Category: Coastal Issues

Our new paper in Sustainable Cities and Society

11/26/2021

Our new paper is published online in Sustainable Cities and Society (impact factor: 7.587). Below please find the abstract:
"The use of social media platforms such as Twitter significantly increases during natural hazards. With the emergence of several social media platforms over the past decade, many studies have investigated the applications of these platforms during calamities. This study presents a comprehensive spatiotemporal analysis of textual content from millions of tweets shared on Twitter during Hurricane Harvey (2017) across several affected counties in southeast Texas. We propose a new Hazard Risk Awareness (HRA) Index, which considers multiple factors, including the number of tweets, population, internet use rate, and natural hazard characteristics per geographic location. We then map the HRA Index across southeast Texas. Utilizing a dataset of 18 million tweets, we employ Natural Language Processing (NLP) along with a set of statistical techniques to perform analysis on the textual data generated by Twitter users during Hurricane Harvey. This enables us to subdivide the tweet contents into several categories per county that would inform crisis management during the event. In all, our study provides valuable information at the county level before, during, and after Harvey that could significantly help disaster managers and responders to minimize the consequences of the event and improve the preparedness of the residents for it. Since HRA is derived based on the meteorological observations and some demographic information, depending on the availability of such dataset and the nature of the hazard (i.e., flood, wildfire, hurricane, and earthquake), this index can be calculated and employed for assessing the risk awareness of a community exposed to either of these natural hazards."

Figure 4. Hazard Risk Awareness index across the counties in southeast Texas affected by hurricane Harvey (Source: Karimiziarani et al. 2022)

Figure 6. Categorized tweets into humanitarian classes across the counties affected by Hurricane Harvey (Source: Karimiziarani et al. 2022)

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Our new paper on perceptions of sea level rise in Climatic Change

10/10/2020

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Our new paper on perceptions of sea level rise has been published in Climatic Change (Impact factor: 4.743). Below please find the abstract:
"Sea level rise (SLR) in the 21st century poses fundamental risks to coastal residents. The U.S. Gulf of Mexico Coast (Gulf Coast) is among the regions experiencing the most rapid relative SLR. Beyond its increasing exposure to SLR and related coastal flooding, the Gulf Coast is home to a large population and displays high social vulnerability. How the coastal population in this vulnerable region perceives the impending risks posed by SLR warrants further examination. Do coastal residents’ perceptions of SLR conform to the scientific projections? We adopt an integrative approach based on a 2019 survey merged with contextual data including percentage of population living within the Special Flood Hazard Area (SFHA) and social vulnerability at the county level, both of which are extracted from the Centers for Disease Control and Prevention. We find that public risk perceptions of sea level change are influenced by political predisposition, with Republicans being less likely than Democrats to expect SLR in the future. Moreover, SLR remains temporally distant issue among coastal residents. We then directly compare public expectations and scientific estimations of SLR in five states of the U.S. Gulf Coast region and find that coastal residents in states that have experienced faster SLR in the past are more optimistic about future SLR by underestimating its magnitude compared to those experiencing slower SLR. Moreover, we find that people likely conflate the severity with likelihood of SLR risk. The contextual force represented by percentage of population living within the SFHA designated by the Federal Emergency Management Agency (FEMA) can significantly influence individuals’ estimations of future SLR, with higher percentages leading to higher estimates. We suspect that the SFHA has become a powerful risk communication tool that influences coastal residents’ judgments about future risk.

Figure 3. Comparison of public estimation with scientific estimation of SLR at five locations in Texas, Louisiana, Mississippi and Alabama, Florida Panhandle, and Florida Peninsula along the U.S. Gulf Coast. Percentages assigned at lower level and upper level in each figures represent percentages of respondents who estimated future SLR to be lower than the 5th and higher than the 95th scientific estimates, respectively (Source: Shao et al. in press).

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Our new paper in Science of the Total Environment

7/19/2020

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Our new paper has been published in Science of the Total Environment (Impact Factor: 7.963). Below please find the abstract:

"Climate extremes will be intensified and become more frequent. One of the regions where this is the case is the U.S. Gulf coast region. This region is susceptible to the impacts of climate extremes. This region has recently experienced large amounts of economic damages caused by high-impact hurricanes and floods. Meanwhile, drought can also pose serious risks once it occurs. By using a 2019 U.S. Gulf Coast survey combined with Standard Precipitation Index, we closely examined retrospective and prospective evaluations of drought and flood among coastal residents. Drawing upon literature on human-environment system, we were interested in how the objective conditions of past drought and flood influenced individual’s perceptions of these hazards and how their retrospective evaluations were correlated with their prospective evaluations of future trends of these hazards. Coastal residents’ retrospective evaluations of past drought and flood were found to be influenced by historic objective conditions. Higher drought frequencies were found to increase the probability of perceiving increasing trend of drought number in the past. Higher flood frequencies were found to decrease the probability of perceiving increasing trend of flood number in the past. Higher intensities of drought and flood were found to increase the probabilities of perceiving increasing trends of drought duration and flood amount in the past. Coastal residents’ prospective evaluations of future drought and flood were found to be influenced by retrospective evaluations of these hazards, suggesting the temporal continuity in human judgement. Moreover, those who relied on a longer time span in reference to the future were found to be more likely to perceive increasing trends of drought and flood. We ended this paper by proposing a theoretical framework to guide future studies and discussing policy implications."

