Causes of Acute Water Scarcity in the Barind Tract, Bangladesh

Abstract

The Barind tract is an elevated landmass (about 11-48 m amsl) comprised with Pleistocene terraces and is situated in the northwestern part of Bangladesh. At present, this area faces scarcity of water. The present study is an attempt to unveil the causes of water scarcity of the area. Several aspects like change in climatic condition, irrigation practice and drainage characteristics of major rivers are the prime factors for water scarcity. Interpretation of recent satellite imagery and historical records reveal that the major rivers of the area like Ganges (Padma), Tista and Kosi have remarkably migrated from Barind tract during last few hundred years. Shifting of these rivers causes great change in hydrodynamics of the Barind tract. As a result, flow of other related rivers of the area like the Mahananda, Kulic, Tangon, Punarbhaba, Atrai, Little Jamuna, Karatoya and Nagar reduces remarkably in the dry season. As a result aquifers in the area are not recharged sufficiently by river water in the dry season. India constructed Farakka barrage on the Ganges (Padma) river in 1975 to divert the flow of water from Bangladesh to the other parts of India. This diversion of water also leads to the decreasing of water in the area. Climatic data interpretation of the last 50 years also reveals that annual rainfall in the area is decreasing while overall temperature is increasing. To boost up the cropping intensity (117% to 200% compared to national average of 174%) and to meet present demand 74% of cultivable lands are being irrigated with 96% share of groundwater owing to unavailability or scarcity of rainfall and hence surface water. Irrigation by groundwater has dramatically been increased (250 times) in the last 30 years. Due to over exploitation, water table progressively declined (av. rate 0.10 m/year) which ultimately leads the area to water scarcity zone. The aquifers are confined or semi-confined and do not get appreciable vertical recharge through clay beds. Recharge is mainly through the exposures of sandy strata in the river beds which are flooded in Monsoon season. All sorts of parameters for water scarcity indicate that this condition may aggravate further if no rescue measures are taken immediately.