Estimating and restoring bedload transport through a run-of-river reservoir.
Estimating and restoring bedload transport through a run-of-river reservoir.
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估计和恢复通过径流水库的底质输送。
DOI：
10.1016/j.scitotenv.2018.11.177
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Thomas Dépret
中科院分区：
文献类型：
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作者：
Thomas Dépret
堰坝或径流坝会破坏推移质转移，由于沉积物饥饿，对下游产生负面生态影响。然而，推移质被截留的方式和程度并不简单，很少有研究探讨这一主题。本研究的重点是一个13公里长的罗讷河水库，法国，由一个导流大坝配备底闸门。我们的主要目标是确定改变的推移质转移下游的程度，并确定在何种程度上的实施生态地貌流（EmF），定义为环境流量，其目标是专门增加推移质转移通过水库，以促进下游栖息地的多样性，可以增加床的流动性。结果表明，水库的形态调整的潜力已经很低，大坝建成前（1968年），在响应粗泥沙供应大幅减少，但这种潜力逐渐减少，由于蓄水。然而，自大坝建成以来，推移质输移的连续性至少部分得以维持。根据数值模拟，对于相对罕见的流量（50年一遇洪水），只有小于中等砾石（d< 14 mm）的颗粒可以输出到大坝下游。电动势的实施可以巧妙地改善推移质转移，因为它将允许大大提高能力：对于2年和50年的重现期洪水，下游可输出的最大颗粒尺寸分别是正常水库运行的9倍和4倍。
Weirs or run-of-river dams can disrupt bedload transfer with negative ecological effects downstream due to sediment starvation. The way and the degree to which bedload is trapped is nevertheless not straightforward and few studies have examined this topic. This study focuses on a 13-km-long reservoir of the Rhône River, France, created by a diversion dam equipped with bottom gates. Our main objective was to determine the degree of alteration of the bedload transfer downstream and to identify to which extent the implementation of Ecomorphogenic Flows (EmF), defined as environmental flows whose objective is specifically to increase bedload transfer through the reservoir to promote downstream habitat diversity, could increase bed mobility. The results show that the potential for morphological adjustments in the reservoir was already low before dam completion (1968) in response to a substantial decrease in coarse sediment supply, but that this potential was progressively reduced due to the impoundment. However, the bedload transfer continuity has been at least partially maintained since dam completion. According to numerical simulations, only particles smaller than medium gravels (d< 14 mm) could be exported downstream of the dam for relatively rare discharge (50-years return-interval flood). Implementation of EmF could neatly improve the bedload transfer since it would allow to strongly increase the competence: for a 2-years and a 50-years return-interval floods, the maximum particle size exportable downstream is respectively 9 and 4 times larger than for normal the reservoir operation.