Abstract Whereas the geomorphic effects of in-channel mining have been widely documented, very few studies have focused on recovery trajectories after mining ended. This paper describes and quantifies the channel adjustment of extended and over-widened mining pits located in a low energy gravel-bed river, and identifies the factors that control their recovery rate. The study was based on aerial photographs and LiDAR analysis, grain-size sampling, bedload computation and geophysical measurements made during ground penetrating radar (GPR) and electrical resistivity tomography (ERT) surveys. We describe the spatio-temporal changes in the morphology of former pits as well as the current surficial longitudinal grain-size pattern in pits and in neighbouring upstream and downstream reaches. Our results show a wide range of geomorphic readjustments. Between 23 and 47 yr after the end of mining, the mining reaches have still not yet fully recovered. The planimetric recovery rate is closely correlated with the ratio of the volume deposited in the pits to their original volume. Finally, the infilled material is only partly composed of bedload and the mainly sandy fine sediments play a primary role in the recovery process. The abundance of sand, controlled by the lithology of the watershed, explains the unexpectedly high recovery rates of some pits despite the low energy of the river.

中文翻译：

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通过原矿区恢复低地砾石河床，砂的关键作用

摘要 尽管河内开采的地貌效应已被广泛记录，但很少有研究关注开采结束后的恢复轨迹。本文描述和量化了位于低能量砾石层河中的扩展和超宽采矿坑的通道调整，并确定了控制其采收率的因素。该研究基于在探地雷达 (GPR) 和电阻率层析成像 (ERT) 调查期间进行的航拍照片和 LiDAR 分析、粒度采样、床载荷计算和地球物理测量。我们描述了前坑形态的时空变化以及坑和邻近的上游和下游河段中当前的表面纵向晶粒尺寸模式。我们的结果显示了广泛的地貌调整。在开采结束后的 23 至 47 年之间，开采范围仍未完全恢复。面积回收率与坑内沉积体积与其原始体积之比密切相关。最后，填充材料仅部分由床体组成，主要是砂质细粒沉积物在恢复过程中起主要作用。受流域岩性控制的大量沙子解释了尽管河流能量低，但某些矿坑出乎意料的高回收率。填充材料仅部分由床体组成，主要是砂质细粒沉积物在恢复过程中起主要作用。受流域岩性控制的大量沙子解释了尽管河流能量低，但某些矿坑出乎意料的高回收率。填充材料仅部分由床体组成，主要是砂质细粒沉积物在恢复过程中起主要作用。受流域岩性控制的大量沙子解释了尽管河流能量低，但某些矿坑出乎意料的高回收率。