Department of Environment Management, Indian Institute of Social Welfare and Business Management, College Square (West), Kolkata-700073, West Bengal, India.
Online published on 13 December, 2011.
Quantification of natural groundwater recharge is a basic prerequisite for efficient groundwater resource management and is particularly vital in an area where shallow groundwater is mostly polluted with highly toxic elements. It is especially critical where large and concentrated demand for groundwater supplies exist such as in urban areas, industrial zones and irrigated fields. Groundwater in English Bazar block of Malda District, West Bengal occurs under unconfined condition in a thick zone of saturation within the alluvial sediments. Potential aquifers have been encountered in the depth range of 44–69 m and 73–89 m where coarse sand and gravel are encountered. The discharge of the well ranges between 215 and 218 m3/hr with drawdown varying from 1.52 to 4.73 m. Transmissivity and hydraulic conductivity of the aquifers as computed by pumping test, ranges from 758 to 2969 m2/day and from 25.27 to 99.20 m/day respectively. Groundwater in this block is generally suitable for drinking as well as for agricultural use, except for some areas where arsenic concentration is above the permissible limit of 0.05 mg/l mostly in tubewells tapping the aquifer at depths between 15 m and 57 m. The annual groundwater recharge, net groundwater availability and groundwater draft estimated from GEC (1997) method is to the tune of 88 MCM, 84 MCM and 57 MCM respectively. Long term trend of water table (1996–2005) is ±5 cm/year (neither rising nor falling) and <-5 cm/year (rising) for pre-monsoon and post-monsoon periods respectively. The stage of groundwater development of this block is about 68%. Therefore, the block can be categorised as ‘Safe’. Quality wise groundwater resource has been estimated using arsenic as an indicator. The total amount of arsenic free groundwater is to the tune of 60 MCM which is about 71% of the total resource. There are eleven villages where the groundwater has high arsenic and twelve villages where more than 50% of the groundwater is contaminated with arsenic. In rest of the villages, the entire aquifer can be tapped for domestic, industrial and agricultural purposes. A phase wise management plan has been chalked out for the entire block.
English Bazar, Malda, Groundwater, Groundwater Estimation Committee (1997), Arsenic
