Remarkable Surviving 
Objects of Hercegovinan
Cultural & Karst 
Agro-Industrial Heritage
The Devon Karst Research Society.

BOSNIA & HERCEGOVINA  -  Principal Sub-Project No. 1.  [DKRS-J I / BiH-RS / H / 120800DPMPP.]
"The Karst Ponor-mills at Dobromani, Popovo Polje, Eastern Hercegovina, Bosnia & Hercegovina."
"Kraška Ponor-mlinovi kod Dobromana, Popovo Polje, Istočna Hercegovina, Bosna i Hercegovina."
"Крашка Понор-млинови код Добромана, Попово Поље, Источна Херцеговина, Босна и Херцеговина."

Details of the last Fully Operational Ponor Mill in Eastern Hercegovina
at Pridvorci in Trebinjsko Polje.

updated 09 May 2016.

Locational Details

The approach to the Ponor Mills 
from the south-east.

The  south end elevation of the 
Bračkovića Ponor Mill, with the
Ćatovića Mill behind.


Trebinjsko Polje forms the natural upstream continuation of Popovo Polje with which it is contiguous from the area east of Lug and Šuma. Trebinjsko Polje is where the Karst River Trebišnjica widens and where, in places, it is not contained or confined in an artificial concrete streambed. 
It is here that, flowing almost due west from the direction of Gorica in the east, the river courses past Crkvina on its left side and the district of Gradina on its right side, then beneath the relocated Arslanagića Most, to reach Blace, where the flow suddenly turns a sharp bend to the left, to continue southwards past the distict of Krš. It then continues southward through the town centre of Trebinje and beneath its two road bridges to reach the district of Bregovi on its right bank. The karst river then takes a final abrupt change in direction to the right whilst simultaneously diverging into three separate stream channels, each of which after some minor meandering, flows generally westwards. This divergence of the streambed has caused the formation of many mid-stream islets. The most southerly of these three river channels from the point of divergence, independently continues southwards before it too turns west and heads for the rural village of Pridvorci, just downstream of which all three river channels re-converge into a single channel again. From here the river then heads in a generally westerly direction towards Trebinjska Šuma before preparing to meet its fomidable subterranean fate in Popovo Polje. 

It is to the village of Pridvorci that our attention will now be diverted and our interest focussed.

Situated about 3 km downstream of the centre of Trebinje, this generally unremarkable little village houses an absolute gem of a karst hydro-engineering relic, representing a valuable if  not unique piece of cultural heritage.
Sat quite squat or low down beside the left bank of the most southerly channel of the karst River Trebišnjica are two twin-turbine Karst Ponor Mills. Both Ponor Mills are located within the same Limestone Coffer Dam or containment structure but have independent water supply inlets from the adjacent Trebišnjica River. The Karst Ponor Mills are known as the BRAČKOVIĆA MLIN and the ĆATOVIĆA MLIN, as named after the principal builders, Messrs. Bračković and Ćatović respectively. They were constructed on top of the Pridvorci Karst Ponor Zone. 
A few metres to the west of the Ponor Mills, a low-quality concrete bridge stucture takes a very small local road from the village on the left (south) bank of the river across the Trebišnjica to the fertile agricultural area on the large island opposite. The bridge features in a local legend, to which we shall return later. We shall now deal with each of the two Ponor Mills in turn, by detailing something of their structure, condition and operation through the use of text and still and moving images.

To make the task easier, we recommend that our browsers read the pages detailing the function, purpose, design, engineering and operation principals of ponor mills, as given in the Sections dealing with the Dobromani Ponor Mills, before continuing with this particular page.

to DPP.APP1.3.11.  (Above) 
The Ponor Mills seen from the approach
road to the south east.
(Photos :  Bogdan Prelević, 03 October 2001.)

Age of construction :
Builders :
Owners :
Function & Production rates :
Condition :



















IMAGES DPP.APP1.3.12. to  DPP.APP1.3.29.  (Above) 
A series of sequential images illustrating
the operation of the Mill and ground flour 
production at the west unit of the
Bračkovića Mill, Pridvorci, culminating in
its transportation by traditional horse and cart!
The images also indicate the position of the redundant west unit in the floor of the Mill.
Also indicated above is the position in the
floor of the wooden planks covering the
access passage leading down to the Turbine Chambers under the Millstones.
(Photos :  Bogdan Prelević, 
03 October 2001.)


IMAGE DPP.APP1.3.1. (above-left).  The Pridvorci Ponor Mills.  (Photo :  Bogdan Prelević, 04 March 2002.)
The Ponor Mill on the left with the modern red-tiled roof is the Bračkovića Mlin; the Ponor Mill to the right is the Ćatovića Mlin. The small concrete bridge referred to in the text above can be seen in the extreme left, top corner of the view, above the Trebišnjica River.
The town of Trebinje can be seen in the far distance on the other side of the karst polje.

IMAGE DPP.APP1.3.2. (above-right).   Bračkovića Mlin, Pridvorci.  (Photo :  Bogdan Prelević, 04 March 2002.)
A view of the west and north external elevations of the ponor mill. The figure is standing on the limestone Coffer Dam encircling the Mills. The water intake orifice and water-gate or penstock are located below and to the left of the figure.

We have spoken with the users of the Ponor Mill and have discovered that it was constructed by the Bračković family about 200 years ago at the turn of the 18th / 19th century, during the period of Ottoman Administration of Bosnia & Hercegovina. The Ponor Mills are massively constructed on solid bedrock consisting of Upper Cretaceous Limestone and straddle the mouth of the ponor caves below. The natural elevation of the ponor zone is 273 m. (896 ft.) asl. 
The other families who helped finance its construction and who still maintain a controlling interest in its operation are (in aphabetical order) :-

This Mill is a twin turbine unit, although at the time of our visits in 2001-2002, only its west turbine unit was functional and actually in use. Using the natural kinetic power of water from the River Trebišnjica as it flows down into the karst ponors under gravity, the hydro-power generated by the falling water was originally able to sustain the operation of two turbines in this Mill, keeping two sets of mill-stones turning to grind flour in an impressive non-stop process after the harvesting of the 100-day Popovo Polje Wheat grain.
The weekly production from each Millstone was 1½ tons of flour. We are told that it took 64 horses each day to take away the combined ground flour produced from all the four Millstones in both Mills at Pridvorci. Flour production was undertaken by the individuals responsible for growing the grain in a tight schedule, whereby each turbine was kept turning day and night, with a minimum of "down-time" between the brief changeover of those using the Mill. Those days are gone. In the very beginning of the 21st Century, only a few individuals continue to require the grinding of their grain by the traditional method and only one or two of these continue to transport their unprocessed grain and the resultant flour production by horse and cart.

The Bračkovića Mlin has had repairs undertaken to its external structure, to keep it in good order. The original roof construction of thin limestone slab tiles has been replaced with the red terracotta tiles of more modern times. Additionally, the original and mainly wooden turbine of the west unit has been replaced with one of a metal construction. The original wooden Turbine and the Turbine Shaft or Spindle now stand against a wall inside the millstone chamber. The original wooden Water Shute leading the water in from the Trebišnjica direct to the turbine, has also been replaced with a metal one.

The Ponor Mill is now in poor condition and has been out of use since 2012.  It requires a small financial investment to restore its mechanism. 

IMAGE DPP.APP1.3.3.   Bračkovića Mlin, Pridvorci.     (Photo :  Bogdan Prelević, 03 October 2001.)
A view of the water-intake channel feeding water onto the metal turbine beneath the millstone chamber.
Also visible is the bedrock limestone wall of the ponor mouth on the right-hand side of the view. 
This physical inspection is being undertaken by Members of the Speleološko društvo "Zelena Brda" of Trebinje.

IMAGE DPP.APP1.3.4.  (above-left). Bračkovića Mlin, Pridvorci.    (Photo :  Bogdan Prelević, 03 October 2001.)
A view of one of the original wooden turbines, with its turbine drive-shaft leaning against the other wall behind it.

IMAGE DPP.APP1.3.5. (above-right). Bračkovića Mlin, Pridvorci.    (Photo :  Bogdan Prelević, 03 October 2001.)
A view of the underside of the roof structure and its condition.

IMAGE DPP.APP1.3.6. (above-left). Bračkovića Mlin, Pridvorci. (Photo :  Bogdan Prelević, 03 October 2001.)
A view of the 3 boards covering the access hatch leading down to the Turbine Chambers beneath the Milling Chamber. Also of note here is the millstone in the floor, adjacent to the hatch and belonging to the redundant east unit.

IMAGE DPP.APP1.3.7. (above-right). Bračkovića Mlin, Pridvorci. (Photo :  Bogdan Prelević, 03 October 2001.)
A view looking down under the access hatch into the passage with its short ladder, leading into the Turbine Chambers.

