The Devon Karst Research Society & Speleološko Društvo "Zelena Brda"
Istočna Hercegovina, Bosna i Hercegovina...|..Источна Херцеговина, Босна и Херцеговина,
FATNIČKO POLJE  -  ФАТНИЧКО ПОЉЕ
Fatnica Polje, Eastern Hercegovina, Bosnia & Hercegovina.
updated 31 May 2010.
(now undergoing substantive revision)

Section 2.0.    KARST HYDROLOGY & HYDROGEOLOGY  -
HIDROLOGIJA i HIDROGEOLOGIJA KARSTA  -  ХИДРОЛОГИЈА и ХИДРОГЕОЛОГИЈА КАРСТА.

The former Content on this Webpage detailing both the Vrela Trebišnjica and the immediate downstream Miruše Basinal-plateau Area, is now being expanded and will be moved to a more logical position in this Website detailing Rijeka Trebišnjica in the
Karstography of the DINARIC KARST IN BOSNIA AND HERCEGOVINA, Part 3. Eastern Hercegovina, Popovo Polje Webpages.
The remaining content on this Fatničko Webpage is being expanded and re-structured.

..........FP Section 2.0. Webpage Contents :
..........Paragraph 2.2.......Karst Springs, Estavelles and Ponors in Fatničko Polje :
..........Paragraph 2.3.......Karst Water Outlet Springs for Fatničko Polje - The Local Base levels of Erosion :
..........Paragraph 2.3.1....General Introduction and Introduction to the Zaravan Miruše :
..........Paragraph 2.3.2....Overview of the Fatničko Polje Karst Outlet Springs  :
..........Paragraph 2.3.3....The Trebišnjica River Spring-group below Bileća  /  Vrela Rijeke Trebišnjice :
..........Paragraph 2.3.4....The Čepelica Stream Spring-group  /  Vrela Rijeke Čepelice :
..........Paragraph 2.3.5....Post-1967 -  Monitored Effects during and after the Submersion of the Trebišnjica  /  Čepelica Spring-groups beneath the artificial Bilećko Jezero :
..........Paragraph.2.4.......Karst Water Quality in Fatničko Polje :
..........Paragraph 2.4.1....Introduction :
..........Paragraph 2.4.2....Overview of the Chemical, Physical and Biological Parameters and Analytical Procedures.

..........Click on the underlined Links above to move down to the Sections more quickly.


2.1.    GENERAL :
Because of its position and complex hydrological and hydrogeological characteristics, Fatničko Polje represents an extremely significant local base-level of erosion in this part of Eastern Hercegovina. It's elevation lies between that of the Cerničko Polje, which is about 350m. higher up but still within the catchment area of Fatničko Polje, and that of the Trebišnjica / Čepelica River Springs, which are about 130m. lower. It is through these Springs that this large catchment area, including Cerničko Polje and part of both Gatačko and Fatničko Polja, are drained. Underground flow-rates in this whole area vary between 0.4 and 14 cm. sec ­¹.
The surface area Rainfall Catchment alone for Fatničko Polje has been calculated as being of the order of 40 km², (Šimunić Z. and Žibret Ž., 1976.).
The contours of the base-level of karstification beneath Fatničko Polje are such that the underground hydrology is bifurcated and that under high water conditions, the water draining from the polje floor will diverge and feed karst aquifers supplying two separate catchments.
More specifically, the elevation of the unseen contours of the base-level of karstification under the polje floor, peak at 400m. asl. Provided the karst underground water levels do not rise above this contour, all water entering the polje through the main vrelo-type karst springs in the north-east corner will drain only towards the Trebišnjica River Springs.
Fatničko Polje is hydrologically active principally in periods of high water when it is inundated. During this period of activity, water will rise above the 400m. a.s.l. contour and because the polje floor and its main ponors are mostly situated to the east of the bifurcated groundwater divide, approximately 85-90% of its drainage flows towards the Trebišnjica River Springs to the south-east and, according to various specialists, the remaining 10-15% flows to the Bregava River Springs to the north-west.
The most significant ponor is the "Pasmica" Ponor, whose water discharges to the Trebišnjica River Springs.

..........
Image FP2.1.  (after Milanović)
Indicates the bifurcated hydrology (watershed) beneath Fatničko Polje, as defined by Lycopodium Spore Tracing. (see Key below).
Vododijelnička zona u području Fatničkog polja utvrđena primjenom likopodijum spora kao obilježivača.

