Working with natural processes to adapt to climate change and to reduce flood risk

地球的气候正在发生变化，改变了河流水流的季节性水文状况以及极端事件（风暴和洪水）的频率和程度。当河流流动时，它们将沉积物从山坡运送到海岸，但驱动这种模式的过程、相互作用和反馈是复杂的（例如，Lisle和Church， 2001）。特定地点的侵蚀或侵蚀程度加剧，这反过来又可能对洪水风险产生影响；例如，通过减少泥沙积聚的河道输送。人类活动可能会改变或限制河流系统中起作用的地貌过程的自然平衡，从而加剧这种影响。自然复杂性、气候变化和人类影响的结合，使得泥沙路径在洪水风险管理中的作用难以理清并建立模型（Slater, 2016; Hicks et al., 2020）。在英国，了解和减轻洪水风险的变化是实施有效和适当的河流管理的关键问题（国家洪水和海岸侵蚀风险管理战略，2020）。该博士项目将与环境局合作，确定促进由地貌引起的洪水风险变化（如沉积物沉积）的潜在因素（如集水区形态、河道限制、过去和现在的土地利用）。特别是，博士生将验证和实地核实现有的地理空间数据集，该数据集预测了英国河流当代侵蚀和退化的位置。将确定高淤积的“热点”，并使用基于gis的集水区地形、土地利用、历史和河道限制等因素的荟萃分析来检查这些地点的类型。将确定可预测由沉积引起的洪水风险增加地区的共同特征，并用于通知可能受益于基于自然的管理解决方案的地点，以减轻洪水风险增加。该项目的研究结果将有助于理解流域沉积物过程的驱动因素，以及气候变化对微妙平衡的河流环境的潜在影响。有机会直接与环境署合作，将确保研究结果适用于英国的当代河流管理，识别并减轻当前和未来地质灾害的风险。

The Earth's climate is changing, altering the seasonal hydrological regime of water flow in rivers and the frequency and magnitude of extreme events (storms and floods). As rivers flow, they transport sediment from the hillslopes to the coast but the processes, interactions and feedbacks that drive this pattern are complex (e.g., Lisle and Church, 2001). Specific locations experience heightened levels of erosion or aggradation, which in turn can have implications for flood risk; for example, via a reduction in channel conveyance where sediment accumulates. Such impacts can be exacerbated by human activity that alters or limits the natural balance of geomorphic-processes at work within river systems. The combination of natural complexity, climate change and human influence make it challenging to disentangle and model the role of sediment routing in flood risk management (Slater, 2016; Hicks et al., 2020).In the UK, understanding and mitigating the change in flood risk is a critical problem for implementing effective and appropriate river management (National Flood and Coastal Erosion Risk Management Strategy, 2020). This PhD project will work with the Environment Agency to identify the underlying factors (e.g., catchment morphology, channel confinement, past and present land use) that promote geomorphic-induced changes in flood risk (e.g., sediment aggradation). In particular, the PhD student will validate and ground-truth an existing geospatial data set of predicted locations of contemporary erosion and aggradation in UK rivers. 'Hotspots' of high aggradation will be identified, and the typology of these locations examined using a GIS-based meta-analysis of factors such as catchment topography, land use, history, and channel confinement. Common characteristics that could predict areas of heightened flood risk induced by aggradation will be identified and used to inform locations which may benefit from nature-based management solutions to mitigate heightened flood risk. The findings from this project will lead to a step-change in the understanding of the drivers of catchment wide sediment processes, and the potential impacts of climate change in delicately balanced river environments. The opportunity to work directly with the Environment Agency will ensure that the results feed into contemporary river management in the UK, identifying and mitigating the risk of current and future geohazards.