Tide gauge data for a substantial and relatively longer period at a particular location may give you some impression/ idea about sea-level. However, Porbandar at Cambay/Khambhat's coast is fairly far from Mumbai at northern west coast. We can take example of rainfall data, white interpreting rainfall data, rainfall is consider a regional factor and scenario at a particular rain-gauge station would be giving you a local impression. It is the density/distance from a particular rain-gauge station to another, which helps while interpreting this data and, therefore, fairy dense rain-gauge stations are always helpful. Similarly, from my point of view, while using Mumbai's tide gauge data with data of a station much far (here Porbandar), it would always be better to collect data from select gauge stations in between as well all along the coastal line, to have an overall idea about sea-level fluctuations/ rise-fall with reference to land. Nevertheless, for a sustained longer period, in addition to tide gauge data, you would rather be required to check marine geological records, lithology/ litho-units exposed etc. One thing is there, satellite altimeter data can be rather helpful.

Best,

AK

Thanks a lot Sir