The Gadar River rises in the Iran

Iran

Iran , officially the Islamic Republic of Iran , is a country in Southern and Western Asia. The name "Iran" has been in use natively since the Sassanian era and came into use internationally in 1935, before which the country was known to the Western world as Persia...

ian Zagros Mountains

Zagros Mountains

The Zagros Mountains are the largest mountain range in Iran and Iraq. With a total length of 1,500 km , from northwestern Iran, and roughly correlating with Iran's western border, the Zagros range spans the whole length of the western and southwestern Iranian plateau and ends at the Strait of...

 near the point where the borders of Iran, Turkey

Turkey

Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...

 and Iraq

Iraq

Iraq ; officially the Republic of Iraq is a country in Western Asia spanning most of the northwestern end of the Zagros mountain range, the eastern part of the Syrian Desert and the northern part of the Arabian Desert....

 meet. From its source, the river first flows towards the southeast and then changes course due east through the Ushnu-Solduz valley. After leaving the valley, the river turns north and flows into marshes bordering Lake Urmia

Lake Urmia

Lake Urmia , ancient name: Lake Matiene) is a salt lake in northwestern Iran, near Iran's border with Turkey. The lake is between the Iranian provinces of East Azerbaijan and West Azerbaijan, west of the southern portion of the similarly shaped Caspian Sea...

. The length of the river is approximately 100 kilometres (62.1 mi), 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...

 is variously estimated as 1900 square kilometres (733.6 sq mi) and 2123 square kilometres (819.7 sq mi) and its 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 0.34 cubic metres (12 cu ft) per second. The Ushnu-Solduz valley has been occupied since many millennia, as testified by the excavations at sites like Hasanlu Tepe

Teppe Hasanlu

Teppe Hasanlu or Tappeh Hassanlu is an archeological site of an ancient city located in northwest Iran , a short distance south of Lake Urmia...

 and Hajji Firuz Tepe

Hajji Firuz Tepe

Hajji Firuz Tepe is an archaeological site located in West Azarbaijan province in northwestern Iran. The site was excavated between 1958 and 1968 by archaeologists from the University of Pennsylvania Museum of Archaeology and Anthropology...

.