What were the causes of the recent floods, and what can we learn from them? Margo Cole talks to Environment Agency head of strategy Pete Fox.
Every few years, the UK has a flooding event that is so extreme that it significantly affects attitudes, and in some cases leads to changes in policy and legislation. This was certainly the case in 1953, when a massive tidal surge hit the east coast, and it was again in 2007.
The last two months have seen weather that was just as extreme as that experienced during those two seminal events. So will the flooding we have seen this time round again lead to changes in attitude or policy? Or have the measures put in place as a result of previous floods been so successful that we can now cope with anything that is thrown at us?
Perhaps unusually, this winter we have experienced almost every type of flooding - coastal, river, surface and groundwater. It has been caused by a series of low pressure systems moving very quickly across the Atlantic, accelerated by especially strong jet streams that have brought heavy rain and high winds since November. The first real flooding impact came at the start of December, when the low atmospheric pressure and resulting high winds coincided with high spring tides to cause a massive tidal surge.
“We saw flooding on the east coast [of England] from the border with Scotland to the Isle of Wight,” says Environment Agency head of strategy Pete Fox. This surge led to breaches in sea defences and flooding in many places, including Boston in Lincolnshire.
West coast surge
Meanwhile, a smaller surge on the west coast affected north west England and west Wales. The surges lasted for a series of three or four tides during 5, 6 and 7 December, before the low pressure weather system moved off and the spring tides abated.
Two weeks later, as part of the same weather pattern, widespread heavy rain affected Wales, the south west and south east of England particularly badly. This was followed by extremely heavy winds and powerful storms on the first three days of January.
“What we’ve seen - and are still seeing - as a result [of these weather systems] is flooding from all sources except reservoirs,” explains Fox. “We had coastal flooding on the east, west and south coasts associated with the tidal surge at the beginning of December and the storms in January, and surface water flooding that caused disruption to travel, including the electricity supply problems at Gatwick.
“The joint flood forecasting centre can predict how much rain is going to fall, and predict the impact of that type of rain on river levels”
Pete Fox, Environment Agency
“We’ve also seen river water flooding on the Medway and the Mole at places like Yalding and Tonbridge, and more recently through the lower Thames; and now we’re seeing groundwater flooding because of the percolation of that water into the ground.”
This groundwater flooding is particularly prevalent in Wiltshire, Dorset and Hampshire, where the underlying geology includes chalk and limestone. “We have quite a few flood warnings on because the aquifers are over full as a result of the rain, so people living on chalk or gravels could see water come up through their floors,” says Fox.
The December tidal surge was, in many ways, very similar to that of 1953, but the impact on property and life was very different. “They were comparable in tide height, and the strength of the wind,” says
Fox, “but in 1953 the surge caused many thousands of breaches in sea walls and [more than] 300 deaths.”
This time, the Agency says there was damage to around 200 defences, and no deaths as a result of the surge, and the total number of properties flooded during the event was around 1,800, compared with an estimated 24,000 in 1953.
“What we’ve seen [since 1953] is a fantastic improvement in flood defences,” says Fox. “The Thames Barrier was built in response to that event, as well as long lengths of shoreline. It was a real wake-up call to start investing in sea defences and gave a real focus on spending money to save people’s lives.”
Last year, the 60th anniversary of the 1953 floods, the Environment Agency and members of the Local Resilience Forum, carried out an exercise on the east coast to test the robustness of emergency plans in the event of a similar flood. “We re-enacted it as if it happened again, so when it came we were better prepared than ever,” says Fox.
If the coastal flood defences and Thames Barrier were legacies of the 1953 floods, being better able to predict and prepare was a major legacy of the events of 2007. One of the recommendations of an exhaustive review in the wake of the 2007 floods by Sir Michael Pitt was the instigation of a flood forecasting centre, run as a partnership between the Environment Agency and the Met Office. According to Fox this centre proved its worth during the recent floods.
“The principal first tidal event was during the afternoon tide - between lunchtime and midnight - on the Thursday [5 December],” he recalls. “I remember getting an email to start the process of planning for it on the previous Sunday.”
At that stage the flood forecasting centre was starting to see that high tides were going to coincide with an area of low pressure. “By the Wednesday [4 December] we were alerting communities and being proactive with the media to be aware of the concerns we had,” says Fox.
