Lancaster Hole and Fall pot flooding, beware!!
- Thread starter adep
- Start date
adep:
I'm not sure I understand this; as far as I am aware, Montagu East is the big passage that leads to Easegill while Montagu West is the somewhat smaller continuation that goes to Waterfall Passage . . . which doesn't fit with your description of crossing from E to W . . . do you mean, perhaps, crossing the Main Stream at Stake Pot? Or have I got it all wrong?
I'm not sure I understand this; as far as I am aware, Montagu East is the big passage that leads to Easegill while Montagu West is the somewhat smaller continuation that goes to Waterfall Passage . . . which doesn't fit with your description of crossing from E to W . . . do you mean, perhaps, crossing the Main Stream at Stake Pot? Or have I got it all wrong?
Pitlamp
Well-known member
The following thoughts may help a little?
I was involved in exploring underwater sections of this hydrological system, at Leck Beck Head and Witches Cave. These are the main resurgences for the water which caused your problem. The water has to pass through a number of highly unstable chokes on its way out to daylight. We've had the opportunity to look closely at these chokes on many occasions over the years and, after every flood, when you go back the terrain has usually changed beyond all recognition. These chokes have cause desperate problems for cave divers and we have never really been able to sort them out.
It's obvious that the degree of restriction to flow in these problem chokes varies considerably. It's possible that one or more of these areas has collapsed following the last but one flood, resulting in a far smaller opening for the water to pass through than normal. If the Lancaster main drain is in spate - but the water can't get out as easily as normal, it's actually quite easy to see why the sump surface in Lancaster would rise extremely fast.
What can we learn from this? I think it shows that, even in a familiar cave system, we should expect the unexpected - despite the forecast. A cave is a natural feature and when nature is in angry mood we all need to be extremely careful. Are we in danger of becoming a bit too reliant on the results of fancy computer number crunching at the expense of using experience and considered judgement?
Having said that, the weather system which gave us that Atlantic storm at the weekend was accurately predicted several days ahead of when it happened and such weather systems can often be very severe. So I'm not convinced that the signs of a possible major flood weren't all there in advance.
Please can I stress though than none of the above is criticism of anybody. Even I wasn't aware it rose that fast in Lancaster, despite being very familiar with the submerged route between there and the risings.
I was involved in exploring underwater sections of this hydrological system, at Leck Beck Head and Witches Cave. These are the main resurgences for the water which caused your problem. The water has to pass through a number of highly unstable chokes on its way out to daylight. We've had the opportunity to look closely at these chokes on many occasions over the years and, after every flood, when you go back the terrain has usually changed beyond all recognition. These chokes have cause desperate problems for cave divers and we have never really been able to sort them out.
It's obvious that the degree of restriction to flow in these problem chokes varies considerably. It's possible that one or more of these areas has collapsed following the last but one flood, resulting in a far smaller opening for the water to pass through than normal. If the Lancaster main drain is in spate - but the water can't get out as easily as normal, it's actually quite easy to see why the sump surface in Lancaster would rise extremely fast.
What can we learn from this? I think it shows that, even in a familiar cave system, we should expect the unexpected - despite the forecast. A cave is a natural feature and when nature is in angry mood we all need to be extremely careful. Are we in danger of becoming a bit too reliant on the results of fancy computer number crunching at the expense of using experience and considered judgement?
Having said that, the weather system which gave us that Atlantic storm at the weekend was accurately predicted several days ahead of when it happened and such weather systems can often be very severe. So I'm not convinced that the signs of a possible major flood weren't all there in advance.
Please can I stress though than none of the above is criticism of anybody. Even I wasn't aware it rose that fast in Lancaster, despite being very familiar with the submerged route between there and the risings.
Bottlebank
New member
O.P.?
Speleotron
Member
Iit's all done by computers but with good forcasters like the met office they look at what the computer says and combine that answer with their human judgment and knowledge of weather systems. Im sure the met computer will give output to a lot of decimal places but then they sit down and go over it, the computer output is just one part of the overall preocess whereas it looks like with metcheck they just believe whataver it tells them. theres a good chapter on this kind of thing in Nates Silvers book.
