HYDROGEOLOGY

H. Al-Basrawi, Naseer; K. Al-Jiburi, Hatem

	HYDROGEOLOGY
Iraqi Bulletin of Geology and Mining
Article 1, Volume 0, Issue 1, 2017, Pages 125-144
Authors
Naseer H. Al-Basrawi; Hatem K. Al-Jiburi
Abstract
The regional topography of the Iraqi Western Desert is characterized by gradual increase in elevation from east to west with some exceptions. In general, the drainage is towards east and northeast. All wadis in the region are intermittent. Generally, the Western Desert is covered by carbonates, clastic and marl. The dip of the strata is almost gentle and towards northeast and east directions, in the western parts is westwards. The main aquifers in the region are within Suffi, Ga`ara, Mulussa, Ubaid, Muhaiwir, Rutbah, Ms`ad, Hartha, Tayarat, Umm Er Radhuma, Akashat, Dammam, Ratga, Euphrates, Injana formations and Quaternary deposits. Ga`ara aquifer is considered as the most important one, on a regional scale, due to its wide extent and high content of water. Most aquifers are recharged from rainfall and runoff of the intermittent wadis in form of leakage losses into permeable strata and through fractures, fissures, joints and cavities, especially into shallow aquifers. It is assumed the presence of a hydraulic connection between aquifers to some extent. Leakage of water is either downwards or upwards, depending on piezometric relation of aquifers, lithology, structure and extent of water-bearing horizons. Groundwater discharge zone is located in the area along the right bank of the Euphrates River. Water river discharge is either in form of underground inflow into the Euphrates, Habbaniya and Razzaza lakes, or in form of springs. The general trend of the groundwater is towards northeast, following the discharge zone along the right bank of the Euphrates River. Locally, different directions of flow may occur through out the region, depending on the geological setting of water-bearing horizons and nature of structure and topography. Groundwater level varies from about 300 m below ground surface, in the western parts to artesian or near ground surface, in recharge zones along Euphrates River. Salinity of water increases with depth and also towards discharge zones. It ranges from fresh in the western parts to very high salinity in discharge areas. Water type also varies from bicarbonate or mixed to mainly chloridic or sulphatic in the discharge zones.

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