The Effect of Gravel on Saturated Hydraulic Conductivity and Water Storage Capacity in Reclaimed Dump Relative to Reclamation Mode
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the National Natural Science Foundation of China(No.51474119)

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    Abstract:

    【Objective】 In open mining, dump is generally a loose rock-earth accumulation body, consisting of coal gangue from mining, topsoil stripped for open mining, rocks and cover soil. The gravels contained in the dump have an important impact on soil hydraulic conductivity and water storage capacity. So far, studies on impact of gravels on soil water have focused mainly on gravels in nature soil, and little has been reported on soil hydrology and erosion of engineering accumulation bodies of mixed rock and soil like dump and dreg dumping site. 【Method】This study was laid out on the Haizhou opencast coal mine. Field investigations were conducted and samples collected for in-lab water infiltration tests and analysis of distribution characteristics of gravels in dumps reclaimed with different vegetation and its impact on saturated hydraulic conductivity and water storage capacity of the soil in an attempt to provide certain theoretical basis for improving utilization efficiency of the water and soil resources. 【Result】 Results show that the total amount of gravels in dump increased with soil depth. The mean content of total gravels in soil profile was the lowest in agricultural land, which may be explained by frequent farming practices. No significant difference was observed in total amount of gravels between different soil layers; In terms of relative mean content of gravels by particle size, the gravels in the dump exhibited an order of (2~10 mm) > (>20 mm) > (10~20 mm), which demonstrates a trend that large-sized gravels are gradually turning into fine ones as affected by a variety of factors. Saturated soil hydraulic conductivity was the highest in shrub land, which was followed by agricultural land and grassland, and it was significantly, positively and linearly related to gravel content. The relationship got closer with increasing particle size of the gravels. Soil water storage capacity was the highest in shrub land and grassland and the lowest in arbor forest land and agricultural land, and it exhibited a significant or extremely significant relationship with content of gravels by particle size; Maximum water-retention capacity was in significant power function relationship with content of gravels by particle size; maximum water-holding capacity was in significant parabolic relationship with the content of gravels 2~10 mm in particle size. For gravels >20 mm in particle size, 14% was the threshold in content affecting soil water storage ability of the soil body. 【Conclusion】The distribution of gravels in dump varies with reclamation mode; Gravel content has a positive effect on saturated hydraulic conductivity of the dump; and gravel content and particle size does too on soil water storage capacity.

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Lü Gang, WANG Lei, LU Xiping, LI Yexin, LIU Yazhuo. The Effect of Gravel on Saturated Hydraulic Conductivity and Water Storage Capacity in Reclaimed Dump Relative to Reclamation Mode[J]. Acta Pedologica Sinica,2017,54(6):1414-1426.

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History
  • Received:March 05,2017
  • Revised:June 30,2017
  • Adopted:July 24,2017
  • Online: September 04,2017
  • Published: