Natural recovery of beaches. Part I.

Natural recovery of beaches. Part I.

The “Playa Teresiano”, Yucatán, México case

Much has been speculated in recent years about beach recovery in Yucatán. Beaches are protected on one side and eroded on the down drift side. And on the way, along 40 km of beaches subject to the same coastal dynamics (between Progreso and Telchac), many constructions have been developed and most of them illegally, without a vision of the integral operation of the system. This, always causing more problems than solutions. Particularly, in the case at issue (km 13 on Progreso-Telchac Highway), in the last two years the Secretariat of Urban Development and Environment (SEDUMA, in Spanish), has coordinated efforts between authorities and society, finally giving the results needed for local beaches. This work consists of understanding that rather than building coastal protection structures, it is necessary to let the beach system “breathe” and to “take care” of its self recovery. This can be achieved by eliminating all the structures that have done nothing but prevent the natural recovery of the beach (Figure 1).

Figure 1 Natural recovery of the beach after removing structures that modify the coastal dynamics (West view of Teresiano).

Specifically, last April, a submerged breakwater was installed on the stretch of beach known as “Teresiano” (Figure 2). This area has not had a solid beach in the past 10 years, and the coastal infrastructure was in a very vulnerable situation. What has worked is simply removing a series of transverse structures (groins) and place a submerged breakwater only in its most critical part where coastal infrastructure (in this case summer houses) was at risk of destruction by extreme weather events, such as “nortes” (strong winds typically bad weather from the north).

This breakwater is a buffer or reducer of wave energy (Figure 3). This causes that waves arriving to the beach decrease their force needed to keep the sand in suspension and therefore it is accumulated in a natural way, without impeding its circulation to other beaches. The recovery is slow but it is what most resembles to the natural behavior of a stable beach.

Figure 3. Submerged breakwater functioning as a wave energy reducer.

It is extremely early to draw conclusions (the installation is about to complete one month). However, the results are beginning to show up (Figures 4, 5, 6). Allowing the sea to “set” natural recovery times, instead of accelerating beach accretion processes in an artificial way, seems the best opportunity to achieve a stable system in the long-term. The challenge now is to ensure that the stabilization of these beaches does not cause erosion on adjacent beaches, in which case restoration measures must be immediate, focused on naturally “keeping sand in circulation” rather than “retaining” it in an artificial way (which had been happening for years).

October 26, 2011: Figure 4 Teresiano beach situation in 2011.

April 17th, 2017: Figure 5 Teresiano beach condition in April.

May 27th, 2017: Figure 6 Teresiano beach situation after 1 month of the breakwater installation.

Conclusions:

  1. The analyzed beach of the Teresiano has been in critical condition for many years. Finally, the partnership between society and authorities has allowed actions to “remove” what is not necessary rather than “putting” new constructions under a local perspective, only intervening in critical points like this case. This seems to be starting to work but there is still a very long road
  2. A high-resolution monitoring of the marine response to the structures is being carried out by the UNAM. This will allow the authorities to take the appropriate measures to achieve step by step a long-term goal, recovering the coastal dynamics broken several decades ago. In addition, the projects will be more complete and environmental authorities will have better elements to authorize or not coastal protection developments.
  3. The collaboration of society is indispensable. It requires its participation in completely eradicating the culture of illegal construction. The case of Yucatan is one of a beach system where beaches are connected to each other along tens of kilometers. Any punctual construction can cause serious repercussions.
  4. The solution presented here cannot be extrapolated by itself to the whole beach system. Each critical section should consider its particularities and any proposed intervention, either “removing” or “putting” new structures (parallel or transversal) must be done under environmental regulations that consider repercussions on the entire system.

This post is also available in: Spanish