Friday, June 12, 2009

Tipaimukh Dam FAQ

By- Diganta

Of late I have been reading about Tipaimukh dam and a lot more about dams themselves. I have gathered a lot of information about that dam in particular. I would like to share it with the readers.

Where is Tipaimukh Dam located?

Tipaimukh is located at South-Western Manipur bordering Mizoram. Most of the people living here are actually of minority Hmar tribe. The proposed Tipaimukh dam is to be located 500 meters downstream from the confluence of Barak and Tuivai rivers. It is a huge earth dam (rock-fill) having an altitude of about 180 M above the sea-level with a average reservoir capacity of 15.5 BCM.

What is the technical purpose of the dam?

The Flood prone areas in East India

There are a couple of basic purposes – flood control and hydropower generation. It has been projected as a hydropower dam because of political purposes. Most of the inundation is in Manipur and Mizoram states, whereas it would moderate floods in lower Assam. To ensure fare share of benefits to those two states, hydropower generation is also taken into account. The states in North-East are having severe power shortage over years (peak shortage upto 25% in Arunachal). Once Arunachal starts producing hydroelectricity from giant Subansiri projects, the North-East India will become energy sufficient. On the other hand, there are no alternative to dams for flood-control of a rainfed river. Incidentally, both flood-control and hydropower generation reservoirs work in similar way – they retain water during Monsoon and release more during lean season, i.e. reservoir is filled up during rainy season and used up in dry season.

The Barak valley, consisting of three of the forty highly flood prone districts in India, goes under water three to four times (2002, 2004, 2007) in a decade. In 1995, plan for flood control Dam in Tipaimukh and reactions in Bangladesh were reported. Very often Barak flood is more devastating than that of Brahamaputra. A detailed assesment (2007 flood report) of floods in Assam can be found here. It has long been alleged that North-East has been neglected in terms of development and lack of flood control is one of the evidences.

The Tipaimukh dam is planned to produce 450MW in lean season and 1500MW in peak. All three states would have 12% share of the electricity and rest would go to the North East grid.

What are the objections to this dam in Indian side?

1.Displacement of people especially of vulnerable minorities
2.Vast forestland to be inundated along with the biodiversity
3.Dams are not fruitful solution to any problems
4.Possible earthquake could have devastating effect

What are the objections to this dam in Bangladesh?

1.Possible river drying and devastation of wetland (Haor)
2.Possible flood in summer/winter in lowlands causing damage to agriculture
Are Dams bad?

There is a widespread belief in India that dams are useful. On the other hand, the World Commission on Dams report on Indian dams has shown that they do more harm than help.

The report has a lot of loopholes in it. While reading, I saw it projects loss of Government (for example – tax on irrigated land did not produce as much revenue as projected) after building the dam as one of the key factors. However, in India, these are calculated as subsidies, i.e., where Government pays on behalf of its citizens. Also, it undermines the food security that has been obtained through irrigated land. It categorizes the agricultural land in two major divisions – rain-fed and irrigated. It shows that irrigated land has little contribution (~20%) to overall growth production. I don’t know how they classify land in West Bengal, where most of the agricultural land uses rainwater in in rainy season and irrigation in winter.

The Central Water Commission report praises dam-oriented water planning and plans for building more dam to hold onto monsoon water in big reservoirs. The purpose is to reuse the precious freshwater resource in dry season and moderate flood in rainy season.

Both of these reports fail to discuss in length the alternative of dams for these purposes and a comparative analysis of dams vs other methods of achieving the benefits. Hence, the entire policy calls for a widespread survey and comparative analysis.

There are reports that advanced nations are not interested anymore in building dams. This is actually true. But this does not necessarily be replicated by India. Most of those advanced nations also have abundant resources. By resources I do not only indicate alternative sources of energy and water, but also per capita land availability and skills required to effectively utilize these. India gets only 1800 cubic meter water per person per year. India has already over 4000 large dams. The only comparable country with similar resources is China, who has built 22,000 of them. At the same time, there is a significant decrease in dam building efforts in India. Between 1971 and 1990, the number of large dams constructed was 2256 and the same after 1990 is only 695. Nowadays, the dams are built only if there is a compulsion for it.

What’s the possibility that Tipaimukh would end up drying the Surma-Kushiyara river system?

A Typical Flood Control Dam outflow graph
It’s highly unlikely. The dam can be used in its full potential without withdrawing any river water. A dam with a reservoir actually augments the flow of a river during dry season, while it withdraws the same during rainy season. One typical flood control dam outflow graph is shown in the picture.

Also, to consider Hydropower generation, a limited discharge has to be there during lean season also. This discharge will add to the flow and increase lean season flow.

