Guess where the donut is
- Thread starter thehungrytroglobite
- Start date
thehungrytroglobite
Well-known member
So close - it's actually the passages ABOVE Kingsdale Master Cave ie. Valley Entrance. Although usually full of dry cobbles, they were half full with water (waist deep at all times for me, though I am moderately small). I've never seen it that wet in there before. We were supposed to be using the donut in the Master Cave but it was too wet/dangerous there. Instead we pulled each other along the canals as fast as we could, including drifting round corners, which was a good way to keep warm (for the person pulling, not for the person in the donut!).
andrewmcleod
Well-known member
I would have assumed it's nearly always primarily inlet/percolation water e.g. coming in from the Milky Way, and only very rarely due to the master cave backing up (except right down by the pitch). I've been down there when there's been significantly more depth in the pools but the master cave is not in flood.
I got the old West Kingsdale survey open and it shows a drop in elevation just after the ducks in the entrance (although that might be an artifact of the folding of the elevation), then a relatively flat roof tunnel for a long time, then a drop off shortly before the pitch (about where you go from a sandy floor to a cobble/rock floor).
With some dubious pixel counting (as a precision of about 7 pixels/metre, and limited accuracy) I reckon the top of the pitch is about 5.7m about the sump level, and heading up the slope at the top of the pitch rapidly gets you to 7.4m. After a short distance you then reach the level of the lower end of the roof tunnel at 9m about the sump level. The junction with the Milky Way is about 9.6m above the sump level, and then the level of the entrance is then about 15m above sump level (is there really a steeper slope somewhere between the ducks and the Milky Way junction or is it just how the elevation is drawn with a fold?)
So in order to reach the top of the pitch, the sump level has to rise (i.e. the Master Cave has to back up) by ~5.5m above normal level, but it has to rise another ~3.5m to get much beyond the head of the pitch and into the bigger bit of the roof tunnel. If it does get that high, each extra metre will probably cause a long stretch to flood since it's fairly flat from there (an extra half-metre will probably get you all the way back to Milky Way Junction). Another four or five metres would be required for the cave to resurge from the entrance, however (has this ever been seen?).
Repeated warning: these numbers are probably dubious as they come from pixel-counting off old scanned surveys
thehungrytroglobite
Well-known member
Yeah it was so different. Usually I find valley entrance extremely boring, but I ADORE canals in caves so this was by far the most fun I've ever had there! Only wish I'd known in advance and brought a wetsuit, the undersuit was very chilly haha
thehungrytroglobite
Well-known member
The water was backing up to a point where there was a bit of a rock/calcite blockage. I can't remember exactly where or how to describe it. But after this blockage it went down from waist deep to knee deep. The waist deep section lasted for quite a while though. The master cave was nowhere near high enough to flow into the upper passages, although I have heard of this happening before (probably quite rarely!). Most of the water seemed to be flowing down what I think is the milky way (the 90m crawl that leads towards Toyland?) and also coming through a waterfall around the area that the duck is in (but the duck kind of just extended and never stopped haha). We were planning to go to Toyland but realised that as most of the water was flowing down the crawl and backing up, it was still raining extensively outside, we didn't know the hydrology of that part of the system super well, didn't have a shelter with us, and were all wearing thin undersuits after spending a good 20mins in neck deep water, that maybe going back through the crawl whilst there was still airspace was a good idea. I got a small ear wetting at one point on the crawl back so the water was reasonably high I think.I would have assumed it's nearly always primarily inlet/percolation water e.g. coming in from the Milky Way, and only very rarely due to the master cave backing up (except right down by the pitch). I've been down there when there's been significantly more depth in the pools but the master cave is not in flood.
I got the old West Kingsdale survey open and it shows a drop in elevation just after the ducks in the entrance (although that might be an artifact of the folding of the elevation), then a relatively flat roof tunnel for a long time, then a drop off shortly before the pitch (about where you go from a sandy floor to a cobble/rock floor).
With some dubious pixel counting (as a precision of about 7 pixels/metre, and limited accuracy) I reckon the top of the pitch is about 5.7m about the sump level, and heading up the slope at the top of the pitch rapidly gets you to 7.4m. After a short distance you then reach the level of the lower end of the roof tunnel at 9m about the sump level. The junction with the Milky Way is about 9.6m above the sump level, and then the level of the entrance is then about 15m above sump level (is there really a steeper slope somewhere between the ducks and the Milky Way junction or is it just how the elevation is drawn with a fold?)
So in order to reach the top of the pitch, the sump level has to rise (i.e. the Master Cave has to back up) by ~5.5m above normal level, but it has to rise another ~3.5m to get much beyond the head of the pitch and into the bigger bit of the roof tunnel. If it does get that high, each extra metre will probably cause a long stretch to flood since it's fairly flat from there (an extra half-metre will probably get you all the way back to Milky Way Junction). Another four or five metres would be required for the cave to resurge from the entrance, however (has this ever been seen?).
Repeated warning: these numbers are probably dubious as they come from pixel-counting off old scanned surveys
The Survex data is online here
(and Survex is free to download and use)
I exported the centreline projected elevation (scale is metres and "normal" sump level is approx 0m)
(and Survex is free to download and use)
Survex - Downloads
survex.com
I exported the centreline projected elevation (scale is metres and "normal" sump level is approx 0m)
The water in the roof tunnel ponds is often very clear, and seems to settle out quickly when the sand is disturbed. This fits with percolation rather than flooding inundation. And I don't remember seeing flood debris in there.
A data logger in the sump with pressure transducer might provide some interesting data for water height. For those wanting a project
A data logger in the sump with pressure transducer might provide some interesting data for water height. For those wanting a project
Babyhagrid
Well-known member
The flow out of milky way was quite fun in height. I assume this is normally dry? And the way up to Toyland was a big cascade of water that was hard to climb up the first part. And the big free climb would have been impossible
