As many of you know the road through Cheddar Gorge is officially closed because of flooding problems.  The Longwood swallet is choked and the entire stream is flowing on the surface down to Blackrock gate, and into the gorge.  The only solution is the re-opening of a swallet that can take the whole flow of water.  The obvious site is the old swallet just downstream from the cave entrance, which used to take the whole flow, but that is not going to be easy while the water is filling it.  The water could be sent down the current cave entrance, which would be a simple and ideal solution for everybody except the caving community.

There is another solution.  The upstream end of the August series terminates very close to the surface.  I am not sure where this relates to on the surface but it is somewhere upstream from the footbridge which crosses the stream.  Opening this swallet would alleviate the flooding problems.  There is nothing quite as effective as the passage of cavers to keep a route clear of accumulating debris, which would be one good argument for making this a second entrance to the cave.

Anyway, that's the suggestion.  What do we think?

In the past the stream sank into the Longwood entrance. It was diverted following a number of cave rescue callouts and until recently sank just below the entrance.
It can therefore be said that cavers have caused the flooding problem by diverting the stream from its natural course.

The simple solution to the current problem is to let the stream flow back into the Longwood entrance for a short period while remedial work is undertaken. This would allow the blocked sink to dry up enough for the debris to be cleared.
It would be advisable to close the cave for the duration of this work, or at least put notices advising visitors that the entrance series may become impassible in wet weather.

Any work carried out on the stream sinks would need permission from S.W.T. also as the valley is within a S.S.S.I. there may be permission needed from English Nature.
The blocked sinks and flooding down the Gorge is not the cavers problem just nature taking its course and the only thing we can do to help out is to send it back down Longwood entrance, until the powers that be decide otherwise.

Andy Sparrow said:

The upstream end of the August series terminates very close to the surface.  I am not sure where this relates to on the surface but it is somewhere upstream from the footbridge which crosses the stream. 

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Wet Gallery is directly below the footbridge which crosses the steam. The vertical distance to the surface is around 50 - 60 feet?

SWT do not want to divert the water into the cave either via the entrance or further upstream. Not at present.  If they ask for our assistance in some way, in the future, I am sure that we will respond positively.

Have the Council figured out they need to fix the sink yet?

Aubrey said:

In the past the stream sank into the Longwood entrance. It was diverted following a number of cave rescue callouts and until recently sank just below the entrance.
It can therefore be said that cavers have caused the flooding problem by diverting the stream from its natural course.

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But surely at some point in past the stream would have sunk at the lower swallet otherwise it wouldn't be there. So you could say that cavers reinstated the stream to an earlier natural course.

Your second sentence would seem to rather recklessly invite the ire of the Council upon cavers.

If SWT and Natural England are involved, this might take a while........

Indeed, Hughie; it seems to be something of a new-found Cheddar tradition to have arterial routes into the village clogged for months on end; almost as though there's a conspiracy to bankrupt the village's handful of remaining traders.

Hughie said:

If SWT and Natural England are involved, this might take a while........

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If? SWT own Longwood Valley and Velvet Bottom down to Black Rock Gate. They are far more involved than cavers are.

Peter Johnson writing in The History of Mendip Caving describes the point where the cave entrance was dug open:

At the terminal part of the Longwood stream there was a small vertical wall of rock through which the water seeped, but in wet weather it overflowed to other swallets further down the valley.

This would suggest that Aubrey's observation - it can therefore be said that cavers have caused the flooding problem by diverting the stream from its natural course - is incorrect.

Johnson also writes when describing the terminal boulder choke of August Hole:

.. a boulder choke very close to the surface - so close, in fact, that the first survey showed it to be sticking out into the air!

I think this refers to the termination of the main gallery rather than the stream inlet indicated on the survey.

If it keeps on raining, like it has been most of the year and still is, something will have to be done,
unless they intend to keep The Gorge permanently closed to traffic.

Andy Sparrow said:

Peter Johnson writing in The History of Mendip Caving describes the point where the cave entrance was dug open:

At the terminal part of the Longwood stream there was a small vertical wall of rock through which the water seeped, but in wet weather it overflowed to other swallets further down the valley.

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Thanks Andy for finding that. I am pleased that cavers cannot be accused of causing the problem.

A few photos of the work carried out at Longwood Valley Sink last week. Starting at

http://www.flickr.com/photos/mendipcaveregistryarchive/9415453099/#in/set-72157624206486779

Sid said:

A few photos of the work carried out at Longwood Valley Sink last week. Starting at

http://www.flickr.com/photos/mendipcaveregistryarchive/9415453099/#in/set-72157624206486779

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Good photos. Linda says she doesn't remember the penguins, though.

Penguin free version starts here 

http://www.flickr.com/photos/mendipcaveregistryarchive/9415453099/#in/set-72157624206486779

Hughie said:

If SWT and Natural England are involved, this might take a while........

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But it didn't, though, did it. The work got done just as soon as the ground conditions allowed. The road was reinstated and over the summer SWT has been working with cavers to ensure that the problem is properly managed for the future. Various other agencies including Highways and councils have also been involved.

Most (not all) of the work is now finished. Most of the volunteer labour has been supplied by cavers. I trust that those businesses that operate in Cheddar are duly grateful. I know the ones that have put their hands in their pockets to contribute towards the costs have expressed that gratitude.

Job now finished, before the end of September as planned.

Longwood main sink has now been cleared back to the depth it was over 30 years ago.

The original entrance to Longwood Valley Sink has been reopened, re-piped, re-gated and the overflow stream bed from upvalley channelled towards it. So now the main sink should absorb just about all the flow and LVS should then cope with any flash flooding events.

This work has been carried out by volunteer labour from the caving community, organised by Linda Wilson, the conservation officer of CCC Ltd and from Somerset Wildlife Trust. The new pipe in LVS was supplied by the Highways Authority and other materials have been funded by a number of the other bodies that were concerned about the flooding.

No caves and no cavers were harmed during the works and Natural England were happy with everything that has been done.

As part of the work, the stream by the entrance to Longwood was straightened out and banked, to keep it away from the entrance shaft, but at some point over the summer a new sink developed quite close to the entrance. Well, you cannot win them all, but at least we did not have to go with any of the wilder ideas about diverting the whole stream down the cave (& silting up the entrance shaft in no time at all).

I'll post some photos later, if I get the time.

Excellent work. here's hoping we don't get another winter like recent ones with all the flooding to test it fully though!

Took this last weekend.

http://www.flickr.com/photos/mendipcaveregistryarchive/9877057015/#

Good work.