Hydrodynamic response of a shallow and microtidal estuaryAlfacs Bay. From high to low frequency processes

Abstract

Using both observations and modelling tools, it is investigated the main hydrodynamic response mechanisms of a microtidal and shallow bay in the Mediterranean Sea: Alfacs Bay. Main objectives are considered using differenttim e-scales approximations: from high frequency processes (corresponding periods of 1 to 3h), through tidal and daily wind influence, to low frequency and average response (days and weeks ). Results revealed a clear circulation dominated by seiches on high frequency scales, demonstrating the effects on water column stratification. Moreover, spatial wind variability becomes a relevant mechanism influencing the hydrodynamic response under energetic wind events. The response at low frequency scales is determined by the combined effects of winds and gravitational circulation mainly due to the fres hwater inputs. Both Bay's geometry -shape and shallow depths- and stratification are found to be much relevant in all the hydrodynamics mechanisms analysed. The results allow the better understanding of main hydrodynamics patterns of an area with strong anthropogenic pressure and notably social and economic role in the region, and being applicable to similar domains. As such, these bodies of water are exposed to several environmental and management problems and need to be considered for pollution protection issues .