Arunachal  dam project may cost India ₹1.13 tn

India may spend ₹1.13 trillion ($14.5 billion) to build the 10 GW Upper Siang multi-purpose storage project at Yingkiong in Arunachal Pradesh, a project that is central to counter China’s ambitious water diversion scheme of the Siang river that feeds downstream into the Brahmaputra.. The 10 gigawatt (GW) Upper Siang multi-purpose storage project will be built at Yingkiong in Arunachal Pradesh.

NHPC Ltd has been tasked with the project that will include building the dam to store around 10 billion cubic metres (BCM) of water. The state-run hydroelectricity producer is currently working on the pre-feasibility report (PFR) for the project.

“This (the dam) is for flood moderation, and power is a byproduct. The tentative investment we had worked out was around ₹113,000 crore. Its height would be 280-300 metres depending on the location of the dam and the capacity of the reservoir,” Abhay Kumar Singh, chairman and managing director of NHPC said in an interview.

Singh said that besides water security and green energy, hydro power projects also help control floods and develop fisheries. The Upper Siang project is among several which have been assigned to NHPC in Arunachal Pradesh. Noting the significance of dams in the border state to counter threats of unexpected water release by the northern neighbour, Singh said: “China is making a dam on the Siang which is known as Brahmaputra in the lower reaches. Around 75% of the water comes from our catchment because of vegetation, but if it (China) completes the dam and opens the gate, some day...” The north-east assumes significance because it has four major river basins -- Subansiri, Lohit, Dibang and Siang. Citing a Central Water Commission study, Singh said that in each of these basins, one reservoir is required. With the completion of each of the four reservoirs, water levels of the Brahmaputra at Pandu, a flood-prone area in Guwahati, will be lower by 1.8-2 metres during peak flood. “If you lower the water level by two metres, you will not have floods. This is very important for flood control and to save lives. Therefore, we need to make one big reservoir in all the four basins,” he said.

On the Subansiri project which has witnessed several hurdles in the past over environmental concerns, he said that there has been very good progress in Subansiri and the company expects to commission two machines in August 2022. While observing that heavy rains since April has impacted dam-related work and other structures, he added that work is progressing “very well”. The total capacity of the project is 2,000 megawatts (MW) and NHPC aims to set up four units by March 2023. The initial target was to set up the units by August 2022.

Singh expects to complete the project by August next year. In the next one year, 2,000 MW will be commissioned, he said.

“In October 2019, we got the clearance from NGT (National Green Tribunal) to resume the work and after that, we remobilized, started work and by March 2020, the impact of covid was felt, which continued for a long time. Despite the covid impact, we have a done a lot of work and this is the reason why we have been able to bring to the stage of commissioning.”

NHPC is also working on detailed desk studies on projects in middle Subansiri and upper Subansiri. “We are ready to award one other package called divergent tunnel... It takes at least two to three years’ time to complete the divergent tunnel works. Once it is completed, we will be able to start the dam work. Right now, we are working on these projects in Arunachal Pradesh,” he said. Noting that there is a lot of water in Arunachal Pradesh, he said that there is high discharge in the rivers there, which has led NHPC to take up several projects in the state.