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Pickering and the floods

From Paul S

Monday, 18 January 2016

Just received the following response from the chap who led the charge on Pickering's flood defences:

Paul, you've got the right Mike Potter. I can provide no end of insights as to what you can do. I am just an ordinary resident of Pickering with no qualifications, other than 8 years of extensive practical experience of seeing an impossible pipedream through to reality. I'll copy a few bits already sent to various people below, which should be a start and give you some ideas and hope.

I am still working closely with Nick Odoni from Durham Univerity and Sarah Whatmore from Oxford. We worked together on the initial study for Pickering flood defences in 2008 and all these years later are still at it... full bore!

There is a proposal, at a relatively early stage, to set up a network with an online facility to share info on NFM/upstream storage schemes and bring the many interested parties together, rather than trying to do each one individually. Watch this space

Already been in contact with David XXX and separately with Judi XXX and Barry XXX, all from Hebden Bridge. We'd love to come and talk to you at some point, preferably to a gathering of all the disparate groups, plus councilors, MP etc to ensure the loudest and most cohesive voice. We are aware that there are opposing voices saying the Pickering scheme would work elsewhere and didn't really work due to low rainfall. Complete nonsense, currently with woeful scientific data to back it up. I worry about the agenda behind this.

Look forward to working with the folk of Calder Valley - hopefully.

Cheers, Mike

Below are some comments sent to one of the many journalists clamouring for attention. I've copied them to you as they will give you a flavour of what our scheme was all about, but are by no means comprehensive

From me, Mike Potter

The Pickering bund is only a 1:25 protection scheme, so a bigger flood event will still flood the town. This sort of scheme, along with the Natural Flood Management measures (which provide about 10% of the 1:25 storage) is not the answer to all our problems in the UK, but it's certainly an important part of the solution. There are very serious questions to be asked, and answered conclusively, about whether we prioritise moorland to be effectively drained for grouse shooting, sheep grazing etc or for maximum water and carbon retention to 'slow the flow'.

Likewise on the floodplains, do we prioritise efficient land drainage for agriculture, or allow rivers to reconnect with their legitimate flood plains to again store flood water. There is surely room for sensible compromise, but will politics get in the way? We should be planning these measures now and looking 30-40 years into the future, not just at the timescale of a Government's term of office.

Another crucial thing about NFM and the bund is that it will be effective (although obviously in a small way) for the full length of the river, and therefore very cost/effective, unlike hard flood defences that only protect the immediate vicinity at great cost. NFM in the upper catchment can also be cumulative over a number of sub catchments (but needs to be properly planned) to give greater protection downstream and perhaps make engineered flood schemes cheaper. I could go on, but will leave it there

From Nick Odoni:

To introduce myself, I am a geomorphologist, specialising in modelling landscape evolution and processes, but have also undertaken research in hydrology and flood alleviation, hence my involvement doing much of the initial exploratory modelling in the "Slowing the Flow at Pickering and Sinnington" project, and before that, the "Knowledge Controversies" project". Specifically, I developed models to help explore flood alleviation possibilities, in order to test whether any of those possibilities (interventions) were potentially useful and where they might best be sited.

Your readers need to realise that it was very much the prior work on the Knowledge Controversies project and the public interest it aroused that led to the bigger STF project later and eventually to construction of the bund. In the first project, the inclusion of local people and the ability to make the best of their local knowledge in the research were crucial elements in its success.

I have to repeat Mike's point that the bund does not give complete protection, against all floods, nor was it ever intended to do so, or even expected to do so. Likewise, the other STF measures - LWD dams, minibunds, riparian buffer strips, more widespread tree planting and so on, are not complete solutions, only contributions that may help to reduce the impact of flooding. The main contribution of all of these measures - I term them "CRIMS", which stands for 'catchment riparian intervention measures' - is to introduce attenuation back into the fluvial system. Thus we have two main effects, broadly as follows:

  • STF/NFM measures slow the flow of water down a stream and river network, so that the peak of the flood wave is delayed in time, maybe reaching a town or settlement downstream some hours later than it would have done without the crims in place;
  • STF/NFM measures also stretch out the flood wave, rather like squashing a triangle, so that the peak flow is lower than it would have been. Thus, the flood stage - the depth of the water - is lower than it might have been without the crims in place.

If these measures are applied in the right way, and particularly in the right location, they can markedly reduce the level of protection that has to be afforded by hard engineered defences, concrete walls, diversion channels and so on; the bund itself, upstream of Pickering, is such a hard engineered structure. Therefore, if we can use NFM and the harder engineered interventions in the right combination,we lessen the work that has to be done by each type of defence on its own, and together we get a much better degree of protection.

Note also that these measures together do not remove the need to dredge. Dredging will still be needed in some places, and will have to be resumed in others. But again, dredging alone is not a complete answer.

I could say a lot more, including how we involve local communities, the need for better modelling and exploration, how we prepare for climate change, the implications for long term landscape management and reform, and the importance of setting up local 'flood drills' and periodic town emergency exercises, and huge threat from groundwater flooding, and so on, but I won't!

Here are some comments sent to Pocklington TC on Thursday that may be of help

Dear Pocklington TC

You may have heard me on Radio Humberside this morning discussing our flood defences along with one of your councillors. Unfortunately, I was only asked one question and not given the opportunity to add the really important stuff. Here it is:

  1. Any upstream storage or Natural Flood Management (NFM) MUST be carefully planned and modelled to ensure it is the right measure and in the right place. Otherwise it may actually increase flood risk.
  2. Such measures are invariably PART of the solution and not the Holy Grail.
  3. There should be absolutely no development on the flood plain and very close scrutiny of how upstream moorland and floodplains are managed for drainage.
  4. Any property newly built within the footprint of a 1:200 flood event should be built to be flood resilient (solid floors, high electrics etc). I have suggested to my MP that this should be a national standard and included in building regs. I'm not holding my breath.
  5. Involve the community fully in this process to ensure a full buy-in and to utilise the considerable experience and expertise that will exist of how, when and where flooding occurs.
  6. Be aware that all flood schemes are built (dependant on available funding) to a finite protection level i.e. 1:25. They will not protect from major events. However, remember that an affordable 1:25 scheme will protect from numerous small events - still vital for the more vulnerable properties.
  7. Upstream storage and NFM will be effective for the full length of the river system (and therefore will score highly in cost/benefit analysis), unlike concrete walls which protect only the immediate vicinity, with other inherent problems. However, floodwalls, dredging etc can have a valid role in certain circumstances.

I'm sure there's more, but these are the ones I was about to stress when cut off.

Can I recommend that these points are circulated to councillors, discussed, minuted, strongly stressed in any recommendation to the planning committee and made widely and openly available to the public and local media in order to 'guide and inform' any formal decision.

On 4, worth noting that the Climate Adaption Committee has already advised this as mandatory condition of planning consent (Lord Krebs in press week before new year to this effect). Also raises larger questions about how the costs / benefits of new development in (unprotected) floodplains should be distributed between main financial beneficiaries (developers and landowners) and main bearers or flood management measures + remedial works when they fail (councils, agencies, insurers, householders/ businesses etc…..).