LITTORAL ENVIRONMENT OBSERVATIONS AND 

 BEACH CHANGES ALONG THE SOUTHEAST FLORIDA COAST 



by 

 Allan E. DeWall 



I . INTRODUCTION 



This report presents an analysis o£ data on beach changes and litto- 

 ral processes at three locations along the southeastern Florida coasts 

 collected by the Florida Ocean Sciences Institute, Inc. (FOSI) , Deerfield 

 Beach, Florida, from January 1969 to June 19 73. The objectives o£ the 

 study were to acciomulate systematic information regarding winds, waves, 

 and currents in the nearshore environment and to relate these factors to 

 observed changes in beach profiles along Florida's southeastern coast. 

 A total of 4,898 beach profile surveys and 1,560 littoral environment 

 observations (LEO) was collected at the beaches of Jupiter, Boca Raton, 

 and Hollywood, Florida (Fig. 1). 



The study was carried out as part of the U.S. Army Coastal Engineer- 

 ing Research Center (CERC) Beach Evaluation Program (BEP) , which has the 

 objective of observing the response of beaches to waves and tides of 

 specific intensity and duration as a first step in developing a system 

 for warning low- lying coastal communities when dangerous beach erosion 

 conditions exist (Galvin, 1969) . The littoral environment parameters 

 analyzed include wind, wave, and longshore current observations. The 

 beach profile variables analyzed include: (a) sand level changes on 

 surveyed beach profiles; (b) the horizontal translation of the mean sea 

 level (MSL) shoreline; (c) volumetric changes above the MSL shoreline; 

 and (d) volumetric changes below MSL, to a distance offshore of 500 feet 

 (150 meters), at Boca Raton. Correlations are drawn between the environ- 

 mental parameters and the observed beach changes. 



1. Previous Work . 



Much of the literature on the geomorphology and sediments of south- 

 eastern Florida has been reviewed by Duane and Meisburger (1969), Meis- 

 burger and Duane (1971), and Field and Duane (1974). Meisburger and 

 Duane (1969) noted a distinct change in the nearshore shelf morphology 

 and in the surface sediments in the vicinity of Boca Raton. They con- 

 cluded that little, if any, sediment is transported into this area from 

 the north and that little interchange of material occurs between the 

 beach and shelf. 



Watts (1953) studied the effectiveness of the sand bypassing plant 

 at South Lake Worth Inlet and derived a relation between the net long- 

 shore transport rate and the height and direction of observed shallow- 

 water waves. (South Lake Worth Inlet is approximately midway between 

 Jupiter and Boca Raton. See Fig. 1.) Based on the volume of material 

 impounded by the north jetty at the inlet over a 14-year period. Watts 

 estimated a net southerly longshore transport rate of 200,000 cubic yards 

 (153,000 cubic meters) per year (to a 27- foot (8.2 meters) depth). 



