Explanation:

The Brahmaputra Valley is said to be one of the most hazard-prone regions of the country — according to the National Flood Commission of India, about 32 lakh hectares or over 40 per cent of the Assam’s land is flood-prone due to this. An important reason apart from the ones mentioned in the question is the ageing of embankments. Though embankments don’t have specific life-spans, the ones in Assam are designed on the basis of flood data of 15 to 20 years and are supposed to remain fit for 25 to 30 years. The filling of embankments with sediment, wear and tear and unscientific distribution across the river valley is one of the major reasons cited by officials for the flood devastation.