The Pazinčica or Pazinski potok (, Fojba), locally Potȍk or Patȍk, is a
river
A river is a natural stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...
in the central part of the
Istrian peninsula, Croatia. It flows above ground before entering its
ponor
A ponor is a natural opening where surface water enters into underground passages; they may be found in Karst topography, karst landscapes where the geology and the geomorphology is typically dominated by porous limestone rock. Ponors can drain s ...
, the , continuing as a
subterranean river
A subterranean river (also known as an underground river) is a river or watercourse that runs wholly or partly beneath the ground, one where the riverbed does not represent the surface of the Earth. It is distinct from an aquifer, which may flow ...
.
It is the longest such river in Istria.
Course
From its source near Borut to its ponor in
Pazin, it has only a few constant
tributaries
A tributary, or an ''affluent'', is a stream or river that flows into a larger stream ('' main stem'' or ''"parent"''), river, or a lake. A tributary does not flow directly into a sea or ocean. Tributaries, and the main stem river into which the ...
: the
Brestovica,
Toplica,
Lipa,
Rakov potok and
Frnežar.
From its spring to its ponor, the elevation difference is a mere to , supported by layers of
flysch
Flysch () is a sequence of sedimentary rock layers that progress from deep-water and turbidity flow deposits to shallow-water shales and sandstones. It is deposited when a deep basin forms rapidly on the continental side of a mountain building ep ...
. Its final section is relatively complex, featuring stone blocks called ''kruge'', lakes called ''puče'' and two larger waterfalls ( and
Pazinski krov).
In its geological history, it once drained directly into the
Adriatic
The Adriatic Sea () is a body of water separating the Italian Peninsula from the Balkans, Balkan Peninsula. The Adriatic is the northernmost arm of the Mediterranean Sea, extending from the Strait of Otranto (where it connects to the Ionian Se ...
through what is now the
Lim valley. The course of the river was then diverted from a northward to a southward direction where, at the contact between flysch and
limestone
Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...
, a ponor was formed.
Flow tracing has shown that the river drains partly into several springs in the valley of the
Raša river, and partly into springs towards the south of the peninsula.
The springs in the Raša valley in question are ''Sveti Anton'', ''Rakonek'', ''Grdak'' and ''Sušaki''.
Hydrology
Its maximum water level is .
The record high discharge of was reached in 1964.
History
In 1935, 1961 and 1964, a to lake formed at the mouth of the ponor.
In 1993, a
footbridge
A footbridge (also a pedestrian bridge, pedestrian overpass, or pedestrian overcrossing) is a bridge designed solely for pedestrians.''Oxford English Dictionary'' While the primary meaning for a bridge is a structure which links "two points at a ...
was built across the river near the ponor, known as ''Vršić'' or ''Most preko Jame''.
Gallery
File:Pazinćica2.jpg, Lower course.
File:Zarečki krov.jpg, Zarečki krov.
File:Slap Pazinski krov.jpg, Pazinski krov.
File:HR-IS-Pazin46.jpg, Pazin Canyon
File:Pazincica river, Pazin, northwest Croatia.JPG, Near its ponor.
References
{{reflist
Drainage basins of the Adriatic Sea
Istria
Rivers of Croatia
Subterranean rivers