Was It a Flash Flood or Not? Categorizing Disaster Types in Historical Records

An aquaculture landscape in Rajapur, Bangladesh. Aquaculture farmers in Bangladesh tend complex aquatic systems that produce fish, vegetables and rice. These systems are especially vulnerable to flooding, which can increase salinity and affect fish health and production. Photo: Jacquelyn Turner, IRI

One of the important applications of climate knowledge is in the area of disasters. Being able to predict the scale of a potential disaster and the risks a disaster could impose on a community in the future is valuable and crucial information for not just government agencies and aid organizations, but also to support individuals and communities to both build strategies to become more resilient, and to anticipate when a disaster is likely to occur.

Disasters can differ widely based on region, climate, time of year, socioeconomic context, and other factors. However, while we have seen significant advances in understanding risk for some disaster types, such as drought and hurricanes, progress has lagged behind for other types — such as floods and particularly flash floods. While floods differ based on the water source and land area, it is generally recognized that flash floods can be especially dangerous.

Andrew Kruczkiewicz, Agathe Bucherie, Simon Mason, and their colleagues have delved into these definitions for a recent paper. We asked Agathe and Andrew for their insight into this intersection of climate data and application.

Some people might see dividing floods into different types as splitting hairs, but it’s true that a “coastal” flood is very different in many ways from a “flash” flood. Why do you think these distinctions are crucial? Why do we need to categorize disasters?

Agathe Bucherie is a research officer at the International Research Institute for Climate and Society (IRI). She supports work on disaster risk management and resilience.

Agathe Bucherie: Not all floods are the same. They can have different root causes and behavior, leading to very different impacts. Understanding and categorizing floods according to their triggers is key to improving disaster predictions. Indeed, techniques used for coastal flood forecasting (for instance based on storm surge models) differ significantly from riverine flood forecasting (commonly using large scale hydrological network monitoring) or flash flood forecasting (primarily based on local and extreme precipitation forecast). Furthermore, flood risk differs significantly in time and space from one flood type to another. Mapping accurately where and when populations are more likely to be affected by each type of flood is crucial to improve disaster risk perception. Unfortunately, some disasters like flash floods remain neglected, and some communities in highlands, far from commonly mapped flood-prone areas such as coastal or floodplains, might feel safe and not aware of the flash flood risk. Floods have very different behaviors, and knowing which type of flood communities are exposed to is crucial for disaster practitioners to anticipate what type of impact to expect. For instance, flash floods, characterized by localized and suddenly devastating events, are the most damaging and deadly flood type globally. Appropriate disaster preparedness and response actions might therefore differ from one flood type to the other.

Read the rest of the interview on IRI’s news site.