Hydro-Meteorological Monitoring of Tskaltubo (Prometheus) Cave System’s Catchment Basin (Caucasus, Western Georgia)

Full text

Open Journal of Geology, 2017, 7, 1774-1785
http://www.scirp.org/journal/ojg
ISSN Online: 2161-7589
ISSN Print: 2161-7570
DOI:
10.4236/ojg.2017.712119 Dec. 12, 2017 1774 Open
Journal of Geology
Hydro-Meteorological Monitoring of Tskaltubo
(Prometheus) Cave System’s Catchment Basin
(Caucasus, Western Georgia)
Lezhava Zaza1*, Tsikarishvili Kukuri1, Bolashvili Nana1, Chartolani Giorgi1,2,
Chikhradze Nino1,3, Naskidashvili Akaki4, Dvalashvili Giorgi2, Dzagnidze Suliko2,
Khomasuridze Zurab2
1Vakhushti Bagrationi Institute of Geography, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
2Faculty of Exact and Natural Sciences, Ivane Javakhishvili Tbilisi State University, Tbilisi, Georgia
3School of Natural Sciences and Engineering, Ilia State University, Tbilisi, Georgia
4Akaki Tsereteli State University, Kutaisi, Georgia
Abstract
Based on the present simultaneous
hydrometeorological data and the analysis
of the actual materials obtained by our studies,
we can suppose the fact of the
occurrence of powerful underground floodings in the hydrodynamic system
of the Tskaltubo Cave. The simultaneous records of the water levels (discharges)
of the underground rivers and atmospheric precipitation show that there are
importantly clear peaks in the hydrographs, when the diurnal sums of
precipitations reach or exceed 50 mm in all observati
on points (in all surface
catchment basins defined by us). Though, a long-
term observation revealed
that only 50 mm of precipitation diurnal sum is not enough for the formation
of strong underground flooding in the cave hydrodynamic system; a rainy p
e-
riod
of several days should precede such kind of precipitation so that the soil
was well saturated with water. Only under these conditions is expected a p
o-
werful flooding. As the analysis of the dangerous flooding formation mecha
n-
ism showed, what is important i
s not the abundance of diurnal precipitation
and their intensity, but the combination of factors such as: the total amount
and duration of precipitation of the predecessor period, precipitation amount
during the flooding maximum development days and the co
verage rate of the
cave system’s surface water catchment area.
Keywords
Estavela, Disaster, Siphon, Charge, Flooding
How to cite this paper:
Zaza, L., Kukuri,
T
., Nana, B., Giorgi, C., Nino, C., Akaki, N.
,
Giorgi
, D., Suliko, D. and Zurab, K. (2017
)
Hydro
-Meteorological Monitoring of Tskal-
tubo
(Prometheus) Cave System’s Catch-
ment Basin (Caucasus, Western Georgia).
Open Journal of Geology
,
7
, 1774-1785.
https://doi.org/10.4236/ojg.2017.712119
Received:
October 30, 2017
Accepted:
December 9, 2017
Published:
December 12, 2017
Copyright © 201
7 by authors and
Scientific
Research Publishing Inc.
This work
is licensed under the Creative
Commons Attribution International
License (CC BY
4.0).
http://creativecommons.org/licenses/by/4.0/
Open Access

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1775 Open Journal of Geology
1. Introduction
In 1984 the karst-speleological expedition of the Vakhushti Bagrationi Institute
of Geography of the Academy of Sciences of Georgian SSR discovered the pre-
viously unknown Tskaltubo karst Cave in the densely populated areas of the
Kumistavi Village of Tskaltubo municipality [1].
In subsequent years, the authors of this paper studied the Tskaltubo Cave Sys-
tem’s karst-speleological [2] [3] [4] [5], geomorphological-geological [6] [7] and
hydrological-hydrogeological [8] [9] [10] [11] features, and the multi-annual
hydrometeorological monitoring of the water catchment basin of the cave sys-
tem was also carried out.
In May 2012, Tskaltubo (Prometheus) Cave was opened to tourists. In the first
year of its opening, 80,700 visitors visited the cave; in the subsequent years, the
number of visitors only from the European countries exceeded 60,000.
It is noteworthy that there were several cases observed in the study area, when
the water from the underground suddenly broke into the main corridor of the
Tskaltubo Cave and resulted in the disastrous consequences. In this connection,
it was necessary to study the karst-speleology and hydrometeorology of its cat-
chment basin and predict natural disasters—floods.
2. Research Goal and Methods
Tskaltubo Cave System and its water catchment basin’s hydrodynamic system
are characterized by a very important condition, which needs detailed study. In
particular, there is a periodically debited Opicho Cave-estavela in the locked
karst cave, with the main entrance of the Tskaltubo Cave in its one end. Wide
neck directed towards the depth is 12 - 15 meters higher than the main entrance
of the Tskaltubo Cave, due to which the outburst water from Opicho Cave gets
into the cave’s main entrance passing through the bottom of the depression.
Each water stream formed within the depression rushes towards the main hall of
the Tskaltubo Cave, because the main entrance is opened to the lowest point of
the depression. Similar case has been recorded several times, when there was an
outburst of approximately 30000 m3 of water from the depths of the ground
during the Opicho Cave activity period. The outburst water gets into the Tskal-
tubo Cave’s main entrance passing through the bottom of the depression, ac-
companied sometimes with the disastrous results.
Therefore, the goal of our research was the study of the Tskaltubo (Prome-
theus) karst Cave System’s catchment basin in terms of karst-speleology and to
predict flooding—natural phenomena.
Regime observations were arranged on the karst surface and underground
water streams during the expedition works. The regime and relationships be-
tween surface and underground waters of Tskaltubo Cave System were specified.
Based on the materials of multi-annual complete-cycle stationary observation
the average monthly and annual charges of karst rivers were identified, as well as
the relationships between the fallen atmospheric precipitations and river runoff.

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1776 Open Journal of Geology
The runoff’s annual fluctuation was studied. In the 12 pre-selected sections,
namely, near the place of the cave the rivers flow out and the upper areas of the
surface water catchment segments, the water discharge was measured by means
of hydrometricrotator—ГР-51. The checkpoints of water and precipitation
measuring were arranged. Analysis of so called hydrometeorological course and
simultaneous hydrometeorological material (records) were carried out to identi-
fy the variability of karst streams discharge.
3. Description of the Research Object
Tskaltubo Cave System is 255 km away from Tbilisi, 16 km away from Kutaisi
and 6 km away from the resort of Tskaltubo (Figure 1).
Figure 1. Location of Tskaltubo (Prometheus) Cave System [12].

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1777 Open Journal of Geology
Tskaltubo limestone massif, in the hearth of which the Tskaltubo Cave System
is conceived, is located among the rivers of Rioni and Tskhenistskali, in the
northern zone of Kolkheti Lowland’s hilly relief and belongs to the speleological
region of Kvemo Imereti.
The length of the massif is 25 km, width—12 - 15 km and the area—250 km2,
out of which the 150 km2 is covered by the intense karst territory; it is mainly
represented by the gorges of the rivers of Semi and Kumistavi and belongs to the
low mountain—forest karst landscape with the moderate humid climate. Here
the highest landmark is 768 meters and the height reduces gradually to the
south, at the site of Melouri, which is the northeastern continuation of the Ku-
mistavi Village. Elevation marks of the site do not exceed 500 m. River. The
mark of the Semi riverbed at Melouri before its entering the narrow canyon is
382 meters. The rate of the karst of the territory is so high that there are depicted
several streams in the vicinities of the villages of Kumistavi, Kvilishori and Me-
louri, which cannot find the surface extension and disappear under the ground
(Figure 2).
Tskaltubo Cave System and its catchment basin’s hydrodynamic system is
characterized by the signs characteristic for structures built by karst rocks (mo-
noclinal and southern stretch), which facilitates the movement of groundwater
to the mentioned direction. Groundwater streams direction is also determined
by the contact areas of karst and nonkarst rocks.
Caves of the region are characterized by well-treated cavities and sharply dis-
tinctive meandering corridors and floors, which indicate a slowdown in the up-
ward movement of the territory or an important break in the development
process. The rate of the cave formation in the massif is identified not only by the
thickness of karst rock sand the frequency of fractures and openness, but also the
water storage and discharge conditions under the ground. The massifis mainly
characterized by the sub-horizontal cavities of corrosive-erosive type, clearly ex-
pressed multilevels and labyrinths, which are geomorphologically sharply
Figure 2. Tskaltubo limestone massif’s geological map.

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1778 Open Journal of Geology
localized at modern or old erosion network; the cavities include the absorption,
underground runoff and discharge areas.
Today the total length of Tskaltubo Cave’s surveyed corridors exceed 15 km,
but based on the facts, we suppose that it is only a part of many tens of kilome-
ters, and it may be even more extensive cave system. General outline of Tskaltu-
bo Cave has been already clearly identified, which covers about 15 km2 of area
built of karst rocks, which is confirmed by the indicative experiments on waters.
In western Georgia, in the conditions of subtropical climate, abundant and
long-term rains are common. According to the c. Tskhaltubo and v. Komuli
weather stations, the mean annual sums of the atmospheric precipitation are re-
spectively 1818 mm and 1853 mm in the cave’s extension areal, and the maxi-
mum of annual sums are 2200 - 2300 mm. Monthly sums of precipitation are
rather high as well. For example, the monthly maximums exceed 400 mm (420
mm—January 1950; 414 mm—July 1946,
et al.
) during the whole observation
period according to the materials of c. Tskaltubo bioclimatic station. Diurnal
sums of the atmospheric precipitation are also high: in c. Tskaltubo—126 mm,
in c. Tkibuli—173 mm, etc.
Northernmost boundary of Tskaltubo Cave system is defined by the sublati-
tudinal segment of the Semi River period, which is characterized by less stable
hydrological regime. In hot summer months the water stream can be observed in
the bed here and there; alternation of absorption centers is frequent. Therefore,
in the upper reaches of the Semi River the river runoff really flows under the
ground, but the underground connection between the Semi River and Tskaltubo
Cave system is less possible.
One of the important objects of underground karst waters discharged within
the research territory is the head of the Tskaltubo River. The Tskaltubo River,
which takes its origin from the territory of the city, is mainly fed on karst waters.
The runoff measurements were made from the year of 1936 to 1940. Three full
annual cycles (1936, 1938 and 1939) of observations are filled up; mean annual
discharge is 1.72 m3/sec. (Table 1) according to the factual material.
The water catchment area before the water measuring checkpoint is indicated
as 25 km2. As the observation line is very short, its assessment became necessary
with regard to the mean multiannual indicators. The data of the weather station
of Kutaisi City was considered the most reliable, on the basis of which the mean
annual discharge—1.49 m3/sec. of the Tskaltubo River was obtained. The mod-
ule calculated in accordance with this index of water discharge is equal to 59.6
L/sec.km2, which greatly exceeds the zonal index (35 L/sec.km2), which should
have been for this section of the Rioni River. Obviously, the officially indicated
area (25 km2) of the water catchment basin of this river cannot provide the men-
tioned amount of runoff in the prevailing hydro-meteorological conditions of
that place.
The study of the large-scale topographic maps revealed that the surface water
catchment area was 49.1 km2. To identify the basin all the negative forms of the

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1779 Open Journal of Geology
Table 1. Tskaltubo River’s mean monthly discharges (m3/sec) at Tskaltubo City (H/M
Service).
