Flooding in the Calder Valley 2020

Mitigation, Protection and Resilience – a joined up approach to minimising flood damage

Chris Griffiths
Monday 10th February, 2020
Once again, towns and villages across the North have been hit by severe flooding. People are dealing with the overwhelming prospect of cleaning up homes and businesses, a process which they know from hard-won experience will take months of work that’s exhausting both physically and mentally. It’s too early to understand the scale of the damage but early reports suggest that storm Ciara was more devastating than the Boxing Day floods of 2015.
In the aftermath of these events, the water management team at Marshalls is frequently asked what we can do to prevent this level of flooding from happening in the future. The irony isn’t lost on us; as the UK’s largest hard landscaping supplier we’re experts in managing surface water, but our head office is right next to a recurring flood site in the Calder Valley in Yorkshire. So what approach do we take to minimise the impact flooding could have on our business?
The answer isn’t simple. There’s not one solution that will solve the flooding crisis, but rather a series of approaches which, if employed at the right time and in the right order, create a joined up and effective response – mitigation, protection and resilience.
A sensible flood response plan should always consider mitigation in the first instance – what can be done to stop flooding in the first place? By catching rainwater where it falls and slowing the rate at which it flows downstream we can reduce demand on sewers and watercourses in a heavy rainfall event, minimising flood risk. Sustainable Drainage Systems (or SuDS) achieve this goal and come in many different forms which can be integrated into landscapes at any scale. These need to be considered as a matter of course in all landscapes, particularly those on higher ground. Permeable paving, such as Marshalls Priora, is an ideal dual-purpose SuDS method; it’s fully engineered and installed to allow water to soak down through the surface where it can be stored in a specially prepared sub-base.
However, no amount of SuDS will stop flooding completely. Rainfall events are becoming more intense, more frequent and longer than we have encountered in the past so we need to look to other techniques to minimise flood damage. Protection methods should be considered in flood risk areas lower down catchments – barrier systems which block water and prevent it from entering or damaging property. These can be permanent (such as retaining walls) or temporary, in the form of flood barriers. Temporary measures should be passive (they should operate automatically in a flood event) and crucially sand bags shouldn’t be considered – once they’ve been used they're contaminated and awkward to dispose of, and besides – they simply don’t work.
Finally, flood resilience measures work by accepting that a property might flood and therefore designing it so that it can get back to normal use as quickly as possible after a flood event. This pragmatic approach includes measures such as hard flooring, raised electricity points and stainless steel kitchens – all of which can be quickly sluiced down and disinfected as soon as flood water has disappeared.
Flooding is the biggest environmental threat facing the UK today. It requires joined up thinking to tackle it successfully, and no single agency is solely responsible. It might be an uncomfortable truth to accept that devastating floods will continue to happen – but perhaps that’s what we need to do to minimise the worst effects when they do.

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