China’s Mega Dam On India’s Doorstep: What It Means Downstream
China has begun building the world’s largest hydropower project where the Yarlung Tsangpo bends south into India. The river becomes the Siang in Arunachal Pradesh and the Brahmaputra in Assam. India’s plan to store water downstream, the Siang Upper project, has set off protests in the Siang valley. The map follows the river from the Great Bend to Assam and sets out what changes for the people along it.
- The blue line is one river: the Yarlung Tsangpo in Tibet, the Siang in Arunachal and the Brahmaputra in Assam.
- The red stretch marks where China is building; its five stations and tunnels are not published, so the stretch and the dashed tunnel route are indicative.
- The yellow stretch marks where NHPC has studied sites for India’s Siang Upper project; the exact sites are not published either.
- The orange rings mark the epicentre of the 1950 Assam-Tibet earthquake. India’s boundary is drawn as published by the Survey of India.
Xinhua and Government of China, 19 July 2025 (investment, five stations, Mainling groundbreaking); China Daily, 23 July 2025 (capacity, annual output, tunnels); Chinese foreign ministry via Xinhua, 23 July 2025. Ministry of External Affairs: India-China MoUs on hydrological data (2002, 2013) and outcomes of 19 August 2025. Montgomery et al., Quaternary Research (2004), for the fall through the gorge. Liu et al., Water (2025), for seasonal flow. USGS for the 1950 earthquake; South China Morning Post, 9 July 2026, for the reported active fault. Assam Water Resources Department (flood-prone area) and Assam Statistical Handbook 2021 (Census 2011 population). PIB, 2 June 2025 (NHRC notice). Statements by the Arunachal and Assam governments and the October 2026 events as reported by PTI, Down To Earth, Business Today and The Wire. Boundary: Survey of India via DataMeet. Rivers: Natural Earth. Medog to boundary is a straight-line measure from an approximate town location.