Image: Breach to the Bourne Eau on 3 January 2024 following Storm Henk. One of more than ten breaches to embanked main rivers that have occured in Lincolnshire this winter. (Ed Johnson)
By Ian Moodie MSci, Technical Manager, ADA
The 2023/24 storm season this year has been much more active with ten named storms so far. In the previous year 2022/23, the UK only experienced two named storms. According to weather specialists, storms are affected by a number of phenomena including sea temperature, extent of sea ice, position and strength of the jet stream, and other climate patterns, such as El Niño, which is currently in an active phase. Whilst no single event can necessarily be attributed to climate change, wetter and more turbulent winters are something the UK will face more of in the future.
The resulting challenges from these storms are being felt across the UK. Storms Babet, Kieran, and Henk between them caused flood misery to over 2,000 properties and most recently, Storm Ischa has caused power outages to over 75,000 houses and businesses and travel chaos across the country. In our lowlands, over ten breaches to embanked main rivers in eastern England have resulted in extensive flooding of many hectares of highly productive agricultural land and inundated a number of IDB pumping stations.
Whilst our main rivers have shown an increasing number of asset weaknesses, in the main, IDBs’ assets and systems across England’s lowlands have coped well with exceptionally high rainfall this winter. In a number of cases IDB pumping stations even coped well with receiving water that has overtopped from embanked main river into their systems.
The UK’s biggest pumping station was one of those many IDB assets that worked harder than ever in its history this winter. The St Germans Pumping Station in the Cambridgeshire Fens was discharging 77 cubic metres of water a second in the wake of Storm Henk – enough to fill an Olympic swimming pool every 30 seconds.
Middle Level Commissioners’ Chief executive, Paul Burrows, said:
“The maximum capacity of this station is 100 cubic metres a second – that’s how much it can pump if all six pumps were working to their absolute maximum and that could pump an Olympic-sized swimming pool in 25 seconds.
“So, over the course of this week, the maximum capacity that’s been pumping has been 77 cubic metres and that’s as much water as we’ve ever pumped out of this system.”
However, those IDBs, particularly in Lincolnshire and the Fens, that have highlighted particular stress and problems are uniquely those where there have been failures to embanked main river assets, allowing significant volumes of excess water to flood into the lowland landscape. Such main river failures include: embankment breaches, chronic seepage through banks or animal burrows, and faults with water control assets. In the case of breaches these will continue to allow water into lowland drainage districts until they are repaired.
In the River Witham catchment between Lincoln and Boston half a dozen breaches to main river embankments resulted in internal flooding to eight IDB pumping stations, and many more were surrounded by flood water making access difficult or impossible. Consequently, all were working for weeks way above their design levels causing damage and in some cases have resulted in mechanical failures that will cost time and money to repair.
Further south near Spalding, the Bourne Eau breached its banks within Welland & Deepings IDB (W&DIDB) drainage district at the start of January. A hole in the banks had been reported to the Environment Agency last summer and while it was monitored, there were no repairs. Consequently, on top of managing heavy rainfall within their own systems to prevent flooding to Spalding, the IDB is now pumping water from main river, a task that their systems are not intended or designed to do. Their major pumping stations at Pode Hole has operated 24 hours a day for much of December and January in the aftermath of Storms Babet and Henk.
W&DIDB Chief Executive, Karen Daft, said the situation was ‘relentless’, but praised her team:
“The guys have been amazing between Christmas and the new year. They really are an excellent team.
“We have had high rainfall. The drainage board system is pumping out the water, the problem is coming from the EA channels overtopping or breaching onto the drainage district.
“We work in partnership with the Environment Agency, but I think we have to take a serious look at how those assets are managed. If those channels were properly maintained, we would not be in this situation.”
Innes Thomson. ADA’s CEO believes that we are ‘sleepwalking’ into an economic, environmental and social disaster if we fail to invest in looking after our water level and flood risk management assets. Innes said:
“For many years, experts have been warning of the need to manage and maintain the flood risk assets we have, alongside building strategic new ones, but only now is there a sense of some political interest in the subject.”
“We will only get a proper grasp of flood risk when Government accepts that investment must be made in a balanced way between building new flood defences and maintaining existing assets and systems. Our changing climate is only highlighting the current weakness in strategy and people will start to vote with their feet on the subject.”
With a general election just around the corner, there will be at least six million potential voters at direct risk of some sort of flooding. In the light of the storms so far, and the recent report from the Public Accounts Committee of MPs that highlighted that England’s flood resilience eroded by poorly maintained defences, ADA strengthens its call to all politicians and prospective parliamentary candidates to ensure that our existing flood defence assets and systems are in a good working order to meet the challenge from our changing climate.
ADA would particularly highlight the follow policy and investment matters:
Timely repair of known problems
We have seen around a dozen failures (breaches/seepage/scouring) of main river embankments so far this winter across lowland Eastern England. In several cases failure has occurred at known weak points owing to animal burrowing or seepage. Whilst these weaknesses are generally reported quickly, action to prevent escalation or repair is lamentably slow. Immediate repair work might generally be in the region of tens of thousands of pounds but with delay and bureaucracy, repair and recovery can be expected to be in the millions of pounds. We need to look at how we can better utilise local skills and expertise for such works, including works through Public Sector Co-operation Agreements (PSCAs) with IDBs.
National Appraisal Guidance
A widely understood but difficult challenge for the Environment Agency and Defra comes with the appraisal of costs and benefits in lowland pumped catchments where the forms of flood risk are often multiple and therefore overlapping schemes by different RMAs ‘compete’ for the same benefits. This can result in some perverse outcomes that do not make best use of taxpayer money, and ultimately drive the wrong behaviours by flood risk managers favouring one scheme over another, whilst allowing the other risks to remain or even worsen.
Build back better and more resilient
When recovery money is received by EA and/or IDBs from previous storm events, the money can generally only be spent on like-for-like replacement. Creating more resilient defences after an event should be the default position. Thinking more broadly and ambitiously for flooded farmland, this could also be about building back with penstocks in banks to allow free-draining of overtopping water after the event (reducing reliance on temporary pumps), or even with controlled overtopping of water (spillways) taking some of the pressure of the banks, but combined with betterment of IDB assets (bigger or more resilient pumps), and enabling IDBs to have a role in operation of such assets to alleviate flooding after the peak has passed. Also, high value farmland can be returned to production with minimal damage and disruption. This is the type of innovative apporach that has come to the fore in the Netherlands with their Room for the River programme.
Integrated catchment approach to river systems
As far back as 2007, Sir Michael Pitt recognised that the UK was dealing with its river systems in a very siloed way. To some extent, that still exists today with risk priorities continuing to drive investment decisions which deliver the goals set. The fixation with the delivery of those goals overshadows much wider and greater benefits to society as a whole in looking at the benefits to people, the economy and the environment over the whole catchment. Whilst less fragmented today, there is still considerable room for improvement.