CONSTRUCTION AND STABILIZATION OF COASTAL FOREDUNES 

 WITH VEGETATION: PADRE ISLAND, TEXAS 



BillE. Dahl, Bruce A. Fait, 

 Alan Lohse, and S.G. Appan 



I. INTRODUCTION 



Flood damage from hurricanes is a constant concern of inhabitants in the Atlantic and 

 gulf coastal zones. Coastal barrier islands provide significant protection against high water 

 through the damming effect of foredunes which characteristically form parallel to the 

 beach. Foredunes on the gulf coastal barrier islands vary in height from less than 10 feet to 

 over 35 feet above mean sea level (MSL). An unbroken foredune ridge affords natural 

 protection to the mainland and back-island from seasonal high tides, storm surges, and 

 hurricane-generated waves. However, the combined effects of man's destructive influence 

 (e.g., overgrazing by cattle and sheep), fire, droughts, and storm surges have denuded large 

 expanses which allow accelerated erosion in areas lacking a vegetative cover (Harris, 1965). 

 Eventually, storm surges breach the foredunes and allow floodwaters to wreak havoc. On 

 Padre Island, these processes have destroyed the foredunes in numerous places. Storm surge 

 erosion also moves considerable sand inland from the beach onto lowland vegetation, into 

 bays and lagoons, and accumulates on roads and in navigation channels adjacent to the 

 islands. After severe flooding from Hurricane Carla in 1961, mainland residents agitated for 

 restoration of the natural dams and even suggested constructing a seawall on Padre Island. 



Increasing elevations of the barrier islands by restoring foredunes would yield obvious 

 benefits. However, except for preliminary trials by a Padre Island National Seashore 

 landscape architect (Tauscher, 1966) and by personnel of the U.S. Army Engineer District, 

 Galveston (Gage, 1970), there is no information on foredune restoration for barrier islands 

 along the Texas coast. 



Sand fences, fences used in combination with grasses, and grasses, have all been effective 

 in sand dune restoration and stabilization along the Atlantic and Pacific coasts (Brown and 

 Hafenrichter, 1948a, b; Davis, 1957; Jagschitz, 1960; Woodhouse, 1963; Zak and Bredakis, 

 1963; Woodhouse and Hanes, 1967; Savage and Woodhouse, 1968). 



This study provides tested specifications on how to use vegetation in tiie restoration of 

 destroyed or denuded parts of foredunes of gulf coast barrier islands. Primarily, grasses were 

 evaluated for their ability to trap moving sand to restore and stabilize dunes. Also, the study 

 evaluated the potential of grasses to stabilize sand accumulated by fences. 



II. LITERATURE REVIEW 



Programs to maintain a protective, vegetated eoastal barrier dune line have long been in 

 existence (King, 1959). A general review of techniques and materials used in Europe is 

 covered in Chapman (1949) and Van der Burgt and Van Bendegom (1949). Similar research 



