An IMEDEA project presents a new coastal model for rising sea levels


• The new model will enable better analysis on how climate change impacts coastlines


Shoreline position is a key factor for beach conditions and is often used to describe how these systems respond to waves and sea levels. Changes in shoreline position are due to various factors that act at different scales.

The IMEDEA-led study (CSIC-UIB), in collaboration with researchers from the Polytechnic University of Catalonia, has developed a model to predict shoreline position based on ‘equilibrium beach profile’ (EBP) analysis. The model has assessed expected changes in shoreline position in light of rising sea levels.



Photo: Es caragol beach. Author: Olaf Tausch


What does the new model do and what improvements will it bring to coastal research?

The new model sets out the limits for defining the active beach area, i.e. which section sees sediment movement due to waves. To date, EBP-based models defined these limits arbitrarily and included different criteria. Most were based on observing the extent of wave impact during major storms. For example, one of the most common approaches uses swells that are only exceeded 12 hours a year. Some models even disregard the exposed section of beach entirely.

The new model, however, introduces a ‘narrow beach’ concept, i.e. a section where marine forcing acts on the entire exposed beach area and, thus, highlights coastline changes that can differ from usual variations.

The study could be used to establish the combined impact from sea levels and waves linked to storms (particularly in a scenario of global change) to obtain shoreline profiles on beaches.

Based on a previous project (PIMA-ADAPTA) where researchers determined the extent of potential coastal floods and expected beach erosion in light of rising sea levels due to climate change, the team noted discrepancies between commonly used models.

The results indicate previous models either provided a significantly different coastline evolution to digital simulation forecasts, or a similar evolution but with high uncertainty.

By comparison, the new model provides a fairly similar evolution to digital predictions, with only slight uncertainty vis-à-vis already existing models.

The two-year national study attempted to replicate the same methodology across all autonomous regions in Spain, and its implementation will enable greater reliability in calculating coastal response to rising sea levels, particularly at a long-term regional, national or global scale.


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