The Chinese Dams on Yarlung Tsampo (Brahmaputra) and our Dams : The real issues

Part – II

By Pradip Kr. Bhuyan

The issue of Chinese dams on Yarlung Tsampo, its tributaries and some related issues have been dealt in Part I of this article. In this Part II of the article, the issues of the proposed Aruchal dams is being discussed. The most vital aspect of all these Aruchal Dams is the water release mechanism from these dams and this vital aspect has been cloaked in secrecy under the guise as Run of the River (RoR) schemes, giving the impression that whatever is flowing in any river in the lean months is also flowing out through the turbines with no ecological damage to the downstream of the dam. Nothing is further from the truth. In reality, the 150+ dams of Aruchal as planned are all Peaking Hydro power projects that holds up water for 20 hours or so to a trickle or some amount of environmental flow (20% of the winter flow as fixed now), and shall create a tsumi every night when all the turbines will be run to produce maximum electricity in the peak hour demand period of evening / night.

These Peaking Hydro Power Projects of Aruchal are the product of “Power at any Cost” policy of the GoI through various ministries like MoEFCC, MOP, MoWR etc. and which philosophy is reflected in the Hydro Power Policy 2008 which in its ‘objective’ has no place for ecology, environment, riparian people, benefits as envisaged in the tiol Water Policies like irrigation, flood control, demographic and social aspects etc. The ‘objective’ of the policy as per sec 2.1 is basically to harness the hydroelectric power potential of the state (Aruchal Pradesh) and to accelerate the pace of this development.

The most disturbing factor of these peaking dams, is extreme variation of flow in 24 hours in the winter lean months which is an inherent built in aspect of all the ‘Peaking Hydro Power Projects’ because of its ture of operation, – holding up water to a trickle for 20 hours, and releasing in 4 hours or so in peak demand period.

Death of Brahmaputra

For Subansiri Lower Hydro Electric Project, the environmental flow (eFlow) as per the Environmental Clearance(EC) by MoEFCC is a mere 6 Cubic Meter per second (cumec) and that for Dibang Multipurpose Dam (DMD) only 20 cumec! If we even assume, that 20% of winter flow will be released as eFlow of Lohit, Dibang, Siang Lower dams as is being proclaimed now, then at the starting point of river Brahmaputra, after confluence of these 3 constituents of Brahmaputra, the mighty river Brahmaputra will have a flow of only 20% or so of its tural flow for 20 hours and a tsumi for 4 hours or so every day in the non-monsoon period. The variation in flow of Brahmaputra will be extreme like, 500 – 600 cumec for 20 hours to 8600 cumec for 4 hours as per design release of water from all the turbines. Even if 50% eFlow, (as recommended by the IIT consortium as an interim measure for Uttarakhand Peaking HE Projects after the 2013 disaster), is released as eflow, the diurl variation of flow will then be 1110 – 1200 cumec or so to 8600 cumec, - a huge variation in 24 hours, each day of the non-monsoon period.  

Similar is the fate of all the individual rivers – Lohit, Dibang, Siang, Subansiri & Kameng. They will be subject to severe flow variations in their respective valleys in winter lean seasons and ecology and environment of the pristine valleys of Aruchal will be destroyed for ever.

This daily extreme variation of flow, well annihilate the dolphins, fishes, turtles and other biota, increase erosion and severely impact the riparian people.  

No flood control component in the Aruchal Peaking Dams :

All the proposed HEPs are peaking hydro electric projects which include the Dibang Multipurpose Dam (DMD), billed as the world’s tallest gravity dam at 288m height. It is claimed by NHPC, the project proponent, that some provision in the storage reservoir is earmarked for flood control in the DMD. But in reality, it is totally insignificant for any effective flood control measure.

Brahmaputra Board (BB) planned a flood control and power generation dam in Subansiri at Gerukamukh of 257m height where the capacity of the reservoir was planned at 14,000 Mcum for effective flood control. The Dibang Multipurpose Dam (DMD), is planned as the tallest gravity dam of the world at 288m but has a storage capacity of paultry 3850Mcum primarily for power generation. All hydro power dams of Aruchal have no effective flood control component and in the inkling of a major flood coming, operators will open all the sluice gates for safety of the dam itself as else, the flood water will overtop the dam. Such sudden opening of the ‘sluice gates’ is happening all the time from the Rangadi Hydro Electric Project located in a subbasin of Subansiri in Lakhimpur district. Bhutan peaking dams regularly creates severe floods suddenly in lower Assam, through release from these peaking dams.  

Sustaible Dams

Sustaible dams are baseload generation dams that produce electricity continuously with a free flowing river where the water of the river flows through turbine(s) and/or over the dam, - i.e. the river flows turally uninterrupted and unhindered as true Run of the River dams. The power house is located in the toe of the dam and (not kilometers away as proposed in many of the peaking dams of Aruchal totally killing the river for long stretches).

