Abstract
Severe gully erosion on spoil dumps, caused by dense concentrated flow derived from platforms, poses a significant threat to the land management of mining areas. However, little is known about the development processes and mechanisms of gullies on spoil dumps. A flow scouring experiment was conducted on an established platform–slope system under 3.6–5.04 m3 h−1. The soils of the system consisted of a surface sandy loam A layer and anunderlying clay loam B layer. The results showed that the platform exhibited a gully development process of headcut-incision–headcut-expansion–stabilization and the steep slope experienced gully development of A-layer incision–A-layer expansion–B-layer incision–stabilization. The results showed 88.97–100% of Froude Number (Fr) decrement and 47.90–88.97% of Darcy–Weisbach roughness coefficient increment finished in the two incision stages on the steep slope. Gully depth has the most sensitive response to flow hydraulics. A significant linear correlation exists between gully depth and shear stress, runoff power, Fr, and Reynolds Number (R2 > 0.337). Overall, the optimal hydraulic indicator varies within different stages for describing the gully morphology development, illustrating the different action mechanism between flow hydraulics and gully morphology. Our findings provide a theoretical support for future mechanistic studies of gully erosion and the land management on spoil dump.
Highlights
Soil erosion has become a global issue
This paper aims to (1) clarify gully morphological variation and development of the platform–slope system, (2) clarify the response of gully morphology to flow hydraulics, and (3) establish the relationship between gully morphology and hydrodynamic parameters to illustrate the morphodynamic mechanism of gully development on the platform–slope system of spoil dumps
The results showed that the gully erosion of spoil dumps exhibited a development process of headcut-incision–headcut-expansion–stabilization on the platform, and experienced a development process of A-layer incision–A-layer expansion–B-layer incision–stabilization on the steep slope
Summary
Soil erosion has become a global issue. The environmental problems caused by manmade accelerated soil erosion are becoming serious, and will strongly affect regional, social, and economic development. Spoil dumps are the main source of sediment during road construction and coalfield development. Characterized by a lack of soil structure and low vegetation productivity [1,2], spoil dump output has 11.19–138.67 times the sediment of the original earth [3]. Erosion accounts for 69.2–86.6% of the total sediment [4]. Secondary disasters, such as landslides and debris flows, evolve and increase the sediment transport load in the nearby fluvial networks and their ecosystems [2]. The research on the mechanism of gully erosion on spoil dumps is weak.
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