Istočna Hercegovina, Bosna i Hercegovina.
Источна Херцеговина, Босна и Херцеговина,
FATNIČKO POLJE - ФАТНИЧКО ПОЉЕ
Fatnica Polje, Eastern Herzegovina, Bosnia & Herzegovina.
updated 30 October 2009.
[under construction with the complete text being added over the coming months.]
Section 2.0. KARST HYDROLOGY & HYDROGEOLOGY - HIDROLOGIJA i HIDROGEOLOGIJA KARSTA
- ХИДРОЛОГИЈА и ХИДРОГЕОЛОГИЈА КАРСТА :
Link Page for
DEJANOVA PEĆINA - DEJAN'S CAVE - ДЕЈАНОВА ПЕЋИНА
Image FP-DjP.000. (above-left) :
This is an historical or contemporary images of the cave entrance of Dejanova Pećina, dated 1890. It is of Austro-Hungarian origin. We have also located one lithographic line drawing of the external entrance area in which women can be seen washing clothes in the karst spring water. This drawing can be seen opposite in Image FP-DjP0. Compare the details of the line drawing opposite with those in the image on the left.
Image FP-DjP.00. (above-right) :
This is a photograph of the cave entrance area prior to the final flooding of the area and the creation of the HET Company's Bileća Lake.
"At the Source of the Trebišnjica near Bileća, ca. 1900."
Image FP-DjP.1. (left) :
This is an old photograph of the cave entrance area of unknown date and origin.
It was probably recorded before the one at top-left,
insofar as the little footbridge in the view below is not in such a developed condition.
Bushes conceal the low-flow conditions of the outflow.
["DEJANOVA CAVE - Speleological and Hydrological Investigation of the Trebišnjica Karst Spring."]
extensive information about this karst spring cave given below, is archive
material, written by Dragutin Petrović in his Article
"ДЕЈАНОВА ПЕЋИНА - Спелеолошка и хидролошка
испитивања на врелу Требишњице." - ["DEJANOVA
CAVE" - Speleological and Hydrological Investigation of the Trebišnjica
Karst Spring"], published in the journal series Zbornik radova Instituta
za proučavanje krša "Jovan Cvijić" Knj. 1. (1955). This can be downloaded
as a .pdf by clicking on the following Link.ДЕЈАНОВА
published Article contains the .....
Image FP-DjP2. (above)
"Карта шире околине Дејанове Пећине. Испрекиданом линијом је означена фосилна, сува долина изнад пећине."
Map of the wider area of Dejanova Pećina. The broken lines indicate the positions or lines of the dry fossil valleys above the cave. This also indicates a line drawing sketch map of the surface area around Vrela Trebišnjice and Vrela Ćepelice, with topographic contours.
of the surface area around Vrela Trebišnjice.
Sketch maps indicating (top) the relative contours along a cross-sectional view and (bottom) the former or fossil
higher level of the surface flow of the River Trebišnjica and the present lower level, (prior to recent inundation).
["THE CAVE AND ITS ADJACENT SURROUNDINGS.]
"Dejanova Pećina is situated in the spring group area of the River Trebišnjica about 2 km. south of Bileća. The cave entrance is situated in a spacious valley formed in limestone about 1 km. wide, which is deeply incised in the surrounding terrain : From the karst springs which issue from along the edges of the base of the valley, originates the River Trebišnjica. Its strongest periodic karst spring is Dejanova Pećina."
"Dejanova Pećina is situated in the most northerly part of the limestone valley. [Ed. Miruše area.] The cave entrance faces south-east and is located at the absolute elevation of 325.2 m. asl. Above it rising like a partition is a cleft in the abrupt natural limestone cliff, rising up to a dry limestone valley above. [Ed. the so-called Bilećko Polje]. The northern part of this dry limestone valley is dissected. In here is located a dry, deep and meandering channel, very steeply descending, that only begins by the edge of the limestone valley, on the top of which a road leads from Bileća to Trebinje and Nikšić. The dry valley firstly descends towards the south then like an elbow turns toward the west to finally to repeat the turn toward the south then twisting west at its bottom end towards the present lower spring group valley, where it takes the full width of the dry valley. By reason of this meandering it cuts its way through limestone and around the dolomitic masses, as also occurs inside Dejanova Pećina, showing at one place in its relief that it cut through a hill which, at one time was 50 m. high. Thanks to its meandering, this channel has the appearance of an overturned Latin letter "S". The long north and west flanks of the aforementioned dry valley break into its larger south part section beneath whose base is located Dejanova Pećina. On the east side of the valley of the Trebišnjica Spring group area, is a low mountain mass, which itself sweeps around and away toward the east. Somewhat to the north and at the base of this mountain mass is a noticeable hollow about 10 m. and width about 25 m. This concave in the limestone appearing like a corridor, is the first part of Dejanova Pećina, formerly attracting only superficial interest."
long spring group area of the River Trebišnjica is formed in the limestone
massif. Its western slopes rise up to Mikolj Glavni [Ed.
now Nikolj Glavni] at 566 m. and then up to 700m to the watershed in
above the northern edge of this area is a spacious wide, dry valley which
itself extends from the north-west to the south-east and which ends just
above the area of the Trebišnjica like a hanging valley, [Ed. again,
the so-called Bilećko Polje]. The mouth of this hanging valley is located
about 100-120 m. above the Trebišnjica riverbed. The entirety of this
dry valley is formed in the same direction as that of the present valley
of the River Trebišnjica. The width of the dry valley is about 2 km. On
its lowest surface can be observed shallow dolines. These undoubtedly represent
the locations of old fossil springs of the River Trebišnjica. From its
present appearance, it has the characteristic morphology of a typical river
valley. It formerly possessed springs on two sides. On the west, one issued
below Rudina and on the east, below Bobotov Duba.
