2. The Brahmaputra River Basin

The maximum discharge of water among the Indian rivers is in the Brahmaputra River. The Assam Valley is considered to be one of the worst flood affected areas of India. In fact, in Assam, floods are almost an annual feature. The main cause of floods in the Brahmaputra basin are: (i) heavy and torrential rainfall— during the rainy season over 200 cm of rainfall is recorded over greater parts of its middle and lower reaches, (ii) silting of the river course due to heavy soil erosion, (iii) landslides, (iv) heavy pressure of population, and (v) shifting cultivation on the surrounding hilly areas. All these factors collectively result in Hooding of the vast areas in and around the Brahmaputra Valley.

All the districts of Assam are inundated almost every year. The worst affected areas in Assam are ‘Majuli’—India’s largest river island, Dhubri, Kokrajhar, Barpeta, Guwahati, Mangaldoi, Sibsagar, Jorhat, Dibrugarh, and Tezpur. According to one estimate, about 80 lakh hectares, i.e. over 45 per cent of the total area of Assam, is flood prone.