Numerical modelling of shoreline evolution in the Aveiro coast, Portugal – climate change scenarios

Abstract

The Aveiro coastal area is highly vulnerable to erosion, because it is constituted primarily by low-lying lands of sandy sediments that are frequently subjected to severe wave conditions and large tidal amplitudes (Coelho et al., 2011), as well as due to the close proximity to the Aveiro lagoon and several urban waterfronts. In this region the problems associated with coastal erosion are often reported and discussed (Coelho, 2005; EUrosion, 2006; Pais-Barbosa et al., 2006; Coelho et al., 2007), constituting a concern for the local populations and stakeholders. Furthermore, the retreat of the shoreline may imply the breaching of a new entrance to the Aveiro lagoon, which would cause major social, economic and environmental impacts. This breaching has only been avoided by emergency works which have been carried out frequently over the past few years. Increased vulnerability is mainly related to the sedimentary deficit registered in the Portuguese coast, due to the decrease of incoming sediments from river sources (Mota-Oliveira, 1997). Over the years the Esmoriz-Furadouro and Vagueira-Mira stretches have been affected by flood and erosion processes due to coastal vulnerability to sea wave’s action (Figure 1). Considering the expected modifications of the coastal erosion drivers induced by climate changes, it is important to define their potential effects, trying to anticipate hydro/morphodynamics changes in coastal areas, through sea-level rise, increase of storminess and rotations in the wave regime. It is expected that these phenomena will increase coastal flooding of low-plains, houses and infrastructures, causing economic damage and eventual patrimonial, cultural and ecological losses. This work applies numerical models to predict shoreline evolution, in a medium-long term perspective, contributing to establish trends and foresee shoreline position scenarios. Two models, GENESIS (U.S. Army Corps of Engineers) and LTC (Long-Term Configuration), were applied to anticipate the shoreline position for the year 2100, through the evaluation of four scenarios in a perspective of the effects of different phenomena associated with climate change.