The Alwand or Halwan (, , ) is a river in eastern

Iraq Iraq, officially the Republic of Iraq, is a country in West Asia. It is bordered by Saudi Arabia to Iraq–Saudi Arabia border, the south, Turkey to Iraq–Turkey border, the north, Iran to Iran–Iraq border, the east, the Persian Gulf and ...

and western

Iran Iran, officially the Islamic Republic of Iran (IRI) and also known as Persia, is a country in West Asia. It borders Iraq to the west, Turkey, Azerbaijan, and Armenia to the northwest, the Caspian Sea to the north, Turkmenistan to the nort ...

. It rises in the

Zagros Mountains The Zagros Mountains are a mountain range in Iran, northern Iraq, and southeastern Turkey. The mountain range has a total length of . The Zagros range begins in northwestern Iran and roughly follows Iran's western border while covering much of s ...

in Iran. The river flows west from the mountains to the city of

Qasr-e Shirin Qasr-e Shirin (, is a city in the Central District of Qasr-e Shirin County, Kermanshah province, Iran, serving as capital of both the county and the district. Its population in 2016 was 18,473. It is a Free-trade zone (FTZ) and is populated ...

, where it turns south and crosses the border with Iraq. It then divides the city of

Khanaqin Khanaqin (; ) is the central city of Khanaqin District in Diyala Governorate, Iraq, near the Iranian border (8 km) on the Alwand tributary of the Diyala River. The town is populated by Kurds who speak the Southern Kurdish dialect. Khan ...

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 a symbol for their unity and Kurdish identity. The river joins the

Diyala River The Diyala (Arabic: ; ; Farsi: , ) is a river and tributary of the Tigris. It is formed by the confluence of the Sirwan and Tanjaro rivers in Darbandikhan Dam in the Sulaymaniyah Governorate of Northern Iraq. It covers a total distance of . ...

at Zengabadh.

Name

According to

Vladimir Minorsky Vladimir Fyodorovich Minorsky (; – 25 March 1966) was a White Russian academic, historian, and scholar of Oriental studies, best known for his contributions to the study of history of Iran and the Iranian peoples such as Persians, Lurs, and ...

, the name "Alwand" is related to the name of the historical city of

Hulwan Hulwan () was an ancient town on the Zagros Mountains in western Iran, located on the entrance of the Paytak Pass, nowadays identified with the town of Sarpol-e Zahab. History Later Arab tradition, as recorded by al-Tabari, considered the town ...

, which lay on the river near the present-day city of

Sarpol-e Zahab Sarpol-e Zahab () is a city in the Central District of Sarpol-e Zahab County, Kermanshah province, Iran, serving as capital of both the county and the district. The town is close to Qasr-e Shirin and the Iraqi border. Demographics Langu ...

Geography

The Alwand basin is located on the western side of the Zagros and covers an area of about 2,700 km². The climate of this region is semiarid to Mediterranean, with cool winters and dry summers. It receives an average of about 530 mm of rainfall per year. The region is characterized by

karst Karst () is a topography formed from the dissolution of soluble carbonate rocks such as limestone and Dolomite (rock), dolomite. It is characterized by features like poljes above and drainage systems with sinkholes and caves underground. Ther ...

terrain, and there are about 35

karst spring A karst spring or karstic spring is a Spring (hydrology), spring (exsurgence, outflow of groundwater) that is part of a karst hydrological system. Description Because of their often conical or inverted bowl shape, karst springs are also known i ...

s in the Alwand basin (12 major and 23 minor).

Geology

The Alwand basin features seven main

anticline In structural geology, an anticline is a type of Fold (geology), fold that is an arch-like shape and has its oldest Bed (geology), beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex curve, c ...

s, which are separated from each other by

syncline In structural geology, a syncline is a fold with younger layers closer to the center of the structure, whereas an anticline is the inverse of a syncline. A synclinorium (plural synclinoriums or synclinoria) is a large syncline with superimposed ...

s. About 36% of the basin is made up of

carbonate A carbonate is a salt of carbonic acid, (), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word "carbonate" may also refer to a carbonate ester, an organic compound containing the carbonate group ...

formations, primarily the

Asmari Formation The Asmari Formation is a geological formation in western Iran. Located in the western Zagros Mountains, it is a carbonate formation that largely consists of limestone, dolomitic limestone, dolomite (rock), dolomite, and marly limestone. There are ...

. The Asmari Formation, which makes up the main body of the anticlines, consists of Tertiary dolomitic limestone and dolomite. Above it lie layers of the

marl Marl is an earthy material rich in carbonate minerals, Clay minerals, clays, and silt. When Lithification, hardened into rock, this becomes marlstone. It is formed in marine or freshwater environments, often through the activities of algae. M ...

-and-

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

Aghajari Formation or the

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate Hydrate, dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk ...

-and-marl Gachasaran Formation. Below it is the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

Pabdeh-Gurpi Formation, which consists of marl and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

. Another carbonate formation, the Cretaceous

Ilam Formation Ilam may refer to: Places * Ilam District, Province No. 1, Nepal ** Ilam Municipality, in the Ilam District, Nepal * Ilam province, Region 4, Iran ** Ilam County, Ilam Province *** Ilam, Iran, capital city of Ilam Province and Ilam County *** I ...

, is made of limestone and is only exposed in the Patagh anticline. The Asmari Formation, confined beneath the impermeable Aghajari and Gachasaran Formations, is the main

aquifer An aquifer is an underground layer of water-bearing material, consisting of permeability (Earth sciences), permeable or fractured rock, or of unconsolidated materials (gravel, sand, or silt). Aquifers vary greatly in their characteristics. The s ...

in the Alwand basin.

References

Rivers of Kermanshah Province Rivers of Iraq Landforms of Kermanshah province Khanaqin {{Iran-river-stub

Name

Geography

Geology

See also

References