Month
Year
I II III IV V VI VII VIII IX X XI XII Mean
annual
1936 0.51 2.15 0.67 2.20 1.21 1.26 1.75 1.44 2.41 4.25 2.32 1.53 1.81
1937 - - 1.38 - 0.65 1.00 0.49 0.62 - 0.82 0.52 - -
1938 2.20 2.09 5.38 3.17 1.59 2.65 0.74 0.57 0.46 0.49 1.19 0.87 1.78
1939 2.39 3.80 2.71 1.34 1.30 0.89 1.14 0.72 2.37 2.30 2.12 2.06 1.93
1940 4.10 1.18 - - - - - - - - - - -
Mean 2.30 2.31 2.54 2.24 1.19 1.45 1.03 0.84 1.75 1.97 1.54 1.49 1.72*
% 11.4 10.4 12.6 10.7 5.9 6.9 5.1 4.1 8.4 9.8 7.3 7.4
*Calculated according to the mean monthly discharges.
relief were considered, which may have been regarded as the surface water ab-
sorption center.
Despite the lack of the observation materials on the runoffs of the Tskaltubo
and Gubistskali Rivers, we can say that the mean discharges of the Tskaltubo
River (which, as it was noted above, include the three years of a full cycle statio-
nary observations) indicate the stability of the runoff’s intra-annual distribution.
According to the regime observation materials, the variability of mean monthly
discharges is quite low and makes only 30.6% of the annual amount. Most of the
part of the runoff is observed in winter—29.2% and in spring—29.2%, while in
summer, in the driest period, it is equal to 16.1%.
The first measurements of discharges on the other main discharge objects
(outlets of the Kumi and Ghliana Rivers) of the underground karst waters in the
vicinity of the Tskaltubo Cave System were carried out on 15 July 1984. On that
day the total discharge of the Kumi outlets was 0.532 m3/sec., while the water
temperature was 14.5˚C. Outburst streams from the debiting karst sinkholes and
disharge siphon center are gathered in the water gauge section. On the same day
the Ghliana River’s underground water discharge was 0.074 m3/sec. and the
temperature—13.8˚C at the place of the outlet on the surface.
Further research revealed that the Kumi River runoff is characterized by a
high fluctuation; on July 20, 1984, the discharge of the stream flowing out from
the underground was 2.1 m3/sec., while on August 9 - 15 m3/sec. The latter was
stipulated because of the heavy rains.
An interesting fact was observed on June 18, 1986. Suddenly (13 h 45 min) a
turbid stream rushed to the edge of periodically debiting Opicho Cave, which is
located 12 - 15 m higher than the main entrance of Tskaltubo Cave. Earlier, in
the wide neck of Opicho Cave was rising above the water level with the speed of
0.2 m/1 min. After 15 minutes, a small stream turned into the powerful and
mighty river and flew to the Tskaltubo Cave’s main corridor through depression
bottom and flooded the cave. Maximum discharge of the outburst water reached
5.645 m3/sec.

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1780 Open Journal of Geology
With this intensity the water was flowing out during the 40 minutes. After the
55 minutes of beginning the outburst, the water amount began decreasing and at
15:30 the outburst was completely stopped.
During the whole time (105 minutes) of Opicho Cave’s activity there was an
outburst of 30 thousand m3 of water from the depth of the ground. The outburst
of almost half of this mass was during those 40 minutes, when the water stream
had the maximum discharge. The water temperature was 14.2˚C (Figure 3).
Data of Tskhaltubo weather station show that there was 78.2 mm of precipita-
tion the day, when there was the outburst of water from Opicho debiting Cave.
Torrential rain caused a sharp rise of levels in the nearby rivers and the flooding
wave overflew the river banks. Great flooding occurred in Tskaltubo Cave’s ma-
jor discharge centers—on the rivers of Kumi and Ghliana. The water of the
mentioned rivers was coming as a fast stream; the overall dischargeby visual as-
sessment was approximately 35 - 40 m3/sec. including the Ghliana share—5
m3/sec. The flooding began in 1986 on the night of June 17-18. It should be
noted that the most part (78.2 mm) of the total amount of precipitation fallen on
June 18, had fallen in the morning at 10 o’clock. During the next 24 hours, when
the amount of precipitation was only 9.2 mm, flooding ended quickly and in the
afternoon of June 19, the Kumi River discharge had fallen to 2.2 m3/sec.
