Abstract: Dune Dynamics in Coastal Zone--Past, Present, and Future
A. Gutman, H. Hennigar, V. Goldsmith
Coastal eolian deposits and associated dune vegetation, major interactive components within the total coastal ecosystem, are being altered dramatically and perhaps irrevocably, by man. Pedestrian and vehicular traffic and construction activities degrade dunes; sand fencing, vegetation planting, and fertilization build up the dune-vegetation system; all are ways in which its "normal" functions in the coastal ecosystem are being affected. For example, one function of the fore dunes is partial protection of inland areas and structures from inundation, wave attack, salt spray, and eolian-sand burial. This partial protection results in a dynamic equilibrium, and allows all eolian depositional forms to act as sources and sinks for onshore and offshore eolian-sand transport, the eby affecting the overall sediment budget.
Field measurements made downwind of onshore-sand transport in areas of stabilized dunes with artificially heightened and continuous ridges, and in area with low natural dunes, indicate differences in eolian transport. The field data show that artificially heightened and stabilized fore dunes result in less sand transport to areas behind the dune. Historical aerial photography (concomitant with dune stabilization since the 1930s) indicates that one result is a greatly increased vegetation cover, which would not have occurred in areas of previously intense sand shifting.
Thus, such alterations are disrupting the long-term equilibrium of the ecosystem by changing sediment-flux patterns (e.g., by decreasing the supply of sand being blown back into the fore dunes).
AAPG Search and Discovery Article #90968©1977 AAPG-SEPM Annual Convention and Exhibition, Washington, DC