Coastal Dunes Study

Coastal Dunes Study

by John McNerney

The sand dunes that front the shoreline of the Pacific coast and the east cape region of Baja California Sur are known as coastal or barrier dunes. This type of dune, such as those found behind the beaches in Todos Santos, act as a buffer against high surf and summer storms, protecting low lying inland areas from flooding. Equally important, these dunes provide a sand reservoir that replaces sand eroded from the beach. The benefits that these dunes provide are often not recognized much less valued monetarily. The purpose of this article, and following installments, is to help people understand their critical function in the natural environment and, with this understanding, perhaps alter their recreational and developmental activities, which often lead to the destruction of these dunes.

Coastal Dune Damage on East Cape of Baja

Coastal dunes are significantly different from sand dunes in desert areas. Desert dunes shift continually in the direction of prevailing winds and have little to no vegetative cover. Coastal dunes, however, are covered in specialized grasses that have the unique ability to survive in shifting sand, continually producing new stems and roots through cycles of burial and exposure. This net of grasses stabilized the dunes and when damaged or removed by human interference, the dunes will begin migrating inland, covering everything in their path and allowing the sea to flood low lying inland areas.

The preservation of this natural coastal environment will only increase in importance in the future, given global climate change, the attendant rising of sea levels and the growing incidences of powerful storms. A coastal dune system, left in its natural state, will slowly migrate inland as the sea level rises and continue to protect inland areas.

East Cape dune damage

In recent years government regulatory protection of coastal dunes has been enacted in many parts of the world, especially those coastal areas developed for recreation over the past century when housing and hotels replaced the dunes. Dunes are the sand reservoir for the beaches and when they are removed, the beaches follow suit. Beach erosion, with the subsequent loss of recreational areas, has severely affected local economies and taxpayers are now funding large-scale coastal dune restoration projects.

More East Cape damage

Local Mexican environmental groups, such as "Sociedad de Historia Natural Niparaja" of La Paz, are working with government officials to enact regulations in Mexico to prevent similar destruction of Baja's coastal dunes.

In a follow up article, we will review simple ideas to protect our coastal dunes, as well as describe areas that have already undergone degradation due to developmental and recreational abuse. If you would like more information on coastal dunes, visit your favorite search engine (we like Google) and search on the terms "barrier or coastal dunes."

In the last issue, I addressed the structure, function and need for preservation of the sand dunes that lie along our coastal areas. Here are two ways we can all help to protect this valuable resource.

Able to withstand the most violent storms, coastal dunes can quickly disappear due to human activities. Driving 4-wheel vehicles and ATVs on and across the dunes destroys the grasses holding the dunes in place. These paths to the beach can eventually serve as openings for the ocean to move inland. If you must drive to the beach, there are numerous bocas (openings) where arroyos run to the ocean and provide less destructive motorized access to the beach.

Electing not to build a home or promote development on coastal dunes is of importance, not only to protect the coastal environment, but to also protect one's potential investment. The beach erosion photo in last issue (see above) showed a partially destroyed house built on a coastal dune. This home was part of a shoreline development called "Las Barrancas" in the East Cape region north of Cabo Pulmo. A severe storm with high surf swept away up to 20 meters of developed beach front property, resulting in partial to total destruction of a number of homes, leaving others perched on newly formed sand cliffs overlooking the beach.

Property owners erect bulkheads and seawalls in an attempt to prevent further erosion of their remaining land. Such structures, as experience in other coastal areas has shown, have proved to contribute to or accelerate local coastal erosion.

This cycle of construction and destruction has been repeated in coastal areas worldwide. The only successful solution has been to protect the existing dunes and restore those that have been destroyed. Eventually, the sea always wins.

Developers Lot Map, Section One

The Las Tunas Dunes

The Las Tunas Dunes System

El Ecosistema de Dunas

The Las Tunas Dunes system is currently a very healthy dune system that stores vast amounts of sand. Our dunes are densely vegetated dunes, containing complex root structures that retain sand. Much vegetation grows to the base of the dunes. As organic ocean debris traps sand, nature creates incentive for new growth to dune base. In this way dunes can regenerate growth after wave attack.

