Ground water is found in a variety of geological formations. Physiographic and geomorphologic settings are among the important factors that control the occurrence and distribution of ground water. Ground water is a replenish able source. Rainfall is the principal source of recharge to ground water. Ground water levels reflect changes in the ground water regime due to recharge to and discharge from the aquifers. Depletion of ground water is defined as “The withdrawal of water from a ground water source at a rate faster than its rate of recharge, usually over an extended period of several years”
The Central Pollution Control Board (CPCB) has established ground water monitoring network in 411 Wells in 21 States. The Monitoring is done on half yearly basis in case of ground water.
The groundwater samples are being analyzed for 28 parameters consisting of physic-chemical and bacteriological parameters (Temperature, pH, Conductivity, BoD, Nitrate-N, Total Coliform, Faecal Coliform, COD, TKN, Ammonia, Total Dissolved Solids, Total Fixed Solids, Total Suspended Solids, Turbidity, Total Hardness, Fluoride, Boron, Chloride Sulphate, Total Alkalinity, P-Alkalinity, Phosphate, Sodium, Potassium, Calcium and Magnesium for ambient water samples apart from the field observation. Besides this, trace metals and pesticides are analyzed in selected samples.
The major sources of ground water contamination are domestic sewage, industrial pollution, agricultural pesticides and fertilizer percolation and natural geogenic activity. The ground water quality is degraded due to geogenic reasons with respect to salinity and major cations /anions. Increase of Nitrates and BOD are due to fertilizer and unsewered sanitation respectively. Ground water is largely affected due to salinity, fluoride, nitrate and arsenic.
The water pollution in rural areas is caused due to discharge of domestic sewage directly or indirectly into water bodies, agricultural run-off during rainy season containing chemical fertilizers and pesticides and effluents from agro-based industries. As per the Department of Drinking Water Supply, the ground water in a total number of 1,79,999 habitations in 26 States have been sound to be contaminated with fluoride, arsenic, iron , nitrate, or salinity.
The Ministry of Agriculture has taken steps to discourage excessive use of chemical fertilizer and pesticides. The Ministry of Rural development has been implementing schemes for improving rural sanitation and providing piped water supply to rural habitations affected by ground water contamination. The Pollution Control Boards have been undertaking regular inspection of agro-based industries in order to regulate their effluent quality.
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