Croydon Council has placed parts of the south of the borough, around Kenley and Purley, through to South Croydon, on a flood alert because of the continuing rising levels of the Caterham Bourne.
A bourne is normally a benign, small chalkland stream that has water in it only very occasionally. But the Caterham Bourne has overflown its banks around Whyteleafe on a couple of occasions already in the past month, and now the flooding issue is moving downstream, into Croydon and the Wandle valley, all the way through to Broad Green and Wandle Park.
The Environment Agency issued a Flood Alert for the Caterham Bourne in Surrey four weeks ago, which stretches all the way through South Croydon through Beddington to Carshalton, and that status has not changed since.
This morning, Steve Iles, Croydon’s head of highways and parks, sent an email to update council staff on the situation.
Iles wrote: “Groundwater levels in the upper Wandle area are high, causing the Caterham Bourne to flow. The Caterham Bourne is located to the south of the borough running through both Kenley and Purley Wards then into Croham, Waddon and then into Broad Green ward as it makes its way into Wandle Park and then into the River Wandle.
“The bourne’s origin is in the upper Woldingham area and then makes its way along the valley coming into the borough along the A22 corridor. The Bourne runs parallel with the Godstone Road in the main and is a combination of open ditch and culvert.
“The intense rainfall received over the past couple of months has saturated the ground causing the flow of the Bourne to increase significantly. During January the area has seen some 220mm of rain which has raised the water table immensely, to illustrate this the water table during the summer months is usually 25 metres below ground, readings taken today at Kenley treatment works recorded the water table had risen to within 0.75 metres of the surface, this means surface water flooding is already being experienced along the low-lying parts of the valley, in particular the Bourne Park Close recreation ground and adjoining open space heading toward the Kenley treatment works up to Bourne View. It is expected that surface flooding is likely to increase as the levels rise, this in combination of the bourne flowing has put the area at high risk of surface flooding.
“For those of you who recall the adverse weather over the Christmas of 2000-2001, where the area suffered severe flooding and the closure of the A22 for a number of weeks. As part of the improvement to the Bourne during that time the council created a Bund in the allotments at Bourne View this enabled the area to flood within rather than putting residential properties at risk.
“This flood area has put us in good stead this time as we have been able to control the flow of the bourne and use this area to relieve the flow. The area is now approximately 75 per cent full and unless rainfall decreases we will need to put emergency measures in place to extract water via tankers and or over pump into sewers, the equipment needed to do this is currently being organised to ensure we can react swiftly.
“Due to the on-going heavy periods of rain and increasing volume of water coming down the valley, this combined with already saturated ground, water table being above ground in the lower parts of Bourne Park recreation ground means overtopping of the bourne is becoming a frequent event along this section.
“We have provided sandbags to a number of residents along Bourne Park Close and the parade of shops between the Police Station and Hayes Lane.
“The trash screens are being kept clear and the flow rate is high, the culverted sections appear to be flowing a full bore, this is causing surcharging of water into the water treatment works. Sutton & East Surrey Water, who manage this site, have put measures in place to protect the pump rooms but surface flooding is occurring.
“Just outside the borough in Whyteleafe the A22 Godstone Road has flooding at the junction of Maple Road as the system is surcharging, at the moment the road remains open and we are liaising with Tandridge council on this.
“Downstream into Purley the bourne is flowing well with no flooding to note at this stage, the bourne then comes into Purley Oaks Depot and the balancing pond is approximately 80 per cent full. We are working with Thames Water to ensure this is managed, we are also investigating the possibility of over pumping back into the surface water system if there is capacity to do so.
“In terms of the weather … unfortunately things are not improving in the short term the theme remains heavy and persistent rain with strong to gale force winds. The accumulative effect of the rest of the week’s rain is likely to see a further 35mm – 75mm of rain over the next three days and the accompanying strong to gale force winds (40–60mph) may lead to significant issues.”
Iles is due to meet tomorrow with various agencies, including Thames Water, Sutton and East Surrey Water and neighbouring local authorities, as well as the Environment Agency.
To report rising groundwater levels or flooding, residents are asked to call the Environment Agency Incident Hotline on 0800 80 70 60. You can also sign up to the free groundwater Flood Alert/Warning service by calling Floodline on 0845 988 1188.
Coming to Croydon
- Purley Swimathon: Feb 8 and 13
- Mark Steel at Ashcroft Theatre, Feb 12
- Croydon Arts Network meeting, Feb 15
- Chinese New Year children’s event, Upper Norwood Library, Feb 18
- Welsh myths children’s event, Upper Norwood Library, Feb 20
- Norwood Society talk, Upper Norwood Library, Feb 20
- Mr Pooter comes to Croydon, Feb 20-22
- Warm and Well event, Upper Norwood Library, Feb 22
- Stop the Incinerator fund-raiser, Feb 24
- Fairtrade event, Upper Norwood Library, Mar 1
- Coulsdon and Purley Debating Society, Mar 3
- Patchwork and quilting workshop, Upper Norwood Library, Mar 3
- Upper Norwood Library Book Club, Mar 15
- Norwood Society talk, Upper Norwood Library, Mar 20
- Croydon Half-marathon, Mar 30
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