When dunes are developed and replaced with structures, they are no longer capable of storing sand. Development on or near the crest of a dune can cause the area to be susceptible to a breach, eliminating any barriers of protection, and decimating vegetation, which contributes to further erosion. It’s an open invitation for potential damage from a storm. When vegetation is stopped, and root penetration is no longer possible, sand is no longer retained and this also leads to more serious wind and water erosion.

Dune grasses may grow on either side of a structure, but won’t grow under a foundation. Once a dune erodes back to a foundation, self-regeneration is at best difficult & slow. Large homes, built tightly together in series, to the edge of the barrier dune (such as the proposed 90 home sites on our barrier dunes), would have to rely on a very thin noncontiguous strip of vegetation to contain the very foundation upon which they sit. Even when someone does adhere to building requirements, such as not to exceed a specific percentage of a lot, no matter what size lot, building that structure still entails destroying most of the dune of the lot that house will sit on......landscaping, hardscaping, patios, driveways, pools, etc...not just the footprint of the floor plan of the actual structure.

We, as concerned neighbors of the Dunes, are at great risk of losing our protection from allowing development to continue on our barrier dunes. Together we must do whatever possible to insist sanctions be put in place and to protect and maintain the health of our dunes. Have we not learned the lessons from other parts of the world… where the importance of dunes has been neglected, and that nature’s purpose for putting them where they were has been compromised?

Building homes at the expense of barrier dunes has happened before. We must learn from the disasters that have occurred in other places with a similar environment. “Each time history repeats itself, the price goes up.”

We have a responsibility to ourselves, to our neighborhoods, and to the future, to safeguard our precious dunes from dense development and steward our dunes habitats as the sanctuaries they are for so many rare plants and endangered creatures.

“When dunes are destroyed by man, there is nothing left to stabilize the remaining sea of drifting sand but man himself.”

This information excerpted from: John Clark, Coastal Ecosystems Ecological Considerations for Management of the Coastal Zone, The Conservation Foundation, Washington, DC in Cooperation w/ NOAA Office of Coastal Environment & US Dept of Commerce

El Ecosistema de Dunas de las Tunas

El Ecosistema de Dunas de las Tunas, es actualmente un ecosistema sano, que almacena grandes cantidades de arena. Nuestras dunas están densamente pobladas de vegetación, con raíces complejamente estructuradas que retienen arena. Mucha vegetación crece en la base de las dunas. Como trampas de arena para desechos orgánicos, la naturaleza motiva el crecimiento de nuevas bases. De esta manera las dunas se pueden regenerar después de recibir la marea.

Cuando las dunas se reemplazan con estructuras, pierden la capacidad de almacenar arena. Cualquier desarrollo en o cerca de la cresta de la duna puede causar al área a ser susceptible a un rompimiento, eliminando cualquier barrera de protección y diezma la vegetación, lo que contribuye a futuras erosiones. Es una invitación a daños por una tormenta. Cuando la vegetación es detenida, y la penetración de las raíces no es posible, el arena no se retiene y esto también provoca a más erosión seria por aire y agua.

Los pastos de las dunas pueden crecer al lado de una estructura, pero no bajo ningún cimiento. Una vez erosionado, la regeneración es muy difícil y lenta. Casas grandes, construidas juntas y en serie, a la orilla de las dunas (como las propuestas 90 casas a orillas de las dunas), tendrían que depender de una muy fina cinta de vegetación para contener los cimientos en los que se construyen.¿Qué pasaría con el banco de la playa si se erosionara?

Nosotros como vecinos de las Dunas, estamos en gran riesgo de perder nuestra protección al permitir el desarrollo en la barrera de las dunas! Juntos debemos hacer lo posible para insistir en el establecimiento de sanciones y la protección y mantenimiento de las dunas. ¿Qué acaso no hemos aprendido las lecciones de otras partes del mundo… donde la importancia de las dunas fue omitida, y donde el hecho de que el propósito de la naturaleza fue ponerlas ahí, ha sido comprometido?

