Brahamaputra Basin
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<strong>Brahamaputra</strong> <strong>Basin</strong><br />
6.2 Ground water quality observations<br />
A large part of Brahmaputra basin’s irrigated agricultural and domestic needs also depends upon<br />
ground water availability and its quality. The Ground Water Quality at observation wells located in<br />
the basin is measured on the basis of main 15 parameters which include values for Magnesium, pH,<br />
Nitrate, Potassium, Sulphate, Electrical Conductivity (EC), Total Dissolved Solids (TDS) , Calcium,<br />
Sodium, Carbonate, Bicarbonate, Chloride, Fluoride, Sodium Absorption Ratio (SAR) and Residual<br />
Sodium Carbonate(RSC) and Arsenic & Iron which are specific to areas. They are further classified in<br />
two categories viz. Irrigation and Drinking Water quality standards as described by Bureau of Indian<br />
Standards (BIS) for ground water quality.<br />
Based upon these all parameters in general the chemical quality of ground water, both from nearsurface<br />
and deeper aquifer zones, is generally good and suitable for the Irrigation and Drinking<br />
purposes in the basin.<br />
The Ground water is generally mildly alkaline in the basin with a pH value ranging from 6.5 to<br />
8.5.The total dissolved solides are low. The chloride and bi-carbonate values are also considerably<br />
low.<br />
However, at many places in the basin, an excess of Fluoride, Iron and Arsenic has been recorded. In<br />
Assam parts of Goalpara, Kamrup, Karbi Anglong, Nagaon districts are observed with excess Fluoride<br />
(>1.5 mg / litre) in Ground Water (Source: CGWB, March 2008). Parts of Cachar, Darrang, Dhemaji,<br />
Dhubri, Goalpapra, Jorhat, Kamrup, Karbi Anglong, Karimganj, Lakhimpur, Morigaon, Nagaon,<br />
Nalbari, Sibsagar, Sonitpur disticts of Assam and East Garo Hills, East Khasi Hill, Jaintia Hills districts<br />
of Meghalaya have iron more than permissible limit in water with occurrence of Iron (>1.0 mg/litre)<br />
in ground water which exceeds the BIS standards.<br />
Bordoloni, Dhemaji, Sisirborgaon blocks in Dhemaji district have excess of Arsenic (>0.01 mg/litre) in<br />
ground water.High Levels of Arsenic in groundwater not only cause significant problems in the<br />
provision of Safe Drinking water. Long term exposure of arsenic has been associated with cancer of<br />
the skin, lung, urinary tract, kideney, liver, and can also produce various other non-cancerous<br />
effects.<br />
www.india-wris.nrsc.gov.in 57
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