Opened in 1982, the Thames Flood Barrier is an iconic symbol of London. As much a world-famous tourist attraction photographed by millions of visitors to the capital each year, it has a crucial function in keeping the city safe as a method of flood prevention.
Now over 30 years old though, there are calls for a fresh look at the situation. With the ever-increasing incidence of flooding throughout the UK, the Thames Barrier is under scrutiny as to the frequency of use when waters rise in London and the security it offers for those living across the floodplains of the area.
Why was it built?
There are a number of areas of London and the surrounding area which are vulnerable to flooding due to them being in low-lying areas. When storm surges and high tides meet – particularly in the spring, the water is funnelled down through the Thames and the rising waters pose a risk to the city.
Following a UK-wide flood in 1953, a total of 307 people in London lost their lives. Attentions quickly turned to looking for a way to ensure that London would not flood again in this way in the future.
Charles Draper undertook the initial design work in the 1950s. He conceived the now famous rotating cylinders from looking at the design of household taps. Greater London Council moved the project forward and the location where it is now sited at New Charlton was chosen due to the combination of the construction of the banks and the chalk river bed.
How does it work?
The Thames Barrier stretches across a 520 metre width of the river and is divided into four spans of 61 metres each and two of 30 metres.
The flood gates are circular segments which when not in use sit under the water to allow marine traffic along the river; they close by rotating. After all segments have moved 180 degrees, the barrier is in place and nothing can pass through. The gates are highest in the middle and these each tower to 20.1 metres tall.
How often is it needed?
The Thames Barrier is being used with a concerning increase in regularity.
Since it was opened, the Barrier has been closed 174 times. Whilst this may not seem a very regular occurrence over 33 years, the issue is that it was required only four times from 1982 to 1989, then 35 times in the 1990s. From 2000 onwards the annual frequency has steadily increased and peaked in late 2013 to early 2014 when it was closed on 40 occasions in a six week period including 20 times in just 10 days in early February 2014.
With the recommended maximum number of closures being 50 due to the mechanical operating strength of the machinery, the original designers may have saved London for over half a century but could obviously not have forecast the changes in the environment and the effects of the then non-existent phenomenon of global warming.
This beautiful piece of modern engineering is a hero in terms of the lives of the millions it keeps safe within the 50 mile square miles it protects, but with the soggy floodplains to contend with, coastal erosion and concerns of the threat of more storm surges over the coming years, there are a number of experts who feel that it is time for the Thames Barrier to be replaced.
Why are there calls for a second Thames Barrier?
The original design was heralded as being a protection to the residents of London until 2070. Based on the data of the time, a replacement Barrier was not predicted before then because of the much lower levels of frequency of use expected.
The constant use as a flood barrier over the past decade means that the mechanical elements are now degenerating and it is felt that a replacement is required by 2030 at the latest. The situation is being investigated but until there is an outcome, it is a case of monitoring frequency and carrying out thorough maintenance so it operates every time there is a threat.
Even though the Barrier can hold back 9000 tonnes of water when fully closed, there are still fears that an unprecedented set of circumstances could mean that it could be breached.
The plans put forward are for the new Thames Barrier to be built sooner rather than later. The mooted sight is downstream of the M25 crossings at Dartford. The financial cost will be high, but so was the original flood defence and even at £5000 each time it closes it has paid for itself time and time again. Protecting almost two million people, half a million buildings and £200 million worth of assets, a new flood barrier would ensure everyone and everything would remain safe.
Flood prevention is something everyone needs to take responsibility for and whilst those in London can currently look at the Thames Flood Barrier when it starts the 10 minute initial closure process and know they are safe, the unpredictability of the forces of nature alongside the environmental impact made on the planet over the past few decades mean that whether we are in London or elsewhere, the evidence that flooding is on the increase means we should all be prepared to look after our homes and loved ones ourselves.