HYDROGEOLOGY OF THE MESOPOTAMIA PLAIN

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

	HYDROGEOLOGY OF THE MESOPOTAMIA PLAIN
Iraqi Bulletin of Geology and Mining
Article 1, Volume 0, Issue 4, 2017, Pages 1-21
Authors
Hatem K. Al-Jiburi; Naseer H. Al-Basrawi
Abstract
The Mesopotamia Plain is characterized, topographically as a flat plain that slopes gently between Baghdad and Basrah, but it is gently undulated in its northern parts. It is totally covered by Quaternary sediments. These sediments are composed of alternation of clay, silty clay, clayey silt, silt, sand and gravel. Fine sediments represent the aquitards, while sand and gravel form the aquifers. These sediments have abrupt lithologic changes, both laterally and vertically, therefore, are considered regionally as a lithologically complex aquifer system. There is a hydraulic continuity within the entire Quaternary aquifer system, but the degree of the continuity differs from place to another, depending on the lithological characteristics of water bearing sediments. It is assumed that, a hydraulic continuity is present between surface water and groundwater aquifers, to some extent. Therefore, effluent and influent river phenomena exist throughout the plain. Moreover, there is a hydraulic continuity between Quaternary aquifer system, in the plain and the underlying pre-Quaternary formations. The groundwater level fluctuations throughout the Mesopotamia Plain depend, mainly on the natural conditions and to some extent on artificial conditions. Generally, water bearing Quaternary sediments, of the plain are considered quantitatively promising, but the problem is concerned with the quality of the groundwater. High salinity of the groundwater prevails throughout the plain, but the groundwater, which is close to rivers and main irrigation channels may be in better condition for exploitation, particularly where phenomenon of induced seepage of fresh water exists, also in areas along Low Folded Zone, where recharge water zones exist. The direction of the groundwater flow is towards the center of the Mesopotamia Plain, from all neighboring regions, because the plain represents a regional discharge zone for the whole Mesopotamian Aquifer Mega System of Iraq. The piezometric level of the groundwater is generally inclined from north and northwest (it is < 200 m, a.s.l., near Makhoul Mountain) towards south and southeast (2 m, a.s.l., near Basrah city). The salinity of the groundwater increases generally from the recharge areas towards discharges areas, within the plain. The chemical quality of the groundwater changes from sulphatic to chloridic type from recharge to discharge areas, respectively, being in accordance with the groundwater movement.

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