Puttock Alan, Graham Hugh A, Ashe Josie, Luscombe David J, Brazier Richard E
Centre for Resilience in Environment, Water and Waste (CREWW), Geography, College of Life and Environmental Sciences University of Exeter Exeter UK.
Hydrol Process. 2021 Feb;35(2):e14017. doi: 10.1002/hyp.14017. Epub 2021 Jan 1.
Beavers can profoundly alter riparian environments, most conspicuously by creating dams and wetlands. Eurasian beaver () populations are increasing and it has been suggested they could play a role in the provision of multiple ecosystem services, including natural flood management. Research at different scales, in contrasting ecosystems is required to establish to what extent beavers can impact on flood regimes. Therefore, this study determines whether flow regimes and flow responses to storm events were altered following the building of beaver dams and whether a flow attenuation effect could be significantly attributed to beaver activity. Four sites were monitored where beavers have been reintroduced in England. Continuous monitoring of hydrology, before and after beaver impacts, was undertaken on streams where beavers built sequences of dams. Stream orders ranged from 2nd to 4th, in both agricultural and forest-dominated catchments. Analysis of >1000 storm events, across four sites showed an overall trend of reduced total stormflow, increased peak rainfall to peak flow lag times and reduced peak flows, all suggesting flow attenuation, following beaver impacts. Additionally, reduced high flow to low flow ratios indicated that flow regimes were overall becoming less "flashy" following beaver reintroduction. Statistical analysis, showed the effect of beaver to be statistically significant in reducing peak flows with estimated overall reductions in peak flows from -0.359 to -0.065 m s across sites. Analysis showed spatial and temporal variability in the hydrological response to beaver between sites, depending on the level of impact and seasonality. Critically, the effect of beavers in reducing peak flows persists for the largest storms monitored, showing that even in wet conditions, beaver dams can attenuate average flood flows by up to ca. 60%. This research indicates that beavers could play a role in delivering natural flood management.
河狸能够深刻改变河岸环境，最显著的方式是建造水坝和湿地。欧亚河狸（）的数量正在增加，有人认为它们可以在提供多种生态系统服务方面发挥作用，包括自然洪水管理。需要在不同尺度、不同生态系统中开展研究，以确定河狸在多大程度上能够影响洪水状况。因此，本研究确定在河狸建造水坝后，水流状态和对风暴事件的水流响应是否发生了改变，以及水流衰减效应是否可显著归因于河狸活动。在英格兰对四个河狸被重新引入的地点进行了监测。在河狸建造了一系列水坝的溪流上，对河狸影响前后的水文情况进行了持续监测。溪流等级从二级到四级，涵盖农业和森林主导的集水区。对四个地点的1000多次风暴事件进行分析后发现，总体趋势是总风暴流量减少、降雨峰值到流量峰值的滞后时间增加、峰值流量降低，所有这些都表明在河狸影响后出现了水流衰减。此外，高流量与低流量之比降低表明，河狸重新引入后水流状态总体上变得不那么“湍急”。统计分析表明，河狸对降低峰值流量的影响在统计上具有显著性，各地点峰值流量估计总体减少幅度为-0.359至-0.065米/秒。分析表明，各地点对河狸水文响应的时空变异性取决于影响程度和季节性。至关重要的是，对于监测到的最大风暴，河狸降低峰值流量的效果依然存在，这表明即使在潮湿条件下，河狸水坝也能使平均洪水流量衰减多达约60%。这项研究表明，河狸可以在实现自然洪水管理方面发挥作用。
