Erosion hazards in a changing climate: making inland communities more resilient

This modelling project aims to quantify how future climate scenarios will affect the frequency and severity of erosion hazards in catchments, the vulnerability of key rural infrastructure and how we might best mitigate their impact. This new understanding will be gained by addressing the following questions: (1) What are the risks posed to rural communities by the impacts of erosion hazards on water quality, infrastructure, ecosystem services and flooding?; (2) How vulnerable and resilient will our rural communities be to increased frequency and severity of erosion hazards in a changing climate?; (3) How will the decisions we make in erosion control affect the resilience and the sustainability of rural communities?
Society has entered a new era of climate change – one where the environmental consequences of warming are being observed and experienced directly, and in which the absence of timely, strategic intervention is taking us closer to more uncertain and potentially more catastrophic climatic impacts. Arguably the most severe impacts of climate change on rural and urban communities will be an increase in the frequency and severity of storms causing an increase in flooding and extreme erosion events. Whilst major advances have been made in the prediction of flood risks and the assessment of vulnerability and resilience of inland communities to flooding, no such major advance has occurred for erosion hazards. Thus no predictive modelling framework exists for erosion hazards that can support sustainable, resilient decision making within a warming climate. Yet the impacts of erosion hazards are of strategic national importance because they are wide ranging, costly and of critical importance to the vulnerability of communities. For example, erosion causes sedimentation in rivers (e.g. Somerset Levels 2014), urban drainage structures and flood defences (Defra, 2010), incurring high maintenance costs and reducing the resilience of drainage networks to future flooding (EA, 2002). Also, erosion causes considerable damage to key infrastructure such as bridges, flood defences and electricity pylons. The spillway collapse at Oroville Dam, California in 2017, due to slope erosion from heavy rainfall, costing more than $200M and causing flooding and the evacuation of over 200,000 people, is a timely reminder that storm-related erosion impacts are severe and far-reaching. Thus creating resilient, sustainable communities depends on understanding the potential future risks of changing erosion hazards and our ability to adapt to them.
Objectives: By developing a novel modelling framework, the project will achieve 3 objectives:
• Quantify the risks and uncertainty posed by erosion hazards in an uncertain changing climate, and their impacts on water quality, ecosystem services and flooding.
• Estimate the vulnerability and resilience of rural communities to erosion-hazard risks in a changing climate.
• Explore the feasibility of building resilience into the present-day infrastructure to create sustainable communities under future climate conditions, and for enhancing environmental health and resilience to flooding.
This new understanding will allow stakeholders to enhance mitigation strategies to provide more benefits for our societies; reducing hazard costs and improving environmental health, resilience to flooding and the sustainability of rural and urban communities.

Methods: The project will involve developing an existing erosion model (Coulthard et al., 2013) to provide two major advances in erosion risk analysis: (1) new capability to model erosion risk at the asset-scale (e.g. individual buildings, bridges, urban drainage components, electricity pylons); and (2) a paradigm shift from deterministic to stochastic approaches, through the development of a framework that provides estimates of erosion risk in terms of uncertainty in future climate scenarios.
The model will include three components, each driving the next: (1) a 2D rainfall-runoff model to resolve asset-scale hydraulics for sub-catchments ; (2) stochastic erosion model for the different slope and fluvial processes that transport and deposit sediment across components of a catchment (e.g. from hillslope to the river); (3) a risk-based model that maps areas and infrastructure at risk from extreme sediment erosion and sedimentation using tools developed by the supervisory team (Knight et al., 2015; Brown et al., 2018). New vulnerability, uncertainty and risk analyses (Balica et al., 2012) will be produced in combination with the new model.