A Dutch-Texan team found that most Houston-area drowning deaths from Hurricane Harvey occurred outside the zones designated by government as being at higher risk of flooding: the 100- and 500-year floodplains. Harvey, one of the costliest storms in US history, hit southeast Texas on 25 August 2017 causing unprecedented flooding and killing dozens. Researchers at Delft University of Technology in the Netherlands and Rice University in Texas published their results today in the European Geosciences Union journal Natural Hazards and Earth System Sciences.
“It was surprising to me that so many fatalities occurred outside the flood zones,” says Sebastiaan Jonkman, a professor at Delft’s Hydraulic Engineering Department who led the new study.
Drowning caused 80% of Harvey deaths, and the research showed that only 22% of fatalities in Houston’s 4,600-square-kilometre district, Harris County, occurred within the 100-year floodplain, a mapped area that is used as the main indicator of flood risk in the US.
Flood zones, or floodplains, are low-lying areas surrounding rivers and streams that are subject to flooding. To assess flood risk for insurance purposes and to set development standards, US authorities outline floodplains for 100- and 500-year floods. These events have a 1% probability (100-year flood) and a 0.2% probability (500-year) of occurring in any given year.
“Hurricane Harvey was much larger than a 100- or 500-year flood, so flooding outside of these boundaries was expected,” says Jonkman. Rainfall totals in the week after the hurricane made landfall were among the highest recorded in US history, with over 1000 mm of rain falling in just three days in large parts of both Harris and surrounding counties. As a result, a report by Delft University found that “unprecedented flooding occurred over an area the size of the Netherlands.”
Nonetheless, it was surprising for the researchers to find that so many of Harvey’s fatalities happened outside the designated floodplains given that these zones are expected to be “reasonable predictors of high-risk areas,” according to Jonkman.
The research began within days of the storm: “We wanted to identify lessons that could be learned, for both Texas and the Netherlands, from Harvey’s impact and the local and government response to the flooding,” says study co-author Antonia Sebastian, a postdoctoral research associate at Rice University’s Severe Storm Prediction, Education and Evacuation from Disasters (SSPEED) Center, who was based at Delft University when Harvey struck.
The team compiled a database of fatalities, using official government records and media sources, which they analysed in the Natural Hazards and Earth System Sciences study published today. They concluded that at least 70 deaths occurred as a consequence of Hurricane Harvey, including 37 in Harris County. Of the Harris County deaths, eight were in the 100-year floodplain, 10 more fell within the larger 500-year floodplain, and 19 were recovered outside the 100- and 500-year zones. “The number of fatalities outside of the floodplains highlights how widespread flooding from Harvey really was,” says Sebastian.
The new study also shows that most fatalities – over 80% – were drownings, many occurring either in vehicles or when people were swept away while trying to get out of their cars. Six people died when their boat capsized during a rescue. The second largest causes of death were electrocution and lack of medical treatment, responsible for 6% of fatalities each.
About 70% of those killed by Harvey were men. The team thinks the reason behind the high percentage of male fatalities could be that men tend to show more risk-taking behaviour, such as driving through flooded crossings or taking part in rescues.
The researchers hope their findings encourage authorities to identify high risk areas outside of the designated floodplains and to take preventive measures to reduce the number of victims in future floods, including closing low water crossings and underpasses during extreme flood events.
Jonkman says that the current flood maps will need to be improved, but that floodplains should not be abandoned as an indicator of high-risk areas. “Better communication of their purpose and limitations would help reduce risk.”
Please mention the name of the publication (Natural Hazards and Earth System Sciences) if reporting on this story and, if reporting online, include a link to the paper (https://doi.org/10.5194/nhess-18-1073-2018) or to the journal website (https://www.natural-hazards-and-earth-system-sciences.net).
This research is presented in the paper ‘Brief communication: Post-event analysis of loss of life due to hurricane Harvey’ to appear in the EGU open access journal Natural Hazards and Earth System Sciences on 19 April 2018.
The scientific article is available online, free of charge, from the publication date onwards, at https://doi.org/10.5194/nhess-18-1073-2018. A pre-print version of the final paper is available for download at https://www.egu.eu/news/401/hurricane-harvey-dutch-texan-research-shows-most-fat... (scroll down to the Media section)
Citation: Jonkman, S. N., Godfroy, M., Sebastian, A., and Kolen, B.: Brief communication: Loss of life due to Hurricane Harvey, Nat. Hazards Earth Syst. Sci., 18, 1073–1078, https://doi.org/10.5194/nhess-18-1073-2018, 2018.
The European Geosciences Union (EGU) is is Europe’s premier geosciences union, dedicated to the pursuit of excellence in the Earth, planetary, and space sciences for the benefit of humanity, worldwide. It is a non-profit interdisciplinary learned association of scientists founded in 2002 with headquarters in Munich, Germany. The EGU has a current portfolio of 18 diverse scientific journals, which use an innovative open access format, and organises a number of topical meetings, and education and outreach activities. Its annual General Assembly is the largest and most prominent European geosciences event, attracting over 14,000 scientists from all over the world. The meeting’s sessions cover a wide range of topics, including volcanology, planetary exploration, the Earth’s internal structure and atmosphere, climate, energy, and resources. The EGU 2019 General Assembly is taking in Vienna, Austria, from 7 to 12 April 2019. For more information, please check http://media.egu.eu closer to the time of the event, or follow the EGU on Twitter (@EuroGeosciences) and Facebook (EuropeanGeosciencesUnion).
If you wish to receive our press releases via email, please use the Press Release Subscription Form at http://www.egu.eu/news/subscribe/. Subscribed journalists and other members of the media receive EGU press releases under embargo (if applicable) at least 24 hours in advance of public dissemination.
Natural Hazards and Earth System Sciences (NHESS) is an interdisciplinary and international journal dedicated to the public discussion and open-access publication of high-quality studies and original research on natural hazards and their consequences. Embracing a holistic Earth system science approach, NHESS serves a wide and diverse community of research scientists, practitioners, and decision makers concerned with detection of natural hazards, monitoring and modelling, vulnerability and risk assessment, and the design and implementation of mitigation and adaptation strategies, including economical, societal, and educational aspects.
Professor of Integral Hydraulic Engineering at Delft University of Technology
Delft, the Netherlands
+31 15 27 85278
George R. Brown School of Engineering
+1 713 348 2398
EGU Media and Communications Manager
Science Editor & Associate Director of News and Media Relations
http://doi.org/10.5194/nhess-18-1073-2018 (the link will be active after the study is published on 19 April, 07:00 CET) –Scientific Paper
http://www.natural-hazards-and-earth-system-sciences.net – Journal: Natural Hazards and Earth System Sciences
Dr. Bárbara Ferreira EGU Executive Office | European Geosciences Union
A promising target in the quest for a 1-million-year-old Antarctic ice core
24.05.2018 | University of Washington
Tropical Peat Swamps: Restoration of Endangered Carbon Reservoirs
24.05.2018 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences