Groundwater Resources of West Bengal:Status and Prospect

Contrary to general impressions, West Bengal has very little extractable natural resource in the form mineral or forest wealth as enjoyed by many other states of India. But in respect of land and water resources, it is perhaps one of the richest in the world in terms of a physio-graphic unit. The state has an abundant average annual rainfall, which even in lean years, rarely goes down below 1000 mm. Sensuo stricto, there are no areas of hydrological drought in the state. There may be visitations of agricultural or economic drought in certain selected pocket because of specific geological and geomorphological factors obtaining in the terrains, occasionally aggravated by stochastic weather phenomena.

Rainfall being the primary source of all natural water resources, West Bengal is blessed with huge surface water and ground water reserves. However, in respect of surface water, though theoretical availability is nearly 5.8 million ha. m. per year, yet the actual utilisable and renewable base is of the order of 2.1 million ha. m. Because, in view of the flat alluvial terrain factors in major parts of the state, not much of the monsoon rains can be stored. Many possible storage structures have been created over the last few decades and perhaps saturation limit of the efforts will be reached very soon.

On the other hand, the average annual dynamic recharge to groundwater bodies is conservatively estimated to be about 2.4 million ha. m. and between 50% and 60% of the same can be exploited. It is a sad commentary on our technological and institutional planning genius that so far we have not been able to harness the huge potential to the best and optimum advantage of all the users. The present quantum of utilisation is hardly of the order of 0.28 million ha. m. annually, Compared to many other states, West Bengal has been rather tardy in starting the development of ground water resources. But if the ultimate target of irrigating the maximum possible 62% of gross cropped area is to be achieved, then much headway has to be made in proper planning in investigation and development of ground water resources. The vast ground water reserves of this state are taken for granted by the lay public as well as planners. But their distribution in time and space are guided by geological and gemorphological factors. Our information and activity base for the aspects have to be progressively refined and vigorously expanded in the coming decades, so that we can make meaningful efforts for optimum and conjunctive use of ground water and surface water resources.