A rationale for coastal wetland restoration through spoil bank management in Louisiana,USA |
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Authors: | R Eugene Turner E M Swenson J M Lee |
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Institution: | (1) Coastal Ecology Institute and Department of Oceanography and Coastal Sciences, Louisiana State University, 70803 Baton Rouge, Louisiana, USA |
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Abstract: | The rationale and outline of an implementation plan for restoring coastal wetlands in Louisiana is presented. The rationale
for the plan is based on reversing the consequences of documented cause-and-effect relationships between wetland loss and
hydrologic change. The main feature is to modify the extensive interlocking network of dredged spoil deposits, or spoil banks,
by reestablishing a more natural water flow at moderate flow velocity (<5 cm/sec). Guidelines for site selection from thousands
of potential sites are proposed. Examples of suitable sites are given for intermediate marshes. These sites exhibit rapid
deterioration following partial or complete hydrologic impoundment, implying a strong hydrologic, rather than sedimentological,
cause of wetland deterioration.
We used an exploratory hydrologic model to guide determination of the amount of spoil bank to be removed. The results from
an economic model indicated a very effective cost-benefit ratio. Both models and practical experience with other types of
restoration plans, in Louisiana and elsewhere, exhibit an economy of scale, wherein larger projects are more cost effective
than smaller projects. However, in contrast to these other projects, spoil bank management may be 100 to 1000 times more cost
effective and useful in wetland tracts <1000 ha in size. Modest spoil bank management at numerous small wetland sites appears
to offer substantial positive attributes compared to alternative and more intensive management at a few larger wetland sites. |
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Keywords: | Wetland Restoration Dredging Spoil Louisiana |
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