..........KEY to Image FP2.1. (left) :
..........1...Polje  /  Polje  /  Поље.
..........2.  Ponor  /  Ponor  /  Понор.
..........3.  Permanent Karst Spring  /  Stalno kraški izvor  /  Стално крашки извор.
..........4.  Intermittent Karst Spring  /  Povremeno kraški vrelo  /  Повремено крашки врело.
..........5.  Established underground water connections  /  Utvrđene podzemne veze  /  Утврђeнe подземне везе.
.
..........A.  Position of Underground Watershed  /  Usvojena vododijelnica radi proračuna sliva  /  Усвојeна вододијелница ради прорачуна слива.
..........B.  Watershed Zone  /  Vododijelnička zona  /  Вододијелничка зона.
..........b - b'  Variable Boundaries of the Underground Watershed Zone  /  Granice vododijelničke zone (takođe su podložne promjeni)  /  Границе вододијелничке зоне (такођe су подложне промјени).

..........Introduction of the spores  /  Upotredljene spore  /  Упotредљене спoрe.
..........Z.  Green  /  zelene  /  зелене.
..........C.  Red  /  crvene  /  црвене.
..........P. Blue  /  plave  /  плаве.
..........N.  Un-coloured  /  neobojene  /  неoбoјене.
..........V.  Violet  /  ljubičaste  /  љубичасtе.



2.2.    KARST SPRINGS, ESTAVELLES AND PONORS IN FATNIČKO POLJE :
The karst springs (permanent and temporary), estavelles and the ponors and ponor-groups in Fatničko Polje are each such important aspects of study within the polje, that they are dealt with in great detail in other Sections of these Fatničko Polje Webpages. Please refer to the INDEX page for a full list of Sections and the topics dealt with.

2.3.    KARST WATER OUTLET SPRINGS FOR FATNIČKO POLJE - The Local Base levels of Erosion :
2.3.1.    General Introduction and Introduction to the Zaravan Miruše :
As indicated in Image FP2.1. above, a bifurcated hydrology exists beneath the floor of Fatničko Polje, giving the phenomenon of two Local Base Levels of Erosion. Under certain high water conditions, a relatively small proportion of the water leaving the polje travels north-west to resurge at the Bregava Karst Springs (Vrela "Bregava"). This particular aspect will be dealt with in future webpages dedicated to Dabarsko Polje.

The majority (85-90%) of water leaving Fatničko Polje (or permanently flowing through the phreatic karst conduits beneath the polje), travels south-east to resurge at karst springs in the now-submerged floor of what is now the HET Bileća Lake (Bilećko Jezero), in an area which was formerly known as the Miruše Basin.
Prior to submersion, this was one of the two former LOCAL BASE LEVELS OF EROSION for Fatničko Polje. This artificial lake has also been known as the Akumulacija Bazena Miruša. Its lower reaches encroach into Montenegrin Herzegovina.
This very interesting area in its own right, has a complex karst hydrological functionality and is situated at an average altitude of 330m. asl. (1083 ft. asl.) and is orientated north north-west / south south-east. As a single karst geomorphological feature and prior to submersion, it may be considered as being an open karst polje; that is, open at its downstream or outlet end only. Its downstream outlet area begins at the north side of the dolomitic "hydrological barrier" near Dobričevo, taking the form of a karstic canyon about 7 km. long. The karstic canyon continues downstream in a southerly direction, past the Estavela "Kljen" at Dobričevo and the Ponors at Tmuša and the Ponors at Pares and the Ponor "Mlinica", opening out again into Trebinjsko Polje at the Grančarevo dolomitic "hydrological barrier" 700m. downstream of the Vrelo "Oko" spring group at Pares.

As an important aspect directly connected with the hydrological functionality of Fatničko Polje, the two northern extremities of the "Miruše Basin" are dealt with here in great detail, addressing both the historical and present situations.

2.3.2.    Overview of the Fatničko Polje Karst Outlet Springs  :
The Fatničko Polje Karst Outlet Springs comprise two geographically and hydrologically-distinct principal groupings. These are :-

..........a)  The Trebišnjica River Spring-group below Bileća / Izvorište Trebišnjice located at 325 m.asl. (1066 ft);
..........b)  The Čepelica Stream Spring-group / Izvorište Čepelice located at 324 m.asl. (1063 ft).

