High technology is coming to the aid of cavers who need to make accurate surveys of complex 3-D cave systems miles away from civilisation.
Accurate surveys are needed not only for scientific interest but also in order to locate points at which caves could intersect – something that is very difficult to spot using cross-sectional paper maps.
A British team encountered the problem on an expedition to explore the complex cavesystems of the Julian Alps in the corner of Slovenia, Italy and Austria.
They solved it by taking along a notebook computer, a solar cell to power it and a satellite positioning handset, explains Mark Evans, one of the organisers of the expeditions by Imperial College Caving Club in London and a postgraduate student in mechanical engineering at the college.
Although it is relatively close to major cities such as Trieste, the area being explored is accessible only on foot, so the expedition party had to carry every bit of equipment.
The computer, a Hewlett-Packard OmniGo 600CT, and the geographical positioning navigator system were no problem as they weighed only a few pounds.
The difficulty was supplying power for the notebook, which, in common with all such computers, can work only for a few hours without recharging.
The solution was to take a solar panel measuring half a metre square, which produced enough current to recharge the batteries between uses.
The survey parties returned each evening to their base camp 1,800 metres high in the Slovenian part of the mountains, with their data on lengths, inclines and directions of the various caverns and corridors.
These were entered into 3-D mapping software called SurvEx, developed by cavers at the University of Cambridge, to create a computer model of the cave system in three dimensions.
The model can be viewed from any angle, rotated and likely intersections zoomed in on. It is like holding a transparent plastic model in your hand.
One of the big time-wasters for cavers in the area is sorting out the entrances to the cavesystem from misleading blind caves.
“There are holes everywhere, at least every 10 metres,” says Evans. “We needed a way of narrowing down the search.”
This was done by sending out a reconnaissance expedition earlier last year while the snow was still on the ground.
Updrafts in a cave tend to blow away any snow covering the entrance, so that these so-called “blowing holes” can be easily spotted.
The party noted their position with a Trimble hand-held satellite navigation terminal so the summer expedition could find them easily, although they were covered with undergrowth.
A French member of the party, mathematician Josselin Visconti, studied the accuracy of the terminal and found it to be much better than the quoted plus-or-minus 20m.
“We did a few tests and found it was better than plus or minus 10m,” says Evans. “A paper is being published in France on that research.”
Evans hopes that the survey will unveil the depths of the Migovic cave system, but the ultimate motivation is the thrill of getting there first.
“When you have discovered something that is new and nobody has been there before you get quite attached to it,” he says. “We hope to get to the best bits first.”
Samuel Taylor Coleridge wrote that Xanadu had caverns measureless to man. Using today’s technology, they could be measured with ease.
