Effect on water resources from upstream water diversion in the Ganges basin

Bangladesh faces at least 30 upstream water diversion constructions of which Farakka Barrage is the major one. The effects of Farakka Barrage on water resources, socioeconomy, and culture have been investigated downstream in the basins of the Ganges and its distributaries. A diversion of up to 60% of the Ganges water over 25 yr has caused (i) reduction of water in surface water resources, (ii) increased dependence on ground water, (iii) destruction of the breeding and raising grounds for 109 species of Gangetic fishes and other aquatic species and amphibians, (iv) increased malnutrition, (v) deficiency in soil organic matter content, (vi) change in the agricultural practices, (vii) eradication of inland navigable routes, (viii) outbreak of waterborne diseases, (ix) loss of professions, and (x) obstruction to religious observances and pastimes. Further, arsenopyrites buried in the prebarrage water table have come in contact with air and formed water-soluble compounds of arsenic. Inadequate recharging of ground water hinders the natural cleansing of arsenic, and threatens about 75,000,000 lives who are likely to use water contaminated with up to 2 mg/L of arsenic. Furthermore, the depletion of surface water resources has caused environmental heating and cooling effects. Apart from these effects, sudden releases of water by the barrage during the flood season cause devestating floods. In consideration of such a heavy toll for the areas downstream, strict international rules have to be laid down to preserve the riparian ecosystems.