IMAGE DPP.APP1.3.8. (above-left).  Bračkovića Mlin, Pridvorci. (Photo :  Bogdan Prelević, 03 October 2001.)
A view looking at the external arrangement of the water-input channel and the elements of its sluice gate or penstock.  This feeds water directly to the Turbine in the Turbine Chamber below the Milling Floor area.
The Water Gate / Sluice Gate / Penstock is operated manually.  The Controls for the Turbine (gears, brake and lock) are all situated beside the Millstone Area.  Ultimately, it is the amount of water allowed to enter
the Mill through the Water Gate, by raising or lowering the Sluice, that determines how much power is available for subsequent control at the Millstone.

IMAGE DPP.APP1.3.9. (above-right). Bračkovića Mlin, Pridvorci.  (Photo :  B. Lewarne, 04 March 2002.)
A view of the water-intake channel, partly submerged by the Trebišnjica River.

Age of construction :
Builders :
Condition :
The users of the Bračkovića Ponor Mill have informed us that it was constructed by the Ćatović family about 210 years ago at the turn of the 18th / 19th century, during the period of Ottoman Administration. The original roof construction of thin limestone slab tiles collapsed inwards in 2014. The general structural integrity of the building is poor as can be seen in the images below, where the entire corner of the structure to the left of the entrance doorway, is parting company from the rest of the building. This is because the mill is constructed on a large unconsolidated boulder choke filling the surface area of the natural ponor mouth.
We currently have no other general or operational information about this Ponor Mill.

IMAGE DPP.APP1.4.1. (above-left).  Ćatovića Mlin, Pridvorci. (Photo :  Bogdan Prelević, 03 October 2001.)
A view of the Ponor Mill main doorway in the south-facing end elevation. Behind it is the Bračkovića Mlin with its open doorway.

IMAGE DPP.APP1.4.2. (above-right).  Ćatovića Mlin, Pridvorci. (Photo :  Bogdan Prelević, 03 October 2001.)
A view of the Ponor Mill west elevation as seen in the yard between the two buildings. The serious cracking of the corner of the Ćatovića Mill behind the juvenile standing on the right, can be clearly seen.

More images of this Ponor Mill will be acquired in due course.

Future Preservation APP1.5.   The Uncertain Future for these Remarkable Objects of Hercegovinan Cultural & Karst Agro-Industrial Heritage :
The future of these Mills is perhaps foretold by the almost derelict present condition of the ĆATOVIĆA MLIN. The users of the BRAČKOVIĆA MLIN told us that there are now very few people who require the use of the Mill and that in a few years' time it will cease operations. Sadly, this has now happened.
The future preservation and conservation of this unique heritage lies perhaps in the hands of the Tourist Industry and perhaps with Educational Karst Tourism.
The Ponor Caves APP1.6.   The PRIDVORCI  PONOR CAVES :
Not much is presently known about the Pridvorci Ponor Caves. A view of the ponor cave mouth below the west millstone of the Bračkovića Mill can be seen in Image DPP.APP1.3.4. above.
We are told by the local inhabitants that the central concrete support pillar of the nearby bridge fell into the floor of the river bed many years ago. This was interpreted as being the collapse of a cave roof into a large cavity below the riverbed. Such an occurence is not to be unexpected in a ponor zone. However, we have no way of verifying the claim.

The water entering the ponor caves has been dye tested under low water conditions to the giant Ombla Karst Spring near Dubrovnik and under high water conditions, when it appears additionally at Vrelo Zavrelje, both situated near sea level in the Dalmatian Littoral Karst, a straight-line distance of km (miles).

Further underground investigations into the ponor caves will be undertaken as soon as time permits.

Feature Film APP1.7.   Film Recording of the Pridvorci Ponor Mills and the Bračkovića Ponor Mill in Full Operation :
© 2004 Speleološko društvo "Zelena Brda", Trebinje, RS-BiH.
Please note that the Film is Copyright and is not for commercial use without the written permission of the copyright owners.

We have fortunately taken a film recording of the Pridvorci Ponor Mills, including the operation of the BRAČKOVIĆA MILL. This Long Sequence Digital Video Feature Film is currently being rendered in readiness for web-publishing. It will be available soon, together with a guide and explanation of the details.

Click on the Link below to view the

Pridvorci Ponor Mills with the Bračkovića Ponor Mill in Full Operation
             (Inactive, colour & monochrome / video streaming file / duration = ??minutes / MB.)

In general terms, the film will indicate the use of each element of the Ponor Mill above the level of the Turbine Chamber during a normal flour-production operation. Importantly, the Film shows minor but very important elements of the design and engineering aspects of the infrastructure controlling the feed-input of unprocessed grain into the Millstones, which ensure the essential smooth and efficient operation of the whole process, but which are not apparent from looking at any of the derelict Ponor Mills in Popovo Polje, where all of the wooden framework surrounding the Millstones have long ago decomposed. 

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