Siang vs Medog: Why India's Answer to China's Mega-Dam Is Stuck in Arunachal

The Indian government describes the Siang Upper Multipurpose Project (SUMP) as a necessary response to China's dam on the Yarlung Tsangpo. As of 17 October 2026, it has not been able to complete even the pre-feasibility survey. The people blocking it are not in Beijing. They are Adi villagers in Arunachal Pradesh's Siang and Upper Siang districts, and the dispute has moved from public meetings to torched vehicles, arrests and preventive detention orders.

A storage argument, not a power argument

SUMP is planned at around 11,000 MW with 9.2 billion cubic metres of storage, and has had national-project status since 2008, according to Deccan Herald. Other reports put the capacity between 11,000 and 12,500 MW. NHPC is the executing agency and began preliminary surveys in 2024. Reporting from 2025 gave an expected cost of about ₹1.13 lakh crore.

China's side is documented in more detail than its capacity. Xinhua reported on 19 July 2025 that Premier Li Qiang announced the start of construction on a hydropower project in the lower reaches of the Yarlung Zangbo, at a ceremony in Nyingchi. The project has five cascade stations and an estimated investment of about 1.2 trillion yuan (roughly 167.8 billion US dollars), and is meant mainly to send power outside Tibet while also meeting local demand. Xinhua's report gives no generation figure. An IDSA commentary cites Chinese reporting of the December 2024 approval as a scale of nearly 60 million kilowatts, which matches the 60,000 MW figure Chief Minister Pema Khandu uses.

Khandu's own case for SUMP has never been mainly about electricity. In December 2024 he called hydropower a by-product and said the purpose was to keep the river's flow natural through the year and to moderate floods if China released water suddenly. In October he made the same point with numbers: China's project is reported to hold about 5.5 bcm, against 9.2 bcm of live storage at SUMP, and power output differs so sharply because the Great Bend gives China an enormous drop in elevation.

That reframing changes what has to be proved. If the argument is about storage, the 60,000 MW versus 11,000 MW comparison is beside the point. The question becomes whether a reservoir of that size in Arunachal would absorb an upstream release well enough to justify what it would submerge. The sources reviewed for this piece contain no published release modelling, and the Chinese storage figure comes to us through Khandu rather than through Chinese documents.

The data gap the dam does not close

On 6 August, at the 36th meeting of the India-China Working Mechanism for Consultation and Coordination in New Delhi, India again asked China to resume sharing hydrological data on the Brahmaputra and to hold an early meeting of the Expert Level Mechanism on trans-border rivers, according to Phayul. The 2013 memorandum covers water level, discharge and rainfall data from three stations on the Yarlung Tsangpo. Phayul reports that Indian officials say no data has arrived since June 2023, a date that fits an IDSA commentary noting that an earlier data-sharing MoU expired on 5 June 2023 with renewal still under negotiation. I did not find an official readout confirming the June 2023 date, so it should be read as reported.

The two tracks are separate. A reservoir would cushion a surprise from upstream but would not tell India when the surprise is coming. The dam answers an information problem with concrete, and the information problem is the one India is raising in diplomatic meetings.

How the survey became the fight

The government says the pre-feasibility report only tests viability and is not approval to build, and that public consultation and assessments would come before any final decision. Opponents, led by the Siang Indigenous Farmers' Forum (SIFF), read the survey as the first step. Their slogan, reported by The Sentinel, is "No Survey, No Dam". Their stated concerns are displacement, loss of ancestral land and livelihoods, ecological damage and the risk of a large dam in a seismically active region. The Adi population is about 3 lakh, according to Deccan Herald.

The recent sequence, as reported:

• 28 September: villagers clashed with security personnel at Geku in Upper Siang ahead of Khandu's visit, according to the Daily Pioneer.
• 30 September: Deccan Herald reports violence at Ugeng village in Siang district, with vehicles torched and protesters hurt in a baton charge. Seven people were later booked under the Arunachal Pradesh Unlawful Activities (Prevention) Act, 2014. Separately, NE Now reports that protesters allegedly vandalised a legislator's residence during Khandu's visit to Yingkiong. Sources differ on exactly where the violence happened.
• 5 October: Northeast News reported that demonstrators reportedly set a Central Armed Police Forces camp on fire and damaged vehicles. SIFF did not attend talks convened by Khandu that day.
• 10 October: Upper Siang Deputy Commissioner Ashok Tajo's office announced preventive detention of four people under the same Act, citing escalating violence, arson and threats to public safety. SIFF spokesperson Tagori Mize questioned the arrests. Other arrests in Pasighat and Boleng were reported separately, so no single detainee count is reliable.
• Around 10 October: the SIFF Youth Wing declared a boycott of talks and set four conditions: withdrawal of central forces from villages, unconditional withdrawal of FIRs, release of those in custody, and compensation for injuries and damaged property.

The community is not of one mind. In June, Arunachal Times reported that 110 households in Geku signed an MoU supporting the survey, and that anti-dam supporters vandalised the houses of some of them two days later. Police sources quoted by Deccan Herald say agitators have attacked homes and crops of villagers who back the survey, and that five BJP MLAs' houses were given security after an attack on one on 30 September. On the other side, Adi Bane Kebang United leader Jirbo Jamoh told Deccan Herald that the group was formed after the state government divided the older Adi Bane Kebang with inducements, and that some villagers were made to sign agreements with promises of livelihood support of up to ₹2.5 lakh. That is an allegation from one party, and no government response to it appeared in the report.

