SEDIMENT TRANSPORT IN THE CAUVERY RIVER BASIN - SEDIMENT CHARACTERISTICS AND CONTROLLING FACTORS

During the monsoon period, 75% of the annual rainfall, 73% of the annual water discharge and 85% of the annual sediment transport takes place in the Cauvery River. Basin geology and river water discharge are the major natural factors controlling the sediment transport. Sediment transport in the Cauvery River is greatly influenced by the presence of two major dams built across the river. An examination of the particle-size distribution of the suspended sediments shows that the less than 20 mum fraction accounts for nearly 60% of the total sediment transported by the river. At dam sites, coarse sediments are selectively removed from the suspended load. The suspended mineralogy is dominated by quartz and feldspar, followed by clay minerals and carbonates. Clay minerals average about 30% and are dominated by the montmorillonite type. The results of our study also demonstrate the importance of such sediment characteristics as particle size and mineralogy in controlling the trace metal distribution in sediments.