Assessment of ground water quality at Basrah, Iraq by water quality index (WQI)‎

Abstract EN

The assessment of water quality is very important for knowing its suitability for various purposes.

Water quality index (WQI) indicates the quality of water in terms of index number for any intended use.

It is defined as a rating reflecting the composite influence of different water quality parameters were taken for calculation of water quality index.

In the present study, ground water samples were gathered from two regions located at Basrah governorate during culturing period in Autumn 2011.

They are Bergussia and Zubair.

Ten well samples were taken from each region for analyzing twelve parameters they are : electrical conductivity (EC), bicarbonate (HCO), total hardness (TH), Calcium (Ca + 2), Magnesium (Mg + 2), Chloride (Cl-), Sulphate (SO-2) Nitrite (NO2) Nitrate (NO3) Sodium (Na+), Potassium (K+) and Boron (B+).

The evaluation of water suitability of present study for human drinking and other domestic purposes was achieved by means of WQI depending on guideline values of WHO (2006) for : electrical conductivity total hardness, Calcium, Magnesium, Chloride, Sulphate, Nitrite, Nitrate, Sodium, Potassium and Boron.

Values of WQI ranged from 2052 to 3511 at Burgussia and from 2219 to 3743 at Zubair and rated unfit to human consumption according to the classification of Tiwari and Mishra (1985).

These values belong to high water electrical conductivity and chloride of the studied wells comparable with other parameters.

Also, correlation coefficient support this interpretation where there are strong positively correlation between WQI values and both electrical conductivity and chloride values (0.997, 0.919 respectively).While in the assessment of ground water quality for irrigation, electrical conductivity at 25°C ECW), Sodium adsorption ratio (SAR), chloride, boron, bicarbonate and nitrate were used to calculation WQI values which ranged from 67.41 to 77.99 at Burjessia and from 67.43 to 77.48 at Zubair.

These values associated with both ECW and Cl- in a strong negatively correlation (-0.968, -0.969 respectively).