4. Results and Discussion
Practice has demonstrated that it is necessary to conduct the direct observations
on specific object within the actual water catchment basin. Otherwise, it is im-
possible to analyze the precipitation related floodings, and moreover, the relia-
bility of forecasting groundwater flooding is being reduced.
Based on the analysis, it is identified that the river runoff fluctuation and at-
mospheric precipitation rhythm seems to be fitted each other, which in this case
is quite noteworthy, because the mentioned river flow is mainly formed at the
expense of atmospheric precipitation.
Regime stationary observations were conducted on the hydrometeorological
elements of the major centers of the underground karst water discharges and
(a) (b)
Figure 3. Outburst of water mass from Opicho Cave-estavela (to the left) and the en-
trance in the usual conditions (to the right) in June 18, 1986.

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1781 Open Journal of Geology
within the water catchment basin of Tskaltubo Cave System since 1987. The ob-
servations covered the full annual cycle. Three rain gauges were installed: at the
checkpoint 1—at the upper area of the surface catchment basin, at the check-
point 2—at the central zone of the surface water absorption and at the check-
point 3—near the outlets of the underground rivers. It was added by the mate-
rials of the Tskaltubo basic weather station, which was located hypsometrically
at a lower elevation. The water gauge checkpoints were arranged at the outlets of
the rivers of Kumi and Ghliana (Table 2).
The water gauge checkpoint of Kumi River—Kvilishori Village was arranged
8.5 km away from the siphon discharge center at the end of Tskaltubo Cave.
Outburst streams from the debiting sinkholes were also gathered at the check-
point. The water gauge checkpoint of Ghliana River—Kvilishori Village was ar-
ranged 10 meters away from the river outlet from the cave. Observations on wa-
ter discharges were conducted by means of the hydrometric rotator ГР-55
(Table 3) at both checkpoints.
On basis of analysis of the existing simultaneous hydro-meteorological data
we can express our preliminary views on the occurrence of a powerful under-
ground floodings in the Tskaltubo Cave’s hydrodynamic system.
Table 2. Amount of atmospheric precipitation in the Tskaltubo Cave vicinities in 1987 by
months.
Months I II III IV V VI VII VIII IX X XI XII
Total
annual
Checkpoint 1
mm 450 162 203 303 47 110 171 148 82 88 209 359 2332
% 19.0 7.0 88 13 2 4.8 7.4 6.4 3.6 3.5 9.0 15.5
Diurnal
maximum 70 30 62 75 11 29 71 70 25 22 74 47
Checkpoint 2
mm 393 134 198 226 41 110 188 167 85 84 212 348 2186
% 18 6.1 9.0 10.3 1.9 5.0 8.6 7.6 3.9 3.8 9.8 16.0
Diurnal
maximum
94 23 56 32 11 26 76 71 23 20 70 48
Checkpoint 3
mm 375 132 200 209 40 116 182 159 80 90 214 360 2157
% 17.2 6.1 9.3 9.7 1.9 5.4 8.4 7.4 3.7 4.2 9.8 16.6
Diurnal
maximum
88 22 59 30 10 25 79 62 24 23 80 47
Tskaltubo City
mm 334 124 165 234 38 144 142 184 80 93 154 368 2060
% 16.2 6.0 8.0 11.3 1.8 7.0 6.9 8.9 3.9 4.5 7.5 17.9
Diurnal
maximum
53 22 54 43 15 33 57 94 24 24 39 51

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1782 Open Journal of Geology
Table 3. Mean, maximum and minimum water discharges (m3/sec.) of the underground
rivers of Kumi and Ghliana in 1987 by months.
