Sea level and currents in the upper reaches of the Cochin estuarine system during October 2000

Abstract

155-163Data on sea level, currents, salinity and water temperature collected in the upper reaches of the Cochin estuarine system (southwest coast of India) during October 2000 have been analysed to understand their variability. The tides near to the mouth of the Cochin estuarine system were found to be of a mixed, predominantly semi-diurnal form during the month. The non-tidal sea level at the same location, showed an overall drop of nearly 9 cm during the period. Spectral analysis of the non-tidal sea level revealed the presence of 4 and 21 day period wave phenomena. The study showed that the sea level as well as currents are dominated by tidal signals (diurnal and semi-diurnal bands) even in the upper reaches. However, the amplitudes were seen to decrease with increasing distance from the mouth of the estuarine system. Conspicuous dominance of the shallow water components was noticed in the currents as compared to the sea level. The data on salinity showed tidal signatures whereas that on the water temperature showed strong solar forcing