How health risk communication best practices can improve community flood risk communication

Communicating with individuals about the risks posed by various emergencies has been a challenging task for organizations responsible for issuing warnings and maintaining public health. The success or failure of those communication efforts can affect patient volume at emergency medicine departments and workload for community health workers and other teams. Professionals who manage emergency preparedness and response must offer recommendations about a range of actions (e.g., evacuate your area vs. find shelter where you are) to various audiences (e.g., people who can easily evacuate vs. people who do not have the resources to evacuate) with sensitive timelines, fluctuating certainty, and messages that are difficult to communicate in plain language. Ineffective emergency health risk communication can result in significant burdens on human health, including acute injuries, loss of life, and mental and physical health challenges post-emergency.

One example situation of challenge for public health and emergency preparedness officials involves flooding due to precipitation and storms. Climate change is increasing the frequency and intensity of extreme weather events, including floods (1,2). Flood risk is increasing faster than household preparedness for flooding, resulting in higher costs when floods occur, and demonstrating a need for better flood risk communication (3,4). Many of the worst floods cost billions of dollars in damage (5). In addition to financial costs, threats to human health from floods are also notable (6). Globally in 2019, floods accounted for nearly half of all natural disasters, affected around 31 million people, and were responsible for 5,055 deaths (7).

Despite existing research on flood risk communication, there is limited clarity on what motivates preparedness behaviors, how context changes motivating factors, and whether households can perform behaviors even if they want to do so (3). As we learn more about those variables, emergency preparedness and flood risk communicators can capitalize on what we already know about effective health risk communication. Here we review evidence-driven health risk communication insights in existing literature and discuss how they may apply to flood risk communication.

Health communication insights

Emotions can affect information processing

Emotional response can affect the way in which information is processed. Nabi has outlined roles for various discrete emotions such as anger, disgust, sadness, and guilt, in audience information processing, attitude change, and message memory (8). Anger can invite message counterarguing, for example, and fear can invite message avoidance under some circumstances if not mitigated by specific behavioral recommendations about how to eliminate the threat (9). In a different example, Weeks found anxiety to affect message processing. Weeks describes anxiety as an aversive state “in response to threatening stimuli … associated with uncertainty, [and] a lack of personal control” [p702 (10)]. The threat of a flood in a person’s community is rife with uncertainty and outside of an individual’s immediate control, circumstances which can invite emotions that affect information processing. When a person is anxious, for example, they can question existing beliefs, look for information, and be more likely to believe information they encounter in the moment regardless of source, even if it is incorrect (10). What does this observation imply for efforts to warn people about the possibilities of flooding in their area? Message testing research to develop warnings should either occur in conditions which mimic the stress audiences will face when an actual flood is looming or should at least ask participants to reflect on how they respond in situations of heightened emotion. When communicators share information in emergency situations such as flooding, audience members are likely to experience emotions with a negative valence, e.g., Stanke et al., suggesting the importance of providing accurate information directly to audience members who may not think to carefully look for information on someplace like a government website (11).

Perceived source credibility matters

The source of health risk information can influence the effectiveness and outcome of communication. Messenger credibility and perceived trust can affect whether audience members believe a health-related message and whether they complete the message’s recommended action, e.g., Prue et al. (12). Prue et al. assessed travelers’ perception of infectious disease monitoring recommendations during the 2014–2016 Ebola epidemic. Findings showed that participants’ intention to adhere to public health behaviors, in this case following post-travel quarantine guidance, was positively related to their trust in the public health program ambassador they met. Their likelihood of adhering to requested public health behaviors was specifically linked to whether the participants perceived shared interests with the source of health information (12). Similarly, in a study focused on seeking information on natural disasters, hazards, and extreme weather, researchers found that respondents tended to report reliance on information sources which shared interests with them (e.g., a local weather reporter who lives in the same flood prone area as their audience) (13). Participants in that same study also described what the concept of trust meant to them, and not only noted that shared interests mattered but also frequently included consistency and intellectual credibility as other aspects of their definition of trust (13). Audiences most frequently identified local sources as being the most trusted, suggesting emergency communication efforts should involve local partners as messengers who can highlight shared social and economic interests with the audience (13).

Other research on wildfire risk communication also suggests implications for applying source credibility insights to flood risk communication. Work by Steelman again found residents to identify local resources as the most trustworthy and useful (14). Importantly, both information access and availability also matter. People reported frequently using convenient or familiar sources of information such as family/friends/neighbors or television, regardless of trustworthiness levels, whereas more trustworthy sources such as local fire departments were harder to access (14). Participants tended to report that interactive sources were the most useful or trustworthy to them, suggesting that the ability to ask questions is important to audiences (14). Maps were the second most used information source; participants also tended to view maps as both useful and trustworthy, perhaps in part because maps offer a viewer agency to look at specific locations of interest to them (14). Effective flood risk communication may benefit from increasing familiarity and convenience of trusted and useful local resources before emergencies occur.

A review of flood risk perception research by Lechowska underscores the importance of looking at the social context in which information about floods appears and in which perceptions are formed (15). Factors such as source credibility perceptions can constrain other predictive factors of risk perception (e.g., age). Flood risk management interventions should consider the nuances of how information sources are perceived and how people get information amidst their daily routines and various social interactions (15).

Audience mental models matter

What individuals hold in mind about past experiences can shape their perceptions of new risks, and research shows this is especially true for people who experience flood events (1,15,16). In a non-flood health risk example, when conducting focus groups about Zika virus in Guatemala, researchers found that participants frequently compared Zika virus disease to other mosquito-borne diseases which had been prevalent in the region for decades (16). Their existing mental models of mosquito-borne diseases were in some ways helpful in understanding similar aspects of the new mosquito-borne risk, but in other ways harmful, as individuals also had low awareness of new aspects of Zika virus (e.g., Zika virus can be sexually transmitted). They may have been unaware of new transmission possibilities, blocked by assumptions stemming from past experiences.

