A ssam is a flood prone State with frequent and long inundation of basins and sub-basins of the Brahmaputra, Barak and other smaller rivers. Assam falls in the highest rainfall intensity zone of the country. The precipitation here is mainly due to the South-West monsoon (June to September). The annual average rainfall of Assam is 2297.4 mm. The State normally receives 2% rainfall in winter season (January-February), 25% in summer season (March-May), 65% in Monsoon season (June-September) and 7% in Post-monsoon (October- December).
The flood can be classified as Early Season Flood, Mid-Season Flood and Late-Season flood on the basis of its time of occurrence in June-July, August- September and October - November, respectively.

Year Crop Damage (HA) Affected Farm Families (Nos)
2007-08 450781 817698
2008-09 419261 906806
2009-10 869342 1595493
2010-11 185794 495194
2011-12 87584 224980
2012-13 612063 1820511
2013-14 74634 116660
2014-15 417104 1163187
2015-16 341178 564735
2016-17 245802 550815
2017-18 1451513 629035
2018-19 12849.49 66679
2019-20 214540.74 801579

The damages caused by the flood in Assam has been observed as follows-
I. Generally, 3-4 nos. of flood waves destroy the cultivated crops in riverbanks apart from eroding fertile cultivated land and brings extreme miseries especially to small and marginal farmers.
II. Occurrence of flood during peak period of Sali paddy transplanting or after transplanting (June-July) destroys seedling in the seed beds and transplanted Sali Paddy fields. If, flood occurs late during July-August and if flood water stagnation prolongs more than a week the predominantly available varieties of rice are unable to tolerate resulting complete damage of both seedling and standing Sali rice.
III. Sometimes harvesting of Autumn paddy (Ahu) in the month of May-June also hampered and damaged the crops at maturity stage.
IV. The early flood during May-June also damages the Summer vegetables, Maize, Sugarcane etc.
V. The late flood during September-October damages the early Rabi vegetables, black gram, green gram etc
VI. Crop loss in the horticultural crops both perennial & non-perennial like betel vine, spices and ornamentals, fruit crops like Banana, Papaya and Pineapple and medicial & aromatic plants.
VII. Large acreage of areas are affected by silt deposition and the soils are not suitable for next year crops.
VIII. There is possibility of pests & disease attack particularly, swarming caterpillar is a major phenomenon after recession of flood.