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The quality of
ground water is alkaline with pH ranging from 7.1 to 9.2, chloride
content ranges between 21 and 1380 ppm. South of Delhi average chloride
content is 250 ppm while in Najafgarh area it is around 1000 ppm
rendering the water saline covering the area of 32 km. Sq. and marginally
saline over the area of 129 sq km.
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The ground water study done by the NEERI for MoEF revealed high nitrate
and fluoride concentrations. High metallic content, particularly manganese
and iron have also been observed in the samples collected. The manganese
content was found to be 0.1 mg/L against the permissible limit of
0.5-mg/L and iron concentration of 4.05 mg/L to 0.337 mg/L have been
observed.
Chemical Quality of Ground Water in South West district
Ground water in maximum part of the South district is fresh and potable
with electrical conductivity ranging from 320 to 4130 micro-mhos/cm
at 25` C. Electrical conductivity values more than the permissible
limit are observed at Deragaon, Molarbund and at Gadaipur. High values
of nitrate are found at four locations i.e. at Gadaipur, at Rajokri
and at Jaunapur. In north Ghitorni and Andheri More, Fluoride is more
than permissible limits. Except chromium concentrations at one locality,
ground water is devoid of pollution by heavy metals. A comparision
of ground water quality from 1983 to 2000 shows quality deterioration
in the central part of the Chhattarpur basin and in the areas around
Nizamuddin. In central part of the Chattarpur basin, quality deterioration
is mainly because of over-development of ground water resources. The
exhaustion of fresh water present at shallow depths is resulting into
brackish water pumping from the tubewells that are tapping the deeper
aquifers of alluvium.
The electrical conductivity of shallow ground water in the Southwest
district varies from 630 to 13200 micro-mhos/cm at 25` C. Detailed
Electrical Conductivity map prepared for this district, ground water
quality is fresh with electrical conductivity 1000 to 2000 micro-mhos/cm
at 25` C. Thus, with over-development of ground water resources in
the district, more and more areas are becoming brackish.
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