In the paragraphs below, we offer some hydrological and other data regarding each individual spring-group. Further information will be added when it becomes available. We have located some historical monochrome and colour images of the areas of interest. These are now included here.

2.3.3.    The Trebišnjica River Spring-group below Bileća  /  Vrela Rijeke Trebišnjice :
This Karst Spring-group has one of the largest yields of water of any spring in Europe and is the direct, permanently flowing source of the Karst River Trebišnjica, formerly the largest disappearing karst river in the world. The following archive photographs indicate details of the area in very different periods of time. We have ensured that the images are of sufficient quality for positional-comparison of the essential features. Each of the photo-archive views has been photographed from a different viewpoint. We thank both Mr Bogdan Prelević for acquiring the photo-archives below and Dr Dragan D. Tabaković for his detailed input to the description of various features in the archive photographs.
However, we start with two Military Maps from the period of late Austro-Hungarian Administration (1912) of Bosnia & Hercegovina, showing topographic details of the Bileća area. Note that the "Trebišnjica Springs" [Vrela Trebišnjica] are annotated as the "Trebinjčica Quellen".

.....
Map 2.3.3.M1. (above-left)...FESTUNGS-UMGEBUNGSPLAN von BILEĆA. (Zusammengestellt aus Kopien der Militäraufnahmssektionen.)..Ausgabe 1912. Blatt 3.
[Translation :  Fortresses and Surrounding Environs near Bileća. (Composed from Copies of the Military Surveys Section.)..Edition 1912. Sheet 3.  Scale :  1 : 25 000. [1 red square on the map = 1 km².]
Map 2.3.3.M2. (above-right)....Militäraufnahmssektionen. Austro-Hungarian Military Field Map
Scale :  1 : 25 000.  Covering the same area as the Map 2.3.3.M1. (left). but in clearer detail.


Photo FP2.3.3-1.  (above-left)....An archive monochrome image indicating a long view of the area immediately downstream of the submerged Izvorište Rijeke
Trebišnjice VRELA "BILEĆKA" (Dejanova Pećina) and its rise-pit or resurgence pool and the associated Mills, Mill Dam and integral Bridge.
The karst hydrological / speleological features of interest are  (1)..VRELO "OKO", with its very short surface streamway joining the main flow of the Trebišnjica at the first bend of its surface course, in the centre-left of the view;
(2)..VRELO NIKŠIČKO, with its short surface streamway joining the main flow of the Trebišnjica at the second bend of its surface course, in the top-left of the view. The building beside this output canal is the TOMANOVIĆA MLIN.
Also of interest are the many buildings.
The substantial stone-construction building in the top-right corner of the view is the original water pump-house supplying the public water-supply system for the town of Bileća and indicated on the Map 2.3.3.M1. above as "Pump werk".
This same building also housed an electric generating station, indicated on the Map 2.3.3.M1. above as "Maschine haus" and was built for the dual purpose in 1883-84 by engineers of the Austro-Hungarian Empire, who by this time, had a substantial garrison stationed in Bileća.
The pump-house and the Bileća water-supply system are of Austro-Hungarian design and construction. In the foreground at the bottom of the view are the two Mills, one on either side of the Mill Dam and integral Bridge.
The Mill on the right bank at the very bottom-right corner of the view is the SALATIĆA MLIN, belonging to Gavrilo Salatić. The opposite mill on the left bank is the POPARA MLIN, belonging to Jefto Popara.
In this view, both Mills have roofs and the POPARA MLIN on the left of the view has a stabling annexe for horses, which were kept at the facility both for transporting unprocessed grain to the Mills and for taking away the resultant ground flour.
The stabling annexe is attached to the left end of the Mill and has a higher roof structure than the Mill itself.
(This is the earliest dated of the photo-archive views of this area. The absolute date for the photograph is unknown. PLEASE NOTE that all references herein to the SALATIĆA MLIN were originally and incorrectly referred to by us as the TOMANOVIĆA MLIN.)
.
Photo FP2.3.3-2.  (above-right)....An archive monochrome image contemporary with Photo FP2.3.3-1. above and indicating a closer view of the SALATIĆA MILL on the right bank.
The photograph was taken from the Mill on the opposite bank when the Trebišnjica Spring Group was in high flow conditions. Note that the roofs on the Mill buildings are still in position.


Photo FP2.3.3-3. (above-left)....An archive colour image indicating a side view of the area of the rise-pit or resurgence pool of the now submerged VRELA "BILEĆKA"
and the immediate downstream section of the Trebišnjica River, to the point of confluence of the streamway of VRELO "NIKŠIČKO".
The karst hydrological / speleological features of interest are :-    (1)..DEJANOVA PEĆINA (submerged in the resurgence pool at the lower extreme-left in the view);
(2)..KOSTOVA PEĆINA beside the main resurgence pool on the left bank - in this view its very short streambed is dry, (at the lower extreme-left in the view.);
(3)..VRELO "OKO", with its very short surface streamway joining the main flow of the Trebišnjica on its left side at the 1st bend of its surface course and now seen with its large exit gulley, (in the centre-left of the view);
as a matter of further interest, the red-roofed building opposite the Vrelo "Oko" outlet is the Hotel "Trebišnjica"; The building to the right and below the Hotel is another pumping station built around the 1930's by Yugoslav Railways.
(4)..VRELO "NIKŠIČKO", with its short surface streamway joining the main flow of the Trebišnjica on its left side at the 2nd bend of its surface course, (in the centre-right of the view).
prominent near the exit is the TOMANOVIĆA MLIN, belonging to Andrija Tomanović.
Many of the buildings seen in Photo FP2.3.3-1. above can also be seen in this view. Additionally, we can see a small white building (water pumping station) on one of the rough roads high above the resurgence pool and the Mills, (in the centre-left of the view).
This road and building are important positional-locators in the modern views of this area which show it to be now mostly submerged. This pumping station was built in 1960.
(The absolute date for the photograph is unknown, although it was taken considerably later than Photo FP2.3.3-1. above.)
.
Photo FP2.3.3-4. (above-right)...An archive colour image indicating a more detailed side view of the area of the rise-pit or resurgence pool of the
now submerged VRELA "BILEĆKA" (incl. Dejanova Pećina) and the immediate downstream section of the Trebišnjica River.
Note that the roofs on the SALATIĆA MLIN and other buildings on the right bank, have gone and that they are now derelict. Opposite this, the POPARA MLIN on the left bank seems to be still intact.
The very short canalized streambed of KOSTOVA PEĆINA beside the main resurgence pool on the left bank seems to contain water in this view.
(The absolute date for the photograph is unknown, although it seems to be approximately contemporary with Photo FP2.3.3-3. above.)


Photo FP2.3.3-5.  (above-left)...An archive colour image indicating a more detailed side view of the area of the rise-pit or resurgence pool of the
now submerged VRELA "BILEĆKA" (the gaping entrance of Dejanova Pećina is in the bottom-right corner) and the immediate downstream section of the Trebišnjica River.
Note that the roofs on most of the visible buildings, have gone and that they are now derelict.
The very short canalized streambed of KOSTOVA PEĆINA beside the main resurgence pool on the left bank seems to contain water in this view.
(The absolute date for the photograph is unknown, although we think it was recorded in the 1960's.)

Photo FP2.3.3-6.  (above-right)....An archive monochrome view of the Karst River Trebišnjica beside the village of Dobrićevo, now submerged below Bilećko Jezero.
The monastery of Dobrićevo can clearly be seen in the centre-left of the view.
(The absolute date for the photograph is unknown.)


Photo FP2.3.3-7.  A modern view of the area indicated in Photo FP2.3.3-3. above, now mostly submerged below Bilećko Jezero.
The view is a photomontage, digitally combining three separate images. Note the position of the two, small white buildings on the rough road, (centre-right).
The smaller of the two on the left is the one formerly indicated in Photo FP2.3.3-3. above
(Photo :  B. Lewarne, 22 July 2004.)

