Category: Flooding - Wanyun Shao, Ph.D

Our new paper on flood perceptions

12/21/2018

Our new paper on how physical geography influences perceptions of flooding just got published online on the Journal of Hydrology. Here is the abstract of this paper:

"How does physical history of flood-related hazards affect individuals’ perceptions? The present study represents a unique effort to understand perceptions of flood hazards in light of the geographic background. Situated in Alabama, the United States, the cities of Mobile and Huntsville display two different physical geographic contexts. Despite one being a coastal city (Mobile) and the other being an inland city, both are similarly vulnerable to flooding. We first present results of historical analyses of heavy precipitation in both cities and analysis of storm surge history in the city of Mobile. We then report results of both descriptive statistical and inferential statistical analyses based on a two-city residents’ survey that was conducted in the spring of 2016. We find that residents in both cities are able to connect the particular natural hazard of flooding with their physical environments. Residents in both cities are influenced by their perceptions of precipitation when making assessments of flooding. Despite the fact that Huntsville has not experienced heavy precipitation events as much as Mobile in recent history, residents of Huntsville tend to link heavy rainfall – the most frequent cause of flooding in that city, with flooding. In contrast, residents of Mobile tend to link hurricanes, more particularly hurricane number, with flooding. These results show that people are attuned to their physical environments and take into consideration their personal observations when forming perceptions of natural hazards. More studies need to be conducted to further investigate the dynamics of physical exposure to hazards and risk perceptions in other geographic areas."

Hurricane Florence broke the silence of 2018 hurricane season

9/11/2018

When many people thought 2018 would be a relatively quiet hurricane season, monstrous Hurricane Florence is barreling towards the east coast. More than one millions coastal residents are facing mandatory evacuation order. It is now classified as Category 4 hurricane. The Saffir-Simpson scale only considers wind speed. In addition to destructive wind, hurricanes bring heavy rainfall as we witnessed during Hurricane Harvey last year and dangerous storm surge. There will be imminent flooding risks.

My analysis article: A year after Hurricane Harvey

8/23/2018

A year after Hurricane Harvey, the decisions to rebuild can affect the future. I just published an analysis article on the Conversation. Here is the last paragraph:

"My recent research shows that even with their flaws, FEMA flood maps influence decisions to purchase flood insurance and overall support for flood mitigation. Policy makers need to seriously consider how to accurately communicate increasing flood risks to the public. Reverting to old flood maps and granting variances to promote development is a recipe for more disasters down the road."

Hat tip to Emily Powell at the National Wildlife Federation, who brought this situation to my attention.

Visit at Princeton

6/21/2018

I enjoyed the visit at the Department of Civil and Environmental Engineering at Princeton University. I have had great discussions with Professor Lin and her Hurricane Hazards and Risk Analysis Research Group.

Princeton Campus

Princeton Campus

Princeton Campus

I am sitting on a chair on Princeton Campus

I am standing in front of the student center

A seminar talk at Princeton University

6/14/2018

I am honored to be invited to give a seminar talk, entitled "Understanding Human Judgement on Environmental Risks and Hazards in a Geographic Context," at the Department of Civil and Environmental Engineering at Princeton University on June 21.

The abstract of the talk is as follows:
"The coupling effects of changing climate and rising concentration of population and assets in the coastal regions have increased the threat of potential damages. There is an urgent need for coastal communities to prepare well for future hazards through mitigation and adaptation measures. A growing number of empirical studies have found that peoples’ motivation of voluntary risk mitigation and adaptation is low unless actual risk can be perceived. Risk perception is thus the precondition for adaptive behavior. It is of both intellectual and practical interests to study what affects individuals’/communities’ risk perceptions. In this talk, I will present four of my previous studies. The first three studies are focused on the individual level and the fourth on the aggregate level. I will start with understanding how local weather and climate affect American public risk perceptions of climate change. I will then discuss how the spatial context represented by past flooding events and estimated flooding risks influence costal residents’ voluntary flood insurance purchase decisions and their support for flood adaptation policies. As many policies are designed and implemented at an aggregate level (i.e., state, county, city), it is necessary to examine aggregate-level risk perceptions. In the fourth study, I will focus on how the contextual hurricane risks in conjunction with community resilience shape county-level perceptions of hurricane-related risks. I will end with a research agenda linking communities’ perception with contextual risks and community resilience. I contend that the cognitive dimension including both risk perceptions and perceived adaptive capacity is not represented in any of the existing community resilience indexes, and therefore needs to be measured, quantified, and incorporated into a more comprehensive index."

Harvey's heavy rainfalls and ocean heat content

5/10/2018

Hurricane Harvey dumped record-breaking rain in Houston in 2017. Now, a new study shows that this extreme amounts of rainfalls actually resulted from unprecedented ocean heat content. This study presents some evidence to support the link between global temperature rise with increasing hurricane intensity.

Our paper published on Annals of AAG

3/19/2018

Our new paper on aggregate perceptions of hurricane risks has been published on the Annals of American Association of Geographers.

Presenting our study at 2017 SRA annual conference

12/19/2017

I presented our study on community resilience and county-level perceptions of hurricane risks along the US Gulf Coast at the 2017 Society for Risk Analysis annual conference in Arlington, VA.

County-level perceptions of hurricane risks along the U.S. Gulf Coast

12/15/2017

In a study that has been accepted by the Annals of the American Association of Geographers, my coauthors and I have examined how community resilience along with objective hurricane risks impacts aggregate perceptions of hurricane risks. We first applied spatial techniques to transform individual-level perceptions to the aggregate level, in this case, counties. The map below displays the geographic pattern of hurricane risk perceptions among coastal counties along the U.S. Gulf Coast. Clearly, there is a concentration of heightened hurricane risk perceptions stretching from southeast Texas to west Florida. Given the recent enormous impact of Hurricane Harvey in southeast Texas and West Louisiana, it is likely that risk perception has further increased among coastal residents who have been affected by Harvey.

Further, we found two aspects of community resilience measured by Cutter et al. (2014), namely economic resilience and community capital, are positively related to aggregate perceptions of hurricanes risks. This indicates that communities with more economic resources and social capital tend to perceive greater threat of hurricanes. The policy implication is that counties with less economic and social capitals need to direct efforts on educating the public about scientific assessments of hurricanes risks.

County Level Risk Perception Scores (Source: Shao, Gardezi, and Xian, forthcoming)

Reference:
Cutter, S. L., Ash, K. D. and Emrich, C. T. 2014. The geographies of community disaster resilience. Global Environmental Change, 29, 65-77.
Shao, W, Gardezi, M., and Xian, S. (forthcoming). Examining the effects of objective hurricane risks and community resilience on risk perceptions of hurricanes at the county level in the U.S. Gulf Coast: An innovative approach" Annals of the American Association of Geographers.

After the historical flood in Houston

9/26/2017

After Harvey dumped over 40 inches of rain in Houston over a few days, the city must come to the realization that it cannot continue to be built and relentlessly expanded by ignoring science. Now, it is time for the city to rethink about its development plan and hazard mitigation policies.