The UK’s Parliamentary Office of Science and Technology (POST) has issued a new report highlighting the importance of adapting urban areas to flooding (see below).
The report comes at a time when floods have caused major travel disruption in London and the South East of England after 40 mm of rain fell in London in 24 hours to 23 June.
The Met Office has issued Amber Warnings (mid level – “be prepared”) for rain for London, South East and East England.
The Environment Agency is warning people that continued heavy rain could lead to further flooding across London, the South East and the East Midlands during the evening of 23 June. As many as six rivers in the London area have reached their highest recorded levels.
The River Rom in East London has burst its banks, flooding around 60 buildings in Romford. London Fire Brigade say that flood water was up to 1 metre deep in some areas and they have rescued over 100 people from the floods.
London Brigade took over 550 weather related emergency calls and firefighters attended over 400 incidents since the severe weather hit. They say that the worst hit areas have been in the east, particularly, Havering, Barking and Dagenham, Bexley, Greenwich, and Lewisham
A London Fire Brigade spokesperson said:
“Our control staff and firefighters have been working tirelessly through the night and into this morning to deal with the huge volume of weather related calls that we have received. Crews are being mobilised to incidents as quickly as possible but we are appealing to people to only call 999 in an emergency – where there is a risk to life or property.
“The high volume of weather related emergency calls received between 0130 and 0630 this morning is nearly twice the total number of all 999 calls that our control officers deal with in a normal day.”
“Incidents attended by our crews have included flooded commercial and domestic properties, flooded roads, and vehicles that have been trapped by flood water. Firefighters also attended a number of calls to reports of property being struck by lightning. Thankfully there have been no reports of serious injuries.”
Roads and Public Transport Hit
Major roads, including the London North Circular and the Blackwall Tunnel, which goes under the Thames connecting north and south London, have been closed. Flooded roads have caused major traffic problems in Battersea, Lewisham and Barking, amongst others.
Public transport has also been affected, with several train stations and tube stations having to shut, including Embankment, Tooting Broadway, Lambeth North, Borough and Canning Town.
Numerous train services were cancelled or delayed as a result of flooded tracks reported at Clapham Junction, West Norwood, Wandsworth Common and Manor Park, amongst others. Flooding also affected the signalling system into London Victoria, with many train services delayed or cancelled.
— Greater Anglia (@greateranglia) June 23, 2016
— Southern (@SouthernRailUK) June 23, 2016
A car abandoned in flood water under a railway bridge in Battersea, south London pic.twitter.com/0pXbT1swoR
— Neil Lancefield (@NeilLancefield) June 23, 2016
Violent showers & lightning affected the southeast last night; further showers are forecast tonight //bit.ly/28RQig5https://t.co/RMlVfzCyLt
— Met Office (@metoffice) June 23, 2016
Further Flood Warnings
Further rain and possible flooding has been forecast. The Met Office has issued Amber Warnings (mid level – “be prepared”) for rain for London, South East and East England.
The Environment Agency (EA) said that more thundery downpours on 23 June could cause further flooding in local communities, affecting properties and disrupting travel as roads, London Underground and rail lines are affected.
EA said that a number of rivers in the London area have reached their highest recorded river levels over the past 24 hours. These include the River Rom, River Wandle, Beverley Brook at Wimbledon, the River Shuttle at Bexley, River Ravensbourne at Bromley and the River Ingrebourne near Rainham, Essex.
There continues to be a risk of flooding from smaller, fast-responding rivers in built-up areas.
Across other parts of the south-east and the East Midlands, there is potential for further surface water flooding as a result of scattered showers.
Doug Wilson, Environment Agency Flood Risk Manager, said:
“Environment Agency teams are out on the ground, supporting communities and our partners to reduce the impacts of the heavy rain, and we will issue flood warnings and alerts where necessary. If travelling, we urge people not to drive though flood water – it is often deeper than it looks and just 30cm of flowing water is enough to float your car.”
Wave of Flash Floods
The current floods in London are part of a wave of flash floods experienced in England and Wales over the last 2 to 3 weeks, as the warmer summer weather has brought with it increasingly warm and humid air, often resulting in storms and short, intense spells of heavy rainfall.
South London felt the first of the summer’s flash floods on 07 June, leaving several cars trapped in flood water on a road under a railway bridge near Croydon.
The next day, three children had to be rescued after vehicles became trapped in floodwaters in North Harrow, north-west London. At one stage fire-fighters carried passengers trapped at North Harrow Tube station after floodwaters reached stairs to the two platforms on the Metropolitan Line.
Torrential downpours also affected parts of the West Midlands from 08 June onwards, including Birmingham city centre, Edgbaston, Great Barr, Handsworth, Oldbury, Wolverhampton and Smethwick, amongst others. Some of these areas were hit by floods numerous times over the last few weeks according to a local newspaper.
POST Report – Adapting Urban Areas to Flooding
Earlier in the week, the UK’s Parliamentary Office of Science and Technology (POST) issued a new report highlighting the importance of adapting urban areas to flooding. POST is Parliament’s in-house source of scientific advice.
The report says that more than 80% of the UK’s population live in urban areas. Extreme rainfall events, exactly like the ones experienced over the last 2 weeks, are predicted to become more frequent and severe in the future as the climate changes. Flooding is then exacerbated by impermeable paving and existing urban flood defences and drainage infrastructure simply cannot cope.
“Urban areas are increasingly being paved over. Impermeable paving prevents rainfall from soaking into the ground and accelerates runoff which puts increased pressure on drainage systems. Drainage systems built before 1940 usually combine urban runoff in the same pipe as raw sewage. During heavy rainfall, excess combined sewage bypasses treatment works, discharging directly into watercourses through overflow pipes.”
The report says that larger engineering projects must be planned so that they avoid increasing flooding risk neighbouring areas.
“Flood embankments, walls and barriers can protect business and property from flooding. However, permanent defences that increase the speed and volume of water in a river may lead to a higher likelihood of flooding downstream communities.”
There is no single solution to manage urban flood risks: a portfolio of solutions will be needed that include traditional flood defences but also flood resilience measures. The selected solutions should be site specific as those that are effective in one urban area may not be effective in another.
Natural solutions could play a significant role, including reducing run-off in urban areas. Urban drainage systems that mimic a natural landscape can reduce surface flooding and provide other benefits. For instance, Water Sensitive Urban Design, an integrated approach promoted in Australia, manages surface water flows to reduce flood risks and provide other benefits, such as improving water quality.