Abstract. Reefs and sand dunes are critical morphological features providing
natural coastal protection. Reefs dissipate around 90 % of
the incident wave energy through wave breaking, whereas sand dunes
provide the final natural barrier against coastal flooding. The storm
impact on coastal areas with these features depends on the relative
elevation of the extreme water levels with respect to the sand dune
morphology. However, despite the importance of barrier reefs and dunes
in coastal protection, poor management practices have degraded these
ecosystems, increasing their vulnerability to coastal flooding. The
present study aims to theoretically investigate the role of the
reef–dune system in coastal protection under current climatic
conditions at Puerto Morelos, located in the Mexican Caribbean Sea,
using a widely validated nonlinear non-hydrostatic numerical model
(SWASH). Wave hindcast information, tidal level, and a measured beach
profile of the reef–dune system in Puerto Morelos are employed to
estimate extreme runup and the storm impact scale for current and
theoretical scenarios. The numerical results show the importance of
including the storm surge when predicting extreme water levels and
also show that ecosystem degradation has important implications for
coastal protection against storms with return periods of less than
10 years. The latter highlights the importance of conservation of the
system as a mitigation measure to decrease coastal vulnerability and
infrastructure losses in coastal areas in the short to medium
term. Furthermore, the results are used to evaluate the applicability
of runup parameterisations for beaches to reef environments. Numerical
analysis of runup dynamics suggests that runup parameterisations for
reef environments can be improved by including the fore reef
slope. Therefore, future research to develop runup parameterisations
incorporating reef geometry features (e.g. reef crest elevation, reef
lagoon width, fore reef slope) is warranted.
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