Loki
Active member
i tried to get out of Peak Cavern once through the 5 arches when it got out of depth. i can report that i was certainly not buoyant with SRT kit and decided to retreat rather than getting sucked into the sump. 18 hours later the water went down enough to get out!
in easegill the high level between fall and stake does flood. i have been in there post flood and only the top foot of the tallest boulders was still dry. on the day of the Carlisle floods the water was all the way up to the hole into Kaths way (where the scaff tube climb through boulders is below the climb to the colonnades).
in easegill the high level between fall and stake does flood. i have been in there post flood and only the top foot of the tallest boulders was still dry. on the day of the Carlisle floods the water was all the way up to the hole into Kaths way (where the scaff tube climb through boulders is below the climb to the colonnades).
Bottlebank
New member
OP - original poster - thanks! And agreed, it's also highlighted the importance of where you get your forecast from.
On which note, looking out the window and at the wind direction, I think I'd be avoiding the Lancaster streamway tonight as well
On which note, looking out the window and at the wind direction, I think I'd be avoiding the Lancaster streamway tonight as well
And, very interesting post Pitlamp.
There are some places that no doubt remain fairly similar with flooding patterns whereas others change. I'm not a diver but aware that sediments do shift around in sumps, however boulder chokes shifting around is something that I normally wouldn't consider. I knew there was a choke in the resurgence area (read about it somewhere, no idea where) but not that it frequently shifted too, food for thought.
As for being reliant on computers, numbers and results; just over a week ago the forecast looked suspect on Friday and I decided to stay at home instead of doing the Saturday trip (the forecast was refreshed and was better by the Friday evening). Some may say I was overly cautious and smile smugly saying they went caving without a problem, well done to them for encountering no problems, this time. I've seen too many dodgy forecasts to entirely trust what I see/read, owing to the job I do I usually check the forecast every day and can confirm that even the day before (extreme example a few hours before) they can and do get it wrong! Although systems such as the one that caused the flooding on Sunday are usually well forecasted.
There are some places that no doubt remain fairly similar with flooding patterns whereas others change. I'm not a diver but aware that sediments do shift around in sumps, however boulder chokes shifting around is something that I normally wouldn't consider. I knew there was a choke in the resurgence area (read about it somewhere, no idea where) but not that it frequently shifted too, food for thought.
As for being reliant on computers, numbers and results; just over a week ago the forecast looked suspect on Friday and I decided to stay at home instead of doing the Saturday trip (the forecast was refreshed and was better by the Friday evening). Some may say I was overly cautious and smile smugly saying they went caving without a problem, well done to them for encountering no problems, this time. I've seen too many dodgy forecasts to entirely trust what I see/read, owing to the job I do I usually check the forecast every day and can confirm that even the day before (extreme example a few hours before) they can and do get it wrong! Although systems such as the one that caused the flooding on Sunday are usually well forecasted.
georgenorth said:
Going back a bit in the thread, but I was trying to remember this the other day too.
I have definitely read in either Descent or Caves and Caving an article of buoyancy of caving gear, but have failed to re-find it when looking.
Does anyone know where the article can be found? I've had another dig through my shelves this evening but still haven't found it.
Thanks.
Alex
Well-known member
Bloody heck Loki, never knew it flooded that badly! I guess the worse case scenario would be re-surging out of Lanc hole! Its only got 40m to go, but I guess it would have a lot more cave to fill before it reaches that. I guess the mud has to get into the high level stuff somehow!
As for buoyancy, I have trouble swimming with just my caving gear without SRT gear, wellies drag your feet down, oversuit not exactly boyant or water dynamic. If I know there is going to be swimming of more than 5 or 10 i.e. I can't glide across, I take a life jacket. Of course I don't take one on every trip so if it floods I know to wait it out.
Currents of flood conditions means you should never swim in flood waters even with life jacket just think how much water is trying to go through the sump, I wager there would be a serious undercurrent.
As for buoyancy, I have trouble swimming with just my caving gear without SRT gear, wellies drag your feet down, oversuit not exactly boyant or water dynamic. If I know there is going to be swimming of more than 5 or 10 i.e. I can't glide across, I take a life jacket. Of course I don't take one on every trip so if it floods I know to wait it out.
