Nearshore suspended sediment concentration and transport pattern along the southern Karnataka coast, India

The nearshore variation in suspended sediment concentration (SSC) is essential to understand the circulation and sediment transport in and around the coastal area. SSC was derived from shoreline to 20 m bathymetric contour for thirteen transects selected between Malpe and Talapady along the southern Karnataka coast, India. Ocean colour monitor (OCM) and in-situ derived SSC was compared for validation of satellite data. High SSC in the southern side of the study area is due to high wave activity, beach erosion, sediment discharge from the river, dredging activity of New Mangalore Port, and construction of offshore reef at Ullal. In-situ samples show high SSC concentration in the bottom waters in estuaries which signify the dominance of bed load transport over suspended load. In nearshore waters, high concentration in the surface, mid and bottom waters are observed along the stations impacted by anthropogenic activities. The in-situ data is observed to be positively correlating (+/- 10 mg/l) with OCM data. SSC values deciphered using the modified Tassan algorithm provides accurate estimates in coastal waters off south-west India. The sediment transport pattern derived from statistical parameters of bed sediment samples showed offshore, southward and northward direction. Natural and anthropogenic structures act as a barrier to coastal sediment transport. The direction of sediment transport patterns in the coastal waters is useful for the maintenance of navigational channels and planning the coastal structures in the coastal zone.