Months
Discharge
I II III IV V VI VII VIII IX X XI XII Mean
annual
Kumi River—Kvilishori Village
Mean monthly 1.15 0.74 0.87 0.79 0.44 0.43 0.58 0.46 0.43 0.42 0.63 0.79 0.64
% 14.9 9.6 11.3 10.2 5.7 5.6 7.5 5.6 5.6 5.4 8.2 16.2
Maximum 29.0 1.49 9.52 3.54 0.57 0.74 14.6 2.44 1.25 0.61 5.73 15.5 29.0
Minimum 0.49 0.55 0.56 0.55 0.37 0.36 0.40 0.34 0.37 0.38 0.41 0.43 0.34
Ghliana River—Kvilishori Village
Mean monthly 0.54 0.17 0.22 0.21 0.05 0.06 0.12 0.06 0.05 0.06 0.16 0.23 0.16
% 28.0 8.8 11.4 10.8 2.4 3.1 6.2 3.1 2.4 3.1 8.3 11.9
Maximum 10.8 0.69 2.10 2.34 0.07 0.18 7.60 1.81 0.64 0.14 4.31 8.05 3.22
Minimum 0.11 0.07 0.08 0.07 0.04 0.04 0.04 0.04 0.04 0.04 0.06 0.05 0.04
Simultaneous records of 1987 (Table 2) of the water discharges (Table 3) of
the underground rivers of Kumi and Ghliana show that the significantly distinct
peaks were occurred then, when the diurnal sums of precipitation reached or
exceeded 50 mm at every checkpoints. For example, by the data of the upper first
rain gauge, in April as if the conditions were created for the occurrence of a
flooding. On April 26, there was recorded 75 mm of precipitation, while in the
previous three days—80 mm. In addition, these precipitations coincided a very
favorable long-term rainy background (from 13 to 20 April, the rain did not stop
and its amount reached 111 mm). But at the other checkpoints such abundant
rainfall was not observed. On April 26 at the checkpoint 2 was recorded 7.5 mm,
while at the lower checkpoint 3 - 27.6 mm. On that day there was no precipita-
tion at all in Tskaltubo. As a result, very low peaks were registered on the hy-
drographs of underground rivers.
As it turned out, the plentiful, but diurnal precipitations, which cover the en-
tire catchment of the cave, is not enough for occurrence of the dangerous flood-
ing. In August 10, 1987, at all checkpoints were registered large amount of pre-
cipitation: checkpoint 1 - 70 mm, checkpoint 2 - 70.8 mm, checkpoint 3 - 62.3
mm and Tskaltubo City—94.2 mm. But as a long dry period preceded these pre-
cipitations, they had unimportant impact on the levels of the underground riv-
ers. During the August 10 the maximum discharge did not exceed 2.44 m3/sec. at
the outlets of the Kumi River and 1.86m3/sec.—at the outlets of the Ghliana River.
Almost the same thing happened in November 3, when the high rainfall was
recorded on the mentioned rain gauge (checkpoint 1 - 73.6 mm, checkpoint 2 -
70.2 mm, checkpoint 3 - 79.5 mm and Tskaltubo City—39.1 mm). This was pre-
ceded by several rainy days, having slightly softened the soil after the 12-day dry
period, but not so much to create favorable conditions for the occurrence of a
powerful flooding. The maximum discharges of this day were: the Kumi River—

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1783 Open Journal of Geology
5.73 m3/sec., and the Ghliana River—4.31 m3/sec.
Particularly high floodings were noted in January, July and December during
the annual cycle of observation on the main centers of discharge of the under-
ground waters of Tskaltubo Cave hydrodynamic system.
In January 31, 1987, maximum discharges of the underground rivers of Kumi
and Ghliana were accordingly, 29 m3/sec and 10.8 m3/sec. Almost in the same
regime was activated the periodically debiting Opicho Cave. This flooding was
preceded by a week-long rainy period. It rained within the entire surface water
catchment basin. Precipitation sums of the previous period in the checkpoints
were from 52.8 to 41.3 mm. Flooding wave began sharp increase in January 29,
when the diurnal amount of precipitation reached 58.0 - 35.9 mm. 93.6 - 50.0
mm—93.6 mm was recorded in the day of occurrence of further discharges. Di-
urnal maximum of precipitations—93.6 mm was recorded at the checkpoint 2 or
in the middle of the surface water catchment basin.
Two other high floodings, which passed in July and December, also occurred
on the background of the previous rainy period.
