WHAT NOW FOR DROUGHT-HIT ROUTES?

As the canal sys­tem con­tin­ues to suf­fer the af­ter-ef­fects of the hot, dry early sum­mer, we ask the Canal & River Trust what the prog­no­sis is for routes af­fected by wa­ter short­age, and for the longer term fu­ture

Canal Boat - - News | Special -

The bad news is that there’s no good news. But the good news is that there’s no more bad news…”

It seems that this old and not ter­ri­bly witty cou­plet rather drily (ex­cuse the pun) sums up the sit­u­a­tion fac­ing the canals at the end of the sum­mer as a re­sult of the dri­est May /June/July pe­riod in al­most a cen­tury. As far as the ‘no good news’ line is con­cerned: the three tran­sPen­nine routes (Rochdale, Hud­der­s­field, Leeds & Liver­pool) and the Mac­cles­field / Peak For­est all have lengthy sec­tions closed in­def­i­nitely as a re­sult of low reser­voir lev­els. They have more re­cently been joined by the Rib­ble Link and Hazel­hurst Locks on the Froghall line of the Cal­don, and there are overnight clo­sures in place at var­i­ous locks else­where. And as the Canal & River Trust’s head of hy­drol­ogy Adam Comer­ford ex­plained to Canal Boat, as we went to press there didn’t look like any re­al­is­tic prospect of them re­open­ing any time soon.

Sure, it’s im­pos­si­ble to sec­ond-guess the Bri­tish weather, but he pre­dicts that in most of these places it would take at least four weeks of wet weather to re­plen­ish stocks enough for any re­open­ings. In what he de­scribes as a ‘hockey stick curve’ be­cause of its shape, any rain that falls will largely go into re­duc­ing the ‘soil mois­ture deficit’ (i.e. soak­ing into the dry soil) with no sig­nif­i­cant ef­fect on flows in streams (and there­fore into reser­voirs), be­fore it even­tu­ally hits the point where the soil is sat­u­rated and the reser­voir lev­els sud­denly start to shoot up. Even with a pro­longed spell of wet weather, that would take a month (which at least means the engi­neers work­ing on the prob­lems at Marple – see news story, page 7 – will have some ad­vance no­tice of when the locks might be wanted for nav­i­ga­tion again); real­is­ti­cally with the more typ­i­cal late sum­mer/early au­tumn weather mix, we’re quite likely to be look­ing at mid au­tumn at least be­fore the clo­sures can come off.

But the ‘no more bad news’ line? Adam Comer­ford’s thoughts on the need for any fur­ther re­stric­tions in the fu­ture are less

pes­simistic. Most of the sys­tem re­mains open, as we went to press no more com­plete clo­sures were planned, and CRT didn’t see any like­li­hood of any more be­ing needed be­fore the end of the peak boat­ing sea­son and the de­cline in de­mand. He feels that some locks which are al­ready shut overnight may see re­duc­tions in open­ing hours, and there may be a need to bring in overnight clo­sures on the Mon­mouthshire & Bre­con, but noth­ing more dras­tic. It’s helped by the fact that even if the dry weather were to re­turn for the end of sum­mer and early au­tumn, the fore­casts in­di­cate that it wouldn’t be any­thing like as hot – ear­lier in the sum­mer, canals were los­ing an inch of wa­ter a day just to evap­o­ra­tion in the very high tem­per­a­tures. Even on the Trent & Mersey, which has borne the brunt of ex­tra traf­fic dis­placed from other wa­ter­ways, CRT hopes to get through – and has man­aged to re­lax overnight re­stric­tions.

On the other hand, on the canals which are al­ready closed, things surely can’t get any worse? Well, ac­tu­ally they can. You might think that the com­plete clo­sure of all locks from Wi­gan to Leeds would see the Leeds & Liver­pool’s reser­voir lev­els start to re­cover or at least sta­bilise, but in fact it takes some­thing like 20 per­cent of the nor­mal sup­ply just to cope with losses such as evap­o­ra­tion and tran­spi­ra­tion (tree roots suck­ing up wa­ter) in or­der to main­tain the level in the longer pounds of the closed canal (the shorter ones in lock flights hav­ing gen­er­ally be al­lowed to drop). If this can’t be main­tained when the reser­voirs hit rock bot­tom, there could be any­thing from mass fish deaths to slip­page of canal banks not sup­ported by the usual weight of wa­ter, and moored boats be­ing stranded high and dry with no ac­cess to wa­ter points and san­i­tary sta­tions. So CRT is analysing the sit­u­a­tion and draw­ing up con­tin­gency plans to pre­vent this by in­sert­ing stop planks and us­ing pump­ing to re­tain what wa­ter it has in ‘safe haven’ sec­tions if the worst comes to the worst.

But in the longer term, what can be done to pre­vent a re­cur­rence? Adam Comer­ford makes the point that this re­ally is an ex­cep­tional year, even com­pared to pre­vi­ous dry years. 2010 saw very dry weather over a much more lo­cal area, while there was a ‘slow burn’ less in­tense dry pe­riod for months on end over a wider area in 2011-12. This year has com­bined hot, very dry weather and a wide ge­o­graph­i­cal spread. How likely is a re­peat, given how it’s af­fected canals (such as the Cal­don) which very sel­dom suf­fer?

As such it leads to the same quandary as (for ex­am­ple) rail­way op­er­a­tors and air­ports con­sid­er­ing spend­ing money on pre­cau­tions for deal­ing with snow – why plan for a once in decades event, when there’s al­ways some­thing else that the money could be spent on in­stead which would be used ev­ery day?

That’s not to say CRT is do­ing noth­ing: there is a long-term project un­der way work­ing on a Wa­ter Re­sources Strat­egy, aim­ing to tar­get im­prove­ments where they’re most likely to be of reg­u­lar use, and some of the schemes are into the de­tailed de­sign stages. These in­clude plans for the Rochdale, where the aim is to make bet­ter use of the large Holling­worth Lake reser­voir (where the prob­lem is that it doesn’t sup­ply the sum­mit level) by com­bin­ing it with back­pump­ing. And on the Leeds & Liver­pool CRT is look­ing to com­bine new feeds from river sources on the Lan­cashire side of the sum­mit with back­pump­ing to raise the wa­ter to where it’s needed. At the same time, smaller projects would see dredg­ing and veg­e­ta­tion clear­ance on some of CRT’s feed­ers, many of which have be­come silted: this is the sub­ject of anal­y­sis to de­cide where it would pro­vide best value for money spent.

In the long term, CRT sees pos­si­bil­i­ties for work­ing with the drink­ing wa­ter com­pa­nies (which are cur­rently into their five-year plan­ning cy­cle) on in­vest­ing in wa­ter trans­fer sys­tems us­ing the canals, which could bring in ex­tra in­come for the Trust as well as help­ing to keep the sys­tem go­ing in droughts.

And fi­nally, a study into pos­si­ble re­in­state­ment of wa­ter-sav­ing side-ponds at locks has drawn up an in­ven­tory of sur­viv­ing side-ponds, and con­cluded that while whole­sale re­in­state­ment would be chal­leng­ing and of doubt­ful value, there are places where it could make sense – es­pe­cially with vol­un­teer lock keep­ers to en­sure that they are used cor­rectly.

For ex­am­ple there are out-of-use side­ponds at Hazel­hurst Locks on the Cal­don: might their use have helped to stave off the re­cent clo­sure?

Wat­ford Locks: hours of op­er­a­tion lim­ited

See canal­rivertrust.org.uk for lat­est de­tails of clo­sures and re­stric­tions.

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