Rivers, foothills and floodplain

Terrain & boundaries

Dhemaji covers about 3,237 sq km on the northern bank of the Brahmaputra. The Arunachal Himalaya foothills wrap around its north and east, Lakhimpur district borders it to the west, and the Brahmaputra itself forms the southern boundary. Average elevation is modest — around 90 metres — and the land is almost entirely flat plain, with the only relief coming from the hill edge along the Arunachal border.

Rivers that built the land

The Subansiri, the Brahmaputra's largest tributary, enters the plains here at Gerukamukh. Alongside it, a network of smaller rivers and streams — the Jiadhal, Moridhal, Telijan, Kaitongjan, Sissi, Gai, Tangani, Dihingia, Kapurdhuwa, Simen and Guttong among them — flow down from the Arunachal hills, carrying large amounts of silt before joining the Brahmaputra. These braided channels are constantly shifting course, which is exactly what gives the district both its fertile soil and its flood risk.

Climate & rainfall

The climate stays pleasant through most of the year, with the bulk of the rain falling during the monsoon. Annual rainfall typically runs from around 2,300 mm to 3,000 mm depending on the year — among the higher rainfall totals in Assam — driven heavily by the north-east monsoon.

Living with floods

Dhemaji is regularly listed among Assam's most flood-prone districts. Close to 27% of the net cropped area is considered flood-prone or flood-affected in a typical year, and the 1950 Assam earthquake is thought to have worsened the long-term flooding pattern of rivers like the Jiadhal. Flood management and embankment work are a constant, ongoing part of life and local administration here.

Forests

Forest cover is scattered through the foothill areas and includes nine reserved forests — Jiadhal, Subansiri, Sissi, Simen, Archiac, Jamjing, Senga, Gali and Pova — spanning mixed and deciduous types, with bamboo, cane and timber as the main forest resources.