Contrasting seasonality of storm rainfall and flood runoff in the UK and some implications for rainfall-runoff methods of flood estimation
Contrasting seasonality of storm rainfall and flood runoff in the UK and some implications for rainfall-runoff methods of flood estimation
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DOI：
10.2166/nh.2019.040
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发表时间：
2019-08
影响因子：
2.7
通讯作者：
Jamie Ledingham;David Archer;E. Lewis;H. Fowler;C. Kilsby
中科院分区：
文献类型：
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作者：
Jamie Ledingham;David Archer;E. Lewis;H. Fowler;C. Kilsby
利用英国520个测量站的数据和网格化的降雨数据集，对暴雨和洪水径流的季节性进行了比较和绘制。年最大日降雨量（AMAX）主要发生在夏季，而AMAX洪水最常发生在冬季。在干旱低地集水区，年日降雨量和洪水最大值的季节性出现率相差超过50%。差异随着集水区湿度的增加而减小，随着降雨量小于日持续时间而增加，并主要取决于集水区湿度，如年平均降雨量的变化所示。在整个数据集中，只有34%的AMAX日洪水事件与年最大日降雨量相匹配（只有20%与6小时最大降雨量相匹配）。降雨量最大值与洪水之间的不连续性可以通过考虑土壤含水量的一致性来解释。这些结果对英国洪水风险估算的降雨-径流方法具有重要意义，因为英国的估算基于高度偏向于夏季的降雨深度-持续时间-频率模型。结果表明，对降雨和土壤湿度的季节性处理不足严重降低了英国基于事件的洪水估计的可靠性。
Using data from 520 gauging stations in Britain and gridded rainfall datasets, the seasonality of storm rainfall and flood runoff is compared and mapped. Annual maximum (AMAX) daily rainfall occurs predominantly in summer, but AMAX floods occur most frequently in winter. Seasonal occurrences of annual daily rainfall and flood maxima differ by more than 50% in dry lowland catchments. The differences diminish with increasing catchment wetness, increase with rainfalls shorter than daily duration and are shown to depend primarily on catchment wetness, as illustrated by variations in mean annual rainfall. Over the whole dataset, only 34% of AMAX daily flood events are matched to daily rainfall annual maxima (and only 20% for 6-hour rainfall maxima). The discontinuity between rainfall maxima and flooding is explained by the consideration of coincident soil moisture storage. The results have serious implications for rainfall-runoff methods of flood risk estimation in the UK where estimation is based on a depth–duration–frequency model of rainfall highly biased to summer. It is concluded that inadequate treatment of the seasonality of rainfall and soil moisture seriously reduces the reliability of event-based flood estimation in Britain.