(Krubera) Cave

Compass & Tape, Volume 17, Number 3, Issue 59 HYDROLEVELING OF VERY DEEP CAVES, WITH AN EXAMPLE FROM VORONJA (KRUBERA) CAVE BY ALEXANDER DEGTJAREV, EUGENE SNETKOV, AND ALEXEY GURJANOV REPRINTED FROM AMCS ACTIVITIES NEWSLETTER, NO. 29 This interesting article on a technique in the beginning of the 1970s. The de- Cave in the Bzybsky Ridge. The length for measuring the depth of a deep cave vice was a vinyl-coated fabric tube 30 of a river passage from the resurgence with high accuracy appeared in Svet to 50 meters in length with a manom- sump at the entrance, called a gryphon (The Light), magazine of the Ukrainian eter with fine scale divisions at one end. by Russian cavers, to the terminal sump Speleological Association, number 29, Such manometers were 25 centimeters is about 1.5 kilometers, and the eleva- 2006. It has been revised and rear- or more in diameter. They were incon- tion difference is only 20 meters. Gena ranged by the editor based on a trans- venient and often broken. The water Somokhin of Ukraine did a hydro- lation for AMCS from Russian by bottle that was used to keep the tube leveling in V. Pantjukhina Cave in the Tatyana Nemchenko, who also kindly filled overturned, and bubbles appeared same area, and the depth of the cave provided some clarifications by e-mail. in the tube. Nevertheless, the method changed from 1508 to 1488 meters. Authors and translator are Moscovites. was used and considered the most ac- New interest in the method appeared curate method of determining depths at after discovery of the deepest cave, n expedition to Voronja Cave was the time. The accuracy was estimated Voronja, in the Arabica Massif in the A held in October 2005. It was or- to be about 2 percent. Cavers from the Caucasus. There was a lot of interest in ganized by the Ukrainian Speleologi- Krasnoyarsk’ club used the method in the true depth of the cave. In the sum- cal Association under the leadership of some caves. In Forelnaja, in the mer of 2005 Gregory Shapoznikiv and George Kasjan, now president of the as- Bzybsky Ridge area of the Caucasus, Larice Pozdnykova, both of Ekaterin- sociation. Cavers from the Russian hydroleveling of a narrow passage burg, Russia, hydroleveled the cave to Geographical Society in Moscow and about 1 kilometer in length gave a level the dry bottom at –2080 meters, accord- the Bulgarian Speleological Federation difference that was 5 meters different ing the conventional tape survey. also took part. One of the aims was to than the one determined by the conven- However, the difference between their measure the depth of the cave by the tional method with a clinometer and downward and return levelings was hydroleveling method. This goal was tape. The depth at the time of Sneznaya quite large, 8 meters, and errors in the partly fulfilled. Leveling was done Cave in the same area went from 720 method were discovered. A new hydro- downward and upward between the to 700 meters when measured by leveling was made in the cave in October entrance and 916 meters depth and hydroleveling, and Kievskaya Cave in 2005. The results are discussed in this downward only from –916 meters to the Zeravsanksij Ridge, Central Asia, article. The influence of atmospheric –1195 meters, at Camp 1200. The work went from 1030 to 980 meters deep. pressure on the readings was discov- was done by two people, Alexander Hydroleveling was also used for other ered, the high accuracy of the method Degtjarev and Tatyana Nemchenko of purposes, such as water-supply work in was proved, and the method of mea- Moscow, supported by Vladimir Solo- expeditions to Central Asia. surement by intervals was introduced. mentzev of Moscow, Fory Kolov of The method was revived in 2000, Alexis Shelepin and Martha Ru- Plevna, Bulgaria, and Svet Stanichev of when Eugene Snetkov made a new shechka, both from Moscow, took part Sofia, Bulgaria. model of the device in which the bulky in the development of the method, and and unwieldy manometer was replaced Alexis Gurjanov took part in the math- ydroleveling is used in building by a diver’s depth gauge. Metallic parts ematical justification. The authors H construction for finding two of the device were made by Constantin could not find any mention of this points with the same height, as in lev- Mukhin. The water-bottle reservoir was method in non-Russian publications. eling a floor. In the simplest case, a tube replaced by a rubber glove, an idea bor- with both ends open is used, attached rowed from Australian wine-makers, hydrolevel device is made of a to a strip of wood. who packaged wine in plastic