A dam which has seen an entire town in Derbyshire evacuated today over fears it might collapse could become “fully broken” within hours and cause “massive flooding”, an expert has said.
Residents in Whaley Bridge were told to leave their homes due to fears water from the Toddbrook Reservoir could swamp their homes after a dam was damaged in flash floods.
An expert from Brunel University in London has now said the damaged spillway of the dam – which contains an estimated 300 million gallons of water – could become “fully broken” within hours.
This could lead to “massive flooding” following the heavy rainfall, and the estimated 1.3m tonnes of water inside the dam is at risk of wiping out the small town if it was to collapse.
Dr Mohammed Heidarzadeh, assistant professor and head of coastal engineering and resilience LAB, said: “Due to heavy rainfall in Whaley Bridge area, the spillway is now broken and a big chunk of its concrete structure is damaged.
“There is a possibility that the spillway could then become fully broken in a few hours. If the spillway is fully gone, the embankment dam will be washed away very rapidly, which could cause a massive flood.”
He added that a similar situation occurred at the Orovill dam in California in February 2017.
However, as long as the core of the reservoir is not damaged, the wall “should be okay”, according to another specialist.
“Within the last few years new valves have been placed in the dam to expedite rapid drawdown in emergencies: presumably, this is happening now,” said Professor Roderick Smith, from Imperial College London.
The former chief scientific adviser for the Department for Transport said the reservoir previously had “issues” with an inadequate valve system which has seen been replaced.
Severe flooding in South Yorkshire in 2007 sparked the evacuation of roughly 700 people around Ulley Reservoir, near Rotherham, over fears its walls could burst due to unprecedented rain and apparent “areas of weakness”.
Police have told residents from the picturesque market town to bring pets and enough medication to last for ‘a number of days.’
Derbyshire police said the town with around 6,500 inhabitants was being evacuated “due to the ongoing situation at Toddbrook Reservoir.”
Police wrote on Twitter: “Whaley Bridge is being evacuated due to the ongoing situation at Toddbrook Reservoir.
“If you are being evacuated then please start heading to #Chapel High School, Long Lane, #ChapelEnLeFrith, #HighPeak, SK23 0TQ, where further direction will be given.
“Officers and staff will be at the school to give further direction but at this time we aren’t sure how long the evacuation will take. Please make alternate arrangements to stay with friends/family, ensure that pets and medication that may be needed for a number of days are taken.”
Heavy downpours brought flooding and scenes of “complete chaos” to parts of the UK today.
Flooding due to sustained rain disrupted all lines on the railway between Manchester Airport and Wilmslow early on Thursday, according to train operator Northern.
A major incident was declared late on Wednesday in Poynton, Cheshire, due to “severe flooding” and local groundwork landscaper Adam Wainwright described the aftermath as “complete chaos”.
He said: “We had flash flooding and heavy rain.
“There have been houses where the flood has had an effect, and it has just ripped through the houses. The water has just gone through the front door and out the back.”
A bridge which partially collapsed due to the flooding in Poynton caused a nearby tree to fall into Simon Howcroft’s garden, where a sinkhole also opened up.
Cheshire Fire and Rescue Service (CFRS) said firefighters, emergency services personnel and staff from Highways England were helping those affected, with a rest centre established at Poynton Civic Hall.
CFRS added: “Please bear with us, crews and police officers are working very hard to get to those in need and the most vulnerable in our communities.”
Police urged people not to ignore “road closed” signs by driving or walking through water.