Recently, there has been much discussion in the electronic and print media about the potential impacts of the Tipaimukh Dam on Bangladesh. The intensity of the buzz has heightened following the remarks made by the Indian high commissioner on June 21, and subsequent comments made by the water resources minister of Bangladesh. In both cases, they have assured the Bangladeshi people that not only the proposed dam will cause no harm to Bangladesh, it actually may even benefit Bangladesh.
In a live talk show organised by Voice of America (VOA), a non-resident Bangladeshi engineer, Dr. Khondakar Abu Sufian, suggested that the Tipaimukh Dam will be a blessing for Bangladesh, because it will have the potential to reduce flooding in Bangladesh by 30%, or the river-levels in Sylhet region will be reduced by 1.5 metres during rainy season. Apparently, this calculation about reduction of flooding by Tipaimukh Dam is based on a study done in 1992-94 under Flood Action Plan (FAP-6).
The opponents of the dam claim that this is a gross violation of international norms and the existing Ganges Treaty between India and Bangladesh. They also raised concerns about unilateral control of an international river by India, and think that the dam will reduce the flow in Surma-Kushiara-Meghna rivers during dry season and will increase during rainy season.
This author attempts to analyse the validity of these opposing claims by applying some basic principles of hydrology that are commonly used in such situations.
First, let's look at the promise of reduction of flow during rainy season. In order for anyone to be able to make this prediction or judgment, one will needs to have access to the water release schedule by India at Tipaimukh Dam, which is not available to anyone in Bangladesh.
One of the authors of the FAP-6 study, Dr. Ainun Nishat, pointed out in the VOA program that the Bangladeshi authorities carried out that study based on many assumptions, which may or may not be true.
In addition, the detailed project report for the Tipaimukh Dam was not prepared by India at that time or was not available to anyone in Bangladesh. The correlation between a river-level and the amount of flow in that river is called the rating curve of that river, which is prepared based on many years of flow-data and by recording corresponding river-levels (also called the stage of a river) during those flow events.
After the dam is built, only India will decide how much water they will release, and when they will release it. Therefore, without having that information about the amount of water to be released at Tipaimukh Dam, no one can predict how the river stage will change in a downstream location in Bangladesh.
So, the prediction that river stage will decline by 1.5 metres during flooding is not substantiated. The proponent of this flow reduction concept, Dr. Sufian, contradicted himself later in the VOA program by saying that "we are in complete darkness about the Tipaimukh project." Then, the question remains, what is the basis for the conclusion that Tipaimukh Dam will reduce flooding and will increase flow during dry season? Does anyone in Bangladesh have the information about the amount of water that India plans on releasing from Tipaimukh? The answer is a resounding no.
If even India promises that, they will release certain amount of water during certain periods, what guarantee is there that they will actually stick to their promise? Will Bangladesh have any written treaty or agreement on the amount released for certain time periods? If the Ganges Treaty is any indication of the reality, can Bangladesh rely on India's promise? Is the precedence there?
The past records do not support this assumption. In a recent interview with a newspaper, one of the members of the Joint River Commission, Mr. Tauhidul Anwar, revealed that Bangladesh did not receive her fair share in 9 out of the last 12 years since the treaty was signed.
The Tipaimukh Dam will have the maximum capacity to hold 15 billion cubic metres (BCM) of water, which, as per the Central Water Commission of India, accounts for about 30% of the total flow of the Barak River. This means that India will have unilateral control over 30% of the flow in an international river. In itself, this cannot be acceptable to a down riparian country (Bangladesh).
To produce electricity, India will have to release water from the dam from its highest level at 178m (when 15 BCM will be captured behind the dam) to 136m. A rough calculation indicates that, the amount of water that will be released equals to about 8 BCM. In other words, about 7 BCM of water will always be kept behind the dam to maintain enough pressure-head needed to generate electricity from the dam. This 7 BCM will be the dead storage (i.e. kept behind the dam permanently), which is equivalent to about 9,000 cusec.
In other words, if that 7 BCM was released evenly throughout the year, then it would equal to about 9,000 cusec of additional flow in the Barak River, which will eventually reach the Surma (60%) and Kushiara (40%)in the amount of 5,400 cusec and 3,600 cusec, respectively.
So, it is possible that during ordinary rainy season (unless there is a major rain event, in which case they will open all gates to secure the dam) flow in the Surma and Kushiara will be reduced by 5,400 and 3,600 cusec, respectively.
But, the same amount of reduction in dry season will have the potential to dry off these two rivers. Therefore, in view of this author the flow in summer will not increase in these rivers as suggested by Dr. Sufian. At least, Bangladesh does not have necessary data to make this judgment.
It should be noted that, the Tipaimukh Dam is being built as per Shukla Commission's recommendations. The same commission also recommended building of a diversion barrage downstream of the dam at Fulertal in Assam. For the Tipaimikh project to be economically viable, most likely, India will build the diversion project at Fulertal or at another suitable location.
The water resources minister of Bangladesh recently said that the Tipaimukh Dam can be beneficial for Bangladesh. If India and Bangladesh designed the project jointly, keeping Bangladesh's needs and demands in the plan, then probably the project could bring limited benefits to Bangladesh.
Since this is not the case, and since India did not even inform Bangladesh about the project, there is no reason to believe that India is designing this project to help Bangladesh out. This is a naive statement on the minister's part.
What is the way forward for Bangladesh? In view of this author, any project in an international river should be undertaken as a joint venture based on free flow of information from both parties involved. Bangladesh should insist on an integrated water resources management plan that keeps the interests of all stakeholders in the basin area.
We must also realise that a river-flow does not just carry water, it also carries sediments, which are essential for the growth of floodplain and delta plain in the face of rising sea level. Without the natural flow of river-water and sediments, the very survival of Bangladesh will be jeopardised in the future. All projects on rivers should incorporate a guarantee clause to ensure normal functioning of riverine eco-systems.
Md. Khalequzzaman, Ph.D., writes from Lock Haven University, US.