Originally, 3.25 km downstream of the spring-source was the confluence with the smaller Karst Stream Čepelica, which thereafter, periodically adds considerably to the surface flow of the Trebišnjica. The local topographical name for the point of confluence of the Rivers Trebišnjica and Čepelica is "MISTIALj".
The Trebišnjica River Spring-group consists of the main karst hydrological features :

..........Established Underground Flowline Data with the Ponor "Pasmica" in Fatničko Polje :

 
a)..Date of Test  =  01 January 1955.
Method  =  Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =  Inundated 2.20 m. water
Water Velocity (sink to rising)  = 7.42 cm sec -¹.
Connection  =  with Vrelo Trebišnjica at Bileća.
No. of Observation Points  =
Quantity of Tracer  = 56 kg.
c)..Date of Test  =  27 November 1958.
Method  =  Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =  Inundated 9.22 m. water
Water Velocity (sink to rising)  = 14.1 cm sec -¹.
Connection  = with Trebišnjica / Čepelica Karst Springs at Bileća.
No. of Observation Points  =  25.
Quantity of Tracer  = 150 kg.
b)..Date of Test  =  27 November 1958.
Method  =  Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =
Water Velocity (sink to rising)  = 7.42 cm sec -¹.
Connection  =  with Trebišnjica Karst Spring at Bileća.
No. of Observation Points  =
Quantity of Tracer  =
d)..Date of Test  = 1959.
Method =  Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =  Inundated 9.56 m. water.
Water Velocity (sink to rising)  = 10.9 cm sec -¹.
Connection  = with Trebišnjica / Čepelica Karst Springs at Bileća.
No. of Observation Points  =
Quantity of Tracer  = 117 kg.


2.3.4.    The Čepelica Stream Spring-group  /  Vrela Rijeke Čepelice :
This Karst Spring-group is the direct source of the periodic Karst Stream Čepelica, which formerly had a surface flow distance of only 2 km before joining the surface flow of the Karst River Trebišnjica. We do not yet have any photographs of the area containing the source springs. From the details on the Austro-Hungarian Map below, we can see that at that time there were at least two water mills in use along the watercourse. We do have images of the Karst Stream Čepelica at two locations upstream of its confluence with the Karst River Trebišnjica.
To portray this very interesting karst location, we start with a Military Map from the period of late Austro-Hungarian Administration (1912) of Bosnia & Herzegovina, showing topographic details of the Čepelica area.


Map 2.3.4.M1....FESTUNGS-UMGEBUNGSPLAN von BILEĆA. (Zusammengestellt aus Kopien der Militäraufnahmssektionen.)..Ausgabe 1912. Blatt 3.
[Translation :  Fortresses and Surrounding Environs near Bileća. (Composed from Copies of the Military Surveys Section.) Edition 1912. Sheet 3....Scale :  1 : 25 000. [1 red square on the map = 1 km².]
Note the road bridge on the map crossing the Čepelica River, as seen in the Photograph FP2.3.4-1. immediately below. The road bridge is also indicated on the 1908 Map.
All such Austro-Hungarian Bridges were allocated a unique "Infrastructure Reference No.", which was embedded as a steel casting in the structure. In this particular case, we do not yet know the number.


Photo FP2.3.4-1. (above-left)...Most u selu Podgradina.  /  The Bridge of Podgradina Village.
An archive monochrome image indicating the Čepelica River passing beneath the Podgradina Road Bridge.
The Road Bridge is of Austro-Hungarian design and construction and carried the main road from Cavtat on the Dalmation Coast to Istanbul and from the Map above, is at an elevation of 333m. asl.
Unfortunately, we cannot yet provide the Austro-Hungarian Road-Bridge Military Survey Number given to this Bridge.
The river appears to be in low-flow conditions. The location is upstream of the confluence with the River Trebišnjica.  The road, its bridge and the village are now submerged below Bilećko Jezero.
(The absolute date for the photograph is unknown.)

Photo FP2.3.4-2. (above-right)...Čepelica - Luke. /  Čepelica - the "Bay".
An archive monochrome image indicating the Čepelica River at the point of Luke or the "Bay", where boats could moor, upstream of its confluence with the Karst River Trebišnjica. The area is now submerged below Bilećko Jezero.
(The absolute date for the photograph is unknown.)

The Čepelica Spring-group consists of the main karst hydrological features;

..........a)  VRELO "ČEPO" :
..........-  It has 3 outlets located at a geological overthrust fault and all of which have a direct connection to the Ponor "Pasmica" in Fatničko Polje, a straight-line surface distance of 17.2 km. This cave entrance is of a large diameter.

