Blanket Peat Restoration: Numerical Study of the Underlying Processes Delivering Natural Flood Management Benefits
Blanket Peat Restoration: Numerical Study of the Underlying Processes Delivering Natural Flood Management Benefits
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DOI：
10.1029/2020wr029209
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发表时间：
2020-12
影响因子：
5.4
通讯作者：
Salim Goudarzi;D. Milledge;J. Holden;M. Evans;T. Allott;E. Shuttleworth;M. Pilkington;J. Walker
中科院分区：
文献类型：
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作者：
Salim Goudarzi;D. Milledge;J. Holden;M. Evans;T. Allott;E. Shuttleworth;M. Pilkington;J. Walker
据观察，通过重新植被和沟渠堵塞来恢复被侵蚀的覆盖泥炭地也可以带来显着的自然洪水管理（NFM）效益（减少和延迟洪峰）。但对于不同的流域过程在每种干预情景下如何相互作用/抵消，缺乏清晰的理解。我们力求通过严格校准 TOPMODEL 降雨径流模型来提供更多见解，以适应不同的实验集水区，每个集水区代表一个干预场景。通过使用校准参数进行数值实验，我们估计了不同过程的影响幅度。我们的研究结果证实了这些以恢复为重点的干预措施的 NFM 益处。在这两种干预措施和我们最大的风暴中，洪水峰值的延迟和减少主要是由于表面粗糙度降低了洪水波速度，从而使地表径流变厚；我们将其概念化为“运动存储”的增加。沟渠堵塞对增加运动储存的影响非常显着，与单独的植被恢复的影响相当。干预措施对“静态储存”（拦截+积水+蒸散）的影响对于较小的风暴来说变得很重要。尽管干预措施总是会增加滞后时间，但当最大降雨强度持续时间长于平均流域延迟时，它们在降低峰值强度方面可能不太有效。我们提出了两种方法来进一步增加流域的静态和运动存储。最后，虽然我们的现场规模数值研究有助于为 NFM 有效性提供证据基础，但它也为未来对这些干预措施进行建模提供了基础。这种流域规模的数值研究对于将我们的研究结果扩展到洪水可能造成社会经济损害的空间尺度是必要的，并为优化这些干预措施的分布式配置提供工具。
Restoration of eroded blanket peatlands through revegetation and gully blocking is observed to also deliver significant natural flood management (NFM) benefits (reduce and delay floodpeaks). But there is a lack of clear understanding regarding how different catchment processes interact/counteract under each intervention scenario. We seek to provide more insight by rigorously calibrating TOPMODEL rainfall‐runoff model to different experimental catchments each representing an intervention scenario. Through numerical experimentation with the calibrated parameters, we estimate the impact‐magnitude of different processes. Our findings confirm the NFM benefits of these restoration‐focused interventions. In both interventions and in our largest storms, both the delay and reduced floodpeaks are primarily due to surface roughness reducing the floodwave speed thus thickening the overland flow; we conceptualize this as an increase in a “kinematic storage.” Impact of gully blocking in increasing kinematic storage is very significant and comparable to that of revegetation alone. Interventions' impact on “static storage” (interception + ponding + evapotranspiration) becomes important for smaller storms. Although interventions always increase lag times, they can be less effective in reducing peak magnitude when maximum rainfall intensity is sustained for durations longer than mean catchment delay. We propose two approaches to further increase catchment's static and kinematic storage. Finally, while our field‐scale numerical study contributes to the evidence‐base for NFM's effectiveness, it also provides a basis for modeling these interventions in the future. Such catchment‐scale numerical studies are necessary to extend our findings to spatial scales where flooding can cause socioeconomic damage, and to provide a tool for optimizing the distributed configuration of these interventions.