Seven rainy days preceded the July flooding with the total amount of precipi-
tation from 70. 4 to 54.0 mm on different observation stations. In July 8 and 9,
during the days of flooding peaks, 122.2 mm of rainfall was registered in the
checkpoint 2 in total. This figure is less than the precipitation sum of those three
days of January, when 185.8 mm—14.6 m3/sec. was registered in the same
checkpoint. Diurnal sum of precipitation was also less—75.6 mm at the check-
point 2 than in the corresponding day of January (93.6 mm). There was no out-
burst of water from Opicho Cave in these days.
In December 4 the continuous rains began, due to which the flooding oc-
curred in December 11, when the maximum discharges on the rivers of Kumi
and Ghliana were respectively 15.5 m3/sec. and 8.05 m3/sec. The flooding wave
was sharply raised in December 10, while the next day it reached the highest lev-
el. Predecessor precipitation sum from 4 to 9 December at the various check-
points was from 113.4 mm to 88.3 mm. In December 10 and 11, the days of ac-
tive development of flooding, the amount of precipitation was 96.9 mm at the
checkpoint 2, and when flooding reached its maximum, the amount of precipita-
tion was 49.3 mm. But Opicho Cave-estavela was not activated even in this case.
Similar works (observations) were carried out in order to study and specify
the relationship of Tskaltubo Cave System’s surface and ground water regimes in
the following years as well (Table 4), where there was approximately the same
picture as in 1987.
5. Conclusions
Simultaneous records of the underground rivers’ water levels (discharges) and
atmospheric precipitation show that there are importantly clear peaks on the
hydrographs, when the diurnal sums of precipitation reach or exceed 50 mm in
every point of observation (in all surface water catchment basin identified by us).

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1784 Open Journal of Geology
Table 4. Measured water discharges in the river sections of Tskaltubo massif in 2008.
No. Section Hydrometric
rotator, turn/sec.
Correlation
coefficient
Water section
area, m2
Water flow speed,
m/sec.
Water discharge,
m3/sec.
1 Mill pond at the Kumi vaucluse
after the opening of dam 11.1 0.7 0.20 1.3 0.180
2 Kumistskali 2nd outlet 6.48 0.7 0.12 0.8 0.067
3 Kumi (1st stream) 4.84 0.7 0.16 0.6 0.067
4 Kumi (2nd stream) 3.22 0.7 0.09 0.4 0.025
5 Kumi (3rd stream) 5.57 0.7 0.14 0.7 0.069
6 Ghliana (at the cave) 1.75 0.7 0.65 0.2 0.091
7 Ghliana (outside the cave) 2.91 0.7 0.04 0.4 0.011
8 Jibilauri 3.33 0.7 0.16 0.4 0.045
9 Kvilishori Cave. Jibilauri vaucluse 5.48 0.7 0.04 0.7 0.020
10 Melouri. Didghele River, at the entrance
of the cave, over the waterfall 2.62 0.7 0.04 0.3 0.008
11 Bgheri 5.08 0.7 0.44 0.6 0.180
12 Semi River (at the Tskhunkuri Village),
beyond the bridge 6.67 0.7 0.20 0.8 0.110
Long-term observation revealed that only 50 mm of precipitation diurnal sum
is not enough for the formation of strong underground flooding in the cave hy-
drodynamic system; a rainy period of several days should precede such kind of
rain so that the soil was well saturated with water. Only under these conditions is
expected a powerful flooding.
Thus, according to the available regime material, the diurnal maximum of
atmospheric precipitation may exceed 100 mm regime was, while the intensity of
rainstorms may reach 4 mm/min. But as the analysis of the dangerous flooding
formation mechanism shows, important is not the abundance of diurnal preci-
pitation and their intensity, but a combination of factors such as: the total
amount and duration of precipitation of the predecessor period, precipitation
amount during the flooding maximum development days and the coverage rate
of the cave system’s surface water catchment area.
Tskaltubo Cave has now a lot of visitors and provision of their safety is a main
issue. The real danger, which can happen to people in the cave, is a sudden
flooding. Opicho phenomenon requires more basic study.
