Warning fatigue - Why impact-based flood warning systems are a game changer

Flood warning systems are a crucial component of preparing and responding to floods. Yet with the rise in flood events due to climate change, many communities are now experiencing repeated flood warnings as the norm. The good news is that technological innovation is being utilised to move warning systems away from a broad one-size-fits-most approach to provide hyper-local warnings in real-time that can help save time, money, and lives.

FloodMapp specialises in real-time flood intelligence and is using its technology to provide an increase in effective warning time through location-specific flood forecasting and flood inundation mapping. At Humanitech, we are working with FloodMapp to pilot an approach that enables emergency managers to access scalable and real-time information to prepare and plan for emergency response activities to flooding. We speak with the team at FloodMapp to learn more about leveraging technology to respond to flooding and building back community trust in flood warning systems.

Warning fatigue - Why impact-based warning systems are a game changer

By FloodMapp

In floodplain management, flood risk studies are an important part of understanding the risk profile for a community and how we can use that information to development a plan and prepare ourselves for what may come next. Flood studies are also instrumental for the purposes of infrastructure design, development control, and to assist in strategic land-use planning and controls. The challenge with these static studies is that they:

Are limited to a finite number of modelled event scenarios (such as the 1% Annual Exceedance Probability). As events occur, they can sit between modelled scenarios, be larger than a modelled scenario, be a coincident event with different magnitudes or be a combination of all these scenarios. Rarely does the weather play by the rules and it can be difficult to determine the area of impact as an event is unfolding due to the numerous variables at play;
May rely on the use of techniques, such gauge rating curves and flood frequency analysis, to derive probability statistics for event based modelled scenarios. The limited available historical record of rainfall and river data (usually a maximum of 100 years) may not be sufficient to extrapolate the probability of what might happen in the future; and
May be limited in geographical reach with not all areas of interest within the modelled area or may not be reflective of significant changes in topography due to development or natural processes.

The key is that accepted hydrologic and hydraulic modelling techniques for event-based scenarios are valid and a crucial element in developing flood risk management plans. However, for emergency managers relying on event-based modelling, it can be difficult to understand the complexities of the unfolding event and select the most appropriate model scenario to determine the likely impact. Without having situational awareness in real time, the outcome is usually lack of warning (due to lack of confidence in what modelled scenario to apply) or to broadcast warnings that cover too broad of an area, are unspecific, and in hindsight seem either overkill or inadequate.

Image: FloodMapp's technology provides real time flood intelligence, offering Emergency Managers live data as a service product before, during, and after a flood.

For anyone who lives in an area affected by frequent disasters, there can be the danger of falling into a cycle of warning fatigue.

The cycle of warning fatigue might look something like this:

a disaster event starts to unfold. People are alerted to the disaster, but the warning is inadequate for a range of reasons: the warning does not cover the area affected; the warning underplays the severity of the event, or the warning comes too late to allow action;
a major catastrophic disaster seems to come from nowhere, taking many by surprise and causing widespread devastation;
as the emergency subsides, recriminations ensue, and systems are put in place to create better warnings next time;
another disaster is forecast;
this time, warnings are over the top. They are well ahead of time (too far ahead); they cover the area affected but in an abundance of caution cover a vast area; the severity is overestimated. General feeling that the warnings caused too much angst since no widespread impact was observed;
another disaster is forecast;
this time, while warnings are still forthcoming, the people in affected areas have lower trust in those providing the warnings. Most people in the warning area assume they won’t be impacted, as was observed in the last event;
this disaster is a major catastrophe with many people underprepared, despite the warnings;
the cycle then repeats.

It can be an uphill battle to get the balance right. The unpredictability of disasters means that warnings need to be given close to the event as it unfolds, but there also needs to be time for people in affected areas to be able to carry out their emergency action plan.

Image: FloodMapp CEO Juliette Murphy developed FloodMapp after seeing the impact of flooding firsthand in Brisbane and Calgary. "I started developing FloodMapp because I wanted to reduce the impacts of flooding and make people safer - and we're well on our way to being able to do that all around the world," Juliette said.

An area for hope may be in turning towards a more impact-based warning model, whereby action-orientated warnings become hyper-localised and impact based. Instead of just one blanket warning for a large area, imagine if flood warnings could be provided street by street.

While general warnings need to cover a broad area, having an idea of specific areas that will be more affected means emergency managers can direct resources where they are most needed, evacuate people most likely to be affected ahead of time, and switch off essential infrastructure to prevent damage and maintain public safety. Hyper-local real-time alerts can

empower communities to help each other, taking personal action to prepare;
be flexible and updated as the latest situational awareness comes to hand; and
expand and contract impact areas to provide the most effective allocation of response resources.

Most importantly, accurate hyper-local alerts can help create more trust for warning systems in general. People may be more likely to act in future because they can understand the impact associated with the warning. It also means people new to an area do not have to rely on historical and local knowledge to understand if they are at risk. Finally, for major infrastructure and essential services, scalable, local, real-time impact-based warnings provide the chance to evacuate, shut down and/or divert resources to ensure public safety, staff safety and continuity of service. This helps not only during an emergency but in the immediate aftermath of recovery as well.

There are many factors why we are seeing more “unprecedented” events in the world. By taking the focus from a broad one-size-fits-most approach to creating hyper-local real time information enabled through technological innovation, we can help save time, money, and lives.

Learn more about FloodMapp's technology on the FloodMapp website.