Urban areas exposed to floods, droughts globally could at least double by 2030: research

The extent of urban areas exposed to floods and droughts, even without climate change, would at least double by 2030, suggests a new research paper appearing the March 2015 edition of Global Environmental Change.

Research authors Burak Güneralpa, Inci Güneralpa and Ying Liu note in Changing global patterns of urban exposure to flood and drought hazards that they considered the changing exposure of urban infrastructure to floods and droughts as a result of urban land expansion between 2000 and 2030.

“Overall, without factoring in the potential impacts from climate change, the extent of urban areas exposed to flood and drought hazards will increase, respectively, 2.7 and almost 2 times by 2030,” notes the study abstract.

Calling their estimates a first for the period, the authors report accurate estimates of potential losses due to changing exposure requires knowledge of where cities will grow in the future. As it stands, “studies that quantify the human and economic costs of increasing exposure of cities to various natural hazards consider climate change together with increasing levels of population and economic activity, but assume constant urban extent,” the abstract states.

The estimates indicate that while the percentage of the global urban land that lies within the low elevation coastal zone (LECZ) increases only slightly to 13% by 2030, this corresponds to a 230% increase in the amount of urban land within the LECZ. In 2000, the abstract states, about 30% of the global urban land was located in the high-frequency flood zones; by 2030, this will reach 40%.

“Globally, urban land exposed to both floods and droughts is expected to increase over 250%,” the abstract notes, but adds there are significant geographical variations in the rates and magnitudes of urban expansion exposed to floods or droughts or both.

For example, the authors report that the emerging coastal metropolitan regions in Africa and Asia will be larger than those in the developed countries and will have larger areas exposed to flooding.

Existing policy options to safeguard urban infrastructure from flood and drought hazards include directing development away from flood- or drought-prone zones, as well as large-scale adoption of “green infrastructure.”

“Decisions, taken today on managing urban growth in locations exposed to these hazards, can make a big difference in mitigating likely losses due to floods and droughts in the near future,” the authors conclude.