Sediment grain size variation on a coastal stretch facing the North Atlantic (NW Portugal)

• Main Authors: R. Silva, P. Baptista, F. Veloso Gomes, C. Coelho, F. Taveira Pinto
• Other Authors: Faculdade de Engenharia
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Ciências da terra e ciências do ambiente; Earth and related Environmental sciences; Ciências exactas e naturais::Ciências da terra e ciências do ambiente; Natural sciences::Earth and related Environmental sciences; Mira; North Atlantic
• Online Access: https://hdl.handle.net/10216/94220

In a context of continued erosion, as is the case for the northwest Portuguese coastal zones over the last two decades, it is common to find urban settlernents at risk along shorelines. To protect economical, social and environmental assets it has becorne increasingly important to effectively plan coastal defense interventions (beach-fill designs, coastal structures functioning and placement studies, and sediment budgets formulations). The sediment grain size is an important parameter involved in these studies and it should be adequately characterized, however it is common to see it categorized by its median diameter, through a reference value. Beach morphologic features frequently change in form and sediment distribution but these changes in sediment dimensions are not as significant as the differences found for different geographical locations. Alongshore and cross-shore trends of sediment grain size in a given location reflect its cumulative energy (wave climate) and stability (cross-shore profile evolution). In the paper, seeking for a relation between beach profile and sediment distribution, a contribution is given to the characterization of' the sediment grain size at some locations along a stretch of the Portuguese northwest coast, between port of Aveiro and Mira beach. Data from three campaigns conducted between 2006 and 2007 was used in the analysis. The observed values of mean median grain size are within the range 0.39 and 0.57 mm in the study site. The mean beach face slope values are between 0.07 and 0.09.