A vulnerability analysis approach for the Portuguese West Coast

摘要

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.