The mechanism behind the standoff is easy to state. The state is deploying central forces to make the survey possible, and the deployment itself has become the grievance. Khandu has said that local people, as owners of the land, have to be taken on board. Each security measure taken to protect survey crews makes that harder.

What the 13 October announcement covers

On 13 October Khandu met the Adi Baane Kebang Youth Wing and the Adi Students' Union and then said on X that he agreed in principle to reduce security deployment in the Siang Valley and withdraw FIRs registered during the protests, as confidence-building measures. One report notes what the post leaves out: it gives no timeline and does not say which FIRs would be withdrawn or when. It does not address the demand to halt survey work, and the government's line that the exercise is not final approval is unchanged.

Two further points limit how far this goes. The groups Khandu met are not SIFF, which had declared its boycott days earlier, and no published response from SIFF to the announcement had surfaced in the reports available by 17 October. And the four detention orders under the Unlawful Activities Act, plus the cases against the people booked for the late-September violence, are not clearly covered by a pledge to withdraw FIRs. On 14 October the state BJP said at a press conference that SUMP should be seen in the context of national security and water management, and that preliminary studies should not be mistaken for a decision to start construction.

India's exposure

The strategic case is built on a border community. The same Adi districts that the project's backers describe as the front line of the water question are the districts where villagers see the project as a threat to their land. Whatever the merits of the storage argument, a survey carried out under heavy security deployment is a poor basis for a decision that the government itself says will require consultation.

There is a diplomatic cost as well. India is asking Beijing for transparency about upstream projects. The consultation record in Arunachal is one place where critics can test India's own practice. Independent researcher Mirza Zulfiqur Rahman told Deccan Herald that India, as a middle riparian on the Brahmaputra, should not copy China by answering a mega-dam with one of its own. Deccan Herald also notes that China, India, Bhutan and Bangladesh have not signed the UN Watercourses Convention, and that no treaty framework governs the river. Khandu has named Assam and Bangladesh among the areas that a sudden release would hit, which gives the downstream states a stake in any arrangement.

Scenario Analysis

Base scenario: partial de-escalation, uneven survey

Security numbers are trimmed and some FIRs withdrawn. The survey proceeds in villages that have already agreed and stays blocked in the rest. This follows from the government's stated commitment to dialogue and from the presence of villages that have signed in support. It depends on SIFF or its youth wing eventually returning to talks. Indicators: a published timeline for force reductions, FIR withdrawal orders, and SIFF attending a meeting.

Alternative scenario: a formal consultation track

The state pauses survey activity in contested areas and opens a structured process. The Human Rights of Arunachal has proposed a round-table including Adi elders, SIFF, headmen, panchayat leaders, youth groups, district officials and NHPC. This requires the government to accept that the survey cannot proceed alongside the boycott. Indicators: a named forum, a pause notice for field work, NHPC's participation.

High-risk scenario: breakdown and polarisation

More arson, more detentions and attacks on villagers who support the survey harden the split inside the Adi community. This follows from the pattern of the last three weeks, and from the fact that the main grievances are untouched. Indicators: new detention orders, further attacks on security camps or private homes, and fresh orders restricting gatherings under Section 163 of the BNSS, which Upper Siang already used earlier.

Intelligence Forecast

Over the next few months, the most defensible expectation is that no construction decision is taken. Survey work will stay incomplete in the most contested villages unless talks resume, while China's project continues from the stage Xinhua described in July 2025. The gap in timing is the practical risk for India's argument: the Chinese project is under construction, and the Indian counter-project has not cleared the stage before a feasibility report exists. This is a forecast, and it would change quickly if SIFF accepts a negotiating framework.

Global Chanakya Assessment

The evidence supports a narrow conclusion. The obstacle to SUMP is not Chinese pressure. It is the gap between the government's strategic reasoning and the local consent it says it still needs. The state has deployed forces to carry out a survey whose results it says will not itself decide the project, and the survey's legitimacy has become more contested than the project's merits.

Two assumptions deserve caution. First, that SUMP's storage would meaningfully limit harm from a sudden upstream release; the public record offers no modelling to test this. Second, that the Adi opposition is unanimous; reports of villages signing in support, and of attacks on them, point to a divided community, which also means any deal with one organisation will not settle the question.

Two developments could change this assessment: a data-sharing agreement with China that lowers the urgency of the flood-modulation argument, or a credible consultation process that brings SIFF back to talks.

Indicators to Monitor

• Whether the Arunachal government issues orders withdrawing FIRs and reducing central force deployment, and on what timeline.
• Whether SIFF or its youth wing attends any government meeting, or restates its four conditions.
• New preventive detention orders under the Arunachal Pradesh Unlawful Activities (Prevention) Act, or new restrictions on gatherings in Upper Siang.
• Any Union government or NHPC statement on the pre-feasibility survey schedule.
• A date for the next India-China Expert Level Mechanism meeting on trans-border rivers, and any public statement on resumed hydrological data.
• Further official Chinese or Indian disclosures on Medog construction progress and reservoir storage.