“It is all about probabilities and risk management,” he adds, “and we are getting better at identifying risk. The joint flood forecasting centre can predict how much rain is going to fall, and predict the impact of that type of rain on river levels. Through modelling we can predict with some confidence if the water is going to come out of its channel, and if so how many properties are at risk.
“The joint centre was a recommendation of the Pitt Review, and it has made a significant improvement - a step change in our ability to predict.”
The 1953 floods led to widespread investment in heavily engineered flood defence solutions, while the Pitt Review into the 2007 floods focused more on issues like prediction and preparedness. So what will be the legacy of the 2013/14 floods?
Fox says the Agency always undertakes a “lessons learned review” after any flood, irrespective of the scale or nature of the event. “This is no exception,” he says. “We will and are collecting the information to help us with that review. It is too early to speculate on how we will change, but some things we know worked well.”
These include the use of warnings, liaison with the media and the use of social media. The Agency used Twitter alerts to let people know what was happening in their area. “There is a system where Twitter alerts can be used by public agencies to issue tweets to [people in] a geographical location even if they are not signed up to receive them,” explains Fox. “The first time they were used was in the December tidal surge.”
Some sea defences were breached during the storms, but there does not appear to be a consistent type of damage, according to Fox. “There was diverse damage to all kinds of defences,” he says. “The nature of the coastal storms we’ve seen was very different: in early December there were some coasts around the North East in particular that were battered by storm waves, but the wave lengths were shorter, so the damage was less.”
“One of our core priorities is to develop an understanding of the risk and then share it - with the people responsible for infrastructure and with people who own houses, so they can make choices about what they do”
Pete Fox, Environment Agency
Meanwhile, on the west coast, there has been some realignment of cliffs and destruction of rock features. “We saw nothing of that scale on the east coast,” says Fox. “The greater fetch of the Atlantic means there were massive waves, and huge power in those waves, so the damage you expect to find is different.”
Although Fox is far from complacent about the damage and disruption caused by flooding, and the Environment Agency’s role in minimising that damage, he says there has to be some element of individual responsibility, with infrastructure owners and householders sharing the risks associated with flooding.
“We have a responsibility to try to manage [the risk] and educate people, and to prepare people as much as we can. One of our core priorities is to develop an understanding of the risk and then share it - with the people responsible for infrastructure and with people who own houses, so they can make choices about what they do,” he adds. “They might take insurance cover out, or put in flood barriers, or they might ignore it and run the risk of losing property and possessions.
“We do a lot of work to see what solutions we can put in place - engineered solutions to minimise risk. But where we can’t, or where it’s not technically feasible or financially possible, it is about putting in place flood warnings or helping people put in their own [solutions].
“We’ve developed a national assessment of flood risk - the maps on the internet are the best assessment of flood risk around England for surface, river and coastal flooding,” Fox explains.
“We use that as the start point for investments where flood defence schemes are financially viable, but that doesn’t prevent others from looking to their own solutions.”
Recent years have seen more emphasis on schemes that involve managed flooding - allowing land to be flooded during extreme events.
These include coastal nature reserves in East Anglia that have some natural protection in the form of raised shingle banks between the seashore and farmland.
“At the beginning of December a lot of these were flooded, but they took the energy out of the tides, preventing damage to the banks behind and the farmland,” explains Fox.
Another example is the use of flood storage areas to store water upstream of properties to prevent them flooding. Although the town of Tonbridge in Kent saw significant flooding in the days before Christmas, Fox says it would have been significantly worse if some of the water flowing in the Medway had not been held back by the Leigh Barrier and stored upstream of the town on an area of land purchased some years ago by the Environment Agency.
Between 21 and 23 December around 90mm of rain fell in the Upper Medway river catchment, over half of it on 23 December, onto ground that was already saturated. Over the next three days the Leigh Barrier held back 5M.m3 of water.
Fox says this is something that is replicated in other locations, but is also calling for more public debate about how farmland in general could provide public benefit, both in flood prevention and for storing water during droughts. He explains that for the last 50 years there has been a policy of installing drainage on farmland so that water is taken off the land as quickly as possible.
What he is suggesting is that some of these drains could be blocked, and the land could then be used to store flood water if necessary, and also to store water at times of drought.
So, if there is to be a legacy from the 2013/14 floods, maybe it will be in the form of a national debate about how we use our land, how we live with water - be it too much or too little - and how we all take our share of the risk.