Floods and flash floods are, by their nature, a multidisciplinary problem: they result from a convergence of atmospheric conditions, the underlying topography, hydrological processes, and the built environment. Research aimed at addressing various aspects of floods, on the other hand, often follows paths that do not directly address all of these fundamental connections. With this in mind, the NSF-sponsored Studies of Precipitation, Flooding, and Rainfall Extremes Across Disciplines (SPREAD) workshop was organized and held in Colorado during the summers of 2013 and 2014. SPREAD brought together a group of 27 graduate students from a wide variety of academic disciplines, but with the unifying theme being research interests in extreme precipitation or flooding. During the first meeting of the workshop, groups of graduate student participants designed interdisciplinary research projects that they then began work on over the intervening year, with the second meeting providing a venue to present their results. This article will outline the preliminary findings of these research efforts. Furthermore, the workshop participants had the unique and meaningful experience of visiting several locations in Colorado that had flooded in the past, and then visiting them again in the aftermath of the devastating 2013 floods. In total, the workshop resulted in several fruitful research activities that will advance understanding of precipitation and flooding. Even more importantly, the workshop fostered the development of a network of early-career researchers and practitioners who will be “multilingual” in terms of scientific disciplines, and who are poised to lead within their respective careers and across the scientific community.
Floods and flash floods can be deadly, destructive to property and infrastructure, and have wide-ranging impacts on people and ecosystems. There also remain important and unresolved questions about how floods have changed over time and how they may change in the future. To fully understand floods and their impacts, it is important to consider what happens in the atmosphere to produce heavy precipitation (a question for the field of meteorology), what happens to the water once it reaches the ground (hydrology), how the flooding affects people (economics, sociology, psychology, emergency management, and many other fields), how the flooding impacts ecosystems (ecology, watershed science), and how floods are likely to change in the future (climate science, policy). These diverse effects demonstrate that floods are by nature an interdisciplinary problem for researchers and practitioners.
Considering the multidisciplinary nature of floods, but the often disconnected lines of research conducted to address various aspects of floods, efforts to integrate the expertise offered by different disciplines would seem to have the potential to bear great fruit for both scientific understanding and societal benefit. With this in mind, the Studies of Precipitation, Flooding, and Rainfall Extremes across Disciplines (SPREAD) workshop was organized and held during the summers of 2013 and 2014. SPREAD brought together a group of 27 graduate students1 from a wide variety of academic disciplines, including meteorology, hydrology, psychology, economics, engineering, history, geography, science and technology studies, and more (Table 1), but with the unifying theme being research interests in extreme precipitation or flooding. Applications for the workshop were solicited by contacting university faculty members to encourage their students to apply and by posting the announcement widely on relevant listservs and social media. Forty-five applications were received and 27 participants were selected based on their interests and experience in interdisciplinary research and the goal of having a broad range of academic disciplines represented.
The SPREAD workshop was inspired by, and in many ways modeled after, other recent efforts to initiate and promote research activities that consider the intersection of weather, climate, and society, including the Weather and Society*Integrated Studies (WAS*IS) workshops; the Dissertations Initiative for the Advancement of Climate Change Research (DISCCRS); the Summer Colloquia sponsored by the Advanced Study Program at the National Center for Atmospheric Research (NCAR); and the Water and Society workshops. These initiatives have led to cohorts of researchers and practitioners with not only expertise in a particular specialty, but literacy and interest in integrating methods and knowledge from those with other specialties. In other words, they are “multilingual,” in the sense that they can understand and speak the language of numerous disciplines. This idea was one of the motivations and underpinnings for SPREAD, which was sponsored by the National Science Foundation under a CAREER grant to integrate research and education in innovative ways.
In particular, graduate students were recruited to be the participants in the workshop for several reasons. Graduate students are typically at the beginning of their research careers, yet are generally working at the cutting edge of their disciplines (or multiple disciplines). They are at the stage of their careers when learning multiple “scientific languages” can be a great advantage for both their thesis/dissertation research projects and their future career prospects. They are also being trained as the future leaders in their field(s), and, with a broad perspective on important unsolved problems of societal importance, have the potential to initiate new and transformative research directions.
The goals of the workshop included 1) identifying current research questions and proposing concrete ideas to address these questions by incorporating methods and data from multiple disciplines; and 2) developing a network of early-career researchers who are ultimately able to do innovative work not only in their disciplinary “home,” but with a broader perspective, as well. The workshop was conducted over two summers so that research ideas could be developed during the first meeting, and then individuals or subgroups could make progress toward those research objectives during the intervening year and present the results at the second meeting. The workshop was held on 16–21 June 2013 at Colorado State University in Fort Collins, and on 23–25 July 2014 at NCAR in Boulder.
