Trebišnjica River
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The Trebišnjica (Serbian: Требишњица), is a river in Bosnia and Hercegovina, Montenegro and Croatia. It is a sinking river, 98 km long above the ground. With a total length of 187 km above and under the ground, it is one of the longest sinking rivers in the world.
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[edit] Upper course
As it flows in the highly karst (limestone) area, the Trebišnjica actually represents a very complex system of the above and underground streams. It originates in Bosnia and Hercegovina from two streams from the Lebršnik and Čemerno mountains:
- one stream, under the name of Mušnica, flows from the eastern to the western border of the Gatačko Polje (Field of Gacko) (from mountain Lebršnik to Bjelašnica, passes through the Klinje lake and next to the settlements of Avtovac, Gacko, Srđevići, Bašići, Drugovići, Kula and Branilovići, before it sinks into the karst in the Cerničko Polje (Field of Cernica, west of the Baba mountain) at the village of Cernica under the name of Ključka rijeka (River of Ključ), after a near-by village of Ključ.
- another stream, under the name of Gračanica, flows from the Čemerno mountain also into the Gatačko Polje, next to the villages of Bahori and Gračanica, before it meets the Mušnica near Srđevići. Both streams are characterized by very sharp, almost erratic bends and changes of direction.
River shortly re-appears in the Fatničko Polje (Field of Fatnica) under the name of Fatnička reka (River of Fatnica), only to sink again after a short flow above the ground.
[edit] Middle course
After the total underground flow of some 30 km, the waters of the sinking Fatnička reka re-appear as a series of very powerful cave springs near the town of Bileća, which are joined into one river, the Trebišnjica, the most important river in the eastern Hercegovina. The river flows to the south, through the depression of Miruša. On the southernmost part of the depression, the river is dammed at the Gornje Grnčarevo village and completely flooded upstream by the artificial Lake Bileća. Almost complete western bank of the lake belongs to the Montenegro.
The Trebišnjica turns west between the villages of Donje Grnčarevo and Lastva into the Trebinjsko polje (Field of Trebinje), being dammed once again at the village of Gorica, with a small reservoir. The river continues to the west following the southern slopes of Bjelašnica mountain, through the town of Trebinje and villages of Dražin Do, Tvrdoš, Gornja Kočela and Donja Kočela, and enters the largest karst field in the Balkans, Popovo Polje (Field of the priest).
In Popovo Polje, the Trebišnjica already used to sink (see Regulation below), right after the Trebinje. In the field, the river turns northwest, next to the villages of Staro Slano, Đedići, Dobromani, Žarkovo, Tilje, Sedlari, Grmljani and Zavala, near the Vjetrenica cave, the largest in Bosnia and Hercegovina. The river then turns north, makes a big curve between the villages of Dvrsnica, Orašje, Čavaš and Turkovići and in the lower Popovo Polje, near the Croatian border, sinks into the several big sinking holes (most notably, the Doljašnica and Ponikva holes).
[edit] Lower course
The waters of Trebišnjica from the Popovo Polje, re-appear as three separate outflows:
- Series of underwater springs (called vrulje; boiling water) near the small sea harbor of Slano in Croatia, northwest of the town of Dubrovnik.
- After some 20 km of underground flow, the Trebšinjica re-emerges as the powerful spring in the great cave near the Gruž, western part of the Dubrovnik. The stream is called the Ombla river (Umbla; or Dubrovačka rijeka; River of Dubrovnik). It is only 4,2 km long but very wide and powerful (average discharge is 24 m³/s; on maps it appears as a small bay of the Adriatic, in which it flows, north of Dubrovnik). The lower part of the river is flooded by the sea (Croatian: draga), its 30 m deep and navigable for 3,7 km (unlike the upper course of Trebišnjica which is not navigable at all). Several suburbs of Dubrovnik (Mokošica, Komolac, Rožat, Prijevor, Lozica) are located alongside the river. Water from the river has been used by the Dubrovnik waterworks since 1437.
The total drainage area of the Trebšnjica covers 4.926 km², out of which 600 km² is shared with the Neretva drainage area (the spring of Čapljina). The drainage area of the central, longest part of the river covers 2.225 km².
[edit] Regulation and importance
For a river that flows in geologically unstable terrain (karst) and with such an interrupted flow, the Trebišnjica amounts enormous potential for hydroelectricity production. As a result, regulatory works on the Trebišnjica were arguably the most massive ones in the former Yugoslavia.
- 1965. The river was dammed at the village of Gorica, creating artificial lake as an auxiliary water basin for the future hydro-electrical power station (HE) Trebinje. The water of the lake is conducted by two parallel, 16 km long, hydro-energetic tunnels into the Croatian village of Plat, on the Adriatic cost, near the Cavtat, where HE Dubrovnik is constructed.
- 1967. The dam for HE Trebinje (or Grnčarevo) was constructed, creating huge Lake Bileća (or Lake Miruša; area 33 km², altitude 400 m, depth 104 m, volume 1,3 billion m³). The old Arslanagić bridge was deconstructed and moved to Trebinje. Together with HE Dubrovnik, two power stations have a power of 422 MW and capacity for production of 2,19 billion kWh yearly.
- 1979. The HE Čapljina is completed, after 8 km long hydro-energetic tunnel and two reservoirs (with volume of 12,5 million m³) began operating. The power station has a power of 430 MW (two aggregates of 215 MW) and capacity for 619 million kWh yearly.
- 1979. To prevent the sinking of the water through the smaller sinking holes in the Popovo Polje, the river bed has been concreted for a length of 67 km.
[edit] References
- Mala Prosvetina Enciklopedija, Third edition (1985); Prosveta; ISBN 86-07-00001-2
- Jovan Đ. Marković (1990): Enciklopedijski geografski leksikon Jugoslavije; Svjetlost-Sarajevo; ISBN 86-01-02651-6
