ambient processes and sediments to develop and evolve in the shoreline environment. Foredune restoration, therefore, should enable the input of sediment to
the foredune location and provide for the opportunity of the foredune to develop in
response to the dimensions of sediment supply and budget. Similar to the concept
of passive and active restoration espoused by Kauffman et al. (1997), the geomorphological thrusts of foredune restoration may consist of taking action to
encourage the availability and function of sediment pathways or the more passive
approach of allowing natural foredune migration as well as in situ growth or
attenuation.
3.3 Conceptual Basis
In the grand geomorphological scheme, there is a conceptual model of processes
acting upon sediments to create geomorphological responses, thoroughly presented
for the coastal system in the synthesis volumes by Trenhaile (1997) and DavidsonArnott (2010). Restoration, therefore, is a condition that takes place within this
model and it treats some aspect of the process–response sequence.
At the outset, it must be conceded that it is difficult to restore the processes of
coastal foredune development because the processes are the dynamics of moving
wind and water. The processes exist, although they may be altered by local
interference. Likewise, it is really not within the general model to restore the forms
because they are the outcomes of the action of the processes interacting with
sediments and plants. The forms may be rebuilt or re-created, but that is a type of
rehabilitation of an existing product, and not a restoration of the conditions that
produce a product. Thus, it is logical that the concept of restoration of the coastal
foredune should be directed at the restoration of the sediment supply that supports
the creation, locus, and evolution of the coastal foredune (Hesp 1989; Psuty 2004).
That is, given the presence of ambient processes that will mobilize sediment inland
from the beach to accumulate at the site of the feature and produce the form (in
association with vegetation), the constraining variable is the availability of sediment. The end product of the process–sediment response model is the foredune,
and it has dimension, form, and location dependent on the presence of the processes acting upon the ambient sediment supply.
Therefore, in terms of restoration of a foredune or its return to a previous
condition, it is the restoration of the available sediment supply to produce the
resulting form that is the conceptual basis for the continuation of foredune
development and evolution. And, importantly, there is no equilibrium form in this
restoration goal because the natural evolution is dependent on the sediment budget,
the net condition between gain and loss, and the vector that may lead to the natural
enhancement, continuance, or to destabilization and destruction of the foredune.
Part of this geomorphological approach is related to scale. Sediment budget is
measured in years to decades to centuries. It is the net measure of accumulation
and release of sediment that produces the resulting landform in some specified
3 Restoration of Coastal Foredunes, a Geomorphological Perspective
35
the foredune location and provide for the opportunity of the foredune to develop in
response to the dimensions of sediment supply and budget. Similar to the concept
of passive and active restoration espoused by Kauffman et al. (1997), the geomorphological thrusts of foredune restoration may consist of taking action to
encourage the availability and function of sediment pathways or the more passive
approach of allowing natural foredune migration as well as in situ growth or
attenuation.
3.3 Conceptual Basis
In the grand geomorphological scheme, there is a conceptual model of processes
acting upon sediments to create geomorphological responses, thoroughly presented
for the coastal system in the synthesis volumes by Trenhaile (1997) and DavidsonArnott (2010). Restoration, therefore, is a condition that takes place within this
model and it treats some aspect of the process–response sequence.
At the outset, it must be conceded that it is difficult to restore the processes of
coastal foredune development because the processes are the dynamics of moving
wind and water. The processes exist, although they may be altered by local
interference. Likewise, it is really not within the general model to restore the forms
because they are the outcomes of the action of the processes interacting with
sediments and plants. The forms may be rebuilt or re-created, but that is a type of
rehabilitation of an existing product, and not a restoration of the conditions that
produce a product. Thus, it is logical that the concept of restoration of the coastal
foredune should be directed at the restoration of the sediment supply that supports
the creation, locus, and evolution of the coastal foredune (Hesp 1989; Psuty 2004).
That is, given the presence of ambient processes that will mobilize sediment inland
from the beach to accumulate at the site of the feature and produce the form (in
association with vegetation), the constraining variable is the availability of sediment. The end product of the process–sediment response model is the foredune,
and it has dimension, form, and location dependent on the presence of the processes acting upon the ambient sediment supply.
Therefore, in terms of restoration of a foredune or its return to a previous
condition, it is the restoration of the available sediment supply to produce the
resulting form that is the conceptual basis for the continuation of foredune
development and evolution. And, importantly, there is no equilibrium form in this
restoration goal because the natural evolution is dependent on the sediment budget,
the net condition between gain and loss, and the vector that may lead to the natural
enhancement, continuance, or to destabilization and destruction of the foredune.
Part of this geomorphological approach is related to scale. Sediment budget is
measured in years to decades to centuries. It is the net measure of accumulation
and release of sediment that produces the resulting landform in some specified
3 Restoration of Coastal Foredunes, a Geomorphological Perspective
35