The Topolnitsa is a river in southern Bulgaria

Bulgaria

Bulgaria , officially the Republic of Bulgaria , is a parliamentary democracy within a unitary constitutional republic in Southeast Europe. The country borders Romania to the north, Serbia and Macedonia to the west, Greece and Turkey to the south, as well as the Black Sea to the east...

, an important left tributary of the Maritsa

Maritsa

The Maritsa or Evros , ) is, with a length of 480 km, the longest river that runs solely in the interior of the Balkans. It has its origin in the Rila Mountains in Western Bulgaria, flowing southeast between the Balkan and Rhodope Mountains, past Plovdiv and Parvomay to Edirne, Turkey...

. It takes its source from Bich Peak in Sredna Gora

Sredna Gora

Sredna Gora is a mountain range in central Bulgaria, situated south of and parallel to Balkan mountain range and extending from the river Iskar to the west and the elbow of Tundzha north of Yambol to the east. Sredna Gora is 285 km long, reaching 50 km at its greatest width...

 close to Koprivshtitsa

Koprivshtitsa

Koprivshtitsa is a historic town in Sofia Province, central Bulgaria, lying on the Topolnitsa River among the Sredna Gora mountains. It was one of the centres of the April Uprising in 1876 and is known for its authentic Bulgarian architecture and for its folk music festivals, making it a very...

; it is known as the Shirineyska in its upper course. Its average discharge

Discharge (hydrology)

In hydrology, discharge is the volume rate of water flow, including any suspended solids , dissolved chemical species and/or biologic material , which is transported through a given cross-sectional area...

 is 55 m³/s and it is 154.8 kilometres (96.2 mi) long; its drainage basin

Drainage basin

A drainage basin is an extent or an area of land where surface water from rain and melting snow or ice converges to a single point, usually the exit of the basin, where the waters join another waterbody, such as a river, lake, reservoir, estuary, wetland, sea, or ocean...

 covers 1789 square kilometres (690.7 sq mi). The Topolnitsa flows into the Maritsa near Pazardzhik

Pazardzhik

Pazardzhik is a city situated along the banks of the Maritsa river, Southern Bulgaria. It is the capital of Pazardzhik Province and centre for the homonymous Pazardzhik Municipality...

 after making a large turn under Trakiya motorway

Trakiya motorway

The Trakia motorway or Thrace motorway, designated A1, is a motorway currently in construction in Bulgaria. It is planned to connect the capital of Sofia with Burgas on the Black Sea through Plovdiv and with Kalotina on the Serbian border. The motorway is named after the historical region of...

. The Topolnitsa Reservoir has a maximum volume of 120000000 cubic metre and serves the area around Pazardzhik. Among the Topolnitsa's tributaries are the Mativir and the Bunovo River. The river's name is derived from the Bulgarian word топола, topola ("poplar

Poplar

Populus is a genus of 25–35 species of deciduous flowering plants in the family Salicaceae, native to most of the Northern Hemisphere. English names variously applied to different species include poplar , aspen, and cottonwood....

").