The Drainage System of North-East India

Abstract

The entire North-East of India is drained into the Bay of Bengal, largely through the two principal rivers of the region, Brahmaputra and Barak, flowing through Bangladesh. The drainage of a small area of Manipur, in its eastern part, finds its way into Chindwin, a tributary of Irrawaddy, which flowing by Yangon (Rangoon) traverses its delta and falls into the Gulf of Martaban, a part of Andaman Sea. Another area not included in the catchment of either of these two principal rivers is the southern part of Mizoram, drained principally by Kaladan, which falls directly into the Bay of Bengal, on the west coast of Myanmar at Sittwe (Akyab). Though the catchment of Brahmaputra extends into Tibet and Bhutan, besides India, much of the rain falling in the North-Eastern states finds its way in the territorial waters of either Bangladesh or Myanmar, before being discharged into the Bay of Bengal.

The Brahmaputra with over two dozen tributaries, joining from north as well as from south, has a total drainage area of 651,334 km² of which 178,000 km², i.e. about 27 %, lies in North-East India. About 70 % of the area of North-Eastern states lies in the catchment of Brahmaputra. A mighty river, flowing for over 1,000 km in India, Brahmaputra has a mean annual discharge of 38,000 cusecs and carries an annual suspended load of 800 million tons.