|CERNIČKO POLJE - ЦЕРНИЧКО ПОЉЕ||
The Devon Karst Research Society.
The Karstography of the DINARIC KARST IN BOSNIA AND HERZEGOVINA
Part 5.3. Eastern Herzegovina.
CERNIČKO POLJE - ЦЕРНИЧКО ПОЉЕ
Cernica Polje, BiH-RS Trebinje Region - Gacko Municipality.
Updated 13 November 2006.
ESTABLISHED UNDERGROUND FLOWLINE DATA
ПОДЗЕМНЕ ВОДНЕ ВЕЗЕ
PODZEMNE VODNE VEZE
HIDROLOGIJA i HIDROGEOLOGIJA KARSTA - ХИДРОЛОГИЈА и ХИДРОГЕОЛОГИЈА КАРСТА :
2.1...HISTORICAL NOTES :
1...The Austro-Hungarian Monarchy karst engineer Philipp Ballif, (1896)*, gives us an appraisal of the karst hydrology of Cerničko Polje at the time of his extensive karst melioration works in the nearby area of Gatačko Polje :-
....."Water Supply :..Through springs, the Stepen Brook and moreover, through the Vilić Pećina in the northwest edge of the basin, at the base of a precipitous cliff, and which probably connects with the ponors draining the Mušnica River.
......Drainage :..Through Ponors, in which both the Stepen and Jasovica Brooks are also swallowed.
......Degree and Duration of Inundation : In the east part of the polje, by the Stepen Brook, though most part inundated annually, this is only for a shorter duration than the one in the west part by Zagradci; there, the impact of the Vilić Pećina from the second half of October through to the middle of April causes the same situation, when the great amount of water coming out of it flows into the great ponor by Zagradci until it can no longer absorb the water, at which time the whole polje then becomes flooded."
Hungarian intellectual Asbóth, János, wrote the following
about Cerničko Polje in
his travels through "Bosznia és a Hercegovina" during 1884*
[Other webpages in this Series deal with the detailed description of individual karst features mentioned in the text below.]
From our current perspective, we can state that the two historical notes above indicate great accuracy in reporting some of the karst hydrodynamics of this strange karst polje. In the dry summer months, the casual visitor would have no indication of the situation that occurs in the very wet winter months. All would be calm, peaceful and for the most part, dry! There would be no indication of the immense karst hydrological chaos that exists here in the height of the wet winter period.
Let us examine the situation step by step and thus, understand the mechanisms controlling where all the water comes from, how, where and why it appears in such a dramatic way and then, where it goes after leaving Cerničko Polje :-
At an elevation of between 810 m - 850 m asl., Cerničko Polje is located
at an intermediate level between Gatačko Polje (882 - 950 m. asl.) and
Fatničko Polje (460 - 480 m. asl.).
[Summarizing so far, we have a long but narrow low-lying basin of non-karstic, impermeable rock (Eocene Flysch), forming the polje-floor of Cerničko Polje, which is bounded all around by mountainous karstified limestone facies. Please refer to the Hydrogeological schema below, which illustrates a Plan View and Cross Section of this scenario.]
Sandwiched between karstified mountain massifs, the non-karstic, impermeable
Eocene Flysch, therefore, forms a locally important hydrogeological barrier
The output of the combined flow of Vrelo and Izvor "Vilina Pećina" into the Central depression of Cerničko Polje is about 50 m³ sec¹. The absorption capacity of the Ponor "Ključka Rijeka" is only about 20 m³ sec¹. For this reason, an intermittent lake appears in the Central depression which back-flows in an easterly direction into the Eastern Section of Cerničko Polje, where another intermittent lake is then created. The connection point between the Central and Eastern Sections of the Polje is illustrated in Section 1. of this series of webpages. It takes the form of a small karst canyon, the origin and functionality of which would be completely obscure, unless seen in the very wet winter months!
Karst hydrological activity in the Eastern Section of Cerničko Polje is less dramatic but, nonetheless, very interesting. Here are groups of ponors centred around the two principle ones of Jasovica Ponor and Šukovići Ponor. Both these ponor groups have a limited absorption capacity. Currently, we have been unable to visit these ponor areas due to the adverse environmental conditions prevailing during our reconnaisance of the polje.
2.2...ESTABLISHED UNDERGROUND FLOWLINE DATA - ПОДЗЕМНЕ ВОДНЕ ВЕЗЕ - PODZEMNE VODNE VEZE :
"KLJUČKA RIJEKA" PONOR ("Key River" Ponor) - PONOR "KLJUČKA
RIJEKA" - ПОНОР "КЉУЧКА РИЈЕКА" :
a Paper given by Borislav Petrović during the Treći
Jugoslavenski Speleološki Kongres (1962), this dye test was cited
as having fast underground connections with "Izvorište Trebiišnjice"
(Trebišnjica Springs) and to a marginally lesser degree with Estavela
"Obod" in Fatničko Polje. This latter point, if correct, would indicate
that Estavela "Obod" may not be a principal outlet but probably an overflow
off one side of the master karst conduit aquifer between Gatačko / Cerničko
Polja and the main outlet at the Trebišnjica Springs. This insight into
the karst hydrology of the area may prove to be valuable to us in our investigations.
"JASOVICA" PONOR - PONOR "JASOVICA" - ПОНОР
"ŠUKOVIĆI" PONOR - PONOR "ŠUKOVIĆI" - ПОНОР
after P.T. Milanović.
/ LEGEND :
Much of the geological information about what lies below the polje-floor was recovered from borehole data and geophysical surveying.
Polje - Церничко Поље
There is much Hydrometric Infrastructure around the Ponor complex in the Central Vrtača. For practical reasons, it was found to be easier to measure the ponor-input rate rather the individual yield of Vrelo and Izvor Vilina Pećina. The Hydrometric Infrastructure consists, firstly, of a gigantic concrete weir across the ponor-approach canyon, through and over which the entire flow of the Ključka Rijeka has to pass until the ponor becomes inundated. Secondly, there is a whole series of water-level guages rising up the southern perimeter wall of the polje from near the position of the weir in the ponor-approach canyon. Of course, the water-level indicator guages can tell nothing about flow-rates but can indicate when the level is reached whereby the backflow or overflow commences from the Central Doline or depression into the Eastern Section of the Polje.
We currently have no information about the possible presence of hydrometric infrastructure at the principal ponors in the Eastern Section of the polje.
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