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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覆盖式泥炭恢复：对提供自然洪水管理效益的基本过程进行数值研究
DOI：
10.1002/essoar.10505089.1
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发表时间：
2020
期刊：
影响因子：
--
通讯作者：
Goudarzi S
中科院分区：
文献类型：
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作者：
Goudarzi S
据观察，水源毯泥炭恢复活动，特别是植被重建和沟堵，提供了显着的自然洪水管理（NFM）的好处。最近的一项前-后-控制-干预（BACI）实验表明，这些干预措施减少了洪峰，增加了滞后时间，但控制这些影响的过程仍不清楚。我们试图确定这些过程在同一BACI网站通过反转TOPMODEL的全径流模型，并通过严格的校准连接到模型参数在每个流域的干预响应。通过数值实验，我们推断出最有可能驱动BACI观测的过程。我们的研究结果证实了这些以预防为重点的干预措施的NFM益处。独立的风暴大小/干预，增加的滞后几乎完全是由于表面粗糙度降低洪水波的速度。我们将其概念化为“移动的”表面存储。在与洪水相关的风暴中，两种干预措施中至少有90%的峰值降低是通过移动的存储实现的。由于沟道堵塞而造成的移动的储存量的额外增加非常显著，与单独的重新植被相当。干预措施对“不动”存储（拦截+积水+蒸散）的影响变得重要的较小的风暴，其中植被减少峰值流量增加蒸散，但不是拦截存储。然而，沟道阻塞增加了积水，但减少了蒸发，因此，相对于单独的重新植被，集水区固定储存没有净收益。虽然干预措施总是增加滞后时间，他们可以在降低峰值幅度在长时间的正面风暴有效性较低。我们提出了两种方法，以进一步增加集水区的表面存储，同时坚持恢复的要求，以保持水位高。
Headwater blanket-peat restoration activities, in particular revegetation and gully-blocking, are observed to deliver significant Natural Flood Management (NFM) benefits. A recent Before-After-Control-Intervention (BACI) experiment showed that these interventions reduce flood-peaks and increase lag-times, but the processes controlling these effects remain unclear. We seek to identify these processes at the same BACI sites by inverting the TOPMODEL rainfall-runoff model and linking the response-to-intervention in each catchment to model parameters through rigorous calibration. Through numerical experiments, we infer processes most likely to be driving the BACI observations. Our findings confirm the NFM benefits of these restoration-focused interventions. Independent of storm size/intervention, the increased lag is almost entirely due to surface roughness reducing the floodwave speed. We conceptualise this as a ‘mobile’ surface storage. In flood-relevant storms, at least 90\% of the peak reduction in both interventions is delivered by mobile storage. The additional increase in the mobile storage due to gully-blocking is very significant and comparable to that of revegetation alone. The impact of interventions on ‘immobile’ storage (interception+ponding+evapotranspiration) becomes important for smaller storms, in which revegetation reduces peak discharge by increasing evapotranspiration but the not interception storage. Gully blocking however, increases ponding but reduces evaporation, such that there is no net gain in catchment immobile storage relative to revegetation alone. Although interventions always increase lag-times, they can be less effective in reducing peak magnitude in long duration frontal rainfalls. We propose two approaches to further increase catchment’s surface storage, while adhering to the restoration requirement to keep the water tables high.