Evaluation of Groundwater Quality and its Usability in the Teeb Hydro geological Basin , East Iraq

Teeb Hydrogeological Basin is locating in east part of Iraq. The studied area is characterized by the presence of confined and unconfined aquifers which are represented by Tertiary (Mukdadiya Formation ) and Quaternary deposits respectively. The climate is classified as dry to semidry. The general flow direction of groundwater is concordance with the topography from north-northeast to south-south west. Groundwater hydrochemical study in the basin depends upon (18) well samples where major cations and anions were obtained. The hydrochemical properties include the study of (pH, EC, TDS), the type of groundwater is sodium sulfate (Na SO4 ). The groundwater is generally of suitable chemical quality for livestock, irrigation, and unsuitable for drinking purpose.

The study area has the semiarid of the Mediterranean sea region with amount of rainfall and high temperatures. Objectives The objectives of this study include studying the occurrence, movement, availability, quality, and uses of groundwater in the basin. The study is intended to aid in planning, development and management of the groundwater resources. The scope of the study included collection and analysis of groundwater samples, water levels and water use to describe the water resources status of the basin. Geologically, the rock formations of the study area are classified as Pliocene Group (Mukdadiya Formation and Bai Hassan Formation), and Quatirnary deposits.

Mukdadiya Formation:
The age of formation is mostly Pliocene and the formation was laid down in a fluviolacustrine environment (Lateef, 1975 ), (Enad, 2007 ).the formation is composed almost purely of terrigenous clastics from silt size to boulder conglomerates. In general, the grain size of the clastics increases upward (Buday and Jassim,1980 ). The lower contact of the formation is gradational and usually put at the base of the first pebbly or conglomeratic bed and /or alluvial deposits. The main areas of distribution of the formation are very variable duo to primary differences and partly duo to erosion too. The Mukdadita sediments which where developed by the rapid erosion of the uplifted (Toruse-Zagros ) mountains and the deposition in troughs. Petrographic study of the Mukdadiya sediments shows that they are immature sediments of lithareine type (in which rocks fragments from the main constituents 64% ). The immaturity and composition of these sandstones requires by high relief or aridity (Ali and Khoshaba, 1981).
Mukdadiya formation forms continuous belt south of Himrene mountain. The formation consists of cyclic deposits of clastic materials coarsening upwards (Barwary, 1993).
The lower contact is marked by first appearance of pebbly sandstones, characteristic of the formation. The upper contact is marked by the appearance of first massive conglomerate (Jassim et al , 1984), (Figure 2).

Bai Hassan Formation:
The age of formation is upper Pliocene. The formation is cropping out in the east parts of the basin. The environmental deposits of the formation is fresh water. Lithologically, formation consists from sandstone, mudstone, and massive conglomerates (Barwary, 1993).
Mukdadiya and Bai Hassan formations are cropping out in north east and east of studied area as shown in (Figure 2).

Quaternary deposits:
The hydrogeological basin located within the foothill zone region and Mesopotamian plain. The foothill region is characterized by the widespread development of the fluvial sediments filling the broad, relatively shallow synclines between the narrow anticline ranges. Towards the anticlines, the gravels into deluvial sediments and out run which cover the slopes of the anticline ridges (Al-Jibuory, 2005). The Mesopotamian plain is built up mostly by deltaic, lacustrine and fluvial sediments connected mutually by much facial vitiation and replacing each other both horizontally and vertically. The top part of the sequences is usually lithologically very monotonous being composed of fluvial flood silts with strong aeolian admixture (Buday and Jassim, 1980). The quaternary deposits including, Pleistocene and recent deposits. They consist of alluvium deposits, which consist of a mixture of gravel , sand, silt, clay and conglomerates of post Pliocene deposits (Hamza et al, 1989).
The contact between Mukdadiya formation and Quaternary deposits are of angular unconformity type (Mahmood, 1986

SAMPLING AND ANALYTICAL PROCEDURE Sampling
Sampling of groundwater within the study area was carried out in 2009, eighteen samples were collected from the wells in the basin ( Figure  3).the samples were collected in polyethylene bottles were previously washed with distilled water and diluted hydrochloric acid.

