The Alwand or Hulwan River is a river in eastern 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....

 and western 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...

. It rises in the 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...

 in Iran.

The river flows west from the mountains to the city of Qasr-e Shirin, where it turns south and crosses the border with Iraq. It then divides the city of Khanaqin

Khanaqin

Khanaqin is a city in Iraq. It is located at 34.3°N, 45.4°E in the Diyala Governorate, near the Iranian border on a tributary of the Diyala River...

 in two parts. It has played a significant role in land cultivation and in establishment of a strong rural society in the area, and is considered by the people of Khanaqin as a symbol for their unity and Kurdish identity.

The river joins the Diyala River

Diyala River

The Diyala River after Darban-e Khan Dam:Kurdish: Sirwan, سيروان, , Persian: سیروان دیاله, is a river and tributary of the Tigris that runs mainly through Eastern Iraq but also Western Iran. It covers a total distance of ....

at Zengabadh.