ABSTRACT OF THE DISSERTATION



Eolian Sediment transport and Dune Formation

on Undeveloped and Developed Shorelines

by PAUL ANDRE GARES, Ph. D.

Dissertation Director: Professor Norbert P. Psuty



Dune formation processes were monitored at two undeveloped and five developed sites during the winter of 1981-82.  Sediment transport, vegetation density, topography, and cultural characteristics were measured in the field.  Wind flow data were obtained from a local weather station.  The variation in sediment transport in the dune system explained by these independent variables is limited.  Vegetation density is the primary factor affecting eolian sediment transport at undeveloped sites.  At developed sites, the effect of vegetation density on sediment transport is reduced.  Topographic variables do not contribute greatly to the overall explanation of variation at either type of site.



Different relationships between the variables exist within separate morphologic units of the dune system.  Sediment transport at undeveloped dune front sites is primarily controlled by vegetation density, but dune foreslope also inversely affects the amount of sand transferred inland from the beach.  At developed sites, sand fences erected along the dune toe reduce the amount of sand moved inland.  Along the dune crest and on the dune

backslope, vegetation density is the primary factor affecting sediment transport at undeveloped sites.  At developed sites, the presence of houses or of coarse sand/gravel surfaces reduces offshore sediment transport.



Significantly smaller quantities of sand are moved by the wind at developed sites than at undeveloped sites.  This results in smaller elevation changes along dunes at developed sites.  The larger amounts of sand moved inland at undeveloped sites produce areas of substantial accretion along the dune front.  In the short-term, developed dune systems are less dynamic than undeveloped systems.



In the longer-term, developed dune systems change rapidly due to human intervention.  Sand fences and bulldozers are used to rebuild the dunes following large storms.  The growth of dunes at undeveloped sites occurs more progressively, as sediment is moved to areas landward of the foredune, creating a positive sediment budget for the dune system.  Sediment budgets at developed sites are balanced or negative due to the inability of the system to move sand inland.