Flood Map Event Validations

Analysing the impacts of UK flooding in February 2020

In Insights, News by Stephanie Brain

Analysing the impacts of UK flooding in February 2020

Throughout February of this year many parts of the UK suffered heavy flooding and horrendous weather conditions brought on by three consecutive winter storm events in quick succession.

 Storm Ciara, Storm Dennis, as well as to a lesser extent Storm Jorge, put immense pressure on environmental authorities and emergency services across England, Scotland and Wales who deployed temporary flood defenses and undertook widespread evacuations. During the storms gusts of wind reaching more than 90mph were recorded, along with heavy rain which brought widespread flooding, causing travel disruptions and left thousands of people without electricity.

Throughout these unfortunate events Ambiental was supporting our customers to understand the impacts of the flooding and to ensure that the flood models we have developed were accurately predicting the observed flooding. Our researchers and technical analysists were busy reviewing the events as they unfolded and preparing comparisons of media reports against our UK products FloodMap, FloodScore and FloodFutures.

The slideshow report which we have prepared comprises some of the key information we have shared with our customers directly as well as through social media during and immediately after the flood events. The report of our findings is available to everyone for download. Simply complete your details in the form below to unlock our in-depth slide presentation containing summaries, facts and images of the flooding  alongside validations of our flood data.

Despite the misery which floods cause these events provide unique opportunities to validate Ambiental flood predictions in order to ensure model accuracy. The outcome of our research study demonstrated that UK FloodMap performed well, as evidenced in the report. This is important for us to ensure our models are providing the best possible predictions so that people, planners, investors and emergency responders are aware of at risk locations well ahead of time.

The images below show a few examples of the flood map validations at specific geographic locations which we share on social media and which are covered in greater detail within the report.

Flood Map Validation Hebden Bridge

The flooding that resulted from Storm Ciara occurred at multiple locations including Hebden Bridge in West Yorkshire. This image shows flooding along Market Street alongside a validation image showing UK FloodMap flood extent in blue.

Flood Map Validation Mytholmroyd

Flooding in Mytholmroyd

The maps show Ambiental UK FloodMap fluvial 30-year.

Our FloodMap assesses residual risks through being available as an undefended model, as well as model which accounts for defences. The Mytholmroyd flooding from Storm Ciara is a stark reminder that flood defences do not guarantee protection and can fail under extreme conditions. The £30m scheme in Mytholmroyd was not due to be completed until the summer and was unable to prevent the River Calder from bursting its banks. In this image the flood defences are shown in pink and the undefended UK FloodMap 1 in 30 year is shown in blue.Flood Map Validation Hawick

Building collapses into the River Teviot at Hawick.

The map shows Ambiental UK FloodMap fluvial 30-year.

Storm Ciara caused a building in Hawick to collapse into the River Teviot. Under flood conditions high velocity flow can increase riverbank chance of failure. Our Erosion Potential model identified this location as at risk, with risks increasing under climate change scenarios. In the image we can see the risk of erosion represented as lines with green representing low erosion potential and red representing high erosion potential. This data is overlaid on Ambiental’s Fluvial 1 in 30-year FloodMap for the area.

Storm Dennis

Only a week later much of the north of England, Wales and northern Europe endured yet more severe winds and heavy rainfall ranging between 40 and 80mm in 24 hours. The peak of the weather event and the flood emergency occurred on 16 February 2020. The Environment Agency issued 347 flood alerts, 282 flood warnings, the highest on record – followed by 7 severe flood warnings in England.

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