Is there any other dam in nearby region that achieve similar goals?

Inflow Outflow graph for Karnaphuli

Yes, the Kaptai dam (Bangladesh) on Karnaphuli achieves the similar goals with a much larger reservoir. It controls flood, generates hydropower and increases navigability in downstream Chittagong port. The Karnaphuli river is also a rainfed river and has high seasonal variation in discharge. A reservoir with a dam was able to moderate and coltrol its flow.

It is interesting to note that this dam did not “dry up” the downstream flow at all, rather it augmented the flow during the lean season and buffered the additional flow during the rainy season.The picture shows the inflow (blue pillars in the graph) to Kaptai lake (the reservoir) and outflow (maroon pillars in the graph) from the dam . The inflow amount would have been the same as the outflow, had there been no Kaptai dam. In the second picture, one can see how the total volume of water in the river basin has been augmented using a reservoir. It shows the Karnaphuli river before and after the dam has been erected and the area inundated to create space for reservoir water.

Another river in context can be discussed since it has also been planned to moderate floods. It’s the Damodar river in West Bengal. It used to be the “sorrow of Bengal” in pre-Independence Bengal but was controlled successfully after DVC project with a series of dams and barrages. There are many periods in several years when the reservoir acted as a cushion and prevented catastrophic floods downstream.

The picture below shows the reservoir filling pattern in one of DVC’s storage facility named Maithon. Kaptai and Tipaimukh should follow similar patterns to fillup reservior. From October to May the reservoir releases more water than it receives, hence the reservoir water volume goes down. The rest of the period, the reservoir gets filled in.

Why is there such a huge difference between lean season and rainy season flow?

Cherapunji rainfall variation by monthThe Barak river basin region receives a lot of rainfall. The highest rainfall area – Cherapunji – is located nearby. However, virtually all of these rain comes during three months of rainy season due to Monsoon. The picture shows monthly variation of rainfall in Cherapunji.

What could be the effect of Fulertal barrage 100 km downstream?

A barrage can be thought as a tool of diverting water. In this case, water could be diverted to irrigate the Barak valley farmlands. This could be done during the lean season when the river flow is augmented, i.e., we have more water than we used to have. This would make good use of the additional flow coming out of the reservoir.

However, the amount of water to be withdrawn at the barrage site, is the key criteria whether it would harm the downstream. If it takes away the augmented portion of the lean season flow – it should not cause any issue. If it takes more, damages are done.

At this point we can do a reality check on how much water can be withdrawn for irrigation. We need to remember that irrigation is not for inundating the landscape, but for effective use of additional water during dry season. Hence, there is an optimal limit of how much water can be withdrawn of a river. The area under cultivation in Barak valley is 220,000 Hectares (in 1992-93, source). I found that Sudan has similar area under irrigation and uses 1.6 BCM of water per year (source, pg 21) from river Nile. Although, Barak valley is not as arid as Sudan is, we can assume at most similar amount of water will be withdrawn from the river. At the same time, the river water volume would be augmented by 15.5 BCM, of which at least 10 BCM would be live storage water. So, even after withdrawal for Barak valley irrigation, the flow downstream would be higher in dry season.

There is a widely held belief among lower riparian states that any amount of water could be diverted from the river upstream. This is not true. The amount of water diverted from a barrage is proportional to the Population (drinking and sanitary needs) and agricultural land available in the river basin. In this case, neither of these two are large enough to take even the water volume augmented by the reservoir.

Why Farakka causes damages downstream, where this barrage should not cause the same?

Farakka does not have any reservoir upstream to augment its lean season flow. So, it’s merely the same amount of water that comes to farakka which is then diverted to the feeder canals. This results in reduced flow downstream.

In fact, one of the proposals from Bangladesh side when Farakka was being built, was to add a reservior dam in Nepal to augment the flow of Ganges during the lean season. The World Bank was ready to fund the project. It did not happen because India stuck to its position to augment flows from Brahamaputra basin. Interestingly, I read that India has of late initiated works on what Bangladesh had proposed. Had this been done a little earlier, Bangladesh would not probably been hurt so much.

In case of this (Fulertal) barrage, the flow is augmented in the lean season. Hence it should not reduce the downstream flow in Surma and Kushiyara. Of course, there should not be any desertification with full potential dam and barrage as I argued in the previous section. The irrigation potential can be fully utilized without harming the lower riparian.

Another aspect of Farakka makes it different from Tipaimukh. The water diverted in Farakka is sent to the Bay of Bengal through a separate channel (Bhagirathi-Hugli). However, the flow of Barak can not be diverted in similar fashion to any of other areas – it has to come downstream. Apart from that small amount of water taken for irrigation of 220,000 Ha of land, the rest is virtually non-consumptive use, i.e. it would be passed downstream. The Tipaimukh dam would only change the temporal distribution of river flow.

