The seven-member panel, set up by the Water Resources Ministry, has also suggested creation of an appropriate mechanism on the lines of Coastal Regulation Zone (CZR) to prevent disasters of similar magnitude in the future.
Besides, it has asked Uttarakhand government to ensure implementation of the model Flood Plain Zoning Bill.
The report of the committee said buildings situated less than 50m from river banks were largely washed away during the unprecedented calamity that hit the hill state last year, killing 580 people and leaving over 5,400 people untraceable.
The other major reasons identified for high discharges in the snow-fed rivers are melting rate of glacier and unprecedented heavy to very heavy rainfall in the catchment.
At some locations, the report said, debris deposited by the river in its main course during earlier floods obstructed the flow in the central portion, leading to severe erosion of banks and causing the river to shift its course.
The members of the committee had visited various affected sites in Uttarakhand to assess the reasons for the widespread destruction and loss of life and property in the floods of June 16 and 17, 2013.
