Tsangpo, Siang, Brahmaputra: the one river behind the hydropower projects now in dispute in Arunachal Pradesh

Background

This standing fact lies behind the Siang Upper Multipurpose Project and the Subansiri Upper project now being contested in Arunachal Pradesh. The same river carries three names along its course: it is the Tsangpo in Tibet, the Dihang or Siang in Arunachal Pradesh, and the Brahmaputra in Assam. The river rises near Mansarovar, flows east along the northern side of the Himalaya, then turns south and cuts a deep gorge across Arunachal Pradesh. It reaches the plains of Assam near Pasighat, where the Dibang and the Lohit join it; from that confluence the stream is called the Brahmaputra. The State's other large rivers are the Subansiri, the Kameng, the Dibang, the Lohit and the Tirap, all tributaries of the same system. The Subansiri is the largest of these tributaries. Because the fall of water across the gorge is steep, almost every large hydropower proposal in the State sits on this river or one of its tributaries.