Presenter
Prof. Olli Varis, Aalto University
Co-author(s)
Dr. Maija Taka, Aalto University
Prof. Cecilia Tortajada, University of Glasgow
Date: Sept. 12th Session No.: RS 13 Theme: 3-7 Submission No.: O-3-7-2
Sub-theme
3. Building Resilience for Disaster Prevention and Mitigation
Topic
3-7. Management of water risks induced by extreme weather and climate events
Body
Urban floods and storm surges, resulting from a synergy of population concentration, land cover change, and environmental change, affect huge and ever-growing populations across the world. The global quantification of their extent is, however, still blurred. The present, soaring high-resolution data availability allows obvious albeit still sparsely investigated and harnessed possibilities for improving disaster risk preparedness. We provide a global synthesis of urban populations’ exposure to riverine floods and storm surges in 1990 and 2015 by using the EU/JRC’s Global Human Settlement Layer (GHSL) dataset, complemented with The World Bank’s World Development Indicator data. Our study reveals that, while the total number of people affected has increased, most of the exposure has shifted from low-income to middle-income countries. This is due to the rapid economic development in a large part of the world’s flood and storm surge prone urban areas. Whereas 70% of the planet’s flood-exposed urban population was from low-income countries, this figure was only 4% in 2015, with the middle-income category growing accordingly. A similar trend was observed for tropical storm surges, where the affected population in low-income countries decreased from 50% to 3% for the same years. Countries in Asia have been the most affected by these events with 75% of exposure to urban riverine floods, and 80% to tropical storm surges. In many rapidly developing countries and urban centers, there has been considerable progress regarding disaster risk reduction strategies. This has been mainly due to national and local authorities, policymaking and implementation, and funding of risk reduction strategies. However, the total growth of human exposure suggests that disaster risk reduction policies and implementation call for enduring effort. Finally, we reflect on the vast potential for enhancing the use of spatial data infrastructure to inform policies as proposed by the Sendai Framework and the post 2015 Agenda of the United Nations.