Executive Summary 

The Taurus-Zagros Mountain range extends across Iran, northern Iraq and Turkey. Geological formations within this range constitute shared aquifer systems in some areas along the boundaries of these countries. Three such areas are identified and described in this chapter: the Halabja-Khurmal and the Central Diyala Basins between Iran and Iraq, and the Zakho Basin between Iraq and Turkey. Other shared basins may possibly exist but remain unknown because of the complexity of the tectonics in the area.

In the Halabja-Khurmal Basin, groundwater is exploited in the Bekhme (Cretaceous) and Pila Spi (Paleogene) Aquifer Systems. The groundwater originates in the high mountains of Iran and flows towards the Derbendikhan Dam Lake in Iraq. A total annual recharge of 214 MCM occurs in the basin, and natural discharge of groundwater occurs mostly through springs.

In the Central Diyala Basin, water is abstracted from the Bai Hassan-Mukdadia (Neogene) Aquifer System. A few springs are reported to discharge into this area and recharge is in the order of 50 mm/yr. Groundwater flow is mainly towards the Diyala River and the quality of water deteriorates with depth due to the presence of evaporites.

Both the Neogene and Paleogene aquifer systems are exploited in the Zakho Basin in the north, which receives about 188 MCM/yr of water. A considerable amount of this water is discharged through springs.

  • Landscape near Penjwin, Iraq, 1991. Source: Ed Kashi/VII.
  • The city of Dahuk with the Zagros Mountains in the background, Turkey, 2005. Source: Ed Kashi/VII.
  • Lake Van, Turkey, 2010. Source: Adel Samara.

Basin Facts 

Riparian Countries Iran, Iraq: Halabja-Khurmal and Central Diyala Basins

Iraq, Turkey: Zakho Basin

Main Aquifers Bai Hassan, Bekhme, Pila Spi
Alternative Names --
Shared Basins Central Diyala, Halabja-Khurmal, Zakho
Renewability Medium to high (20-300 mm/yr)
Hydraulic Linkage with Surface Water Strong
Rock Type Bekhme, Pila Spi: carbonate, karstic
Bai Hassan: intergranular
Aquifer Type Semi-confined
Extent of Catchment Central Diyala: 11,760 km2
Halabja-Khurmal: 566 km2
Zakho: 1,960 km2
Age Bai Hassan, Pila Spi: Cenozoic
Bekhme: Mesozoic
Lithology Shale, limestone, sandstone
Thickness Bekhme: ≤1,000 m
Pila Spi: ~1,500 m
Bai Hassan: ≥2,500 m
Average Annual Abstraction --
Storage --
Water Quality Fresh (≤1,000 mg/L TDS) except in deeper layers of Central Diyala Basin saline (3,000 mg/L TDS)
Water Use Mainly agricultural
Agreements --
Sustainability --