"The direction of the valley and the direction of the Trebišnjica riverbed conform to the direction of that extending along the Main Canal of Dejanova Pećina."
Image FP-DjP4. "План Дејанове Пећине" - ["Plan of Dejanova Cave"].
KEY TO LEGEND :..1. Lake Water. 2. Tufa. 3. (Otseci). 4. Collapse Material.
& EXPLANATION of Text in Image FP-DjP4. opposite :
inwards from the bridge before the entrance) :
KEY TO LEGEND :..1. Limestone. 2. Dolomite. 3. Clay.
["Transverse profiles of the narrowest parts of the "Main Canal" (A) and the "West Canal (B)".]
[The Scale is in metres.]
["MORPHOLOGY OF THE PASSAGES OF DEJANOVA CAVE.]
entrance of Dejanova Pećina has a three-cornered appearance turning then
straightening from the south-east to the south-west. The width near the
bottom is about 4 m. and it is about 6.5 m. high. It has an absolute elevation
at 325.2 m. asl. This form of transverse profile entrance is geologically
inside the entrance, the cave increases into a spacious chamber whose greatest
parts (middle and western) contains the water of the lake. This is the
length in a north-south direction is about 25 m. (82 feet) and its width
is about 20 m. (66 feet). The roof rises in an arch to a visible height
of 12m.-15 m. (39 - 49 feet). During the present research the level of
the lake water was at an elevation of 324.5 m. asl. (05 October 1954),
which in relative terms is 0.7m. below the bottom of the cave entrance
and about 1.5 m. below the bottom of the riverbed which takes the streamwater
from the cave after temporary periods of rainfall during the year. The
base of this small streambed slopes down from the Entrance
Chamber towards the small bridge in front
of the cave and then is further inclined towards the streambed of the Trebišnjica.
The depth of the lake water is about 1 metre but is suspected to increase
in the greater part of the Chamber next to the only limestone wall.
"From the Entrance Chamber run three cave passages - the "West Canal", which extends west then north-west; the "Main Canal", which runs north then north-west and one small fissure-passage running east then north-east."
"The Main Canal extends mainly in a north-west direction with its base undercut to the east. It is spacious and from its beginning in the Entrance Chamber, is from between 3.5 m. to 4 m. wide and is 5 m. high. Its steeply sloping side walls are inclined down to the east and its cross-sectional profile is eliptical in shape. At a point 14 m. in from the beginning of the passage, on its west side at its base, can be observed a horizontal opening to a fissure. This is the opening to one short recess and a drop which is 1.7 m. deep. This superficial passage is a way through to the "Central Lake" whose level is identical to the water level of the lake in the Entrance Chamber. Coming from the Main Canal one can see through to the Central Lake over a limestone ridge of 2 m. high and 3 m. wide. Exiting over this step on to a low platform from the Main Canal, you arrive at the rounded shore of Central Lake at its most southerly part. East of this platform is observed a short cave passage which continues below water-level.
[To be continued]
Image FP-DjP7. "Шематска скица механизма рада пећинских сифона Дејанове Пећине" -
["Schematic sketches of the mechanism of the working of the cave syphons of Dejanova Cave"].
["HYDROLOGICAL CIRCUMSTANCES AND THE WORKING MECHANISM OF THE CAVE SYPHONS.]
[Text to follow]
"Dejan's Cave" is formed in Upper Cretaceous Limestone and Dolomites. In terms of karst hydrology, it is predominantly an Allogenic (B-Type) Karst Resurgence Spring, with significant Authigenic (A-Type) contributions. As such, we would expect a considerable build-up of sediment to have accumulated in the form of a sediment-fan at the base of the reservoir downstream of the spring-zone.
The complexity of this very dynamic karst spring zone is illustrated by the simplified plan and sections of the previously accessible cave passages, which were surveyed at a time of low water. The surveyed cave passages total 510 metres (1673 ft.) in length, all of which is now submerged deep below the impounded water of the HET Company's Bileća Lake Reservoir. The karst hydrological mechanism of the outlet zone as interpreted by Petrović.in his simplified sections given in.Image FP-DjP7..above, indicate that the main entrance at Dejanova Pećina is an intermittent spring under natural conditions. The interconnected spring outlets downstream of Dejanova Pećina at Vrelo "Oko" and Vrelo "Nikšičko" continue flowing long after the yield at the main outlet has reduced or has even stopped.
As for the possibilities of a modern technical investigation of this complex karst spring-cave zone, such an enterprise would be encumbered by the present depth of submersion of the whole cave system beneath the HET Company's Bileća Lake, impounded by its Grančarevo Hydro-electric Dam. At the maximum level of water impoundment [ie..400.09 m.asl. (1313 feet a.s.l.)], the cave entrance would be situated 75 metres (246 feet) below the level of the artificial lake. A modern exploration of the cave is technically possible but has an inherently high level of risk attached to it. One aspect of minimizing the many risks would be to co-ordinate the underwater exploration at a time of very low water in the lake combined with very low underground water flows. Such a time would be in the late summer period following a dry winter or even better, following a long series of dry winters. Such rare and ideal circumstances ocurred in the summer of 2003 but the opportunity of diving was not taken up at that time.
At the present stage of planning, a reconnaissance dive was due to take place in the Summer of 2005., in order to ascertain the accessibility of the main cave entrance and its condition together with the nature of the physical problems encountered. The water conditions were far from ideal and the dive was postponed.
If it is deemed to be useful and sufficient information arises from such a reconnaissance dive in the future, a separate Webpage will be annexed via a Link within the Fatničko Polje Webpages - Section 2., to provide both the dive results and any associated future plans.
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