Core Figure - Figure 4. Retrospective evaluations of drought and flood risk and association with objective conditions (a) and their correlations with prospective evaluations of drought and flood risk (b). In (a), filled circles, circles with cross, empty circles depict the frequency, duration, intensity, respectively, of drought (red) and flood (blue). In (b) filled (empty) circles depict retrospective evaluations on past drought and flood numbers (past drought duration and past flood amount). The bars represent confidence intervals of all the estimated coefficients (Shao and Kam, 2020)

Graphic Abstract

Figure 2. Number of states under regional drought events (red) and regional pluvial flood events (blue) (Shao and Kam, 2020)

Figure 3: Monthly time series of the relative search activity indices on drought (a) and flood (b) between 2004 through 2018. Dark (light) lines depict the averages (maximum and minimum values) of the relative search activity indices over the five Gulf costal states (Shao and Kam, 2020)

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A new paper in Disasters

6/28/2019

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Our new paper was published in Disasters (impact factor: 1.797). Here is the abstract:

"It is of significance to assess and depict community vulnerability to floods and hurricanes. Over the past several decades, flooding and hurricanes have affected millions of people and caused massive economic losses. Despite efforts to reduce risks, these natural hazards remain to be a considerable challenge to coastal communities. In this paper, Geographic Information Systems (GIS) methods are used to analyze coastal communities’ vulnerability to hurricanes and flooding along the U.S. Gulf coast, which is prone to these two hazards. Specifically, two types of quantitative indicators are developed: exposure to hurricanes and flooding, based on data from multiple sources such as National Climate Data Center and National Flood Insurance Program among others, and a social vulnerability index, constructed on census data at census tract level. These indices are combined to depict the spatial patterns of overall community vulnerability to flooding and hurricane hazards along the U.S. Gulf Coast. Results of this study can potentially inform disaster management agencies, county governments and municipalities of areas with heightened community vulnerabilities. The demonstration of geographic distribution of community vulnerability can assist decision makers in prioritizing to‐do items and designing policies/plans for more effective allocation of resources. We end this paper by discussing the limitations to the present study and the practical implications of the assessment."

The following two figures are from this article (Shao et al. forthcoming).

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A new paper in Environmental Research Letters

4/15/2019

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Our paper on public support for flood mitigation was just published on Environmental Research Letters (impact factor: 6.192). Here is the abstract:

"What is the decision-making mechanism people rely upon to mitigate flood risk? Applying Bayesian Network modelling to a comprehensive survey dataset for the U.S. Gulf Coast, we find that the overall support for flood mitigation can be inferred from flood insurance purchase behavior (i.e., without insurance vs. with insurance purchased mandatorily, voluntarily, or both). Therefore, we propose a theoretical decision-making mechanism composed of two dimensions including informed flood risk and sense of insecurity. The informed flood risk is the primary determinant on one's overall support for flood mitigation. Risk mitigation decisions are largely contingent on the level of risk that is effectively conveyed to individuals. Additionally, sense of insecurity plays a moderate role in determining individuals' overall support for flood mitigation. The sense of insecurity can move people toward overall support for mitigation, but the effect is not as large as the informed risk. Results of this study have fundamental policy implications. The flood risk informed by Federal Emergency Management Agency's flood maps not only provides the compulsory basis for flood insurance purchase but also determines individuals' overall support for flood mitigation. Flood map inaccuracy can immensely mislead individuals' overall risk mitigation decision. Meanwhile, this flood risk mitigation decision-making mechanism inferred from a survey data in the U.S. Gulf Coast needs to be tested and validated elsewhere."

In this paper, we proposed a flood mitigation decision-making mechanism (please see below). One implication of this study is that "the importance of risk information in overall flood mitigation decisions. Although the flood premiums do not reflect real risks due to discounts, flood hazard zones have effectively conveyed the risk to homeowners. Risk signals can thus be delivered to homeowners through various means."

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Our new paper on flood perceptions

12/21/2018

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Our new paper on how physical geography influences perceptions of flooding just got published online in the Journal of Hydrology (impact factor: 4.405). 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."

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My analysis article: A year after Hurricane Harvey

8/23/2018

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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.

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Visit at Princeton

6/21/2018

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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

I am sitting on a chair on Princeton Campus

I am standing in front of the student center

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A seminar talk at Princeton University

6/14/2018

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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."

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Harvey's heavy rainfalls and ocean heat content

5/10/2018

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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.

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<<Previous

Our new paper in Sustainable Cities and Society

Our new paper on perceptions of sea level rise in Climatic Change

Our new paper in Science of the Total Environment

A new paper in Disasters

A new paper in Environmental Research Letters

Our new paper on flood perceptions

My analysis article: A year after Hurricane Harvey

Visit at Princeton

A seminar talk at Princeton University

Harvey's heavy rainfalls and ocean heat content

Wanyun Shao, Ph.D

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