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

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.