..........Established Underground Flowline Data with the Ponor "Pasmica" in Fatničko Polje :

 
a)..Date of Test  =  27 November 1958.
Method  =  Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =  Inundated 9.22 m. water.
Water Velocity (sink to rising)  = 14.1 cm sec -¹.
Connection  = with Trebišnjica / Čepelica Karst Springs at Bileća.
No. of Observation Points  =  25.
Quantity of Tracer  = 150 kg.
b) Date of Test  = 1959.
Method  = Na-fluorescein.
"Pasmica" Ponor Condition in Fatničko Polje  =  Inundated 9.56 m. water.
Water Velocity (sink to rising)  = 10.9 cm sec -¹.
Connection  = with Trebišnjica / Čepelica Karst Springs at Bileća.
No. of Observation Points  =
Quantity of Tracer  = 117 kg.
..........b)  PONORS and SPRINGS ON THE LEFT SIDE OF THE ČEPELICA STREAMBED :
..........-  (Details to follow in due course).

2.3.5.    Post-1967 -  Monitored Effects during and after the Submersion of the Trebišnjica  /  Čepelica Spring-groups beneath the Artificial Bilećko Jezero :
The HET Co. Bileća Lake (Bilećko Jezero) is an artificial reservoir. The initial filling of the reservoir was begun on 21 August 1967 after the completion of the construction of the 123 m. (403.5 feet) high hydro-electric Grančarevo Dam. The impounded water has an effective elevation Hmax of 400.09 m.asl. (1313 feet), creating a maximum surface area of 27.6 km2 and containing a maximum impounded volume of 1.3 billion m3..of water. Milanović states that there is evidence that this impoundment creates an additional underground storage volume, estimated to be about 15% the volume of the surface reservoir, ie. 1.3 x 109 m3 water, contained in the caverns, fissures and conduit aquifers of the karstified limestone between Bileća and Fatničko Polje.
During the formation of the artificial lake and the drowning of the two karst spring-groups, hydrological observations via borehole piezometers in the area behind the Trebišnjica River Spring-group below Bileća indicated the existence of an underground accumulation of water, whose volume was estimated to be about 15% of the volume of the surface accumulation.
The flooding of the Miruše area has had several permanent effects on the hydrological functionality of Fatničko Polje :-
..........-  When the level of the Bilećko Jezero is below 360 m.asl. (1181 feet), the natural karst hydrological régime operates.
..........-  When the level of the Bilećko Jezero is between 360-370 m.asl. (1181-1214 feet), the influence of the Lake is observed only in the hydrology of the immediate background area of the Trebišnjica River Spring-group below Bileća.
..........-..When the level of the Bilećko Jezero is above 370 m.asl. (1214 feet), it affects the hydrology of the more distant background as far away as Fatničko Polje and Plana. The observed effect is that the rate of the rise of maximum flooding levels in Fatničko Polje is altered, because the difference in elevation between the

Ponor "Pasmica", the principal outlet for the water in Fatničko Polje, and the Trebišnjica River Spring-group below Bileća decreases from 130 m. (427 feet) to 64 m. (210 feet).
..........-  When the level of the Bilećko Jezero is at 400 m.asl. (1312 feet), and the inflow to the Lake is  >125 m3 sec -1  the level is maintained.
..........-  The critical inflow at the Bilećko Jezero level of 397 m.asl. (1302 feet) needed to overflow it is 220 m3 sec -1.
..........-  A new karst-water outflow point has formed at a level of 363 m.asl. (1191 feet) in the vicinity of the Dejanova Pećina, due to the unblocking of old and previously inactive underground karst canals.
..........-  The effective elevation Hmax of 400.00 m.asl. (1312 feet) of the Bilećko Jezero is at the same elevation as the level beneath Fatničko Polje at which the bifurcation of its hydrology is initiated and water loss begins to take place in the direction of the Bregava Springs.
(We should perhaps be grateful that at least this self limitation has been designed into the hydro-electric infrastructure!)
Some of this data is used by the HET Company in controlling the balance between maintaining the throughflow of water whilst generating electricity.

In general and on average, it has been reported that the creation of the Bilećko Jezero has reduced the height of the flooding in Fatničko Polje by 1.8 metres, although it has increased the length of time of the flooding events.
At maximum water-level (when this is coincident with heavy atmospheric precipitation), the Bilećko Jezero has also created new karst spring sources in the area known as "Bilećko Polje". This is the shallow basin area to the north of the town centre of Bileća, at a mean elevation of 430 m.asl (1476 feet).
By definition of the term, it is not a true "karst polje", even though it is often referred to as such in the literature. The Bileća area is not dealt with here in the Fatničko Polje webpages.

