Maria Ines de Carli reports on the seminar by Dr Alexandra Toimil (IH Cantabria)

On Friday November 23rd, Dr Alexandra Toimil from the Environmental Hydraulics Institute “IHCantabria” gave a seminar on the topic: “A probabilistic framework for the assessment of coastal erosion”.

During the talk, Dr Toimil introduced us to a new framework that tries to fill a gap there currently is in impact assessment of coastal erosion. This methodology consists of a probabilistic framework used to predict erosion in beaches and its economic consequences. In the particular example explained in this seminar, the study area covered 57 beaches along 650 km of the coast of Cantabria.

The framework has three main components: hazards, exposure and vulnerability. The hazards identified in beaches were waves, storm surges and astronomical tides (with short term effects), and sea level rise (with long term effects). These compose an impact model which produces shoreline changes. Socio-economic scenarios describe the beach exposure component; and beach vulnerability is characterized by vulnerability curves. All the components conform a damage model and as a result the socio-economic valuation of erosion risk is obtained.

For this particular case of study, the impacts model was calibrated with a 60 year long reanalysis database and the future shoreline model was run in each of the beaches considered by combining 1000 hourly time series of waves, three seal-level rise curves and storm surges.  The product of this model is the shoreline retreat between 2010 and 2100 due to the three main different future climate scenarios considering different emission scenarios predicted by IPCC.

As a result, this probabilistic framework can estimate which beaches will disappear due to climate change and the rate at which the shoreline can change over time. Secondly, for each beach, the expected annual damage can be calculated and the losses of beach recreation value can be determined.

Finally, Dr Toimil remarked that this framework can further be improved by accounting for the uncertainties coming from the exposure and vulnerability components. Nonetheless, this methodology has already been adopted by Spain in order to inform decision making towards an adaptation to climate change. This model has yet to be implemented in other coastal environments worldwide but it has been stated that it can be adapted to use the different data sets each region may have available and we are looking forward to assess the diverse outcomes it may produce and the evolution of the framework itself.

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