Construir casa a expensas de la barrera de las dunas ha ocurrido antes. Debemos aprender de los desastres que han ocurrido en otros lugares con un hábitat similar. “Cada vez que la historia se repite, el precio sube.”

Tenemos una responsabilidad con nosotros mismos, con nuestros vecinos, y con el futuro, de resguardar las preciadas dunas de un denso desarrollo y de auxiliar los hábitats de las dunas como santuarios que son de tantas raras plantas y criaturas en peligro de extinción.

“Cuando las dunas son destruidas por el hombre, no hay nada que estabilice el resto del mar, de la arena a la deriva, si no el hombre mismo”.

Esta información extraída de: John Clark, Consideraciones Ecológicas de Ecosistemas Costeros para Administración de la Zona Costera, Fundación de Conservación, Washington, DC en cooperación con NOAA Oficina de Hábitats Costeros y el Departamento de Comercio de EUA.

Eco Disaster for the Barrier Dunes

Ocean Developing plans to make rows of giant houses (90) on the barrier dunes with sea walls like this all along the coastline. This is an Eco Disaster for the dunes and the community that cannot be reversed. Concerned residents of BCS Please lend your support!

Our Goals:

Research and scientific studies on the negative impact of development

Petitioning the Mexican Government to establish Natural Protected Areas

Educational and Community Outreach. Co-ordinate with other Environmental Groups.

File legal complaints to government agencies about building in environmentally sensitive areas.

Investigation in to corruption and fraud associated with development projects.

http://www.bestoftodossantos.com/blog/importance-of-todos-santos-dunes

PRESERVE OUR COASTLINE

Todos Santos, Baja CA Sur

“Protect What You Love”

Destruction of barrier dunes by the impacts of development:

Causes accelerated sand and wind erosion of our coastline.

Inceases flooding in severe storms, putting neighboring homes at risks.

Intrudes upon turtle nesting habitat of endangered species.

Destruction of natural foliage of dunes and wildlife.

Over-strains the struggling, local infra-structure; consistent water shortages, power failures, inadequate sewage treatment, and poorly maintained roads.

Newly built houses built on the barrier dunes are not in compliance with environmental restrictions

Overbuilding on shifting sand dunes not only compromise their very purpose of protecting low lying areas, but it destroys the health of precious ecosystems.

This community opposes building on the barrier dunes.

PRESERVEMOS NUESTRAS FRANJAS COSTERAS

PRESERVEMOS NUESTRAS COSTERAS

Todos Santos, Baja Ca Sur

"Proteje lo que Amas"

Destrucción de la barrera de dunas por impactos del desarrollo:

Riesgo de estabilidad. Causa rápida erosión por vientos y arena de nuestra zona costera.

In crementa los riesgos de inundación en casos de tormentas severas, poniendo nuestro vecindario y casas en riesgo.

Afecta los lugares de anidación de la tortuga marina y habitat de especies en peligro de extinción.

Destrucción de la vegetación y vidasalvaje.

Acabara nuestra ya amenazada infraestructura: disminución de los volumenes de agua, fallas eléctricas, tratamiento inadecuado del drenaje y el escaso mantenimiento de los caminos.

Las nuevas casas construidas sobre las dunas no cumplen con la reglamentación y restricciones ambientales

Sobreconstrucción o cambios en las dunas no solamente compromete su propósito natural de proteger las tierras más bajas, además destruye la salud de este precioso ecosistema.

Nuestras metas :

Investgación y estudios científicos sobre el negativo impacto del desarrollo

Hacer peticiones al gobierno mexicano para establecer areas naturales protegidas

Coordinarnos con otros grupos ambientalistas para apoyarnos mutuamente y intercambiar información

Presentar denuncias y quejas ante oficinas gubernamentales acerca de construir en areas ambientalmente sensibles

investigar actos de corrupación y fraude relacionados con proyectos de desarrollo

http://www.bestoftodossantos.com/blog/importance-of-todos-santos-dunes/