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.
Highlights
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
The time to runoff initiation varied between 6–48 min when the first rainfall event occurred, and decreased rapidly from 1–6 min to 1–3 min during the second and third rainfall events (Fig. 1)
The time to runoff initiation was different among substrates, which decreased in the order of S > tailings incorporating soil (TS) > loose tailings (LT) > crusty tailings (CT) > tailings incorporating soil and mushroom residues (TSM) > tailings incorporating mushroom residues (TM)
Summary
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. 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]. Soil erosion is a particle size-selective process, especially for the non-homogeneous mining waste[27], and fine particles and nutrients are removed[28], which severely affects the sustainability of ecological restoration[29]. Runoff rate and sediment concentration have been found to be closely related to intrinsic soil properties[35,36], especially the content of fine particles with aggregate structure[14,37,38]
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