Hydrodynamics and spatial zonation of the Capo Peloro coastal system (Sicily) through 3-D numerical modelling

Since advection and diffusion are the main physical processes that influence the cleaning capacity of coastal transitional waters, the 3-D spatial distribution of the water renewal times was used to delineate a physically-based zonation scheme. The temporal and spatial variations of the hydrodynamics are assessed using a validated three dimensional hydrodynamic finite element model. The developed methodology was applied to the Cape Peloro system, a coastal protected area located in the Messina Strait (Italy) consisting of two connected small brackish basins: the shallow Lake Ganzirri and the deep meromictic Lake Faro. The hydrodynamics of the two coastal lakes shows strong seasonal and spatial variation. The 3-D distribution of the water renewal times suggests a horizontal partition of the Lake Ganzirri into two sub-basins and a vertical zonation of the Lake Faro, with the mixolimnion extending till 10 m depth and the presence of a persistent bottom stagnant layer. The derived physically-based zonation scheme helps in explaining the highly heterogeneous spatial distribution of many biogeochemical variables in the Cape Peloro coastal system.