When a major flood event occurs, risk managers must act quickly to provide useful data to the insurance industry so that they can assess who may be impacted, plan their resources and understand the immediate impact on their business in terms of losses and claims.
As a result, at JBA, we have developed a dedicated event response approach so our clients can react to the event effectively.
Techniques for mapping flood events
There are many ways to map major flood events, including digitising from aerial imagery or satellite data and undertaking 2D hydraulic modelling. However, both methods have their challenges; digitising does not necessarily provide you with the maximum flood extent and shadows may cause distortion of flooded areas. It can also take some time to obtain and can be expensive or of poor quality. Similarly, 2D hydraulic modelling of the flooded area can be too time consuming for large-scale events, especially when time is critical for an insurer.
Our approach
So, how do we overcome this?
At JBA, we can respond rapidly to major flood events due to our market-leading global flood maps. These map up to 6 return periods in almost every country in the world for river and surface water flood and, for some countries, coastal flood too. This readily available data allows us to quickly provide useful information to insurers when they need it most.
By using our flood maps and their associated hydrological inputs, we can create a flood event footprint.
Flood Event Footprints
We aim to produce a flood event footprint within seven days. However, for floods of a longer duration, for example on the River Danube when flood peaks can take several days to reach the sea, we can use our maps to predict what will happen as the peak progresses, with the footprint updated frequently as new areas are flooded over time.
Using river and rain gauge information, or JBA’s innovative Flood Foresight® forecasting application, we begin by extracting peak rainfall and river levels at each affected gauge. Using this, a predicted return period for these gauges is derived by comparing the flood peaks with our hydrological databases, assigning the predicted return periods of each gauge to the return periods of the nearest pre-existing flood map. Pictured: flood footprint from 2019 flooding in Canada
At JBA, we have also created our unique hydrological accumulation zones (HAZ®) dataset to complete the process; these hydrologically sensible boundaries follow catchment areas rather than geopolitical boundaries, allowing us to identify areas that may be affected by the same flood event.
By assigning a return period to each affected catchment in the HAZ and extracting the associated flood mapping from our pre-existing maps, these are merged together to create a single flood footprint, covering multiple catchments and flood sources.
Our event response team provides insurers with both depth data and extent information, with depths particularly useful in helping to predict the cost of repair to properties.
The importance of validation
Once we have an initial footprint, these are then validated. If the event is short and small-scale, validation can be done rapidly. However, for large-scale events or those that last longer, it may be necessary to provide several footprints that evolve over time as the flooding develops.
We obtain validation information to identify which areas were affected and where defences have overtopped or breached, which can come from media articles, social media, government websites and on-site visits, as well as drone footage and aerial imagery. Using this information, we adjust our flood mapping to represent the reality on the ground.
What about data prior to a flood event?
JBA can also provide flood footprints before an event occurs using our sophisticated flood forecasting software. With insights available up to 10 days in advance of a flood event and data refreshed up to every three hours, proactive decision-making can help mitigate the effects of flooding.
Why is all of this important?
Our event footprints allow insurers to carry out their vital work as quickly as possible. It can help to determine the overall expected loss and predict the number of expected claims in a given area. It can also help insurers to identify potential fraudulent claims or claims that have been recorded incorrectly, giving them a much more comprehensive and consistent view of their risk.
If you would like to find out more about our event response services, including Flood Foresight, get in touch today. You can also find out more about our hydrological techniques in our blog exploring the JBA Global Catchment Database.
