Beach Nourishment and Protection (1995) / Chapter Skim
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5 Environmental Issues Associated with Beach Nourishment
5 Environmental Issues Associated with Beach Nourishment
Pages 107-126
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From page 107... ...
Technical and scientific knowledge is incomplete, especially with respect to the indirect effects on biota that use the habitats affected by nourishment operations. SUBAERIAL BEACH HABITATS The subaerial beach can be divided into two major zones.
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From page 108... ...
Sand sources with a high silt/clay content are generally avoided, although some nourishment projects have used material with a relatively high percentage of these fine-grained materials (e.g., Reilly and Bellis, 1978~. In addition to its not being particularly suitable as beach fill material, dredging sand deposits with a high percentage of fines can have adverse effects on existing biota in adjacent habitats as a result of increased turbidity and sedimentation.
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From page 109... ...
Macrofauna typically found in the intertidal zone include haustoriid amphipods, polychaetes, isopods, mollusks, and some larger crustacean species such as mole crabs (Emerita spp.) and burrowing shrimp (Callianassa spp.J in the lower intertidal and swash zones (Dexter, 1972; Croker et al., 1975; Shelton and Robertson, 1981; Knott et al., 1983; Williams, 1984~.
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From page 110... ...
To date, no studies have been published on the effects of beach nourishment on shore bird foraging patterns. The effects of beach nourishment on the nesting success of threatened or endangered sea turtle species is another major concern related to beach nourishment projects completed in southern regions of the United States.
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From page 111... ...
However, some physical aspects of the nourished beach can influence the viability of turtle nests and nesting activities, and proposals to conduct nourishment projects during the turtle nesting season have generated considerable debate, particularly in Florida. There are several known effects that active nourishment operations can have on sea turtles during the nesting season.
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From page 112... ...
even documented greater hatching emergence success and hatchling weights for a nourished beach in Boca Raton compared to an adjacent natural beach. The results of these studies suggest that nourished beaches can provide a suitable habitat for turtle nesting, but more research is needed to resolve all the problems of this complex issue.
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From page 113... ...
Physical alterations may include: · burial of bottom habitats in the surf zone as the beach is widened; · increased sedimentation in areas seaward of the surf zone as the fill material redistributes to a more stable profile; changes in the nearshore bathymetry and associated changes in wave action; and · elevated turbidity levels, particularly in the vicinity of the pipeline effluent.
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From page 114... ...
Motile invertebrates and fishes typically found in this zone should be able to avoid most of the direct effects of beach nourishment, although larval forms found in the surf zone could be adversely affected by high turbidity levels if they occur. Two surveys of fish populations conducted in Florida before and after beach nourishment showed no evidence of adverse effects to the composition and abundance of the fishes sampled (Holland et al., 1980; Nelson and Collins, 1987~.
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From page 115... ...
BORROW SOURCE AREAS There are many environmental issues related to the sites used for the source of sand material for beach nourishment projects. Potential source areas include sand deposits in upland areas; deposits in estuarine, lagoonal, or inlet systems behind the front beach; sandy shoals in channels that may be dredged for navigational purposes; and sand deposits in nearshore areas within the operational depths of dredging.
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From page 116... ...
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From page 118... ...
The majority of those studies have shown decreases in the mean grain size, including, in some cases, increases in the percentage of silts and clays in the borrow sites following dredging. Data on the refilling rates of borrow pits are especially lacking, but both published and unpublished observations suggest that many borrow areas used in past nourishment projects had not filled in or were filling at a slow rate when they were reexamined (Watts, 1963~.
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From page 120... ...
More monitoring should be conducted to resolve whether these areas return to the physical and biological conditions that existed before dredging and, if so, how long it takes. This monitoring is particularly needed in regions where there has been little, if any, physical or biological monitoring of borrow areas used for beach nourishment projects.
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From page 121... ...
1972. Ecological monitoring of two beach nourishment projects in Broward County, Florida.
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From page 122... ...
Proceedings of the 5th Annual National Conference on Beach Preservation Technology. Florida Shore and Beach Preservation Association.
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From page 123... ...
In: Sixth Annual National Conference on Beach Preservation Technology. Tallahassee: Florida Shore and Beach Preservation Association.
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From page 124... ...
Pp. 295-309 in Proceedings of the 1988 National Conference on Beach Preservation Technology.
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From page 125... ...
New Directions in Beach Management: Proceedings of the 5th Annual National Conference on Beach Preservation Technology. Tallahassee: Florida Shore and Beach Preservation Association.
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From page 126... ...
Pp. 242-257 in New Directions in Beach Management: Proceedings of the 5th Annual National Conference on Beach Preservation Technology.
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