Identification of Msf tide amplification using a network of spatially distributed tide gauges

Abstract

Attenuation of tidal range (approx. 73%) and amplification of fortnightly Msf tide (approx. 10-fold) in the southern region of Kochi backwaters has been identified based on measurements by a network of spatially distributed rotary transducer based float-driven tide gauges. Hysteresis is within o.8 cm. Linearity is better than 1% beyond 25 cm. Accuracy is better than 1.6% and + or - 0.2% respectively in the range 10-100 cm and 101-200 cm. Field inter-comparison measurements with SBE pressure-based tide gauge yielded linear relationship between the two measurements. It is shown that whereas the generation of Msf tide in the northern estuary is attributable to non-linear interaction between M sub(2) and S sub(2) tides, its amplification in the southern estuary is due to variable bottom frictional effects at fortnightly periodicity.