Risks, adaptation and resilience on coasts and in cities
A vast majority of the world’s population live in cities and along coasts. As a consequence, these areas are full of property developments, infrastructure and industries worth trillions of dollars. People and property along coasts and in cities are increasingly vulnerable to disasters caused by extreme weather events that are getting more common due to climate change. Hazards commonly faced by communities living in these areas include floods, erosion, water shortages, extreme heat and more.
Water-related disasters along coasts and cities are costly, both in terms of lives and in terms of economic damage. Therefore, governments and humanitarian organizations are increasing efforts to prevent, prepare for and mitigate the consequences of such events. In addition to the immediate harm, such disasters cause long-term indirect risks such as loss in productivity and effects on human health and the environment. Risk-reduction strategies are therefore needed urgently in these areas.
Flooding is becoming increasingly common. In 2010, one billion people lived in areas with high flood risk, a number expected to rise to 1.6 billion by 2050
Most of this increase is due to people living near rivers that might flood, although the impact of coastal flooding is also projected to increase rapidly in the 2nd half of the 21st century.
Sandy beaches and mangroves provide a first line of defence against floods and other coastal storm impacts, and they also provide other ecosystem services such as ecological habitats and recreation areas. But they often are at risk: many of the world’s coastlines suffer erosion due to sand mining, sea-level rise and coastal structures that interrupt the alongshore sand transport.
Key research
With appropriate numerical models, sound, science-based strategies for managing complex sandy coasts can be developed.
Paper 'Modelling storm impacts on beaches, dunes and barrier islands'
Journal of Coastal Engineering
Paper 'Estimating coastal recession due to sea level rise: beyond the Bruun rule'
Journal of Climatic Change
Paper 'Climate-change impact assessment for inlet-interrupted coastlines'
Nature Climate Change
Paper 'Efficient Modeling of Complex Sandy Coastal Evolution at Monthly to Century Time Scales'
Frontiers in Marine Science Journal
Paper 'Probabilistic projections of the stability of small tidal inlets at century time scale using a reduced complexity approach'
Nature Scientific Reports
Challenges
IHE Delft addresses challenges related to risks, adaptation and resilience along coasts and in cities by focusing on three main questions:
- How can we increase the present-day and future resilience of coasts and urban areas, considering the uncertainties associated with climate change, human activities and other drivers? What are the ways in which resilience can be used as a driver for sustainable development? Through which pathways can we achieve this target?
- How can we unlock the economic potential of multifunctional (green) infrastructure in coastal zones and in urban areas? How can the economic value of the benefits they bring be determined and recognized? What role could green infrastructure play in integrating coastal zone development and urban functions?
- How will climate change impact coasts and urban areas, and how can we quantify such impacts? What quantitative tools and approaches do we need to develop to enable a shift from scenario-based decision making to risk-informed decision making?
Research activities
- Generation of the state-of-the-art projections of climate change hazards at global, regional and country scale
- Development of state-of-the-art detailed and reduced complexity impact models to assess coastal erosion, coastal flooding, river flooding and urban flooding at different spatio-temporal scales
- Probabilistic hazard modelling and quantitative risk assessment at local scale
- Long term (multi-century) process-based modelling of estuarine dynamics
- Nature-based solutions to enhance coastal and urban resilience at different time scales
- Integrated coastal zone and urban flood risk management
IHE Delft experts use a combination of numerical modelling (at global, regional and local scales), data analysis (remote sensing, reanalyses, field data) and stakeholder engagement to provide state-of-the-art insights and advice geared for on-the-ground decision making for coastal and urban planning, engineering and policy development.
The 6th assessment report of the Intergovernmental Panel on Climate Change
The IPCC 6th assessment report provides the most updated and comprehensive understanding of the climate system and climate change, both now and into the future.
Highlighted publication
Summary of the 2021 IPCC climate change report
This document is a plain-language summary of the IPCC Working Group I climate change report released in August 2021. It was written by members of the Working Group I Technical Support Unit (WGI TSU) and several authors of the report. The 'Summary for All' is meant for policymakers and others who want to learn and contribute to immediate climate action. Roshanka Ranasinghe, IHE Delft's Professor of Climate Change Impacts & Coastal Risk, contributed to the summary and is a member of the IPCC Working Group 1 Technical Support Unit.
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