Adel Miah M
Interdisciplinary Sciences Research Center, P. O. Box 4941, University of Arkansas at Pine Bluff, Pine Bluff, AR 71601, USA.
J Water Health. 2005 Dec;3(4):435-52. doi: 10.2166/wh.2005.053.
The Bengal basin has the world's densest water diversion constructions on the natural courses of rivers. The most damaging water diversion construction is the Farakka Barrage upon the international River Ganges. The diversion of water through this barrage and other constructions upstream of it has reduced the Ganges flow rate by 2.5 times. The resulting downstream effects are the depletion of surface water resources, more withdrawal than recharge of groundwater, sinking groundwater table, spread in depth and extension of the vadose zone, changes in surface features, climatic changes, etc. An investigation was carried out to find the contributions of water diversion to the arsenic contamination of groundwater in the Bengal basin. The reasonable scenario for arsenic contamination is the oxygen deficiency in groundwater and aeration of arsenopyrites buried in the sediment that would remain under water prior to 1975. The mineral forms water-soluble compounds of arsenic when react with atmospheric oxygen. These soluble arsenic compounds infiltrates to the groundwater. This article summarizes the short-time and incomplete study-based quick conclusions reached by investigators that have totally avoided the vital issue of water diversion. It then shows the depleting condition of the water resources under continuing diversions, the generation of favorable condition for arsenic release, the reasons for low sulfur concentration, the reason for first contamination in the Hugly basin, and the hindrance to water's self-purification. The articles advocates that the restoration of the virgin wetland ecosystems in the Bengal basin following the stoppage of the inordinate amount of unilateral upstream water withdrawals can remove the catastrophe.
孟加拉盆地在河流的天然河道上拥有世界上最密集的引水工程。最具破坏性的引水工程是位于国际河流恒河上的法拉卡大坝。通过该大坝及其上游其他工程的引水，已使恒河的流量减少了2.5倍。由此产生的下游影响包括地表水资源枯竭、地下水抽取量超过补给量、地下水位下降、包气带深度扩展和范围扩大、地表特征变化、气候变化等。开展了一项调查，以确定引水对孟加拉盆地地下水砷污染的影响。砷污染的合理情形是地下水中缺氧，以及1975年之前埋在沉积物中、原本处于水下的毒砂曝气。这种矿物与大气中的氧气反应时会形成水溶性砷化合物。这些可溶性砷化合物渗入地下水中。本文总结了调查人员基于短期且不完整的研究得出的快速结论，这些结论完全回避了引水这一关键问题。然后展示了在持续引水情况下水资源的枯竭状况、砷释放的有利条件的产生、低硫浓度的原因、胡格利盆地首次污染的原因以及水的自我净化的障碍。文章主张，在停止上游过度的单边取水后，恢复孟加拉盆地原始的湿地生态系统能够消除这场灾难。