Tskaltubo Cave System’s hydrometeorological monitoring requires proper at-
tention and organization. We consider it necessary the creation of the perma-
nent regime of hydro-meteorological network in the vicinity of cave system,
which will provide the identification of diurnal levels, debits, solid deposition
charges and chemical composition (including the CO2) of the rivers (Kumi,
Ghliana, Tskaltubo outlet, Semi, etc.).
References
[1] Jishkariani, J., Tsikarishvili, K., Kobulashvili, T. Jamrishvili, A., Kapanadze, V.

L. Zaza et al.
DOI:
10.4236/ojg.2017.712119 1785 Open Journal of Geology
(1986) The Latest Research Results of Tskaltubo Cave System. Reports Theses of
Scientific Session of Vakhushti Bagrationi Institute of Geography, Metsniereba, Tbi-
lisi, 31-32.
[2] Tintilozov, Z.K. (1976) Karst Caves of Georgia (Morphological Analysis). Book.
Editor Tsereteli D.V. Metsniereba, Tbilisi.
[3] Tatashidze, Z., Jishkariani, J., Tsikarishvili, K., Jamrishvili, A., Kapanadze, V.,
Kobulasvili, T. and Geladze, G. (2002) Tskaltubo Cave System—The Largest Karst
Cavity in the Imereti Region
. Bulletin of the Georgian Academy of Sciences
, 166,
514-517.
[4] Tatashidze, Z.K., Jishkariani, V.M., Tsikarishvili, K.D., Jamrishvili, A.R., Kapanadze,
V.M., Kobulashvili, T.G. and Geladze, G.V. (2004) New Karst Cave in Tskaltubo
Vicinity (Western Georgia), in the Book Peshchery (Caves),
Interuniversity
Collection of Scientific Transactions
, Perm, 48-52.
[5] Tatashidze, Z., Tsikarishvili, K., Jishkariani, J., Jamrishvili, A., Geladze, G. and
Lominadze, G. (2009) Tskaltubo Cave System (Editor, Prof. Ramin Gobejishvili),
Petite
, Tbilisi.
[6] Liponava, K. (1985) Tskaltubo limestone Massif’s Relief Development Features.
Mountainous Areas Productive Forces Development Problems. Reports Theses,
Tbilisi, 14-15.
[7] Tsikarishvili, K., Lezhava, Z., Asanidze, L., Bolashvili, N., Chikhradze, N. and
Chartolani, G. (2015) Geomorphologic Features of Sataplia-Tskaltubo Limestone
Massif.
Earth Sciences. Special Issue
:
Modern Problems of Geography and Anthro-
pology,
4, 108-112.
[8] Vladimirov, L. and Gigineishvili, G. (1973) Water Balance Patterns in the Karst Re-
gion of the Greater Caucasus. Abstracts of papers submitted to the 6
th International
Congress of Speleology
, Olonouc, Czechoslovakia.
[9] Gigineishvili, G.N. (1979) Karst Waters of the Greater Caucasus and the Main
Problems of Karst Hydrology. Metsniereba, Tbilisi.
[10] Gigineishvili, G., Tatashidze, Z. and Tsikarishjvili K. (2007) Geographic-Hydrological
Arguments on Possible Expansion of the Tskaltubo Cave System.
Bulletin of the
Georgian Academy of Sciences,
175, 67-70.
[11] Lezhava, Z., Bolashvili, N., Tsikarishvili, K., Asanidze, L. and Chikhradze, N. (2015)
Hydrological and Hydrogeological Characteristics of the Platform Karst (Zemo
Imereti Plateau, Georgia). Sinkholes and the Engineering and Environmental
Impacts of Karst.
Proceedings of the
14
th Multidisciplinary Conference
, Rochester,
5-9 October 2015, 93-100.
[12] Lanchava, O. and Tsikarishvili, K. (2016) Tskaltubo (Prometheus) Cave System.
Publishing House Tbilisi State University, Tbilisi.