In connection with our investigative research currently being undertaken in Estavela "Obod" in Fatničko Polje, it has become apparent that the low-water levels prevalent in the dry season in the early 1960's before the drowning or submersion of the Local Base Level of Erosion outlet springs, can no longer be observed.
This is borne out by comparing the 1960's cave survey of the accessible vadose cave passage at the bottom of the Estavela "Obod" 1st Underground Vertical, with what can be observed now at low-water level. This short section of previously accessible Vadose Master Cave is also now permanently under water.
(Please refer to the details given in Section 8. of the Fatničko Polje webpages.)

The actual prevailing water-level of the Bilećko Jezero can be obtained from the water-measuring station at the Grančarevo Facility or from the HET Company Offices in Trebinje.


Photo FP2.3.5-1.  A view of the modern Topographic Map showing the Submerged area of the Trebišnjica  /  Čepelica
Spring-groups and their confluence with the Karst River Trebišnjica, now beneath the artificial Bilećko Jezero.
(This was recorded from the 1 : 50 000 scale maps produced by Yugoslavia.)

2.4.    KARST WATER QUALITY IN FATNIČKO POLJE :
2.4.1.    Introduction :
Our principal interests in monitoring the water quality at all hydrologically-active locations in the polje, are equally to assess the karst process itself and to assess each site for its suitability as a habitat. It is also necessary to monitor water contamination levels and to pin-point their sources. The hydrophysico-chemical parameters and characteristics that we are interested in, have been defined, as have those for micro-biological and bacteriological parameters. Procedures and methodology for verifying sightings of existing cave and karst fauna by direct observation and their appropriate simultaneous recording have been agreed and implemented.

The water quality at all locations in the polje will vary greatly with time and as a result of the prevailing human-impact and of short and long-term changes and fluctuations in the natural environment.
The Fatničko Polje Karst Water Quality Database and Species Sightings Records will be the receptacle for our recorded observations only in this polje and is undertaken within the remit of the separate Principal sub-Project No. 2. ["Speleological Investigation of Fatničko Polje"] of the Main BiH Project :-

Project No. 3.  [SDZB-DKRS-JI / BiH / H / SLO / UK / 140800PTPH ].
"A Joint Strategy for the Protection of the Proteus anguinus and its Natural Karst Habitat in the Trebišnjica River Valley."
"Zajednička strategija zaštite u podzemnog endema Čovječje Ribice (Proteus anguinus) i njezinog prirodnog krškog staništa u dolini rijeke Trebišnjice."
"Заједничка стратегија заштите у подземног ендема Човјечије Рибице (Proteus anguinus) и њезиног природног кршког станишта у долини ријеке Требишњице."

(NB. It should be noted that, as a permanent feature, a separate Database will be the receptacle for our recorded observations in all other geographical areas of the Main BiH Project No. 3.)

2.4.2.    Overview of the Chemical, Physical and Biological Parameters and Analytical Procedures :
The paragraphs below give an insight into the karst water sampling philosophy and our general approach to physico-chemical, chemical, biological and micro-biological analysis to yield the most accurate, reliable and repeatable results. We have removed the previously incomplete details referring to actual chemical analytical procedures, which are now in a completed and greatly expanded form. Although this information has been relocated into the Technical Support Pages for Project workers in the pages of the Main Project, it is also available as MS Word v.7. documents in A4 format, via Links with unrestricted access located near the bottom of this Page.
..........2.4.2.1....General Principle of Karst Water Sampling Procedures and Notes :
.......... Insofar as aqueous carbonate / hydrogen carbonate chemistry is inherently unstable, all physico-chemical parameters relating to this chemistry are determined in situ at the sampling site, whether underground or not, and are most definitely not sampled and transferred in containers to a laboratory site for chemical analysis at a later time.
..........-  Insofar as cleaning the electronic instrument electrodes are concerned, these should only be rinsed in de-ionized water. Distilled water is not a suitable alternative.

In situ or dynamic analysis is therefore undertaken for the following determinants :-
..........pH,  Eh,  Dissolved O2,  Total Hardness, Calcium Hardness, Magnesium Hardness, Hardness Saturation Level (with respect to calcium carbonate), sample Temperature,  ambient Temperature,  Electrical Conductivity,  and Total Dissolved Solids.
The results arising from such analyses are referred to as the dynamic pH and the dynamic Eh  etc., as opposed to results taken from static samples which have been collected, taken away from the site and analysed at a later time.

