Beyond Human Interventions on Complex Bays: Effects on Water and Wave Dynamics (Study Case Cadiz Bay, Spain)

Bays are coastal environments with significant socio-economic importance, which has led to the development of human interventions in their interior that can have an important impact on the water and wave dynamics, which in turn modify their morphodynamics and water renewal capacity. In order to deepen our understanding of these impacts, numerical modeling was used in a bay in southern Spain to analyze the effect of inner harbor expansion and channel deepening, including the baroclinic and wave propagation effects, as well as variations in salinity and temperature. The results show that the deepening of the channel decreases the amplitude and speed of the tidal wave as it propagates through the bay, reducing the effects of friction and increasing the flushing time. The system evolves from convergent to a damping system that can potentially reduce the effects produced by projected sea level rise. In addition, the seasonal variability of salinity and temperature is reduced, increasing the bed shear stresses and resulting in increased turbidity that can affect the biogeochemistry of the bay. Finally, wave heights decrease along the main waterway, although the yearly-average wave energy flux is only slightly modified on the interior beaches of the bay. However, significant variations are observed during storms, which could affect the morphodynamics of these beaches.