PLANTING GUIDELINES FOR DUNE CREATION AND STABILIZATION 



by 

 Paul L. Knutson 



I. INTRODUCTION 



Foredunes function as reservoirs of sand that nourish eroding beaches 

 during high water, and as levees that delay the inland penetration of 

 waves and storm surges (see App. A for a glossary of terms). These dunes 

 are usually naturally created and maintained by the action of beach grass- 

 es which trap and hold blowing sand. Erosion occurs if this vegetation 

 is damaged by drought, disease, overgrazing, traffic, or waves during 

 severe storms. Damaged dune systems can be restored by planting beach 

 grasses. 



II. APPLICATIONS 



1. General . 



Beach grasses may be used to form dunes on any backshore that is 

 about 300 feet (91 meters) wide and has an adequate supply of moving 

 sand particles. (In these areas sand will deposit around the beach 

 grasses, bits of debris, and other obstructions.) However, in most 

 cases, beach-grass planting is used to restore damaged dunes. There are 

 three types of dune damage that may occur: (a) Wind erosion often occurs 

 on the seaward face of foredunes where vegetation has been destroyed. 

 As erosion continues, "bowl-shaped" depressions ca.lled bloiJouts are 

 formed (Fig. 1). (b) During severe storms, weakened parts of the dune 

 line may be breached, forming "washover channels." These channels may 

 flood periodically (Fig. 2). (c) In some areas, wind and wave erosion 

 level the original dune field, leaving a "barren" backshore (Fig. 3). 



2. Specific . 



a. Stabilizing Blowouts . If wind erosion occurs on the seaward 

 face of a foredune, the entire disturbed area should be planted. 



b. Closing Washover Channels . Beach grasses will not survive in 

 washover channels subject to periodic flooding and wave action. To pre- 

 pare these areas for planting, erect six parallel rows of 4-foot-high 

 (1.2 meters) picket snow (sand) fencing, spaced 10 feet (3 meters) apart 

 in a 50-foot (15 meters) width, 1 year before planting. After the spaces 

 between fences have filled with sand, the area is ready for planting. A 

 dune 2 to 3 feet (0.6 to 0.9 meter) high may be formed with construction 

 equipment to avoid delay; however, this method costs more. This initial 

 dune should be built 50 feet landward of the estimated dune line to allow 

 for dune widening. A final base width of 100 feet (30 meters) or more 



is desirable. About 4 to 5 years after the initial planting, another 

 50- foot-wide strip may be added immediately seaward of the existing veg- 

 etation if the 100-foot width has not developed naturally. Dunes built 



