Coarse sediment transport in fluvial systems serves an important role in determining in-stream physical habitat, spawning potential and benthic community structure. However, despite more than a decade of pressure in Europe to restore stream continuity under the Water Framework Directive (WFD), there have been relatively few empirical studies on how low-head, run-of-river structures (i.e., weirs) disrupt the processes and dynamics of bedload conveyance. In this study we present an investigation into how coarse sediment is transferred through a low-head dam via the real-time monitoring of bedload transport over a weir in southeast Ireland. Critical discharge values for particle entrainment over the structure were derived from the novel use of a stationary RFID antenna, coupled with continuous recording of water levels and sediment captured downstream using pit-style sediment traps. The stationary RFID antenna was installed along a weir crest using both ‘pass-under’ and ‘pass-over’ configurations as a means of detecting the moment bedload tracers moved over the dam crest. Results show that 10% of tracers deployed upstream were detected passing over the weir, while a further 15% that were not detected were recovered downstream. These results indicate bedload material as large as the upstream D₇₀ (i.e., 90 mm) can move over the structure during infrequent high-flow events. However, thorough searches of the seeded area upstream of the dam also suggest that as many as 43% of the total number may have passed downstream, indicating that tracers moved over the weir after the antenna was damaged during a high-flow event, or were missed due to either particle velocity or signal collision. In addition, 30 of the tracers that remained upstream were shown to have either been buried due to the subsequent influx of sediment entering the reservoir, or were reworked though the surface material. Critical discharge values indicate size-selective transport patterns may dominate and a strong correlation between event peak discharge and total bedload captured downstream. These findings provide more evidence that low-head structures may eventually adopt a morphology that allows for the intermittent storage and later export of a channel's bedload downstream as hypothesized by other authors. Building upon these findings and those of other recent field studies, we present a set of possible schematic models that offer a basis for understanding the unique ways low-head dams can continue to disrupt sediment conveyance long after they have reached their functional storage capacity. The limitations of using a stationary RFID antenna and possible recommendations for future studies are discussed.

河流系统中的粗大泥沙输送在确定河内物理栖息地、产卵潜力和底栖群落结构方面起着重要作用。然而，尽管欧洲在根据水框架指令 (WFD) 恢复河流连续性方面有十多年的压力，但关于低水头、径流结构（即堰）如何破坏河流的实证研究相对较少。底物输送的过程和动力学。在这项研究中，我们通过实时监测爱尔兰东南部堰上的泥沙传输，对粗泥沙如何通过低水头大坝进行了调查。结构上颗粒夹带的临界放电值源自固定式 RFID 天线的新颖使用，再加上使用坑式沉积物捕集器对下游的水位和沉积物进行连续记录。固定式 RFID 天线沿着堰顶安装，使用“通过”和“通过”配置作为检测床载示踪剂在坝顶上移动的力矩的手段。结果表明，部署在上游的示踪剂中有 10% 被检测到通过了堰，而另外 15% 未被检测到的示踪剂在下游被回收。这些结果表明床载物质与上游一样大 而另外 15% 未被检测到的则在下游被回收。这些结果表明床载物质与上游一样大 而另外 15% 未被检测到的则在下游被回收。这些结果表明床载物质与上游一样大d ₇₀（即，90 毫米）可以在不频繁的高流量事件中移动到结构上。然而，对大坝上游播种区的彻底搜索也表明，多达 43% 的种子可能已经通过下游，这表明在高流量事件中天线损坏后示踪剂移动了堰，或者由于粒子速度或信号碰撞而错过。此外，30 个留在上游的示踪剂被证明要么由于随后进入水库的沉积物流入而被掩埋，要么通过表面材料进行了重新加工。临界流量值表明尺寸选择性的传输模式可能占主导地位，并且事件峰值流量与下游捕获的总床量之间存在很强的相关性。这些发现提供了更多的证据，表明低水头结构最终可能会采用一种形态，允许间歇性存储和随后向下游输出通道的底物，正如其他作者所假设的那样。在这些发现和其他近期实地研究的基础上，我们提出了一组可能的示意图模型，这些模型为理解低水头大坝在达到其功能存储容量后很长一段时间内继续破坏沉积物输送的独特方式提供了基础。讨论了使用固定 RFID 天线的局限性以及对未来研究的可能建议。我们提供了一组可能的示意图模型，这些模型为理解低水头大坝在达到其功能存储容量后很长一段时间内继续破坏沉积物输送的独特方式提供了基础。讨论了使用固定 RFID 天线的局限性以及对未来研究的可能建议。我们提供了一组可能的示意图模型，这些模型为理解低水头大坝在达到其功能存储容量后很长一段时间内继续破坏沉积物输送的独特方式提供了基础。讨论了使用固定 RFID 天线的局限性以及对未来研究的可能建议。