rainfall events, with intensity of 60, 90 and 120 mm h −1 for the first, second and third event, respectively. Significant differences (p < 0.05) were found in erosion characteristics among the six reclaimed substrates. TM had the lowest sediment yield but the highest runoff volume without obvious rills. LT, CT and TS had the highest sediment yield rates and severe slope erosion morphology. With the increased number of rainfall events, the runoff rates of the six substrates all increased, but only the sediment yield rates of LT, CT and TS increased, the sediment yield rates of other substrates increased first and then decreased. therefore, adding agricultural organic wastes such as mushroom residues to tailings and reducing soil addition may be an effective way to reduce erosion and promote ecological restoration in soilless tailings areas. Mining is essential for maintaining society's current life style and economic development. However, mining also impacts the environment 1-3. One of the most significant environmental impacts from mining is soil erosion, which has received increasing attention 3-8. Waste dumps generated from mining usually consist of unconsolidated waste rock, parent material, tailings or their mixtures 9,10. The waste dumps are piled on the land surface in the form of overburden dump. They usually become the material source for debris flow, river sediment, and hyper-concentrated sediment flow of artificially accelerated erosion 11,12 as well as the source of wind erosion 13,14. The erosion forms and characteristics of mining waste dumps are different from those occuring naturally 5. Accumulated overburden dump material is prone to gravity erosion 12 , causing abrupt increases or decreases in sediment yield 15. Erosion in coal waste slag has shown extreme sediment fluctuation at the beginning of runoff, accompanied by local debris flow 16. Martín Duque et al. 1 observed that tailing deposits underwent severe erosion after long-term abandonment, and as a result, caused a mosaic-like erosion and sedimentary landforms with gully formations upon and piping within deposits. Therefore, at a larger scale, it is important to reconstruct stable post-mining landforms and control erosion, which have been claimed in mine reclamation regulations in different countries 17,18. Most of the traditional landform reconstruction is in the form of terraces and contoured banks 3. Recent studies indicated that geomorphic-based mi...

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Experimental Study on Failure Mechanism and Mode of Fly-Ash Dam Slope Triggered by Rainfall Infiltration

“…The larger the slope ratio, the more obvious the sliding failure characteristics; the smaller the slope rate, the more obvious the runoff erosion damage. However, the above conclusion is different from the erosion effect on the slope under rainstorm conditions [47,48]. In the tests, the slope ratios of S1, S2, S3, and S4 before rainfall were 1:2.1, 1:3.2, 1:2, and 1:3, respectively.…”

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