If you stopped 100 people in the street and asked either:

1) Should we do more flood prevention?

OR

2) Should we do more flood prevention which is going to cost you £100 more on your council tax bill?

I’d wager the answer would be rather different! However, most times this question is asked as in case 1) (in the media etc)

Anyone up for some guerilla ditch blocking?

I noticed whilst reading reports on the Boxing Day floods that where I used to live in the Colne Valley didn’t have any serious flood damage.

Same thing occurred to me Mint Imperial. The Holme Valley also got off lightly but I’d compare Colne Valley more with Calderdale geographically anyway. Fascinating stuff about the different attitudes to upland management in the two areas. Hopefully someone in the know will be able to apply some proper hydrology work to this to substantiate the effect or otherwise of the approaches to management.

This

“Having actually been in town at peak flood height, and seen the effect that even a temporary gap in the rain made to river levels, it really isn’t a big leap to suggest that controlling land absorption and run off is key to this.

By the time the water is in the rivers in the valley bottom, either you’re screwed, or the folk down the road with the shorter walls are screwed.”

I was there too and spent most of the last 10 days volunteering out of the Town Hall for the clear up. A key for me is in harnessing the fabulous explosion of community and awareness that occurred this last week.

Every tree we plant, every tributary we slow and dam, every millpond we re-use will allow the speed at which water enters the system and reduce the peak of the flood.

By concentrating on the bits of land where landowners will let us take action first, we can have an immediate impact. For the first time in my life I’d be interested in planting trees on a Sunday, or looking for small streams to dam in the Pickering model.

We can then look at the Walshaw Estate and others later on. I like the idea of a council tax levy so that the real social cost of draining land to improve grouse shooting is properly reflected in what people pay to shoot.

^ there being some of the problem with a change.

It is small scale, local, individual landowner and household reliant.

Government is swayed by big business, big business is swayed by big contracts and lots of lumi jackets and machinery with signs and nice offices.

One landowner at at a time, one community at a time, is a difficult, slow process.

A flood alleviation scheme for the Upper Calder Valley and other Pennine valleys and upland areas in Britain.

https://www.linkedin.com/pulse/flood-alleviation-scheme-upper-calder-valley-other-pennine-bradshaw

My home for almost 20 years now has been a small holding 350 metres above sea level in the South Pennines above Hebden Bridge in the former West Riding of Yorkshire, here I have developed my business as a consulting geotechnical and structural engineer. In this time I have witnessed a number of minor, serious and on Boxing Day 2015 a very serious flooding event which has resulted in very extensive damage to the community within which I live and where my children go to school and attend college. This latest flood comes after two serious floods in June 2012 which occurred only two weeks apart. These events place huge strain on the infrastructure, businesses and housing stock of the lower lying valley areas, although upland areas have also been affected with a flash hillside flood in 2012, in this most recent flood event some hillsides have been affected by landslides or are under the threat of imminent failure.

The community has rallied round and the help from volunteers from these valleys and from afar has been tremendous, with all sections of the community getting involved with the clean up. We must not however forget that this is three major floods in three and a half years, clearly this is not effective use of the time of hardworking people or resources, and whilst Yorkshire folk are known for their resilience a solution must now be found.

The source of the River Calder is 400 metres above sea level at Heald Moor above Portsmouth near Todmorden, and the Upper Calder Valley which contains the former mill towns of Todmorden, Hebden Bridge and Mytholmroyd is typified by fast flowing streams flowing steeply to the valley floor where they join the Calder, from upstream to downstream these are Midgelden Brook, Jumble Hole Clough, Colden Water, Hebden Water , Cragg Brook and Luddenden Brook. Aside from Centre Vale Park in Todmorden, the cricket club at Eastwood, land opposite the Stubbing Wharf pub and Calder Homes Park in Hebden Bridge there is very little land area in the valley bottom suitable for flood attenuation by land storage. Other areas of large riverside land at Brearley Fields between Mytholmroyd and Luddendenfoot are too far downstream from the towns of Hebden Bridge and Mytholmroyd to prevent flooding in those towns.

The mill towns established themselves around the fast flowing streams when water power was king, before the development of steam, these are some of the earliest towns to industrialise in the world. The engineers of the day designed weirs and millraces to channel water to mill ponds to be used during dry periods to power the mills. These valleys had flooded for centuries and the valley floor was boggy and waterlogged for long periods but before the valleys were developed this was not an issue. The construction of the mill ponds did however attenuate the flows during heavy rain, allowing the lower lying areas to be developed as the tendency to flood was reduced. These mill ponds have either fallen into disrepair or have purposely been decommissioned to avoid the requirement for inspections under the then Reservoir Safety Act 1975 which required an inspection every 10 years by a Panel (Civil) Engineer appointed by the Secretary of State. Similar legislation applies today under the Flood and Water Management Act 2010.

