Storms and flash floods — what can be done?
Has anyone else found themselves (or their washing) drenched from a sudden downpour in the last few weeks? If you’ve seen any of the news headlines from recent weeks you’ll know that wet hair and washing is the least of problems. It’s the way that these summer storms catch people off guard that means they can have severe consequences and cause considerable losses. Back in the summer of 2007 the UK experienced a catastrophic amount of rainfall, with flooding causing around £4bn worth of damage — an estimated £3bn being insurable losses. These figures may be from a while ago, but since then climate change is better understood and has moved higher up the “agenda”, with the MetOffice predicting that summer downpours will continue to intensify - becoming 5x more likely by the end of the century.
Since last week various regions across the UK have experienced flash flooding as persistent hot weather created the ideal conditions for intense localised storms, last week in particular South East England and Central Scotland were badly affected.
For the purpose of validating our forecasts we decided to look back at some of the flooding events from last week. To identify how accurate our forecasting abilities are for a particular flood event we used social media outlets (Twitter, Facebook etc.) and news stories (BBC, The Guardian etc.) to corroborate the prediction.
On 13th August, areas south of London experienced heavy rain, lightning and hail which led to severe flooding events later in the afternoon, causing considerable disruption.
The M25 was flooded from around 4pm, causing it to close between junctions 6 and 8. Many drivers were left stranded or trying to navigate dangerous conditions. It took over 3 hours for Highway England to pump enough water out of the road that they could access the hard shoulder and finally let those stranded continue on their journey. Further delays continued until the early hours of the following morning.
Several areas in Croydon have been severely affected by surface water flooding in previous years and are left susceptible due to the areas topography and pattern of urban development. Source.
This particular area in Purley Oaks — a stretch of road leading up to one of the train station entrances — has seen severe flash flooding in previous years too, see below for images from August 2015. For these business owners, the high intensity of rain fall and lack of prior warning means that they may not have been able to prepare.
On the previous day, 12th August, Scotland experienced similar weather. Aberdeenshire in particular was hit badly with flash flooding with multiple roads being closed, trains cancelled and schools shut (on what would have been their first day back since lockdown). You can see some other examples of where we predicted flooding in Aberdeenshire on our website.
For the events included in this post, and many others that have been widely covered in the press, our forecasting technology actually predicted that the flooding events would occur over 6 hours in advance of when they did.
At Previsico we are big believers that most flood losses are avoidable if you can provide people with an accurate warning and give them time to protect their property or assets. As part of our participation in the Lloyd’s Lab we worked with insurers to show how providing alerts to customers can help reduce losses by over half, reduce premiums and support claims teams.
We are looking to turn the tide (sorry…couldn’t resist) on how flooding is dealt with.
Thanks to my colleague, Amelia Harris, who put a lot of work in to putting these validations together!
If you would like to find out more about what we are working on at Previsico or have any thoughts for us then please leave a comment or get in contact: lucy.coutts@previsico.com
