Multiscale analysis of morphodynamic processes in estuaries and their integration into dredging projects

Abstract

Estuaries are crucial areas from a socio-environmental point of view, being the ecosystem for a wide range of life forms, the economic foundation of many coastal nations, and the connection between land and open sea. Communities inhabiting these areas need to transport people and commodities by water, thus entailing the dredging of waterways to inland ports. Deepening of navigation channels in estuaries usually results in the alteration of tidal behavior and related morphodynamic processes. The knowledge of the spatio-temporal response of estuaries to dredging activities is still limited; therefore there is a real need to use and combine different methods and tools when exploring the effects of such interventions. It is the aim of this Thesis to enhance the understanding of the main morphodynamic processes involved in the dredging activities, and the implementation of multiple tools when assessing these projects in estuaries. This Thesis achieved the objective using data and field measurements in two Andalusian estuaries, where both the role of the forcings and the dredging strategies differ: the Guadalquivir estuary and the Punta Umbría inlet. In the case of the Guadalquivir estuary, whose inland port belongs to the Spanish Port System, the presence of numerous stakeholders pose a challenge when managing dredging projects. The recent proposal to deepen the navigation channel confront the interests of different parties due to the possible environmental impacts in the system. This concern attains the effects of tides and freshwater discharge into the turbidity, saline intrusion and, generally, the ecological and chemical state of water masses. In the case of Punta Umbría inlet, the Regional Government of Andalusia manages the inland port. A database specifically designed to assess the dredging projects in these regional ports was used. The evaluation of all these dredging activities executed in the past twenty years pointed Punta Umbría as a particularly problematic port. Indeed, it has one of the highest average prices per intervention, where the volume of mobilized sediment in the navigation channels is the second highest.