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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (9): 3194-3206.doi: 10.13287/j.1001-9332.202009.018

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Erosion morphology and the characteristics of runoff and sediment yielding in platform-slope system of opencast coal mine

SU Huan1, WANG Wen-long1,2*, KANG Hong-liang1, BAI Yun3, GUO Ming-ming1 , CHEN Zhuo-xin1   

  1. 1State Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, Shaanxi, China;
    2Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, Shaanxi, China;
    3Key Laboratory of Ecological Rehabilitation of Northern Shaanxi Mining Area, Yulin University, Yulin 719000, Shaanxi, China
  • Received:2020-05-20 Accepted:2020-07-08 Online:2020-09-15 Published:2021-03-15
  • Contact: * E-mail: wlwang@nwsuaf.edu.cn
  • Supported by:
    the National Natural Science Foundation of China (41761062,41701316) and the National Program on Key Basic Research Project of China (YS2016YFC0501604).

Abstract: In the open pit, runoff from the platform is large discharge and rapid afflux, which often results in serious gully erosion of dump slope. The study of erosion process under catchment conditions of the platform-slope system is still backward. In this study, field scouring experiments were conducted to investigate runoff characteristics and sediment yield processes of the platform-slope system under different flow discharges (48, 60, 72 and 84 L·min-1). Our results showed that rill erosion dominated the platform-slope system under the flow discharge of 48 L·min-1, and gully was formed under 60-84 L·min-1. The flow velocity of the platform and the slope showed an abrupting-fluctuating-stable trend with the duration of discharge. The flow velocity of the platform was smaller than that of the slope, with the magnitude of reduction at 8.3%-67.1%. The highest flow velocity appeared on the up-slop/down-slope, being 18.5%-44.6% higher than that of the middle-slope. In general, the sediment yield rate of the platform and the slope varied with the duration of discharge, with the sediment yield rate of the slope being 17.4 times as that of the platform. The ratio of gully width to depth showed substantial difference between the platform and slope. The platform generally had the largest ratio than the slope. For the slope, the largest ratio appeared on the middle-slop/down-slope, being 1.36-1.93 times as that of the up-slope. The morphology of rill and gully along the platform to down-slope presented in the form of “wide and shallow-narrow and deep-wide and shallow”. Rill erosion mainly concentrated in the platform and the middle slope under the flow discharge of 48 L·min-1, contributed 29.9% and 26.8% of the total erosion volume, respectively. When the flow discharge increased to 60-84 L·min-1, the largest average across-section areas (1083.25-1737.86 cm2) formed on the up-slope accounted for 36.1%-44.7% of the total erosion volume. Our results provided evidence for modelling soil and water erosion of the platform-slope system in opencast coal mine.

Key words: erosion, morphology, flow velocity, platform-slope system, runoff scouring experiment