Dear Sudhir: I too was wondering how Gujarat ( and Maharashtra) are suffering so much from floods, considering all their dams. What I did not know was the facts of the two states having as many dams as you informed us they do.
It is another highly informative and timely article. Thanks for all you do to educate us. Best. Chandan ---- Vombatkere <[EMAIL PROTECTED]> wrote: > To > Ms.SUNITA NARAIN > > Dear Sunita ji, > > I am submitting the short article below, which I hope will find favour for > early publication in DTE. > > Best wishes, > > Sudhir Vombatkere > **************************************************************************************************************** > > > FLOOD DISASTERS > > Why, God, every year? > > By > > S.G.Vombatkere** > > > > Almost every year, floods ravage various states. According to news reports in > most of the cases, the flood disaster has been caused by panic release of > water from dams since inflow to the reservoir was very high. Maharashtra and > Gujarat, both hit by floods this year, together have more than half of the > country's 4,500 large dams, so it is a moot point whether dams provide > protection from flood. > > > > Flood, a natural phenomenon, becomes a disaster when large quantities of > water arrive very quickly or do not recede quickly. Rainwater comes too > quickly either because of unprecedented rainfall and/or due to deforestation > that causes very fast arrival of water in the main rivers. A large dam can > "control" flood only if the reservoir has sufficient empty capacity to absorb > the sudden arrival of water. But in practice, reservoirs are never emptied in > anticipation of flood because water from the reservoir is required for > irrigation or power generation. (If it is a low rainfall year and the > reservoir is empty, the flow will merely fill the reservoir and the > downstream river will get no water at all). When the flood does arrive, the > sluices are opened to save the dam and people, assured of protection from > flood, who have occupied the flood plain below the dam, suffer because of the > sudden release of water from the reservoir. > > > > Some claim that flood can be relieved by diverting water from flooded areas, > preferably to areas that are water-starved. In the case of the Ganga basin in > Bihar, flood flow is 50,000 cumecs but only 5,280 cumecs in the dry season. > Diversion of water is an impractical idea because the largest canal (100 > metres wide and 10 metres deep) can divert a mere 2,000 cumecs or 4% of the > flood flow, while in the non-flood season the canal cannot be used since it > will draw 38% of the water when it is needed most. This is apart from > technical problems of ensuring that the canal diverts water without the heavy > sediment load even if such a canal is constructed, and the social problems of > population displacement by inundation due to the barrage constructed for > feeding the canal. > > > > Thus, while large dams may offer flood management advantages in a limited > temporal or spatial context, they also create larger magnitude problems that > are not generally recognized. Flood management and the performance of India's > large dams for flood "control", irrigation and power generation over the past > few decades needs urgent and transparent review. > > > > (417 words of text) > > _____________________________________________________________________________________ > > ** Maj Gen S.G.Vombatkere (Retd) is a military engineer holding a PhD in > Structural Engineering from I.I.T., Madras. > > CONTACT DETAILS: > > Maj Gen S.G.Vombatkere (Retd) // 475, 7th Main Road // Vijayanagar 1st Stage > // MYSORE - 570 017 > > Tel: 0821-2515187 > > E-mail: [EMAIL PROTECTED] > > ______________________________________________________________________________________ > > > > _______________________________________________ assam mailing list assam@assamnet.org http://assamnet.org/mailman/listinfo/assam_assamnet.org
