Spatial Variability Analysis of Renewal Time in Harbour Environments Using a Lagrangian Model

The water quality in port domains is highly dependent on the capacity for renewal and mixing with external water. This study uses Lagrangian modelling to investigate renewal time in Barcelona, Tarragona, and Gijón harbours (Spain), which represent semi-enclosed micro-tidal and meso-tidal environments. For this purpose, different particle-tracking simulations have been carried out in each of the ports to study the trends of circulation and water renewal trends both on the surface layer and at the bottom. The results indicate that in microtidal Mediterranean ports, the renewal time is longer at the bottom (32 days in Barcelona and 61 days in Tarragona). Conversely, in the mesotidal port of Gijón, located on the Cantabrian coast, the opposite pattern is observed, with higher renewal times at the surface (14 days). While the results from Lagrangian modelling exhibit magnitudes comparable to in situ measurements from previous studies, it remains essential to evaluate the specific characteristics of each method and compare these findings with other similar works.