“How New Technology is Helping Prevent Flooding in London”

Tackling flood before it begins

The impact of our changing climate on how we live and work is one of the latest challenges facing local authorities. Record-breaking dry spells, followed by wet weather can see councils having to deal with park fires one day and flash floods the next.

In the summer of 2021 the London Borough of Sutton experienced this challenge first hand. The long hot summer resulted in hard parched ground, so when the rain came the borough’s drainage system couldn’t cope. The result was a number of flash floods across Sutton.

With extreme weather predicted to continue, the London Boroughs of Sutton and Kingston wanted to find a better way of monitoring the risk of flooding to reduce the impact it has on lives, property and vehicles.

The birth of a ground-breaking new Internet of Things (IoT) Programme

Sutton and Kingston collaborate with three other London Boroughs as part of the South London Partnership (SLP). In 2018, the SLP recognised that technology could be a powerful ally in helping with flooding and other issues faced by local authorities. They successfully secured funding to develop an IoT programme which focused on addressing real world problems via the collection of data and insights gained from IoT sensors deployed around various locations. These sensors could have multiple uses, including measuring water levels from floods.

As the scale of the programme grew, the decision was made to expand the scope to include building a brand new IoT data platform. This would overlay data in ways not previously possible and give the potential for profound insights by breaking the data silos within the local authority community. It would also allow data to be more widely available to the public.

Diving beneath the surface of flooding

In 2021, after an open tender using the SPARK CCS Framework, Aquasition was awarded the contract to provide the first IoT sensors to be installed in the road gullies and soakaways of Sutton and Kingston’s known flooding hotspots. This was rapidly followed by an expansion into Richmond who had similar issues and had been monitoring the trial results from Sutton and Kingston.

The sensors remain there today and continuously monitor key drainage data – both water height and the speed at which it is rising. Additionally, each installed sensor is assigned a status to show whether water capacity is full, close to filling, or low enough to be of no concern. Automatic alerts are then assigned to officers who can log onto the platform to get further information.

During dry spells, the technology can deduce other circumstances such as high silt levels when water never falls, or a continuous top up which could be a sign of clean or waste water pipes leaking into the gullies.

To give a 360-degree view, the platform is also connected to rain forecast information and the two streams of data are pooled together to create both tactical and strategic information.

What has happened since this technology trial in Sutton?

The results have been incredible. Not least because of the insights the new technology has created which show the precise location and nature of potential flooding sites.

This IoT system has already been adopted by the SLP’s neighbouring council of Wandsworth.

What advantages have we seen?

1. Cost benefits from cleaning & maintenance. Crews are now informed of two crucial bits of information: where the critical areas are that need urgent attention and which areas are safe from flooding. Therefore, vehicles such as gully suckers can be assigned to the areas that matter – without the need to go everywhere. The average combined cost of a gully clean and associated road closure is around £2.5k, so reducing these represents a big saving. Cleaning crews also have insight into the best locations to dispose of their own waste, so they don’t congest already overworked drains.
2. Working more constructively with partners, such as Thames Water, to reduce sewage and freshwater leaks. Leaks can be pinpointed and the elements of each incident better understood. This clarifies responsibility and has led to better collaborative working with water companies.
3. Keeping businesses and residents on the road. Low lying areas underneath bridges can cause traffic chaos when they flood. Monitoring the rate at which silt builds up in areas like Wallington Bridge and Worcester Park has led to electronic signage being installed which warns and diverts road users prior to encountering a flooded location.
4. Identifying the best candidates for drainage investment. Monitoring via sensors has shown where drainage investment can have the biggest impact – helping to allocate precious funds effectively.
5. Local Authorities are acting on a proactive informed basis rather than reacting to alerts from the public, such as on twitter when cars start floating away!

Find out more
If you would like to have a conversation about how this technology could help your vulnerable residents, please contact Andrew Parsons andrew.parsons@kingston.gov.uk or Pierre Venter pierre.venter@sutton.gov.uk.