Analytical methods
The hydrogen ion concentration pH) and electrical conductivity (EC, µs cm -1 ) were measured in the field by using a pH meter, portable EC meter respectively . chemical analysis for the cations, calcium (Ca), magnesium (Mg), sodium (Na), and potassium (K) was accomplished in the laboratory using an atomic absorption spectrophotometer. The anions, nitrate (NO 3 ) and sulfate (SO 4 )were measured by spectrophotometer techniques. Titration methods were used to determine the concentrations of chloride (Cl ) and bicarbonate (HCO 3 ; Cl was measured by using potassium chromate (K 2 CrO 4 ) as an in dicater and silver nitrate (AgNO 3 ) as titration solution ; HCO 3 was measured by titrating the samples with 0.02 NH 2 SO 4 , using methyl orange as an indicator. Results of chemical analysis are given in (table 4) and (table 5).
RESULT AND DISCUSSION Physical Properties

Odor, Color and Taste:
The groundwater in studied area is odorless and colorless, while it was brackish or salty taste in all of the water samples because elevated TDS causes to be salty or brackish taste.

PH-Values:
the hydrogen ion concentration is expressed as pH, which is the reciprocal of the logarithm (base 10) of the hydrogen ion concentration in moles per liter. Natural water has a pH value of (7.0), pH of an alkaline water is more than (7.0)and an acidic less than (7.0) (Al- Shablaq, 1998).

Total Dissolved Solid (TDS):
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According to (Davies and De Wiest, 1966), (Drever, 1997) classification, water on the basis of the (TDS), as shown in (table, 3). Table 2: Physical parameters of groundwater samples of Teeb Basin The ( TDS ) values of water samples were ranged between (2230 -7615) mgl -1 with a mean of (4940.8 )mgl -1 . All groundwater samples in Teeb basin area is classified on the basis of the TDS, (table 2). The values of TDS are high more than the Maximum Permissible Level (MPL), recommended by Water Health Organization (WHO, 2004). All water samples considered to be of brackish water (TDS 1000-10000 mgl -1 ).
The salinity contour map for the Teeb basin area is shown in (Figure 4). The map shows that the salinity increase from the recharge area in the north east towards the inner parts of the basin given rise to high saline water in the south west parts.

Electrical Conductivity (EC):
The Electrical Conductivity of a solution is a measure of its ability to carry an electrical current (Awni et al , 2007).
The (EC) of groundwater samples were measured at the field with Digital device that adjusted to (25 C 0 ). The (EC)values ranged between (2787-9640) µs cm -1 with a mean of (6190 )µs cm -1 (table 2)  Electrical Conductivity (EC) depends on the concentration of total dissolved solids (TDS) , therefore it can be use to estimate the concentration of total dissolved solids in the groundwater of basin by use the formula (1).
The high TH values in the basin, due to lithology of pliopleistocene rocks and overlain alluvium affected on the TH of the water samples, since the pebbles of Mukdadiya and Bai Hassan Formations are mostly of limestone and dolomite.  Ions
Sodium and Calcium are the dominant cations in the groundwater in this basin, while sulfate is the most abundant of the anions (tables, 4, 5 ).
The high concentrations of sodium and sulfate in groundwater are due to the chemical weathering of rocks and soil in the basin.   Groundwater Use Groundwater uses for human drinking purpose: The WHO standard has been used as guides for the water quality evaluation for drinking purpose. The groundwater quality in studied area is unsuitable as drinking because most of the parameters are out of the recommended guide levels (table, 6).

Groundwater uses for Livestock purpose:
On the basis on Altoviski (1962) classification, all of the groundwater samples are good for livestock use (table 7). Table 7: classification of livestock water (Altoviski, 1962) Parameter s

Groundwater use for irrigation:
The groundwater was evaluated for irrigation using the Sodium Absorption Ratio (SAR) values to determine its suitability. The SAR was computed using the expression developed by (Todd, 1980) as : SAR = r Na / [ r(Ca + Mg )/ 2 ] 0.5 Classification of irrigation water based on SAR values is shown in (table,  8 ). On the basis of this classification all of the groundwater samples belong to excellent and good water class for irrigation purpose ( SAR < 10, SAR 10-18 ).

CONCLUSION
The groundwater resources of the Teeb Basin, east Iraq were evaluated and studied to aid in planning, development and management. The principal sources of groundwater in this basin are classified as Pliocene and Quaternary Aquifers systems.
The lowest TDS values is 2230 mgl -1 and the highest is 7615 mgl -1 . The dominant cations in the basin are Sodium and Calcium while Sulfates is the most abundant of the anions. Hence, groundwater from this basin is of the Na + Ca -SO 4 type. Based on this chemical quality, the groundwater of the Teeb basin is not suitable for drinking, and suitable for livestock and irrigation purposes.