THE BRAHMAPUTRA VALLEY

THE BRAHMAPUTRA VALLEY

The Brahmaputra Valley lies in between the North-Eastem frontier Hills, Patkai and the Naga Hills and the Karbi-Meghalaya Plateau, and occupies a most significant part of the physiography of north East India.

Generally, the plains of the catchment area of the river Brahmaputra from Sadiya to Dhubri is known as the Brahmaputra Yalley or Assam Yalley. It is located in the north-eastern corner of Indian Union between longitudes 89° 46 *E and 97° o4*B, and latitudes 25°00»N and 28° 18*N.

The valley is an alluvial plain formed by the deposition of sediments brought by the river Brahmaputra and its numerous tributaries. It extends from Sadiya in the east and Dhubi in the west. The Brahmaputra valley is very extensive, it is about 720 km long and 96 km in width on the average.

The Brahmaputra valley is narrow near the Karbi Hills (due to the underlying rock structure) and very much extensive in the undivided Lakhmipur district.

The valley has been built by the deposition of aluvium, about 170.0 metres thick upon a depression created during the period of Himalayan upliftment. Thus Brahmaputra valley is the eastern most continuation of the Indo Gangetic trough.

The main stream and its numerous tributaries flowing from either side are mainly responsible for deposition of the alluvial debris.

Slope: The Brahmaputra   valley on the whole has a gentle slope from east to west. Sadiya, situated at the head of the valley has an altitude of 135 metres, Dibrugarh 104 metres, Guwahati 5l metres and Dhubri 34 metres.

The valley is bordered in the north by a narrow belt  known as bhabar which are deposited coarse sands and pebbles brought down from the Himalayan region by the swift flowing mountain streams.

On either side of the Brahmaputra river there lies the flood plain which supports a series of swamps and beels. The extensive flood water of the river Brahmaputra   and its tributaries has given rise to the formation of permanent marshes known as beels. Dipar, Bildara, Roumari, Satdala, Kapla, Kodomani, Chalchala, Bangalmari, Barbeel, Garangabeel, Chatabeel, Mohmari etc. are examples of such marshes. Many beels have formed as a result of the formation of ox-bow lakes by the rivers.