The town of Pickering in North Yorkshire is a very good example of where flood attenuation has protected the town from the most recent Boxing Day floods. Here according to the Independent newspaper ( http://www.independent.co.uk/news/uk/home-news/uk-flooding-how-a-yorkshire-flood-blackspot-worked-with-nature-to-stay-dry-a6794286.html ) they have built 167 leaky dams of logs and branches, added 187 obstructions to smaller drains made from bales of heather, planted 29 hectares of woodland and finally constructed a bund to store up to 120,000 cubic metres of water. Whether the bales of heather are suitable for the fast flowing waters of the Upper Calder Valley is a matter of detail but something along those lines is a worthy consideration. As for leaky dams, the mill ponds of the Upper Valley could be dredged and their dams reinstated, and may even be used at the same time for power generation with a little forethought. Tree planting and reinstatement of moorland peat bogs hitherto drained for the purposes of game shooting are also worthy considerations.

Turning to the bund idea used at Pickering, this could be achieved possibly at Calder Homes Park, although with the Rochdale canal on one side and the Calder on the other which both burst their banks on Boxing Day it did little in its current capacity to prevent flooding in Hebden Bridge and downstream in Mytholmroyd. The land opposite the Stubbing Wharf on the north side of the A646 at Mytholm has been derelict for years and various planning applications to construct a supermarket have been mooted. There are clearly ownership issues here but this is a large area of land which I estimate from Google Earth to be around 55000 square metres (including the playing field), which if allowed to flood to a 2 metre depth would provide 110000 cubic metres for flood storage, at very little cost aside obviously the land purchase and the culverts required below the A646. There are advantages here over Calder Homes Park as this land is upstream of the town of Hebden Bridge.

So far then we have the following measures all worthy of consideration:

Reinstate former mill ponds in the Midgelden Brook, Jumble Hole Clough, Colden Water, Hebden Water , Cragg Brook and Luddenden Brook valleys adopting the leaky dam approach with dams emptied after cessation of rainfall and falling river levels.
Consider damming smaller tributaries with “softer” approaches subject to testing.
Tree planting on the higher catchment areas. Much has been done already but there is a time lag element here as immature trees do not have the water demand that established forestry provides.
Reinstatement of peat bogs.
Consider the use of Calder Homes Park / Eastwood cricket ground for storage with additional engineering to increase capacity.
Consider the use of the land at Mytholm for storage with additional engineering to increase capacity.
Consider the increased use of the playing fields at Brearley by additional engineering to increase capacity for protection of the lower reaches beyond, Sowerby Bridge and Elland for example which have recently suffered. I estimate the land area here to be 80000 square metres, raising the bunds by 1.0 metre would provide an additional 80000 cubic metres of flood storage at very little cost.
Finally consider the use of deep tanks for storage at key tributaries, Jumble Hole Clough and Hebden Water for example. These are clearly costly but are a highly effective solution for additional or “bolt on” capacity to a system primarily designed using the less costly approaches previously noted. Such a tank exists adjacent to St Michael’s Church at Mytholmroyd (below the lock up garages in George Street) , its purpose is as a stormwater interceptor designed to capture raw sewage from the sewers during storms, which is then pumped back into the sewers once the storm has passed. This prevents spillage to the Calder and improves the water quality. The same type of tank can be installed purely for storm water attenuation from surface water drains. The Mytholmroyd tank was 14 metres internal diameter and about 17 metres deep so had a capacity of some 2500 cubic metres. Additional capacity is attainable by increasing depth or diameter each depending on site constraints such as available land area and ground conditions. This is a long way from the 120,000 cubic metres at Pickering however I am suggesting these are placed at key tributaries to attenuate their flows to the Calder alongside the measures noted above particularly the mill pond storage and the downstream Mytholm / Calder Homes Park with improved capacity. They are ideal for placement in series with one linking to the other spaced along the valley at intervals. With the limited space available in the Calder Valley especially at its upper reaches these tanks offer the additional capacity such a system as a whole might need due to their small footprint. The construction at George Street in Mytholmroyd used secant bored piles used to form a circular bored pile wall, this is a fast approach for construction in the valley bottoms and avoids problems with water ingress and soil collapse. They can be made deeper once the rock is reached by conventional shaft rings.

