SUSPENDED SEDIMENT DISTRIBUTION AND RESIDUAL TRANSPORT IN THE COASTAL OCEAN OFF THE GANGES-BRAHMAPUTRA RIVER MOUTH

An examination of suspended sediment dispersal in the coastal ocean off the Ganges-Brahmaputra river system using shipboard and satellite data reveal distinct patterns of sediment distribution and sediment motion which help explain the dynamics of the world's largest sediment dispersal system. During the low-discharge period, suspended sediment concentration distribution is mainly a function of tidal energy and the sediments are primarily transported as a suspension population. Satellite and sea-bed data indicate that transport of river sediments is largely restricted to an area landward of about the 20-isobath during the low-discharge period. A simplistic estimate of residual transport and its separation into tidal and non-tidal components indicate that non-tidal transport contributes about 47% of the total transport and has transport directions mostly southwestward during the northeast monsoon. The tidal residual transport, which contributes about 53% of the total transport, however, does not show any particular direction for most of the stations, although some landward stations show shoreward transport. Although few water-column measurements were made during the high-discharge period, data from this and previous studies suggest that the dominant transport direction is to the southwest for most of the year.