Multi-criteria characterization and mapping of coastal cliff environments: A case study in NW Spain

This paper presents a novel approach to characterize cliff exposure to marine action that combines wave power and biology. This multidisciplinary approach is illustrated through a case study on a coastal stretch in NW Spain - the Catedrales Natural Monument. The engineering perspective is based on quantifying the wave power acting on the cliff. To this end, a statistical characterization of the wave climate in deep water is carried out, and relevant sea states are propagated numerically from deep water to the cliff. Four levels of cliff exposure, from sheltered to exposed, are defined based on wave power and mapped onto the study area. As for the biological perspective, ecological factors, bioindicated variables and biological indicators characterized through field observations are considered and, on this basis, also four levels of cliff exposure are established and mapped. In general, there is good agreement between the exposure patterns obtained through the engineering and biological perspectives; however, there are some differences in certain areas. The upshot is that the engineering and biological points of view should be regarded as complementary. The multi-criteria characterization performed in this paper may be used as a management tool to establish different degrees of exposure to marine action on cliff coasts elsewhere.