The Pickering scheme was implemented at a cost of £2m according to the Independent. The cost of a scheme as I describe for the Upper Calder Valley I suggest is likely to be higher, however, the economic and human cost of this continued flooding must be immense and the long term benefits of such a scheme are ongoing and substantial. The downstream benefits at Sowerby Bridge, Elland and the lower reaches beyond are of course a bonus.

Not only should a scheme be considered for the Upper Calder Valley but also for other upland areas with narrow fast flowing streams falling to narrow constrained valley floors elsewhere throughout Britain that are liable to frequent and devastating flooding. Simply raising river walls is not the answer and is not sustainable, building additional deep tanks, or additional mill ponds, or where possible bunded areas on riverside flat land offers flexibility should rainfall intensity continue to increase. Flood attenuation and keeping water in the catchment is the only sustainable way for towns and villages in the uplands to continue to exist.

In the case of drained land upstream we’re potentially not talking about “flood prevention” but about “stopping causing flooding”. The entire goal of drainage is to get water off the land fast; tbf if large scale drainage isn’t contributing to flooding issues downstream then it’s not doing its job.

There also needs to be a complete change in attitudes about flooding, one that encompasses a whole watershed and not just flooding hotspots. This would need an acceptance and understanding of the root causes of flooding in a given catchment and the implementation of a combination of locally appropriate measures, be that upland attenuation or levees around towns – essentially the correct mix to reduce risk and increase resilience. This would need attitudinal, political, and policy shifts, and none of that seems to be on the horizon.

Just be very careful about some of the facts appearing around the Pickering scheme. The rainfall (and hence event return period) experienced for Pickering is not the same as , for example at Hebden. I’m not saying at all that any of the conversations and arguments are invalid. It’s just not as clear cut as is presented in some arguments.

In order to give people an idea of scale. I don’t know the area, but picking a gauge on the Calder at Mytholmroyd, peak flow before 2014 is around 60cumecs. That would fill a 120,000 cubic metre storage reservoir in 30 minutes.

Flood storage reservoirs are not necessarily an easy option.

edit – obviously I understand you don’t attenuate all of the flow, it’s more of an illustration of the scale of the undertaking.

Thanks pictonroad thats fair. But the basic principle that every measure to retain rainfall in the hills taken slows a volume of water from entering the river system, reducing the peak flow is still broadly right.

Some of the measures might be less effective than Pickering.Some might be more so. But by investing at the top of the cachment we could impact on peak flow all the way down through Mirfield/York/Leeds etc.

@faustus what happened in Hebden Bridge was really unusual. Our Council has been decimated by cuts and the first 4 days we had 2 council staff working alongside maybe 500 volunteers in town. I’m hoping that it will be the community, not policy or taxation or government that looks to drive tree planting and leaky dams.

And as soon as I’ve typed this it feels ridiculous 🙂

Sure, I agree it’s great for communities to take it in hand. But on a larger scale it needs to happen across whole catchments to make the best of it, and for policy to be thought of in that way. I have huge empathy for councils and the EA, as they have taken big cuts in budget and manpower and get left to take the flak. It’s entirely in government hands to change policy (and spending) approach so that communities are more empowered to act in the way that is right for them. As brilliant as community/volunteer led initiatives are, flood prevention needs to encompass as much of the catchment as possible, and this will include land owners and farms that local communities may not be able to affect change upon. This is where changes in legislation and funding also need to be directed. As pictonroad says, the Pickering scheme isn’t conclusive, and I would think that to protect larger areas, a lot more would have to be done in the catchment than they have done in order to be successful (i.e. changing land management practices on a much wider area), and that may be beyond the reach of communities to do.

Absolutely, I firmly believe in presenting the facts to the local communities, time and time again they have shown understanding and common sense that belies the screaming headlines.

Whilst you have scale of flooding in mind. On Christmas Day 2013 the Leigh Flood Storage Area on the River Medway went from empty to full in one day. At peak flow, water was flowing OUT of the structure at 150tonnes per second, the structure was still required to store 7million tonnes of water in one day.

Sobering figures.

Mark avery

Agree with all you say.

This makes for interesting reading especially the comments section.

http://m.yorkpress.co.uk/news/14188665.EXPLAINED__Why_we_raised_the_Foss_barrier_on_Boxing_Day___Environment_Agency/