Once the Peaking HEPs which are on paper only as of now (except Subansiri Lower HEP), are converted to Baseload HEPs, these HEPs will generate sustaible power continuously as true Run of the river projects. There will be no sluice gates. These type of HEPs, completely elimite all the downstream ecological disasters associated with the Peaking HEPs as the river will flow freely downstream of the project without any hold up of water. There will be no cause of ‘Panic release’ of the reservoir water, creating sudden disastrous floods, as the dams will not have any sluice gates! The reservoirs will be small, the height of the dams reduced, - making them safer to seismological disasters. These projects will generate sustaible Baseload power for the country’s growing Baseload demand.

The proposed 150+ plus dams of Aruchal can easily be converted to sustaible true Run of River (RoR) projects including Subansiri Lower Hydro Electric Project :

The present peaking dams of Aruchal are easily convertible to free flowing run of the river (RoR) hydro electric projects like the Zangmu Dam of Chi on Yarlung Tsampo, because no actual construction has started in any of the four major basin of Aruchal – Lohit, Dibang, Siang, Kameng. (In Kameng a project is under construction by NEEPCO on two tributaries of Kameng, - Bichom and Tenga. It is small project and need not be disturbed.)  Only major project that is under construction is the Subansiri Lower Hydro Electric Project (SLHEP) by NHPC Ltd., in the Subansiri basin. But since the dam is at a low level of construction, - 72m of the dam is yet to be constructed, it can easily be converted to a baseload project even utilizing the present powerhouse as constructed – i.e. the river flows either through turbines and/or over the dam. There will no sluice gates. This changeover will ensure a reduced height of the dam and a free flowing river at all times.

It is pertinent to point out that in 2010, a GOM (Jairam Ramesh, Prab Mukherjee, Sushil Shinde) decided to scrap the under construction Loharing pala Dam on Bhagirathi (Ganga) by NHPC who by then had completed 20% of the project work, because of spiritual and environmental issues. This goes to show environment, ecology and right of other stakeholders in a river cannot be brushed aside.

Effect of Yarlung Tsampo

In winter lean months, the water of Yarlung Tsampo may constitute around 50% - 57% of the Brahmaputra’s flow at its starting point near Dibru Saikhowa tiol Park (DSNP) after the confluence of Lohit, Dibang & Siang. It means, if Chi diverts 30% or so of its water in Tibet, for irrigation, water supply and other usage (HEPs donot hold up water), it will mean reduction of flow in Brahmaputra at its initial starting phase near Dibru Saikhowa tiol Park (DSNP) by about 15% - 20% based on data as available as a kind of indicative figures. But the situation will improve as the river flows downstream and major tributaries like Buridihing, Subansiri, Kameng etc. join the river.  Also, in monsoon period, because of the heavy rainfall in the Aruchal valleys, the above non-monsoon situation of dependence on Tsampo water on Brahmaputra for its integrity will reduce significantly.

A landmark development for Ganga

In a landmark development, GoI, through the Ministry of Water Resources, River Development & Ganga Rejuvetion, has submitted an Affidavit in the Hon’ble Supreme Court in 1A No. 6 of 2013 on 31st May 2016  concerning peaking HE Uttarakhand Projects in which it is submitted that,  “The Ganga Himalayan basin is inclusive of Bhaghirathi Basin, Alakanda Basin and Mandakini Basin and form the origin path of Ganga and in order to secure / rejuvete the rivers, her conservation all along the origin path of the river is most required step in Ganga Rejuvetion Unfettered/un-interrupted flow of river in all the three river basins i.e. Alakanda, Bhaghirathi and Mandakini is, therefore, crucial to the conservation of Ganga”.

This is a quantum jump forward to remove the gasping environmental scerio of the Ganga basins and the river Ganga itself.

The Real Issue – , The peaking dams of Aruchal: These dams are a life and death issue for Assam and the Aruchal valleys as the extreme variation of flow per day from these dams, will annihilate the total ecology of the river Brahmaputra, - dolphins, fishes and other biota. The riparian people’s lives will be become topsy turvy, - the Luit as we know will be lost for ever. The pristine valleys of Lohit, Dibang, Siang, Subansiri & Kameng will also die ecologically. This threat looms over our head and will happen suddenly one day after a decade or two if these peaking dams of Aruchal are commissioned as planned now. It will be a fait accompli then, - too late to do anything but to die alongwith Brahmaputra!

Ganga and Brahmaputra

What is applicable to the Ganga cannot be different from Brahmaputra and must be adhered to Brahmaputra as well as there cannot be two yardsticks – one for Ganga, another for Brahmaputra. Read in the context of the Brahmaputra, it means unfettered / uninterrupted flow of the three rivers – Lohit, Dibang & Siang, the constituent tributaries of Brahmaputra, alongwith Subansiri and Kameng which augment the Brahmaputra flow in its initial formative stage of flow and this must be a guiding principle for the HEPs of Aruchal. This can be met only by scrapping the Peaking format of these HEPs which are basically on paper at this moment to be replaced by Baseload HEPs for 24x7 continuous generation for power and turally flowing rivers – unfettered and unhindered.

We have the opportunity to make the above changes now for all the 150+ proposed hydroelectric projects in Aruchal as no work has started in any of the projects, including in the Subansiri Lower Hydro Electric Project, work of which is stalled since Dec 2011 due to people’s protests and 72m of the dam is yet to be constructed.