Effect on Water Resources from Upstream Water Diversion in the Ganges Basin

Abstract

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.

Man‐made climatic changes in the Ganges basin

“…Figure 1 illustrates the approximate locations of these water-diversion constructions (by dark and numbered circles around the border and open circles in the list of international rivers) along with nine major dams and barrages of the adjoining West Bengal state in India (Adel, 2001). …”

“…Illustration of the river systems of Bangladesh and West Bengal (India). The approximate locations of the Farakka Barrage and other dams and water-diversion constructions in the Hugli and Ganges basins are shown (Adel, 2001) Figure 3. Illustration of the average annual discharge rate of the Ganges through Bangladesh (Hebblethwaite, 1997) …”

Assessing groundwater resource and its sustainability in drought prone area of India

“…where G R is renewable groundwater resource in m 3 and N is total population. The renewable groundwater resource is obtained by a simple groundwater budget equation 14), 15) considering the negligible recharge during nonmonsoon season.…”

“…For example, to determine GIR for a major crop Jowar (sorghum), NIR was estimated by CROPWAT model to be 387.20 mm (it generally varies around 400 mm 22) ) and 0.65 23) of E F for Solapur district was used in equation (4) . From these results, groundwater abstraction for irrigation is estimated to be 31.14 million m 3 . Most of the crops don't need irrigation during monsoon season hence irrigation volume is less (9.89 million m 3 ) as compared to non-monsoon season (21.25 million m 3 ).…”

“…Globally groundwater is estimated to provide at least 50% of drinking water needs, 40% of industrial demand (that do not use urban mains water), and 20% of irrigation water-use 2) . Three problems dominate groundwater uses: depletion due to overdraft; water logging and salinization mostly due to inadequate drainage and insufficient conjunctive use; and pollution due to agricultural, industrial and other anthropogenic activities 3) . In particular, decline in water table is an ubiquitous problem.…”