Variations in Tidal Constituents along the Nearshore Waters of Karnataka, West Coast of India

The characteristics of tidal constituents along the nearshore waters of Karnataka, west coast of India, are described. These are based on the sea level data measured at three locations by the Valeport wave and tide gauge during the presummer monsoon period. The objective of the study is to identify the tidal and nontidal variations along the coast. Analysis shows that astronomical tides are responsible for most of the observed sea level variability along the Karnataka coast. Ninety-seven percent of the variation in measured sea level at Honnavar and Malpe and 96% of the sea level variation at Kundapur was due to tide. The observed nontidal sea levels were related to local wind forcing. The study shows that when the wind from the south was strong, a rise in sea level was observed, and when the wind from the north was strong, a fall in sea level was observed. Correlation between the alongshore component of wind and nontidal sea level was 0.54 at Malpe and 0.48 at Honnavar. The nontidal sea level variation was found to vary according to the significant wave height. High residuals of sea level were found during high waves. Amplification of shallow-water constituents were relatively high compared with other constituents from south to north along the study area.