What’s the possibility that an Earthquake would cause the dam to collapse or at least create a few cracks in it?

Damage due to earthquake cannot be ruled out though the possibility is remote. In case there is a really high intensity earthquake, it could cause the dam to have cracks. I believe Indian designers would take necessary steps to prevent any damage to the dam since it is known to be located on a geo-tectonic faultline. A basic text literature on dams says -

“If the dam site is located in a seismic zone, the most suitable type of the dam is one which can resist the earthquake shock without much damage. Earth dams and rockfill dams are generally more suitable for such sites, provided suitable modifications are made in the design. However, by adopting suitable measures and considering various forces and factors affecting the seismic design, other types of dams can also be provided.”

To add to the above literature, the Tipaimukh dam is indeed a rock-fill dam to mitigate the risk of a possible earthquake.

I would also like to add here that Japan has more than 2000 dams even though the whole of Japan is Earthquake prone. There were many earthquakes in Japan for last 100 years and no news of dam failures due to earthquake yet. Last 150 years of history did not record any incident of dam failure anywhere in the world due to an earthquake. In these days, building an earthquake safe dam is merely a choice of technology.

How the 15.5 BCM capacity of the reservoir would be filled up and what would be its consequence?

The first time it would be filled up from the empty position. Hence, it would require 15.5 BCM of water. Most likely, it would be filled up over a few years depending on flow during the rainy season. However, till the fill up is completed, the downstream flow will be lower. Dam fill up is generally done during high flow so that the effect is moderated downstream.

It also needs to be mentioned that reservoir fill up is a one time process. This would have no effect over long term yearly flow of the river. Some of the experts projected that 15.5 BCM of reservoir would cause 491 cumec (which is equivalent of 15.5 BCM per year) reduced flow downstream. This is not true. The dam is filled up only once and the water is used dynamically to fill up in rainy season and to release in dry season (look at Maithon reservoir graph and Karnaphuli inflow-outflow statistics).

Recently there was a contention between India and Pakistan regarding this first time fill up of the reservoir.

How would this affect the ecological balance of the region?

Dams, like all other man-made infrastructures, are actually disasters for ecological balance of a region. When a dam creates it’s own rule of ecology, the existing one is demolished. A brief overview of how Dams cause damage to ecological balance can be found here.

In this particular case, there are a couple of major ecological balance shifting. In India, this could potentially cause destruction of a vast forestland. In Bangladesh, it could potentially damage a vast natural wetland, known as Haor. Although, the extent of the damage to the Haors could not be measured at this point, the damage due to inundation is obvious.

I need to add a point on ecological balance in general. Shift in ecological balance does not always mean a problem in short term. It causes problem in the long term. Any flood moderation structure would cause damage to ecology – be they embankments or dams – as floods are part of ecological balance. There are two options – the first is to allow people to live with the floods and cause no damage to the ecology. The second is to establish a flood moderation embankment and damage the ecology for the long term. In this part of the world, building a flood moderation structure is more popular because of high population density in the floodplains. The problems of flood affected people generally exceeds by far the concern of damaging the ecology even in the long term. People assume that by that time, they would probably have sufficient technology to counter the backlash of Nature. Also, the democratic society creates pressure on the Administration to act proactively towards moderation of human problems. If humans are illiterate and unaware of long term damages, the short term solutions get political preference.

Of late, there are a lot of proposals floating against traditional flood moderation structures like river training, embankments and dams. However, the alternatives floated with those arguments are not significantly different than the structures they argue against and the alternatives do actually retain a lot of problems those are created by current structures. Although the alternatives are claimed to be more sustainable in Nature, a complete feasibility study along with their long term effects are yet to be observed, i.e. they are not yet tested to be sustainable, only claimed to be sustainable.

What are the Haors and how they are going to be damaged by this project?

A haor is a wetland ecosystem in the north eastern part of Bangladesh which physically is a bowl or saucer shaped shallow depression, also known as a swamp. It receives surface runoff water by rivers and channels. Consequently, a haor becomes very extensive water body in the monsoon and dries up mostly in the post-monsoon period. The haor basin is an internationally important wetland ecosystem, which is situated in Sunamganj, Habiganj and Moulvibazar districts and Sylhet Sadar Upazila, as well as Kishoreganj and Netrokona districts.

