Century-scale dataset of bathymetry and shoreline position for Tagus ebb-tidal delta, Portugal.

Understanding long-term coastal changes requires comprehensive records of morphological data spanning extended periods, ideally over multiple decades. Nevertheless, significant challenges arise from the restricted availability and accessibility of reliable data, especially in the case of complex coastal systems dominated by wave-current dynamics, such as ebb-tidal deltas (ETDs). This study introduces a new dataset for Tagus ETD in central Portugal, from 1845 to 1985 based on historic nautical charts available for the area. The data includes: (1) high-resolution bathymetric surfaces of ETD configuration for years 1845, 1879, 1893, 1929, 1939, 1960 and 1985; (2) shoreline position of three different indicators (Low-Water Line, High-Water Line and foredune dune seaward limit) at the adjacent coast for the same years; (3) rates-of-change for shoreline position of the High-Water Line indicator. Data also includes an uncertainty assessment for hydrographical and shoreline position information estimated from historic nautical charts. These data provide a valuable resource for describing, understanding, and modelling the long-term behaviour of ETDs not covered by other currently available datasets.