Improving flood risk assessment in flashy catchments under a changing climate

我的博士学位将建立在之前在纽卡斯尔大学的工作基础上，该工作收集了英国各地计量器的次小时降雨数据，并利用这些数据重新分析降雨事件概况，从而衍生出六种雨形仪形状，用于更新设计降雨概况。我的博士学位最初旨在调查极端降雨事件，以评估降雨剖面形状与温度的关系，以便以此作为气候变化可能对未来降雨产生影响的指示。除了从收集的测量记录中评估观测到的降雨数据外，我的博士学位还将分析和比较对流允许模型模拟结果的降雨剖面。气候模式的进步使高分辨率模式能够代表云中的对流等小规模影响，从而提供更准确的预测。虽然计算要求意味着这更局限于本地而不是全球，但对于我专注于英国的博士学位来说，这是可以接受的。博士的下一阶段将是使用ReFH2软件从更新的降雨剖面中导出洪水水文图，六种设计的水文图形状，并将它们与洪水研究报告（FSR）中现有的两种水文图形状进行比较，这是英国水文分析的当前标准形状。两个FSR曲线都有一个对称的单峰钟形，它不随风暴持续时间或位置而变化，但冬季风暴的形状更宽，更低，夏季风暴的形状更峰，更高。六个更新的剖面包括三个水平变化的前加载、中心（对称）和后加载形状，以及两个垂直变化的每个剖面加载的更高和更低的峰值版本。洪水水文测试将主要集中在小而浮华的集水区，因为这些集水区对降雨事件最敏感，尤其是可能受到气候变化高度影响的短时强降雨。预计将对大约20个集水区进行测试，使用洪水估算手册（FEH）网络服务的描述数据。博士学位的最后阶段将是在水文和/或水力模型模拟中应用降雨剖面，如纽卡斯尔的SHETRAN、CityCAT或HiPIMS软件，以评估不同剖面形状对洪水风险的影响。如果时间允许，将对模型地形进行进一步的模拟，以反映自然洪水管理干预措施，目的是评估如何最好地适应气候变化的影响。建议对文献中使用的将气候变化应用于洪水风险估计的方法进行回顾，以便为我的博士学位提供气候变化应用的信息。本博士课程的成果将更新目前对洪水风险的认识，从而有助于在未来的洪水管理项目中应用适当的设计风暴，并可能为相关测试情景的洪水风险评估提供指导。

My PhD will build on previous work at Newcastle University which had collected sub-hourly rainfall data from gauges across Great Britain and used this to re-analyse rainfall event profiles resulting in derivation of six hyetograph shapes for the purpose of updating design rainfall profiles. My PhD initially aims to investigate extreme rainfall events to assess how rainfall profile shapes are related to temperature, in order to use this as an indication of the effect climate change may be expected to have on future rainfall. In addition to the assessment of observed rainfall data from the collected gauge records, my PhD will also analyse and compare rainfall profiles from convection permitting model simulation results. Advances in climate modelling have enabled high resolution models which can represent small-scale effects such as convection in clouds and thus give more accurate predictions. Although computational requirements mean this is more limited to local areas than globally, this is acceptable for my PhD which is focussed on Britain. The next stage of the PhD will be to use ReFH2 software to derive flood hydrographs from the updated rainfall profiles six design hyetograph shapes and compare them to the existing two hyetograph shapes from the Flood Studies Report (FSR), which are the current standard shapes for hydrological analysis in Britain. The two FSR profiles both have a symmetric, single-peaked bell-shape, which does not vary with storm duration or location but has a broader, lower shape for winter storms, and a peakier, higher shape for summer storms. The six updated profiles comprise three horizontal variations of front-loaded, centre (symmetrical) and back-loaded shapes and two vertical variations giving more-peaked and less-peaked versions of each of the profile loadings. The flood hydrograph testing will be predominantly focussed on small, flashy catchments since these are most responsive to rainfall events, in particular short, intense rainfall which is likely to be highly affected by climate change. It is anticipated that approximately 20 catchments will be tested, using descriptor data from the Flood Estimation Handbook (FEH) web service. The last stage of the PhD will be to apply the rainfall profiles in hydrological and/or hydraulic model simulations, such as Newcastle's SHETRAN, CityCAT or HiPIMS software, to assess the effect of the different profile shapes on flood risk. If time allows, further simulations will be undertaken with the model terrain adjusted to reflect natural flood management interventions with the aim of assessing how best to adapt catchments for the effects of climate change. It is proposed to undertake a review of methods used in the literature to apply climate change in flood risk estimation in order to inform application of climate change for my PhD. The outputs of this PhD will provide an update to current understanding of flood risk and hence help inform application of appropriate design storms for future flood management projects and potentially contribute to guidance for flood risk assessment on relevant scenarios to test.