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

地球气候正在变化，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)的频率和强度。当河流流动时，它们将沉积物从山坡输送到海岸，但驱动这种模式的过程、相互作用和反馈是复杂的(例如，莱尔和丘奇，2001)。特定地点的侵蚀或淤积程度较高，这反过来又可能对洪水风险产生影响；例如，通过减少淤积泥沙的渠道输送。人类活动改变或限制了在河流系统内发挥作用的地貌过程的自然平衡，这可能会加剧这种影响。自然复杂性、气候变化和人类影响相结合，使得对泥沙输送在洪水风险管理中的作用进行分离和建模具有挑战性(斯莱特，2016；希克斯等人，2020)。在英国，了解和缓解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署合作，以确定促进地貌引起的洪水风险变化(例如，泥沙淤积)的潜在因素(例如，集水区形态、河道限制、过去和现在的土地利用)。特别是，这位博士生将验证现有的地理空间数据集，预测英国河流当代侵蚀和淤积的位置，并对其进行实地验证。将确定高沉积的“热点”，并使用基于地理信息系统的荟萃分析来研究这些位置的类型，这些因素包括集水区地形、土地利用、历史和河道限制。将确定可以预测由淤积引起的洪灾风险增加的地区的共同特征，并将其用于告知可能受益于基于自然的管理解决方案以缓解洪灾风险增加的地点。该项目的发现将导致对流域广泛泥沙过程的驱动因素以及气候变化在微妙平衡的河流环境中的潜在影响的理解发生阶段性变化。与环境署直接合作的机会将确保将结果提供给英国当代的河流管理，确定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.