Currents of flood conditions means you should never swim in flood waters even with life jacket just think how much water is trying to go through the sump, I wager there would be a serious undercurrent.
steviet_scg
Member
I always find threads like these really helpful - so thanks for sharing.
We had Sunday down for a long time as a kids caving day. I had to teach them the art of not going caving - they are getting much better at making cups of tea now
I eventually relented and we stuck our head in Yordas - as Fulk said earlier - it was right up to the entrance steps. The kids were profoundly amazed.
Bit of video a couple miles downstream of Ingleton on the Greta at about 5:30
We had Sunday down for a long time as a kids caving day. I had to teach them the art of not going caving - they are getting much better at making cups of tea now
I eventually relented and we stuck our head in Yordas - as Fulk said earlier - it was right up to the entrance steps. The kids were profoundly amazed.
Bit of video a couple miles downstream of Ingleton on the Greta at about 5:30
Mike Hopley
New member
adep said:
My SRT kit, including bag & harness, weighs under 3 kg. What are you putting in yours?
I suspect the main problem is the general difficulties of swimming in caving kit, especially in challenging circumstances. Nevertheless a few extra kilos makes it worse, and entanglement in your SRT kit could be a hazard too.
That video is fascinating . . . and sobering . . . and a bit scary.
One thing I have a problem with is the physics behind some of this stuff. For example, it's often said that wellies full of water will drag you down; but why? The water in your wellies is displacing . . . err . . . water, which has the same density as does that outside your wellies. So why does it drag you down?
One thing I have a problem with is the physics behind some of this stuff. For example, it's often said that wellies full of water will drag you down; but why? The water in your wellies is displacing . . . err . . . water, which has the same density as does that outside your wellies. So why does it drag you down?
Fulk, I think it's more that as the weight of them is at the end of your leg, dragging them through the water is quite hard so might be better to take them off and carry them, I wonder if they how long they would stay a float if you put them in upside down?
Hmm, I think I will avoid swimming, though there's no change there, I swim like a brick at the best of times.
Hmm, I think I will avoid swimming, though there's no change there, I swim like a brick at the best of times.
My experience is that in wellies I find it harder to swim using any kind of foot stroke rather than none, so my preference is to use my arms only.
This works because I make sure I add to my natural flotation using a couple of bits of karrimat shoved down my front - all those closed cells are very good for buoyancy. This gives me a more effective trim in the water and a more stable position as my legs aren't moving up and down. The head-up swimming position also keeps my upper chest and throat a tiny bit higher (and fractionally drier and warmer) in the water, and it also helps that I can see where I am and where I'm heading for.
Of course I also make sure my bag is positively buoyant so I can just tow it behind me.
This works because I make sure I add to my natural flotation using a couple of bits of karrimat shoved down my front - all those closed cells are very good for buoyancy. This gives me a more effective trim in the water and a more stable position as my legs aren't moving up and down. The head-up swimming position also keeps my upper chest and throat a tiny bit higher (and fractionally drier and warmer) in the water, and it also helps that I can see where I am and where I'm heading for.
Of course I also make sure my bag is positively buoyant so I can just tow it behind me.
Bottlebank
New member
Good video.
Water entering your wellies and suit displace air. A full set of caving gear including SRT kit weighs around 10 to 15kgs dry, largely depending on size, initially your suit is full of air which compensates.
The old BSAC "A"test included a couple of lengths swimming with, if I remember rightly, around four or six pounds of lead, and was hard work but you could sustain it. A wet set of kit weights six or seven times that, without additional buoyancy you simply sink. A pound of lead and a pound of wet fleece are exactly the same weight. Add in cold water, deep water and currents and the end result is not good.
Have a look at the Porth Yr Ogof description on the UK caves database if you still have any doubt.
Water entering your wellies and suit displace air. A full set of caving gear including SRT kit weighs around 10 to 15kgs dry, largely depending on size, initially your suit is full of air which compensates.
The old BSAC "A"test included a couple of lengths swimming with, if I remember rightly, around four or six pounds of lead, and was hard work but you could sustain it. A wet set of kit weights six or seven times that, without additional buoyancy you simply sink. A pound of lead and a pound of wet fleece are exactly the same weight. Add in cold water, deep water and currents and the end result is not good.
Have a look at the Porth Yr Ogof description on the UK caves database if you still have any doubt.