Haors in flood season - villages are islands
During the rainy season, haors turn into a vast inland sea within which the villages appear as islands. Occasional high winds during July to September generate large waves in the haor, which may cause considerable damage to homesteads. During the dry season, most of the water drains out leaving one or more shallow beels which become mostly overgrown with aquatic vegetation or completely dry out by the end of dry season exposing rich alluvial soils extensively cultivated for rice. As population increased in Bangladesh, boro (a rice variety) cultivation expanded onto these haors, leading to a large area being drained. Thus, the very existences of these wetlands are now threatened.

As the dry season flow would increase and rainy season flow decrease due to the dam – these wetlands would be impacted. The amount of inundation during the rainy season would reduce the water-logging of villages. At the same time, during boro cultivation, less water would be drained out, i.e. less land would be reclaimed to start cultivation. So, there are both threats and opportunities with the new seasonal variation of flow. A lot has been said on effect of Tipaimukh on haors. It is argued that the change in flow would eventually cause haors to dry up. I do see a possibility of haors getting dried up but not as a result of change in flow variation. The haors are already drying up as more and more population is trying to reclaim them. A couple of reading (link1, link2, link3) on this topic can make my point clear.

A brief look at where the Government of Bangladesh priorities are throws some different aspects of haors. As per the Daily Star report, Govt has started a massive flood control measure in Sylhet. This includes raising embankments and creating irrigation channels to divert water from the river flow. These would also do the same with the haors, reduce the inundated area dry up haors as flood water would not be allowed to enter those. The long term flood action plan (FAP) of Bangladesh clearly mentions eleven goals of flood moderation. The clause (7) says -

“Reduction of flood flows in the major rivers by diversion into major distributaries and flood relief channels; “

However, this goal also would have adverse effect on haors since river diversion implies less water for wetlands.

Tipaimukh dam would do the same that Government of Bangladesh already planned for – it would damage the current water cycle of haors. Haors are replenished by the floods and any effort to moderate the flood would cause the same – be it is done in India or in Bangladesh. The choice between “letting people to live with the floods” and “saving haors” – is open to individual personal views. It’s a choice with threats and opportunities.

Are there any other effects of the Dam?

Like the haors in Bangladesh, a lot of small wetlands exist in Barak valley also. Once the flood moderation kicks in, those would also probably dry up due to lack of replenishment. The valley would become dependent on irrigation water during dry season. Since the irrigation water is more regular – it would actually improve the consistency of cultivation in that area.

Similarly, Bangladesh plan for flood moderation and river diversion can also utilize the augmented flow in dry season. But a lot of these benefits would actually depend on how efficient the irrigation planning would be.

How does this case goes as per International Water Laws?

Neither India nor Bangladesh is a signatory of any of the International Water Laws (Such as Convention on the Law of the Non-navigational Uses of International Watercourses and Berlin Rules). However, neither of these are very specific laws – these are just framework of cooperation.

As I discussed in details in my earlier post, the equitable share of benefits can be claimed by any of the river basin countries. The obligation not to cause significant harm is a “best effort” clause and to achieve flood control a minimum extent of harm is justifiable. About the equitable distribution of the benefits, I am optimistic. Once the North-East India produces surplus electricity, a fair share of that can be exported to Bangladesh at a reduced price. For the time being, the barrage at Fulertal could divert some of the water to irrigate in Bangladesh, as suggested by B. G. Verghese (Member of Center for Policy Research) in his presentation to World Bank. He also noted -

“Indeed, Tipaimukh was the first flood moderation study suggested by Bangladesh when the Indo-Bangladesh Joint Rivers Commission was established in 1972.”

In this context, I need to mention that lower riparian does not have a veto power over a river development project upstream even if it harms them. For example, only 25% of Nepalese population has access to electricity. A huge population of Nepal is displaced every year due to floods. If Nepal plans to add 10,000 MW of electricity and want to achieve flood control in its rivers – the lower riparian India and Bangladesh cannot object without a mention of less harmful alternatives.

The project at Tipaimukh is still waiting for clearance from the state of Mizoram (Official status). Once that happens, I hope we would see the planners and designers would publish detailed data on the site and will not violate the obligation to exchange information.

How are the protests in India?

In India, protests are taking place mostly in Manipur and Mizoram, where most of the displacement would take place. Despite the promise of 12% free electricity, a lot of people stood against the dam. I saw a lot of newspaper editorials, blogs and pictures of protest from Manipur and Mizoram. However, the issue had little impact on the 2009 Indian Election as the ruling parties won again in both of these states. The Govt of Manipur has already picked up 5% stake in the project. I don’t see any reason why Barak valley in Assam is not happy with it.

I mentioned in my writing that dams do have short term benefits and it seems people are more interested in those.

No comments:

Post a Comment