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are involved in the marine dynamic. Beaches of these environments, like those associated to wetlands, can be characterized as emerged or submerged thanks to geological processes, as the subsidence or raising, that cause that the medium level
migrates above or below to the average of the historic sea level.
The shoreline of coastal lagoon is under the classification of barrier island formed
by a coastal bar whose geometric configuration in plant and profile is function of
wave features that arrives to its coastal zone. Generally, these barrier systems are
integrated to a body of water with salty features or estuarines when they have communication with any river source. These systems, that are known as wetlands or
coastal lagoons save a large biodiversity and have a fundamental role as weather
regulators. From the marine environment perspective, these natural elements have a
beach profile of thin width, an alignment that allows the dissipation of wave energy
and also, permits the sediment transport along the littoral.
Currently, one of the most common problems in littoral zones of coastal wetlands is the coastal erosion caused by anthropic or natural impacts. For the analysis,
it is used morphologic temporal domains that vary in function of the shore affectations. Therefore, it defines three stages known as short, medium and long-term. In
the long-term (years-thousand of years), the erosion process is manifested in a special domain of regional context and it is associated with events derived from the sea
level rise and geological changes (Cooper and Pilkey 2004; Javrejeva et al. 2012).
In intermediate scales (years, decades), usually the erosive phenomena is influenced
by an unbalance in sediment transport rates as product of the inappropriate establishment of coastal structures or interventions in the upper part of the basin, as the
reservoirs to the energy generation or flood abatement (Komar 1998; Cooper and
Pilkey 2004). In the short-term, it is related with waves with a high content of
energy, wave trains that directly influence in the beach where all their energy is dissipated, and any coastal process resulting in the loss of material from the beach.
The resilience of coastal bar that protects a wetland is assessed from its regulatory capacity with external forces, or from a mechanical perspective, when it is
capable to maintain a mass balance in sedimentary terms. On this subject, it can
mention the positive or negative regulation to characterize processes through which
the beach assures a proper functioning (Ruiz 2009). The positive behaviour occurs
in a waterfront that remains invariable in spatial and temporal terms; regardless of
the solicitations exposed. The negative scenario is reflected when exists a temporal
variation of sediments so the system adapts to the forcings of maritime weather
without losing control.
The interpretation of that resilience is what defines the concept of equilibrium in
a bar or in a coastline given that it can be affirmed with certainty that a beach has
equilibrium when the quantity of gained or loosed material remains unchanged in
time, and mechanically represents a conservative phenomenon. It is a concept that
allows to assess the variability of beach shape in a temporal threshold and it is used
as support to predict changes that will happen in the bar for variations in conditions
that govern the coastal dynamic. Therefore, the static equilibrium is the state in
which the bar is allocated when not appreciably variance in time. The slightest
change in the configuration during a period of short and medium-term implies a
transference to the domain of dynamic equilibrium.
9 Physical and Morphological Changes to Wetlands Induced by Coastal Structures
are involved in the marine dynamic. Beaches of these environments, like those associated to wetlands, can be characterized as emerged or submerged thanks to geological processes, as the subsidence or raising, that cause that the medium level
migrates above or below to the average of the historic sea level.
The shoreline of coastal lagoon is under the classification of barrier island formed
by a coastal bar whose geometric configuration in plant and profile is function of
wave features that arrives to its coastal zone. Generally, these barrier systems are
integrated to a body of water with salty features or estuarines when they have communication with any river source. These systems, that are known as wetlands or
coastal lagoons save a large biodiversity and have a fundamental role as weather
regulators. From the marine environment perspective, these natural elements have a
beach profile of thin width, an alignment that allows the dissipation of wave energy
and also, permits the sediment transport along the littoral.
Currently, one of the most common problems in littoral zones of coastal wetlands is the coastal erosion caused by anthropic or natural impacts. For the analysis,
it is used morphologic temporal domains that vary in function of the shore affectations. Therefore, it defines three stages known as short, medium and long-term. In
the long-term (years-thousand of years), the erosion process is manifested in a special domain of regional context and it is associated with events derived from the sea
level rise and geological changes (Cooper and Pilkey 2004; Javrejeva et al. 2012).
In intermediate scales (years, decades), usually the erosive phenomena is influenced
by an unbalance in sediment transport rates as product of the inappropriate establishment of coastal structures or interventions in the upper part of the basin, as the
reservoirs to the energy generation or flood abatement (Komar 1998; Cooper and
Pilkey 2004). In the short-term, it is related with waves with a high content of
energy, wave trains that directly influence in the beach where all their energy is dissipated, and any coastal process resulting in the loss of material from the beach.
The resilience of coastal bar that protects a wetland is assessed from its regulatory capacity with external forces, or from a mechanical perspective, when it is
capable to maintain a mass balance in sedimentary terms. On this subject, it can
mention the positive or negative regulation to characterize processes through which
the beach assures a proper functioning (Ruiz 2009). The positive behaviour occurs
in a waterfront that remains invariable in spatial and temporal terms; regardless of
the solicitations exposed. The negative scenario is reflected when exists a temporal
variation of sediments so the system adapts to the forcings of maritime weather
without losing control.
The interpretation of that resilience is what defines the concept of equilibrium in
a bar or in a coastline given that it can be affirmed with certainty that a beach has
equilibrium when the quantity of gained or loosed material remains unchanged in
time, and mechanically represents a conservative phenomenon. It is a concept that
allows to assess the variability of beach shape in a temporal threshold and it is used
as support to predict changes that will happen in the bar for variations in conditions
that govern the coastal dynamic. Therefore, the static equilibrium is the state in
which the bar is allocated when not appreciably variance in time. The slightest
change in the configuration during a period of short and medium-term implies a
transference to the domain of dynamic equilibrium.
9 Physical and Morphological Changes to Wetlands Induced by Coastal Structures