Ref.: PTDC/ECM/66484/2006

Budget (Total/UALG-CIMA): 164000 Euros/ 7593 €

Starting date: 02-01-2008

Ending date: 01-03-2011

Coordinator: Anabela Oliveira (LNEC), Alexandra Cravo (CIMA)

Domain: Engenharia Civil e de Minas

 

Abstract:

The downstream areas of coastal streams contain small estuaries and lagoons of complex nature due to the strong morphological changes of their inlets. These morphological changes often lead to the inlet closure, as a result of the action of waves, tides and intermittent river flows. Hydrodynamics, morphodynamics and water renewal are thus highly variable, both at seasonal and shorter time scales, which hampers the monitoring, the forecasting and, ultimately, the management of these systems. This strong dynamics makes the intermittent coastal streams very sensitive to contamination/pollution, as contaminated discharges may have very different consequences depending on the capacity of water renewal of the system at that time. MADyCOS aims at improving the current understanding of the hydrodynamics, morphodynamics and potential for fecal contamination of intermitent coastal streams, through an interdisciplinary study that integrates distinct but complementing methodologies: field data acquisition, laboratory research and high-resolution numerical modeling.

The small dimensions of the intermitent Aljezur coastal stream system make it an ideal testbed for the proposed methodology. This system, located in an environmentally protected area, presents a very dynamic inlet which closes occasionally. Simultaneously, the Aljezur coastal system has significant importance both at ecological and local economy (tourism, aquaculture) levels, both inside the stream and in the coastal area. Maintaining the high standards of water quality, for both ecological and recreational purposes, has been a growing concern for the management authorities. Indeed, any increase in antrophogenic pressure may lead to the aggravation of the pollution loads, with potential damaging consequences for the ecosystem and the quality of bathing waters at the two official beaches. Evaluating the impact of this antrophogenic pressure requires the detailed knowledge of the inlet’s morphological evolution, dependent on the relative strenght of each forcing, and of the evolution of the fecal contamination plumes for specific environmental conditions.

The project has both generic and site-specific goals. The generic objectives are:

-To develop and validate a new methodology to combine models, field surveys and laboratory assays in hydromorphologic and fecal contamination studies of morphologically dynamic coastal systems;

-To increase current knowledge on the hydrodynamics, residence times, morphodynamics and dominant processes for the decay of bacteria in intermittent coastal systems;

-To develop and validate a new 3D model of fecal contamination for coastal systems with new formulations for bacterial decay;

-To validate the morphodynamic model MORSYS2D in an intermittent coastal stream.

The goals for the Aljezur system are:

-To characterize the hydrodynamics due to waves, tides and river flow, and their relative importance in driving the morphological changes and the water exchange;

-To identify the sources of fecal contamination and the potential for contamination of the system´s beaches for different hydromorphological conditions.