Coelho, C., Silva, R., Veloso-Gomes, F., and Taveira-Pinto, F. 2009. Potential effects of climate change on northwest Portuguese coastal zones. – ICES Journal of Marine Science, 66: 1497–1507. Coastal erosion is a common problem in Europe; a result of the dynamic nature of its coastal zones, of anthropogenic influences, such as coastal interventions and littoral occupation, and of the effects of climate change. The increase in the occurrence of extreme events, the weakening of river-sediment supplies, and the general acceleration of sea level rise (SLR) probably tends to aggravate coastal erosion on decadal time-scales. Describing vulnerability and risk patterns for energetic environmental actions is important for coastal planning and management to rationalize the decision-making process. To minimize negative effects, the various processes causing erosion must be understood to assess the possible prediction scenarios for coastal evolution in the medium to long term. This paper describes the application of a coastal (shoreline evolution) numerical model to a stretch of the Portuguese coast to determine the effects of various scenarios of wave action and SLR that might result from climate change over the next 25 years. We conclude that the effects of SLR are less important than changes in wave action. The numerical model was also applied in a generic situation to compare shoreline evolution with and without anthropogenic intervention.

Coastal dynamics and erosion processes may cause serious damage, especially to people and assets in urban fronts, and they therefore merit special attention. To diminish the effects of these natural dynamics on coastal areas it is necessary to understand the various processes involved. The classification of a coast in terms of vulnerability and risk will only be possible when foresight capacity is improved, making the planning and decision processes easier. Coastal zone vulnerability to energetic environmental actions (waves, tides, winds and currents) may be considered to be biophysical systems sensitivity and morphological changes as the response. The present changes in the frequency of extreme events, the weakening of river sediments supply, the generalized sea level rise and other climatic changes, together with the advance of urban fronts towards the sea, may worsen the consequences of floods and land loss. The vulnerability analysis of coastal zones is crucial for appropriate land use, and is a complex process which involves many parameters. As a first approach an effective methodology is proposed and applied to the coastal region of the Aveiro district, south of Porto, Portugal, where the volume of available sediment is currently deficient in relation to the transport capacity, and it is predictable that the erosion situation will become further aggravated in some regions. This methodology consists of obtaining a global vulnerability index, which results from the weighting of each independently classified vulnerability parameter. This approach is complemented with a coastal line evolution estimation using numerical modelling.

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