The agenda for the 2013 workshop was organized so that the first two days consisted of presentations from prominent researchers and practitioners in interdisciplinary science and research. The opening keynote presentation was given by Bill Hooke of the AMS Policy Program, who outlined the importance of working at the interface of science and society, and how flood policy has evolved over time. Other presenters included Eve Gruntfest (National Science Foundation), Rebecca Morss (NCAR), J. J. Gourley (National Severe Storms Laboratory), Dave Gochis (NCAR), Kelly Mahoney (NOAA), and a remote presentation by Marshall Shepherd in conjunction with a similarly themed summer course at the University of Georgia. In addition to the results of their own work, these presenters also discussed their own successes and challenges in conducting interdisciplinary research. The students also gave brief presentations about their areas of research, and took part in a hands-on exercise with Geographic Information Systems (GIS) software. In this exercise, the participants divided into subgroups and were provided with several datasets from the deadly 31 May 2013 tornadoes and flash flood in central Oklahoma, including radar, precipitation, and streamflow observations, National Weather Service (NWS) warnings, storm reports, and articles from news media. The participants were able to integrate these various sources of information to better understand the spatial and temporal scales that must be considered in a multihazard event such as this.
On day 3, attention turned to historical floods that had occurred in Colorado, including the Fort Collins flash flood of 1997, the Big Thompson flood of 1976, and the 1982 Lawn Lake dam break flood in Rocky Mountain National Park. Marsha Hilmes-Robinson, floodplain manager for the City of Fort Collins, offered insights about the lessons learned and actions taken after the deadly Fort Collins flash flood, and then the group departed to visit several sites in person, led by hydrometeorologist Matt Kelsch of UCAR/COMET. This trip in June 2013 proved particularly meaningful when in September 2013 many of the same areas experienced historic flooding. During the 2014 workshop, Matt Kelsch again led a tour to areas that were flooded in September 2013, which included some of the same locations that the group visited in June 2013. Several participants noted that seeing the long-term effects of the different types of floods in person, along with the “before-and-after” perspective between 2013 and 2014, were valuable for providing physical and societal context for their research (Fig. 1).
Motivated by the field trip and other discussions during the week, one recurring topic of conversation and debate was the idea of return periods for rainfall and flooding (e.g., the “100-year flood”). Return periods are formally defined by an annual exceedance probability: the probability, based on historical observations, that a given amount of rain will fall at a location, or a river or creek will reach a certain level, in any given year. These probabilities are then often converted into return periods, so that an event with a 1% chance of occurring in any year is referred to as a “100-year event.” Along Spring Creek in Fort Collins, a monument indicates the water level for the 25-, 50-, and 100-year floods, along with the high-water mark from 1997 (which is considerably higher than the other levels). However, important questions were raised about how a monument like this would be interpreted by those visiting the site, such as whether this would make residents more likely to prepare for future floods, or instead lead to complacency. Some of the student participants are actively working on statistical methods to improve the estimation of return periods, while Brian Rumsey (history, University of Kansas) has conducted research on how the “100-year flood” became so widely used for policy and decision-making. Because flood and rainfall return periods are used for the design of infrastructure as well as for public understanding of floods, sorting out the complex set of questions surrounding how they are developed and communicated is a timely and naturally interdisciplinary research problem.
These discussions then led into the other primary objective of the workshop: developing multidisciplinary research projects that could be carried forward over the year in between the formal meetings of the workshop, and potentially beyond. These vibrant discussions over the last two days of the 2013 workshop led to the initiation of several studies that will be briefly described in the next section.
RESEARCH PROJECTS INITIATED AT SPREAD.
The development of a Flash Flood Severity Index (FFSI).
A large group of workshop participants, led by Amanda Schroeder (atmospheric science, University of Georgia, and now an NWS forecaster), has worked together to design a study with the objective of quantifying the severity and impact of flash floods. Other notable natural hazards have well-established scales that are used to classify their severity, but no such scale exists for flash floods. One possible reason for this is that it is very difficult to objectively categorize flash floods, precisely because they are a combination of meteorological, hydrological, and societal factors. For example, the same amount of rainfall over different watersheds can lead to very different flood responses, and an equally swift rise in a creek or river will have varying impacts depending on the infrastructure and population density of the surrounding area.
To work toward the development of a flash flood severity index (FFSI), this group has employed a variety of research methods representing multiple disciplines. Semistructured interviews were conducted with NWS forecasters, hydrologists, and managers to better understand their current practices in issuing flash flood warnings and to assess their needs for classifications of the impact of flash floods. Nearly 70 flash floods representing a spectrum of impacts and geographic locations were analyzed using meteorological and hydrological data and flood reports from official sources and media reports. Based on the results of the interviews and case studies, a preliminary index was proposed with five categories ranging from minor to catastrophic flooding. With further development and refinement based on feedback from the scientific and operational community, this index could be used in postevent assessment (akin to the Enhanced Fujita scale for tornadoes) and provide useful historical context to NWS staff and researchers as they evaluate the impacts of flash floods in the future. The detailed results of this research and the proposal for the FFSI are described in an article by Schroeder et al. in the Journal of Hydrology.
Interpretations of flood return periods.
