Comparative Morphodynamics Between Exposed and Reef Protected Beaches Under Hurrricane Conditions

Abstract

It has been widely documented that coral reefs play a very important role in the dissipation of wave energy. Observations of beach morphology, made before and after a major hurricane that hit SE Mexico in October 2005 (Wilma), show widespread erosion at an exposed beach (Cancun), but unexpected beach accretion 25 km south at a beach fronted by a fringing reef (Puerto Morelos). The DELFT 3D morphodynamic model is used at a regional scale to explain the divergent morphological behavior of both beaches and explore the processes involved at both sites. A combination of offshore transport at the exposed beach, large scale southward sediment transport and onshore transport along the reef protected beaches seems to be the main explanation for the observed morphological behavior. Dune erosion and beach face sand relocation are also partially responsible for the beach progradation at the reef protected site.

Micro Sand Engine Beach Stabilization Strategy at Puerto Morelos, Mexico

“…Under extreme storm conditions, the storm surge is considered the most important threat. During hurricane Wilma, in October 2005 it reached 2.5 m at the beach (0.5 m in deep water) [34].…”

“…In summer, the frequent storms and tropical cyclones define the patterns [33]. 90% of the records at buoy 42056 (NDBC-NOAA) show a relatively small significant wave height (< 1m) and small wave periods (< 8 s), and thus the predominance of locally generated seas [34]. The fine sand is the results of this wave climate, but under hurricane conditions the beaches are very vulnerable to dramatic erosion processes.…”

A Comparison of Beach Nourishment Methodology and Performance at Two Fringing Reef Beaches in Waikiki (Hawaii, USA) and Cadiz (SW Spain)

“…In fact, some studies have taken into account the former geologic setting to design multifunctional artificial reefs that serve several purposes [8].One common type of geologically-controlled beach is situated landward of areas of hard bottom, such as rock or coral reefs. Reefs have large impacts on coastal hydrodynamics, sediment transport, and morphology, such as by influencing water level fluctuations [9], wave set-up and cross-reef currents [10], wave breaking, wave-induced flows, and wave attenuation over reef platforms [11][12][13][14][15], which affect the beach morphodynamics tidal range at multiple scales [16][17][18][19], even under hurricane conditions [20,21].Despite clear evidence that beaches with reefs behave differently to their non-reef counterparts, there has been scant attention given to how reefs should be considered in beach nourishment projects. A recent study by Habel et al [22] focused on the methodology of a beach nourishment at Royal Hawaiian Beach (RHB), Waikiki, which is fronted by a fringing coral reef.…”

“…One common type of geologically-controlled beach is situated landward of areas of hard bottom, such as rock or coral reefs. Reefs have large impacts on coastal hydrodynamics, sediment transport, and morphology, such as by influencing water level fluctuations [9], wave set-up and cross-reef currents [10], wave breaking, wave-induced flows, and wave attenuation over reef platforms [11][12][13][14][15], which affect the beach morphodynamics tidal range at multiple scales [16][17][18][19], even under hurricane conditions [20,21].…”

The role of the reef-dune system in coastal protection in Puerto Morelos (Mexico)

“…On the other hand, 25 heights of 3-4 m have been observed for sand dunes in Puerto Morelos (Ruiz de Alegria-Arzaburu et al, 2013). Mariño et al (2014) pointed out that during the Category 5 hurricane, Wilma, in 2005 the combined presence of dunes, a coral reef, and sand transported from Cancun during the event protected the coast of Puerto Morelos. This suggests that the coast is less vulnerable to extreme events where the reef-dune system is maintained.…”