Tipai dam to wreak eco havoc for long
The Tipaimukh Dam will decrease water flow in the Barak river during the monsoon, reduce the navigability of the Surma and the Kushiyara, dry up some beels and haors and increase riverbank erosion 100-150km downstream.
The impact of the dam, like reduced water flow during the monsoon, will be visible immediately after the dam is operational; but the impact on ecology will continue for the next few centuries, a hydrological impact study has noted.
If India builds the dam on the Barak at Tipaimukh in Monipur, around 26 per cent of haors in Sylhet and around 11 per cent in Moulvibazar will become dry, the study claims.
The Barak enters Bangladesh territory and splits into two tributaries, the Surma and the Kushiyara.
The study says that the water inflow during monsoon will be reduced up to 10 per cent in June, 23 per cent in July, 16 per cent in August and 15 per cent in September at Amalshid point on the Kushiyara.
At Kanairghat and Sylhet station on the Surma, average water level will drop by 0.75 metre and 0.25 metre, in those months, the study titled 'Hydrological Impact Study of Tipaimukh Dam Project' has said.
The study was conducted by the Institute of Water Modelling (IWM) Bangladesh in 2005.
The report summarised the overall nature of impact in six categories, including hydrological impact, impact on flooding patterns and on river-floodplain-wetland ecosystem, impact on morphology, impact on water quality, dam-break and overall in general.
The study says that during a drier monsoon season when Bangladesh will be needing water for fish and cultivation, the dam authorities will hold 27 per cent more water in June, 16 per cent in July, 14 per cent in August and 4 per cent in September than an average monsoon year.
The study predicts that the 390-metre-long and 162.5-metre-high dam will change the hydrological pattern of the Barak, the second largest drainage system in northeast India, and reduce the navigability of the Surma and Kushiyara downstream.
The dam will add to the overall deposition on the riverbeds of the Surma and Kushiyara and both the rivers will loose navigability and erosion will continue over a hundred kilometres downstream.
The study further says that the pre-monsoon water inflow in April and May will increase up to 25 and 15 per cent due to release of water from the dam just ahead of the monsoon.
It says that it will cause moderate to severe floods in some parts of the Sylhet region in April and May and inundate boro fields at harvest time.
The impact on the river-floodplain-wetland will destroy the natural integrity of the ecosystem and the consequences of this will induce the loss of habitat for many species and even cause extinctions in the north-eastern region of Bangladesh.
Dam break is another big issue for the downstream region, the study expressing concern quoted Joseph Ellam, Pennsylvania state director of dam safety, “With the exception of nuclear power plants, no man-made structure has a greater potential for killing a large number of people than a dam.”
The government of India has never officially informed the Bangladesh about the content of the study until now.
Ainun Nishat, vice-chancellor of Brac University and an eminent hydrologist of the country, yesterday said, “The dam should have been a project of both the countries and if it was properly designed and managed, India and Bangladesh would have benefited.
“We don't know what India is now doing.”
Quoting Indian foreign ministry officials, a Bangladesh foreign ministry press release yesterday said India is to provide details of the development on Tipaimukh Dam once the offices open today.
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