This year there have been global news reports of water everywhere – and not a drop we'd like to see creeping into our homes (even if some of us may like a little beach activity)! Flooding is no joke - it's a serious threat that affects millions of lives costing the UK economy an estimated £2.2bn annually with a current spend of around £800 million per annum on flood and coastal defences.
Preventing flooding is of course the ideal, but being prepared to respond practically in the face of an event can also have a significant impact on managing the emergency. So, knowing that flooding usually overwhelms natural and man-made drainage systems, what if we could shore up our defences using the power of data to identify properties in areas at risk of flooding and mitigate the impact? This was the ask from our colleagues in the Flood Management team and Communications and Marketing team who wanted to use the project outputs to aid proactive communication to all households at risk, and make them aware of the availability of the Property Flood Resilience (PFR) Grant, which provides up to £8,000 of flood protection measures to homeowners in Essex to enhance their properties’ resilience against flooding. This initiative helps support homes that have flooded, or are at risk of flooding, to assist owners in making long term plans to achieve goals for risk mitigation.
Our analysis focused on extracting addresses in Critical Drainage Areas (CDAs) or those within areas at risk of flooding defined by the Environment Agency, as these meet the grant's eligibility criteria. There are about six flooding sources that we know of, and we focused on two of these. The first, flooding from surface water that happens when there is a heavy downpour and the water does not drain away quickly enough. This results in rainwater pooling at ground level causing flooding. Surface water flooding is unpredictable and somewhat localised (the PFR grant is only available for surface water flooding). And the second, river and sea flooding which occurs when a river or sea overflows its bank and causes damage to structures or communities nearby.
We used flood risk (surface water and rivers and seas) data from the Environment Agency, CDA data provided by the flood management team in ECC along with address data for properties in Essex from our internal database to obtain addresses at risk of flooding. Parish and district level boundary data was also used – the former to estimate counts of at-risk properties and then aid communication in raising awareness of the grant at the parish level and the latter to determine counts at the district level. As there are different risk levels associated with flooding, we used extent of flooding from surface water risk levels:
- 1 in 30 - high risk and denotes that each year, there is a chance of flooding of greater than 1 in 30 (3.3%)
- 1 in 100 - medium risk and denotes that each year, there is a chance of flooding of between 1 in 100 (1%) and 1 in 30 (3.3%)
- 1 in 1000 - low risk and denotes that each year, there is a chance of flooding of between 1 in 1000 (0.1%) and 1 in 100 (1%).
In addition, we also extracted the number of addresses at risk of flooding from rivers and seas with three risk levels of “high”, “medium” and “low” – as per estimates from the Environment Agency.
At county level, there’s an estimated 8,506 properties at high risk of surface water flooding (i.e. 3% risk), 14,825 properties at medium risk of surface water flooding (i.e. 1% risk), and 38,374 properties at low risk of surface water flooding (i.e. 0.1% risk) across Essex, and our results show that Basildon and Maldon districts feature as the districts with the highest and lowest counts of residential properties at risk at all three risk levels respectively. It is important to state that these results only reflect flood risk without including climate change allowances. In addition, larger and more populated areas naturally show a greater number of properties at flood risk. This is due to the greater number of properties being factored in.
To help the team identify areas with the greatest number of residential addresses at risk and allow for targeted communication with property owners, we created a choropleth map that features counts of residential properties at the parish level. The map details the number of residential addresses at risk of surface water flooding at all three levels of risk and includes the number of residential properties at risk in critical drainage areas.
Now that residential properties at risk have been identified, Essex County Council is able to support residents by raising awareness of relevant funding available to homeowners to mitigate the impact of flooding. This flood risk analysis along with recent global flood events demonstrates that being prepared is essential when it comes to flooding. Remember, knowledge is power and, in this case enables property owners to take steps to keep our homes dry(ish) when the skies open up.
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