2019-08-23 

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Flooding from the Sea Inevitable

Science has irrefutably pointed to rising sea-levels and whilst there is some debate about the exact future quantum, the evidence is now clearly there for us to see and act upon.

Some people challenge the difference that half a metre’s increase will make but forget that we narrowly averted a major disaster of potential 1953 proportions, or worse, back in December 2013, when we experienced a North Sea tidal surge.

Washbanks

Washbanks

Half a metre of water extra in 2013 would have been the straw that broke the camel’s back along large swathes of our eastern coastline. Some people say the sea level rise could be much higher, much sooner, if Artic/Antarctic ice melt continues along recent trends.

We cannot just continue to build our sea defences higher and higher over time, with the huge costs that would involve. Adaptation and resilience are the key to the future, and a greater understanding of the consequential losses caused by coastal flooding is needed. 

On this particular point, Robert Caudwell, Chairman of the Association of Drainage Authorities (ADA), the membership organisation for drainage, water level and flood risk management authorities throughout the UK, explains, “Rather than building higher defences in lowland coastal areas, we need to be building and maintaining defences more resilient and strong enough to resist damage from water overtopping them. 

“Sudden embankment failures of the sort witnessed around the Humber Estuary during the tidal surge of 2013 put life and property at greater risk and must be minimised.”

The other significant phenomenon which leads to coastal flooding is wave action and planning for a resilient coastline should always consider the foreshore and the restoration of intertidal habitat, which can lessen the impact of waves on primary defences. 

Deeper water means higher waves with more energy and so creating shallow intertidal margins helps to dissipate wave energy. Unfortunately, the current regulatory process and costs deters from restoring and preserving intertidal habitat and more needs to be done by government to reduce this constraint.

When sea water does come over the top of tidal defences, and statistically it will, critical infrastructure (e.g. pumping stations) within rural coastal areas should be made resilient to those occasional events so that the overtopped water can be quickly and efficiently pumped back out to sea. 

This is where effective partnership working starts to pay dividends. Not every stretch of sea defence requires the same attention, and this is where, supported by Government, the principal Risk Management Authorities (RMAs) can rely more on a range of others such as Internal Drainage Boards and Community Groups to cost-effectively maintain and manage lower risk coastal flood defences.

Many of our sea defences are built using a variety of local materials of variable quality and it just depended on what you could get hold of historically to create a barrier. We need to better understand the structural integrity of our sea defences to lessen the risk of sudden failures when they are under pressure and a greater use of geophysical monitoring techniques could enable more targeted preventative maintenance of sea embankments.

Finding money to justify our attention to our sea defences on this finite island should be seen as a priority, but it currently is not. There is a slight increase in the perceived importance of our coastal defences and those who manage them, but they remain poor cousins to their inland river flood defences which receive the lion’s share of Flood Defence Grant in Aid. 

Yes, it is right to prioritise spending to protect people, but that protection is not only physical, but social, economic and environmental combined. 

Robert Caudwell continues by saying, 
“It is time for the valuation of food-producing land and production attributed to the benefits of FCERM (flood and coastal erosion risk management) schemes to be properly reappraised along with the separation of funding and benefits apportioned to schemes tackling coastal flooding from other forms of flooding. 

“We also need a mechanism to effectively harness greater private investment in flood and coastal risk management infrastructure, such as an independent Green Infrastructure Bank, separate from Treasury control.”

Recent more positive intentions are emerging around the use of Environmental Land Management (ELM) schemes, which would incorporate annual payments for farmers in return for FCERM services, such as washlands/flood storage areas, through management agreements, and investment in FCERM schemes creating economic growth. FCERM research and innovation must remain accessible to RMAs and UK research institutions following a future UK exit from the European Union.

Public engagement remains a crucial part of any partnership along our coastlines and sufficient time and effort must be made to engaging and building relationships with communities facing coastal flooding/change.

ADA

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