Since people in both Arunachal and Assam are heavily dependent on the Brahmaputra river for their quotidian water needs, the diversion of lean season flows will affect their day to day existence and the flora, fauna and the river ecology of the region. Large volume of water storage by China at the Great Bend Project could also lead to artificial floods during monsoon in Arunachal Pradesh and Assam.
The Chinese project will also reduce lean season flows in the river, thus, techno-economic feasibility of the Lower Siang Hydroelectric Project (2,700 MW) in India will be severely affected. With a view to counter the threats from the upper riparian neighbour, construction of Upper Siang Hydroelectric Project (HEP) with large water storage in the reservoir will keep the river alive during the lean season and will also absorb any flood water release after construction of Great Bend project.
Siang Upper Hydroelectric Project is proposed to be located in Upper Siang district of Arunachal Pradesh NHPC and NEEPCO have jointly been assigned the task of construction of this project. On December 30, 2022, NHPC has submitted a pre-feasibility report of the project. Installed capacity of the project would be 11,000 MW. Reservoir of the dam will have a storage capacity of 9 billion cubic meter (BCM). Estimated cost of the project would be ₹1,13,000 cr ($ 13.13 b). Such large investment in Upper Sian will give a boost to the economy and infrastructure of Arunachal Pradesh and the entire northeast.
Notably, out of total annual electricity generation of about 47,000 MU from Upper Siang in a 50% mean year, 12% will be given free to Arunachal Pradesh. This means the state will get 1320 MW free of cost. Even with conservative estimate of sale rate of ₹6.00 per unit, Arunachal Pradesh will get an annual revenue of ₹3,384 cr from free power in a mean year. In addition, 1% of revenue from the project i.e. approximately ₹282 cr per annum would be distributed amongst locals. Each project-affected family would get 100 units of electricity as per the provision contained in the National Hydro Power Policy 2008. This would be in addition to the Rehabilitation and Resettlement compensation.
Upper Siang project, once constructed, will become backbone of the economy of Arunachal Pradesh and will usher in an era of prosperity in the state, providing employment and generating business opportunities for the local population. Fish breeding in the 125 km length of the reservoir would enhance income of locals . Water transport in precipitous hilly terrain and water sports activities in the reservoir will be other attractions.
This project will be crucial to combat the impact of climate change in Brahmaputra basin, to keep the temperature rise commitments made during the 2015 Paris Agreement, achieving net zero carbon emission targets committed during the COP26 in Glasgow and during the COP27 in Sharm El-Sheikh, Egypt. Upper Siang Project will help India to move quickly on the path of energy transition by phasing down coal generation to non-fossil fuel renewable energy. It will reduce approximately 32 MT of CO2 annually, being presently released from coal-based plants.
A recently concluded study on climate change in Arunachal Pradesh by the author depicts that the present average annual temperature of 29° C will increase by 1.5° to 2°C by 2060 and by 2.3° to 2.8°C by 2100. This study also depicts that the present average annual precipitation of 2987mm will decrease up to 7.5% to 10.2% by 2060.
The construction of safe dams in India to address water and energy security is essential. In this context, construction of the Upper Siang is a step in the right direction.
Solar and wind power generation has seen exponential growth in the past, yet a lot more is required to be done. Ending October, 2023, out of total installed capacity of 4,25,536 MW in the country, renewable energy share is 1,78,633 MW which includes 46,850 MW of hydro generation. By the year 2030, renewable energy will increase to about 5 lakh MW. With significant injection of solar and wind renewable into the grid, storage dams with hydropower generation including pump storage have become the backbone of energy transition. Siang Upper Hydroelectric Project (11,000 MW) with water storage of 9 BCM can effectively be ramped up and down (increased and decreased) as per power demand. It will provide grid stability and will also help in integration of large scale renewable energy into the system.
Water stored in Siang Upper dam will be crucial in providing water security, keeping in mind the extreme events and adverse climatic occurrences worldwide due to global warming.
Positive impact of Upper Siang would, however, be directly visible in the event of diversion of the Yarlung Tsangpo by China to the north. It is equally important that while designing Siang Upper Hydroelectric Project, risk factors on account of extreme events due to climate change as well as due to sudden release of water from the upstream proposed dam at the Great Bend by China be incorporated in the design parameters.
