Morphodynamic evolution and influence of dredging activities in small-scale mesotidal estuaries: the case of Punta Umbria (southwestern Spain)

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Miguel Á. Reyes-Merlo, Ángela Tintoré-Parra, Manuel Díez-Minguito, Miguel Ortega-Sánchez, Miguel Á. Losada

Chair(s): Esther Stouthamer

Tuesday 30 june 2015

15:05 - 15:25h at Asia (level 0)

Themes: (T) Special session, (ST) Deltas from multiple pressures to integrated solutions

Parallel session: 6C. Special session: Deltas - from multiple pressures to integrated solutions

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Punta Umbría (Huelva) is one of the major estuaries in the South Atlantic coast of Spain, facing to the Gulf of Cádiz. In the past, the natural state of the ecosystem was characterized by the presence of littoral bars, barrier islands and sandy capes. However, since 1950s the urban occupation and the emergence of new activities such as industries, fisheries and recreational navigation have altered the dynamics of the area. The impacts of human interventions along the rivers and coast of Huelva province caused that the estuary mouth is no longer in balance, with a high tendency to closure. Nowadays, the most relevant engineering problem in the estuary is the maintenance of the operational capacity and the security of the navigation channel. Regular or urgent dredging's have been the strategy during 2002-2014, with five interventions in total. Nevertheless, managers are demanding a more stable and sustainable policy, since the economical cost and the environmental impact are elevated. This work presents an integral analysis of the morphodynamics of the estuary, based on high-resolution bathymetric information, hydrodynamic data and the implementation, calibration and validation of the numerical model Delft3d. The evolution of the channel morphology is described through 15 multi-beam bathymetries collected between 2002 and 2014. Water currents, salinity, temperature and elevations at the outer boundary and inside the estuary were obtained during a field survey between May and September of 2014. Different management scenarios and their effects on the morpho-hydrodynamics of the estuary were analyzed. Besides the regular dredging’s, we considered the deviation of the navigation channel, the prolongation of the existing dike and the design of a sediment trap. Results for such strategies and the best alternative for managing will be presented in the Conference.