Storm surges kill more people than winds associated with tropical cyclones and than earthquake-triggered tsunamis and yet they are one of the most underestimated, misunderstood natural hazards.
Nearly all the casualties and the economic losses from both Hurricane Sandy (2013) and Typhoon Haiyan (2013) were due to water and waves rather than wind. These cases are far from unique – at least 2.6 million people have drowned in coastal flooding, particularly caused by storm surges, in the past 200 years.
Rising sea levels as a result of climate change and growing urban populations in coastal cities are likely to worsen the challenges.
The World Meteorological Organization is therefore involved in a series of initiatives to increase awareness of storm surges and to improve forecasting and warnings tools to protect communities and strengthen resilience in low-lying coastal areas. The aim is to strengthen flood forecasting and management and build integrated multi-hazard early warning and disaster response platforms.
The Coastal Inundation Forecasting Demonstration Project (CIFDP) has pilot initiatives in Bangladesh, Fiji and Indonesia with plans to expand these to other countries, including those in the Caribbean. Progress in implementing the projects was discussed at a meeting in Geneva from 14th to 16th May.
Both Bangladesh and Fiji are exceptionally vulnerable to coastal hazards, due to the low-lying coastal zones and exposure to frequent rainfall and tropical cyclone events. More than 350,000 people were killed by Cyclone Bhola in Bangladesh in 1970, and since then the country has introduced widespread and effective community-based disaster preparedness and response. Bangladesh hopes to benefit from the development of efficient forecasting and warning systems based on robust science as a result of the Coastal Inundation Forecasting Demonstration Project, said S.H.M. Fakhruddin.
The top-level scientists who have reviewed the progress of CIFDP projects said the experience of Bangladesh could be instructive for the Philippines, which is still reeling from Typhoon Haiyan, known locally as Yolanda. An estimated 6 000 people were killed in November 2013 by the typhoon, which was one of the strongest ever to make landfall.
Lessons from Haiyan and Sandy
A post-Haiyan assessment team of international experts visited the Philippines and Viet Nam in April 2014 and will present its findings to WMO’s Executive Council in June. Among the findings will be the need for clearer communication of risks and impacts.
The Philippine meteorological service, PAGASA, issued accurate advance warnings about the typhoon, including of storm surges up to 7 meters. But people failed to evacuate because they underestimated the devastation this would cause.
“People just didn’t understand what storm surge was,” said Paul Davies, chief meteorologist at the UK’s Met Office and a member of the assessment team. In the absence of mandatory evacuation procedures, he said that one of the survivors in the worst hit town of Tacloban told the team that “I would rather die with my refrigerator than let it be taken by a storm surge.”
The team also concluded that there is a need for a more integrated multi-hazard approach to warnings which have traditionally emphasized wind speed. Evacuation centers and cyclone shelters need to factor in the risk of storm surge and coastal inundation and so not be in areas at risk of flooding, said Davies.
A lack of public understanding of storm surges slowed the evacuation response during Sandy – which was no longer classed as hurricane force when it impacted on New York and New Jersey in October 2012.
Lessons from Sandy raised another essential issue on how the scientific and technical knowledge should be explained and delivered to the emergency management community. On an experimental basis starting with the 2014 hurricane season, the U.S. National Hurricane Centre will issue graphical forecasting for Probabilistic Storm Surge Heights, above ground level, describing areas of possible inundation by storm surges and tides. Developed over several years in consultation with broadcast meteorologists and others, the map will show land areas where, based on the latest forecast, storm surge could occur, and how high above ground the water could reach in those areas. The map will be updated every six hours in association with each full advisory package.
The U.S. National Hurricane Centre is planning to extend its support for the neighbouring countries in the North and Central American region as a whole, Jamie Rhome of the National Hurricane Center’s storm surge unit told the meeting.
The Coastal Inundation Forecasting Project is coordinated by the Joint WMO-Intergovernmental Oceanographic Commission’s Technical Commission for Oceanography and Marine Meteorology and the WMO Commission for Hydrology in order to meet the challenges of coastal communities’ safety and socio-economic sustainability through the development of coastal inundation forecasting and warning systems at the regional scale.