Myths and realities of groins for recovery of beaches (2nd part).

Myths and realities of groins for recovery of beaches (2nd part).

By Enrique Alvarez del Rio.

In the previous release we discussed about the great controversy that has involved in Yucatán to put or not groins as a measure for beach protection and recovery. The cases of both success and failure are very numerous and it is clear that putting them by “recipe” is simply very dangerous for beach sustainability.

Whenever a groin is placed, a positive and rapid reaction can be expected. This, because usually in few days an accumulation of sand, that makes us gain dry beach area, is already perceived. However, what implies its greater risk, is that the deterioration develops very slowly, in an area that has nothing to do with the section to be protected, and when it becomes perceptible, the damage is not so simple to reverse.

In this release the “San Bruno zone”, located at Yucatán´s northern coast, is reviewed (see Figures 1 and 2), because it is an area with few interventions and where reversing any negative impact is feasible relatively easily. In subsequent releases, we will analyze currently critical coasts (Chelem, Chuburná, Chicxulub), where a sustainable alternative is possible, although it would require a very orderly government-society partnership.

Figure 1. San Bruno zone where the natural movement of sand that forms beaches is outlined.

Figure 2: Groin´s recovery / deterioration effect.

The pictures show by themselves what the problem is: We are retaining sand to the east of the groin, which should be feeding the beach to the west of it. If this retention is done uncontrollably and without understanding how much sand we can stop without affecting the system, the damage is inevitable. Any analysis of this intervention will be conclusive that the solution worked, and very well, for the beach which wanted to protect. But it is also inevitable to conclude that the damage to the surrounding areas was greater and today is out of control.  We would then have to remove the groin, or continue to place them in the West direction, which in turn, will require new groins as the problem is NOT being solved. It is ONLY transferring. In fact, in a general perspective analysis, the property that was protected is inheriting the effect of interventions that were made to the East, where the impact of possible affected areas was not evaluated in the beginning.

A first conclusion is the regularization of structures. The first step is the commitment not to carry out illegal works which undoubtedly solve the local problem, but aggravate the system in general. What is worse, not having them identified, can hardly be evaluated, monitored and, where appropriate, regulated and improved. This approach may seem absurd since the importance of all works being legal should be understood by itself. However, the large number of works without authorization and without any coordination between them, is undoubtedly one of the causes of the current beach deterioration.

On the northern coast of Yucatan there is no doubt that protection structures are necessary. There is no possible scenario to remove them all, since the system has been affected for decades. But if this is not done under a comprehensive strategy, the global deterioration will increase until it becomes irreversible.

In the next release, we will be exemplified spurs fields that work and do not work that also allows us to identify in what conditions to place them and how to do it.

This post is also available in: Spanish