BharatSangraha

Siang & Adi Belt · Eastern Himalaya & Brahmaputra Belt

Terrain and eco-zones

Wet, and unevenly so. Pasighat at the mouth of the gorge takes well over 4,000 mm a year and is among the wettest inhabited places in India, with rain from March through October rather than a single tight monsoon. Altitude does the rest of the work: subtropical at the fan, temperate broadleaf by Yingkiong, snow above Tuting and along the Shi Yomi ridges. Winter is dry and clear, and it is the only season in which the roads are dependable.

Landforms

The Siang gorge — the river drops from roughly 3,000 m at the Tibetan side of the bend to about 150 m at PasighatSteep ridge-and-spur country with villages sited on shoulders above flood levelThe Siang alluvial fan at Pasighat, where the gorge opens and the river begins to braidThe Ziro plateau — an unusually flat, high valley floor in the Subansiri basinJhum slopes in a rotating patchwork of cleared, cropped and regenerating forest

Rivers and waters

Siang — the Yarlung Tsangpo above the bend, the Siang inside the gorge, and part of the Brahmaputra once the Dibang and Lohit join near KoboSiyom (Yomgo) — the Aalo river, joining the Siang at PanginSubansiri — the parallel basin to the west, the Brahmaputra's largest northern tributaryYamne, Sike and Sigen — the short, violent Abor Hills tributaries that cut the road every monsoon

Through the year

SeasonMonthsTypicalWhat it is like
Dry winterNovember–February5–22 °C at Pasighat, below freezing above TutingThe travelling season and the season for building. Cane bridges are inspected and re-lashed, roads hold, and the hearth-smoked meat put up after the last hunt is at its best.
Pre-monsoonMarch–May15–30 °CAran in early March, Mopin in April, Etor in May — the whole festival calendar sits here, before the rain closes the hills. Jhum plots are burned in this window.
RainsJune–September22–33 °CContinuous rather than dramatic. Landslides take out the Pasighat–Yingkiong and Trans-Arunachal roads most years, and the Siang runs brown and unrunnable.
HarvestSeptember–October18–30 °CSolung falls at the start of it, and the year's apong is brewed from the new rice.

Best time to visitLate October to early April. September if the point is Solung at Pasighat; the first week of April for Mopin at Aalo; November to March for the Tuting–Pasighat river descent, when the Siang is clear and low.

The climate, landforms, rivers and seasons of Siang & Adi Belt, and the best time of year to visit. (4)