bags with A 50-meter transparent tube filled In Russia, measuring the depth of a cock at the bottom. A buyer could with water, on one end of which a rub- caves by the hydrolevel method began drink from a package that did not leak ber glove is placed, and on the other a when upset, and the wine did not oxi- metal box with a transparent window. Translator and participant in the level- dize when the container was partly An electronic diver’s depth gauge or ing Tanya Nemchenko: empty. The new model was used for watch with a depth-gauge function is [email protected] vertical measurements in Mchishta submerged in the box. The tube is 1 Compass & Tape, Volume 17, Number 3, Issue 59 coiled or on a reel. If the rubber glove accuracy of 0.2 percent, or 4 meters for There will also be random error due is placed on one station and the box a cave depth of 2000 meters. For com- to placement on the stations, most of- with the depth gauge is placed on a parison, geometric measurement with ten a rigging anchor bolt. The gauge of lower one, then the hydrostatic pressure a tape and slope measurement gives an the hydrolevel was placed on the bot- between the two points, according to error not less than 2 percent, 40 meters tom station with an accuracy of about Pascal’s law, depends only on the dif- for a 2000-meter-deep cave, hydro- 1 centimeter. The water-reservoir glove ference in heights and the liquid density. leveling with the old manometer was laid on the palm of a hand with the The route of the tube does not affect method gives about 2 percent, and baro- top of the glove aligned on the top sta- the pressure in the box. Adding read- metric leveling can give an accuracy of tion. On average, the position error of ings of the gauge from consecutive pairs 15 meters, regardless of the depth of the glove was also about 1 centimeter. of stations gives us the depth of the cave the cave, but has a number of method- It is possible to estimate the error due in relative units. They are relative be- ological difficulties. to these random deviations. Random cause depth gauges are calibrated for errors partly cancel according to the sea water, and we fill the hydrolevel et’s consider separately errors that formula R = x ÖN, where R is the total with fresh water. Therefore we deter- L are random and systematic. expected error in N measurements, each mine a coefficient to recalculate the Random errors. There is an error due of which differs from the true value by measurement in meters. For this purpose to the discrete scale divisions of the x on average. For example, in our case a measuring tape is hung on a free drop, gauge device or calibration tape. Each of 80 stations to a depth of about 1200 with the 0 on the tape and the glove of measured value, on average, differs meters, errors in placing the device on the hydrolevel at the top point. The from a true one by one quarter of the station of a total of 2 centimeters each gauge reading is taken with the box at scale division. For the tape, it is 0.25 time would add up to 2 Ö80 = 18 centi- several vertical locations, according to centimeters, and for the depth gauge meters. Assuming 160 stations to a the tape, for example, at 5, 10 ,15, 20, used, with a display reading to 0.1 depth of 2000 meters, the error from and 25 meters. The Casio watch with meters, is it 2.5 centimeters. However, this source would be about 25 centime- depth gauge that we used works from 1 there are ways to reduce the reading ters. As noted above, errors due to the to 30 meters sea water. The relative uncertainty for the depth gauge, as de- discrete scale of the depth gauge will values read are plotted on a graph scribed later. be about the same size, and they will against the tape values. The points Frequently, flow of liquid in the tube, therefore contribute about the same should lie on a straight line, and the expansion of the tube under pressure, amount to the expected random error, parameters k and b, describing the line and possible slow equilibrium of pres- and random errors are expected to add h = kx + b, are determined by math- sure due to such causes is suggested as up to no more than half a meter in 160 ematical methods. h is the true differ- sources of errors. This is completely stations to a depth of 2 kilometers, con- ence in station heights in meters and x incorrect. Pressure in a liquid is trans- siderably less than the claimed error of is the reading of the hydrolevel in mitted with the speed of sound in the 0.2 percent for the method, or 4 meters relative units.

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