Literature mostly said that to calculate shoreline change, download the satellite date and calculate NDWI to generate shoreline. But I want to know, what will be an alternate reference to download satellite images? will I have to consider High Tide data and its timings? like, for example if I want to download data for the year 1991 and 2011 for all 12 months than the satellite data I will be downloading should be somewhere or nearby to the respective month date- High tide value data given by IMD?