Belarus
Belarus,, , ; alternatively and formerly known as Byelorussia (from Russian ). officially the Republic of Belarus,; rus, Республика Беларусь, Respublika Belarus. is a landlocked country in Eastern Europe. It is bordered by ...
and Lithuania. The river is an example of a rare phenomenon of
river bifurcation
River bifurcation (from la, furca, fork) occurs when a river flowing in a single stream separates into two or more separate streams (called distributaries) which then continue downstream. Some rivers form complex networks of distributaries, typ ...
.
At first, the Kotra and Ūla form one river, known as the Pelesa, which originates in Belarus and flows in a northwestern direction. Just past the
Belarus–Lithuania border
The Belarus–Lithuania border is an international border almost in length between the Republic of Belarus (Member states of the Commonwealth of Independent States, CIS member) and the Republic of Lithuania (Member state of the European Uni ...
, between the villages of and Kazliškės, some southeast of
Varėna
Varėna (; pl, Orany; yi, אוראַן ''Oran'') is a city in Dzūkija, Lithuania.
History
The town was founded in 1862 near the Warsaw – Saint Petersburg Railway, south of Sena Varėna (Old Varėna). At that time it was a small settleme ...
, it branches out into two independent rivers: the Kotra, a tributary of the
Neman
The Neman, Nioman, Nemunas or MemelTo bankside nations of the present: Lithuanian: be, Нёман, , ; russian: Неман, ''Neman''; past: ger, Memel (where touching Prussia only, otherwise Nieman); lv, Nemuna; et, Neemen; pl, Niemen; ...
, and the Ūla, a tributary of the Merkys. This situation arose in the second half of the 19th century when the Ūla, due to its channel erosion, crossed the water divide between its own and the Kotra's
drainage basin
A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...
s. As a result, the Ūla enlarged its basin by some and the Kotra lost two of its tributaries. These processes also caused a decrease in groundwater levels and the almost total disappearance of several lakes in the area.
The Kotra flows along the Belarus–Lithuania border for and the remaining through Belarus. It then flows along the southern border of Čepkeliai Marsh, the area protected as a
nature reserve
A nature reserve (also known as a wildlife refuge, wildlife sanctuary, biosphere reserve or bioreserve, natural or nature preserve, or nature conservation area) is a protected area of importance for flora, fauna, or features of geological or ...
With the changes in drainage basins and groundwater levels, some of open marshes overgrew with trees. The Kotra and its surrounding marshes form
wetlands of international importance
A Ramsar site is a wetland site designated to be of international importance under the Ramsar Convention,8 ha (O)
*** Permanent 8 ha (P)
*** Seasonal Intermittent < 8 ha(Ts)
**
and Cepkeliai Ramsar siteVarėna district municipality established a reservoir to protect the natural Kotra environment.
References
*
*
* Cepkeliai . ''Long Term Ecological Research (LTER) Network in Lithuania''. Institute of Ecology of Vilnius University. Accessed 9 October 2006.