siang

Siang is the upper course of the Brahmaputra River in the Indian state of Arunachal Pradesh. The river system originates on the Tibetan plateau as the Yarlung Tsangpo, and after entering India it is locally known as the Siang. It flows southeast across Arunachal Pradesh, draining a high-relief landscape and supporting a range of ecosystems. The town of Pasighat lies along its banks and serves as a regional waypoint in the Siang valley. As a major headwater, the Siang contributes substantially to the Brahmaputra, which continues into Assam and then Bangladesh.

Hydrology and ecology describe the Siang as a fast-moving, sediment-rich river with pronounced seasonal variation driven by the monsoon. Floods and landslides are common in the monsoon season, shaping valley habitats and influencing local livelihoods. The Siang basin hosts diverse flora and fauna and supports fisheries and irrigated agriculture for nearby communities. The river and its valley are also targets for hydroelectric and irrigation development, reflecting its strategic importance for energy and water resources, while raising concerns about environmental and social impacts.

Culturally, the Siang valley is the homeland of several indigenous communities, including groups such as the Adi and Nyishi. These communities have long depended on the river for water, food, transportation, and cultural traditions. The Siang thus plays a central role in the natural and human landscape of Arunachal Pradesh.