High Frequency Floods and their Magnitudes in the Indian Rivers

Tn this study the frequency of floods at gaugeldischarge (GID) sites of Indian rivers have been examined using the 14 year data of 1986 to 1999. Only the data of such G/D sites have been considered which have experienced 250 floods during this period. it is seen that such frequent floods do not occur in the central and peninsular rivers but only in northeast and north Indian rivers. In northeast India, such floods have occurred in 8 rivers including Brahmaputra at 12 G/D sites while in north India 9 rivers including the Ganga at 20 G/D sites have registered 150 floods, The worst flood-prone sites have been found on the Brahmaputra at Dibrugarh and on the Beki River at Road Bridge and on the Kosi River at Baltara. These sites have experienced floods whose frequency is 150 to 177 in the 14 year period. The magnitude of flood deviations at different sites have also been examined. Deviations of the order of 5 m to 18 rn above the respective danger level (D.L.) at G/D sites have been observed on some of these rivers.

This study has shown that enormous waterresources are available in this country. Every attempt should and must be made to conserve it for use in deficient rainfall regions of the country through a system of reservoirs and canals.