..........2.4.2.2....The Physico-chemical Determinants and Analytical Procedures :
The following is a list of the determinants which we have begun monitoring in 2002 and the hydrological years beyond, in what was an interim approach both to the short-term plan of karst water analysis in the polje and to the long-term plan for similar monitoring of all Proteus anguinus Habitat Locations in the Trebišnjica Karst River Catchments. This flexible type of approach has already allowed us to develop and establish a suitable and relevant permanent monitoring régime, enabling us to begin developing a Data Series for all Proteus anguinus Habitat Locations for at least the 30 year period of the life of the Project.
.
...........  dynamic pH  /  dinamic pH  (0.00 -14.00)
.............direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Glass Electrode and Temperature Probe and with Temperature Compensating Device set at automatic for 25 º C.
...........  dynamic Electrical Conductivity  /  dinamic Električna Provodljivost  (µS / cm.) direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Conductivity Probe and Temperature Probe.
...........  dynamic Total Dissolved Solids  /  dinamic Količina rastvorene materije  (mg / litre)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with TDS Probe and Temperature Probe.
...........  dynamic Eh Redox Potential  /   (mV)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Eh Probe and Temperature Probe.
...........  sample Temperature /  Temperatura vode  ( º Celsius)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Temperature Probe.
...........  ambient Temperature  /  Temperatura vazduha  ( º Celsius)  direct method using a Palintest PT146 Electronic Waterproof 800 Microcomputer with Temperature Probe.
...........  dynamic Dissolved Oxygen  /  Kiseonik  (mg / litre)  direct method using a Palintest PT148 Dissolved Oxygen Meter and Temperature Probe.
...........  dynamic Turbidity  /   (NTU)  direct method using Palintest Micro 900 Turbidimeter.  (not yet undertaken)
.
...........  dynamic Calcium Hardness  /  dinamic Kalcijum Tvrdoca  (as mg / litre calcium carbonate) direct method by EDTA Titrimetric Complexometry.
...........  dynamic Magnesium Hardness  /  dinamic Magnezijum Tvrdoca  (as mg / litre calcium carbonate)  direct method by EDTA Titrimetric Complexometry or through calculation "by difference".
...........  dynamic Total Hardness  /  dinamic Ukupna Tvrdoca (as mg / litre calcium carbonate) direct method by EDTA Titrimetric Complexometry.
...........  dynamic Carbonate Under-  or Super-Saturation Level  / dinamic Zasićenost  (as mg / litre calcium carbonate)  direct method by EDTA Titrimetric Complexometry.
.
........... .total Copper  /  Ukupna Bakar  (mg / litre Cu)  direct method by Palintest tablet count.
...........  Chlorides  /  Hloridi  (mg / litre Chloride)  direct method by Palintest tablet count.
...........  Nitrates  /  Nitrati  (mg / litre Nitrate)  direct method by Palintest tablet count.
...........  Phosphates  /  Fosfati  (mg / litre Phosphate)  direct method by Palintest tablet count.
...........  Sulphates  /  Sulfati  (mg / litre Sulphate)  direct method by Palintest tablet count.
...........  Ammonia  /  Ammonijak  (mg / litre Ammonia)  direct method by Nutrafin reagent drop count test.
...........  Iron  /  Gvožde  (mg / litre Iron)  direct method by Nutrafin reagent drop count test.

Additional qualitative values will be added to the list above as of August 2009.

..........2.4.2.3....EDTA Complexometric Titrimetric Determination of Calcium, Magnesium and Total Hardness and the Determination of the Carbonate-saturation value :
There are standard procedures for determining the above parameters and which can be reliably employed underground by appropriately trained personnel for in situ analysis. The analytical procedures detailed below have been reliably used in the Devon Karst Research Society's "UK Karst Hydrological Programme" since 1976.

The sampling procedures and chemical analytical methodologies were agreed upon and the relevant training of the Project's Research Assistants was completed during 2003. Revision training is undertaken annually during at least one of the Society's visits. All materials resourcing has been achieved.
The initial, interim methodologies using Palintest Tablet Count procedures are now reserved for non-carbonate determinations and it is to be hoped that they will be replaced in due course with more accurate methods.

more to follow


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