Research focused on hurricane preparedness similarly has suggested that prior experiences with natural disasters can significantly affect performance of preparedness behaviors, e.g., injury during a past hurricane made participants more likely to evacuate in the future (1). Researchers recommended that health risk communicators consider how the audience’s past experiences may shape their perspective on current risks, and how that may shape their behaviors. Emphasis of new aspects of a risk is especially important if the audience has previous experience with similar risks (16).

In many areas, people are experiencing flood emergencies for the first time due to changing climates and changes in the built environment, e.g., more impervious surface (1,2). However, individuals also may have experiences with flooding second-hand (e.g., seeing flood emergencies on social media, having a loved one who experienced a flood) (15). Audience mental models of what flood risk can mean may impact how audiences think about their own flood risks (15). For people who have never experienced a flood before themselves, flood risk communicators may use analogy or direct comparison of other floods to improve understanding of flood risk. In areas that are historically prone to flooding, where some residents have experienced numerous flood events, comparison to previous floods may be helpful to improve understanding as well, but risk communication should emphasize what is new (e.g., underscore how much higher water levels are projected to be than previous floods).

Group differences can affect risk communication

People vary in how they process information, in part due to differences in cognitive ability (17,18). Cognitive ability is people’s mental capacity for mind-based skills, such as memory, problem solving, logical decision making, and literacy (19). Age, along with social determinants of health (e.g., education, social activity, stress levels, etc.) are factors that impact cognitive ability (19,20).

Differing cognitive abilities impact health risk information processing and recall, which in turn impacts health related decision making and behaviors (17,18). For a general population, studies showed that presenting risk information numerically was more effective (e.g., higher knowledge gain) than presenting non-numerically, and that presenting in both numeric and non-numeric form is likely best practice (18). In comparison, individuals with higher numeracy and education were less affected by how risk information was presented (18).

Reducing message complexity (e.g., using plain language) benefits all audiences by increasing comprehension and is essential to ensure equity across audiences, as some groups have cognitive challenges (e.g., lower literacy) (21). For instance, older adults tend to have more difficulty hearing, reduced comprehension, and limited recall of risk information (17). Reducing health risk message complexity and audio message speed can improve information recall (17).

We also need to consider structural factors, however, which extend beyond an individual person and include the effects of systemic racism and community resource differences that contribute to disparities in health as well as information access and processing. Some communities are disproportionately impacted by poor social determinants of health, which in turn can complicate message attention and processing (2). Flood risk communicators must acknowledge this intersectionality, as people experiencing socioeconomic disparities are more likely to live in flood prone areas (2). Particularly challenged populations, for example, can include high proportions of people with relatively low income, minoritized identities, relatively limited education, disabilities, relatively young or old age (ages under 16 and over 75 years), or single-parent households (2). Despite facing more flood exposure, these groups also face structural racism in housing and have fewer resources to respond to floods, which increases likelihood of injury and extends recovery timelines (2,22). Climate change is projected to make the disproportionate effects of flooding on socially vulnerable populations worse (2). Flood risk communications must account for the intersection of varied cognitive ability, social vulnerability, and lack of resourcing for residents of flood-prone areas.

Application example: flood warning information sharing

Researchers at RTI International and the University of Vermont are partnering on a new project that focuses on flood risk communication, bringing together an interdisciplinary team including contributors with expertise in communication research, design thinking, economics, hydrology, and the intersection of human and environmental systems (23,24). The interdisciplinary nature of the team reflects recognition of the importance of communication research and behavioral science. The team is working with six communities in the United States with relatively recent flood experience to understand how flood communication moves within communities (or does not) to encourage injury prevention and flood loss mitigation efforts. Although there are formal processes and systems in place in the United States to share warnings and alerts, available research lacks evidence about the informal networks people in communities use to learn about, assimilate, and share information to guide flood response action. That underscores the vital importance of formative research on message design and placement to inform work by government agencies to warn communities about flood inundation. Specifically, the findings from this research will support the implementation of National Oceanic and Atmospheric Administration (NOAA)’s newest flood warning technology, Flood Inundation Mapping (FIM), by providing flood communication recommendations to improve technology adoption and effectiveness.

Conclusions

Flood risk communication, like other emergency communication, can prevent injuries and the loss of life. Optimally informing organizations and community residents about flood risks will require learning from health risk communication best practices, especially considering gaps in flood communication research. By taking into account audience emotions, perceptions of source credibility, audience past experiences, and potential group differences, communicators can optimize future message design and delivery. Understanding the formal and informal channels through which flood warning information moves in different communities will help ensure people see those optimized messages. With greater future attention to the science of risk communication, we can provide effective flood communication when communities need it. Effective flood risk communication can reduce important burdens on public health and emergency medicine systems as our changing climate continues to pose challenges for healthcare.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the editorial office, Journal of Public Health and Emergency. The article has undergone external peer review.

Peer Review File: Available at https://jphe.amegroups.com/article/view/10.21037/jphe-24-27/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://jphe.amegroups.com/article/view/10.21037/jphe-24-27/coif). B.G.S. serves as an unpaid editorial board member of Journal of Public Health and Emergency from June 2023 to May 2025. All authors report that they work on a project funded by Cooperative Institute for Research to Operations in Hydrology, which is briefly mentioned in this essay. The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

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