Major increases in Asia Pacific flood exposure by 2020



In a recent study undertaken by JBA Risk Management, findings suggest that some rapidly growing Asian cities may see increases of up to 36% in the population at risk of extreme river and surface water flooding by 2020. 


The Asia Pacific region, more commonly referred to as APAC, has over half of the world’s total population. Among the 26 countries making up this territory, several host many of the world’s most populous cities and rapidly emerging insurance markets. Given that several of these cities lie next to major river systems, prone to extreme flood events, JBA Risk Management assessed some of the potential broad scale impacts future flooding could pose in the region.


The study has initially focused on four principal Asian cities; Jakarta, Bangkok, Manila, and Singapore. JBA’s 30m resolution global flood maps (GFMTM) were then compared to high resolution population density projections to estimate the exposed population in both 2010 and 2020. The findings highlight that significant population increases are projected for all four Asian cities and that the number of people exposed to extreme river and surface water flooding (classified using the 1/200 year maps) could increase by over 30% in the 10 year period from 2010 to 2020. When compared to the JBA river flood extent for a 1/200 year return period, Bangkok and Jakarta show population exposures of 5.3 million and 5.2 million. This would represent a 36% and 33% rise from 2010 levels respectively. Manila could see increases of around 27%, whilst Singapore was the lowest at 17%. Similar increases were noted for surface water as well.

The study made use of UN projected population density data from the Worldpop project (www.worldpop.org), an open initiative aimed at providing spatial demographic datasets at 100m resolution for multiple years including 2010 and 2020. Using a Geographical Information System (GIS), the JBA River and Surface water (30m resolution) hazard maps were compared to the Worldpop projections, together with CRESTA boundaries to determine the cumulative population at risk.

With total gross premium increases in APAC averaging 6.6% annually from 2002-2014, study findings further highlight the growing insured flood risk exposure in the region and the subsequent challenges this poses for risk management.

The JBA Risk Management study also supports similar findings from other research on global flooding. The World Resources Institute issued a report in March 2015 highlighting how climate change and demographic increases alone would more than double annual global river flood risk from 2015-2030 (http://www.wri.org). Thailand and Indonesia were identified in the top 15 countries accounting for 80% of this increase.

Note: JBA figures quoted in this research refer to the 10-year change from 2010-2020 and do not account for the differential flood depth within the exposed area, which would differ markedly. Likewise, it is important to note that a 1/200 year flood represents an extreme level of flooding. 

Author: Iain Willis

Flood in Focus