Based on the varying interpretations of flood return periods even among the workshop participants who are generally familiar with this topic, an experiment was designed to examine how these concepts are understood by the broader populace. Jared LeClerc, a Ph.D. candidate in psychology at the University of Washington (who has since completed his degree), conducted an exploratory study to address some of these research questions. The study presented three different expressions of the flood risk to the participants, in the context of a monument similar to the one at Spring Creek in Fort Collins, but for a fictional location (“Bison City”). The first expression used return periods like those actually on the Spring Creek monument: 10-year flood, 100-year flood, etc. The second used percentages to represent the same risk: a 10% chance of happening in a given year, a 1% chance, and so on. The third expression was neutral, with letters (A, B, C, etc.) corresponding to the different levels of risk. The study also aimed to learn whether people’s interpretation of the flood risk would be affected by the recency of a flood at that location.
For example, one question on the survey asked “How likely do you think Bison City is to experience a flood this year?”, with different participants being given the return-period expression of risk, the percent expression, and the neutral expression, and with some participants told that a flood occurred the previous year, and others told that Bison City had not seen flooding in about 10 years. For those given the percentage expression of risk (i.e., a 1% probability of occurring in a given year), there was no significant difference in the participants perception of the likelihood of experiencing a flood this year between those who were told that a flood had and had not occurred recently. On the other hand, for the participants given the return period expression of risk (i.e., a 100-year flood), those who were told that a flood occurred the previous year rated the risk of flooding this year lower than those who were told that no flooding had occurred in 10 years. In other words, the hypothesis was supported that discussing a “100-year flood” leads people to believe that when one such flood occurs, another will not happen again for a long time. This research was exploratory and was limited by a relatively small sample size, but nonetheless raises questions for future research at the interface of meteorology, hydrology, and society.
Other research projects.
The projects highlighted above reflect only a small subset of the projects initiated at or inspired by the workshop. A couple of additional projects are summarized below:
Ben Miller (economics, University of California, San Diego) examined the economic value of weather warning systems such as NOAA weather radio.
A multidisciplinary group is examining weather events that include multiple hazards, such as a near-concurrent threat of tornadoes and flash floods, along the lines of what occurred in the El Reno/Oklahoma City area on 31 May 2013. Components of this research led to an article that was published in Weather and Forecasting in 2015.
Furthermore, numerous students reported being motivated to take courses outside their primary discipline and completing class research projects that incorporated interdisciplinary approaches.
FEEDBACK, DISCUSSION, AND REFLECTION.
Feedback from the student participants was very positive, with many stating that it provided new ways of looking at scientific and societal issues related to flooding. For example, one student noted, “One of the strong points of the workshop was how it opened my eyes to how other fields look at flood events,” and another commented that they left the workshop feeling “reinvigorated and optimistic about doing good science.”
However, one theme that ran through some of the student feedback was that efforts to integrate the physical and social sciences can still leave a disconnect between the two lines of inquiry. For example, whereas most of the physical scientists felt that they learned a lot about the research methods offered by the social sciences (e.g., “I have so much more insight into the social science perspective and methods after this workshop”), some of the social scientists found it challenging to be truly integrated members of the research team (e.g., “I think that the social scientists still had difficulty getting their perspectives represented in the final group projects”). This suggests that even though efforts (including this workshop) to integrate the methods, approaches, and “languages” of the different sciences have largely been successful, there remain challenges to overcome in the future. These challenges were a major topic of discussion during the second meeting of the workshop in 2014—particularly how to highlight interdisciplinary experience and interests during the job search process.
Before the initial workshop, a Facebook group was organized for the participants in the workshop to post relevant articles, job opportunities, and topics for discussion. This group remained active through the 2013 and 2014 workshops, and continues to be a place where the participants keep in touch to share information about their progress through graduate school or their new careers, publication of journal articles, and current flood-related information. In addition to this virtual communication, we have organized a SPREAD lunch or dinner at each of the AGU and AMS Annual Meetings since the workshop so that those attending the meetings can reconnect.
Overall, the SPREAD workshop brought together graduate students at the cutting edge of research on extreme precipitation and floods, highlighting the inherently multidisciplinary nature of floods along with the opportunities for solving scientific and societal problems that come with applying diverse academic methods and perspectives. The workshop resulted in several fruitful research activities that will advance understanding of precipitation and flooding. Even more importantly, the workshop fostered the development of a network of early-career researchers and practitioners who will be “multilingual” in terms of scientific disciplines, and who are poised to lead both within their respective careers and across the scientific community.
The SPREAD workshops were supported by NSF grant AGS-1157425. Thanks to all of the participants in the workshop, and to all of the speakers and presenters. Special thanks to Jared LeClerc, Jen Henderson, JJ Gourley, three anonymous reviewers, and editor Greg Byrd for providing constructive feedback that helped improve this manuscript. The efforts of Matt Kelsch in leading the tour of Front Range flood locations in both 2013 and 2014 are appreciated immensely. Thanks also to Clark Evans for suggesting the “SPREAD” name for the workshop, and to Karrie Butler of Colorado State University for organizing all of the logistics for the workshops in both 2013 and 2014.
FOR FURTHER READING
In addition to the primary graduate student participants, four undergraduate students also attended and participated in portions of the workshop.