Marine hydrodynamics between San Sebastián and Hondarribia (Guipúzcoa, northern Spain): Field measurements and numerical modelling

Abstract

During 2000 and 2001 and at the beginning of 2002, current meters were deployed at 25, 50 and 110 m water depths along two transects: one offshore of San Sebastian and the other offshore of Hondarribia. At the same time, hydrographical cruises and the collection of sediment samples were undertaken over the coastal section. The aim of the study was to improve the knowledge of seasonal changes in the coastal water circulation. The main results obtained are three-dimensional measurements of water flow, a description of the seabed sedimentology between 50 and 90 m depth, and an improved description of the effect of the circulation patterns on the dispersion of pollutants. Two different patterns of surface water circulation were identified, related to oceanographic and meteorological conditions in autumn-winter and spring-summer. Analyses undertaken on three-dimensional current meter data also improved the understanding of seasonal variations in marine currents. All the field data were incorporated into a numerical model for the simulation of currents. This numerical model contributed, together with the field measurements, to the improvement of the description of general seasonal variability patterns in the currents. The effect of this circulation on the dispersion of pollutants was also analysed.