The impact of run-of-river dams on sediment longitudinal connectivity and downstream channel equilibrium
The impact of run-of-river dams on sediment longitudinal connectivity and downstream channel equilibrium
复制标题
径流坝对沉积物纵向连通性和下游河道平衡的影响
DOI：
10.1016/j.geomorph.2020.107568
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发表时间：
2021
期刊：
影响因子：
3.9
通讯作者：
Renshaw, C.E.
中科院分区：
文献类型：
--
作者：
Magilligan, F.J.;Roberts, M.O.;Mackenzie, M.;Renshaw, C.E.
过去几十年的大量研究表明，水坝，特别是大型水坝，其流量调节结构会使流域支离破碎，并切断沉积物和营养物的正常下游流量。较小的，跨渠道的径流（RoR）大坝，更常见的分布在整个流域的关注较少。利用一套在新英格兰（美国）的RoR大坝，我们量化的推移质通量，通过，并超出水库，我们计算的砾石clasts.We的停留时间使用传统的渠道调查，以评估（不）平衡的渠道形式和开发两个平衡指标的基础上，满滩剪切应力和满滩盾参数。此外，我们划分的平滩通道盾参数作为推移质和悬移质成分的线性组合，以更好地量化响应沉积物供应变化的通道演变。为了实现这些目标，我们在791个砾石碎屑中嵌入了射频识别（RFID）PIT标签，大小从15 mm到81 mm不等，随后在蓄水池内和上游部署。在从部署地点运输的503个示踪剂中，移动的中位累积距离为30 m，研究期间的最大累积位移为758 m。在所有五个地点放置的标记岩石中，有276块岩石在大坝上方移位，其中204块在高排放事件之间在水库中度过了一段时间;其余的岩石在单个高排放事件中通过水库和大坝传输。在那些示踪剂，花时间在水库传输之前，在不同的网站，平均水库停留时间从19到203天不等。示踪剂的中值粒径被运送过大坝是相同的那些在研究期间移动和类似的中值粒径的通道床。这些示踪剂的虚拟速度的分布是近似对数正态分布，非常广泛的分布超过六个数量级。方差分析表明，速度的分布被划分为两个统计相似的组，与速度较慢的两个较小的流域（13平方公里-21平方公里），平均坡度较高的较大的流域（89平方公里-438平方公里），平均坡度较低。我们的结论是，RoR大坝传输和陷阱的上游沉积物供应在同一范围内的物理条件，产生流动性和捕获在河流的自然到达尺度的形态单位。由于RoR水坝可能不会捕获比天然河段中通常隔离的更多的沉积物，因此这些水坝不会断开沉积物的规范下游通量，也不会导致水坝下游的河道形态不平衡。低于RoR水坝的河段具有与不受水坝影响的可比平衡河段相似的地貌特性。然而，小的，跨RoR水坝的通道上的形态平衡状态的影响很小，并不意味着RoR水坝没有生态足迹。
Considerable research over the past several decades shows that dams, especially large, flow regulating structures, fragment watersheds and serve to disconnect the normative downstream flux of sediment and nutrients. Less attention has addressed smaller, channel-spanning Run-of-River (RoR) dams that are more commonly distributed throughout watersheds. Taking advantage of a suite of RoR dams in New England (USA), we quantify bedload flux into, through, and beyond the reservoir, and we calculate the residence time of gravel clasts.We used traditional channel surveys to evaluate (dis)equilibrium channel form and develop two equilibrium metrics based on bankfull shear stress and the bankfull Shields parameter. Additionally, we compartmentalize the bankfull channel Shields parameter as a linear combination of bedload and suspended load components to better quantify channel evolution in response to changes in sediment supply. To accomplish these goals, we embedded Radio Frequency Identification (RFID) PIT tags in 791 gravel clasts ranging in size from 15 mm to 81 mm, which were subsequently deployed within and upstream of the impounded reservoirs. Among the 503 tracers that were transported from their deployment location, the median cumulative distance traveled was 30 m and the maximum cumulative displacement during the study period was 758 m. Of the total tagged rocks placed at all five sites, 276 rocks were displaced over the dam, 204 of which spent time in the reservoir between high discharge events; the rest were transmitted through the reservoir and over the dam in a single high discharge event. Among those tracers that spent time in the reservoir prior to transmission over the dam, the average reservoir residence times at the different sites ranged from 19 to 203 days. The median grain sizes of tracers that were transported over the dam were identical to those that moved during the study period and similar to the median grain size of the channel bed. The distribution of virtual velocities of those tracers that moved was approximately log-normal and very broadly distributed over more than six orders of magnitude. An analysis of variance revealed that the distribution of velocities was partitioned into two statistically similar groups; with slower velocities in the two smaller watersheds (13 km2–21 km2) with higher average slopes compared to the larger watersheds (89 km2–438 km2)with lower average slopes. We conclude that RoR dams transmit and trap the upstream sediment supply within the same range of physical conditions that produce mobility and trapping in the river's natural reach-scale morphological units. Because RoR dams are likely not trapping more sediment than is typically sequestered in natural river reaches, these dams do not disconnect the normative downstream flux of sediment nor result in channel morphological disequilibrium downstream of the dam. Reaches below RoR dams have similar geomorphic properties to comparable equilibrium reaches unaffected by dams. However, the minimal effect that small, channel spanning RoR dams have on the morphological equilibrium state of a channel does not suggest that RoR dams have no ecological footprint.
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美国过去在受沉积物影响严重的系统中拆除小型水坝的比较
影响因子：
3.9
作者：
S. R. Sawaske
通讯作者：
S. R. Sawaske
DOI：
10.1016/j.scitotenv.2018.11.177
发表时间：
2019
期刊：
The Science of the total environment
影响因子：
--
作者：
Thomas Dépret
通讯作者：
Thomas Dépret
DOI：
--
发表时间：
1967-02
期刊：
Journal of the Waterways and Harbors Division
影响因子：
--
作者：
R. Kellerhals
通讯作者：
R. Kellerhals
恢复水生生态系统的连通性需要扩大水坝和道路交叉口的库存
影响因子：
10.3
作者：
S. Januchowski‐Hartley;Peter B. McIntyre;M. Diebel;P. Doran;Dana M Infante;C. L. Joseph;J. Allan
通讯作者：
J. Allan
影响因子：
5.4
作者：
K. Gregory;C. Park
通讯作者：
K. Gregory;C. Park