Relationship between Canal and Levee Density and Coastal Land Loss in Louisiana

摘要

Nearly 1% of Louisiana's coastal land becomes water each year. This land loss affects everything from wildlife, fisheries, and recreation to the economy and culture. A part of this loss results from natural, unmanageable factors, but manageable factors are also responsible. The report discusses one of the manageable factors: canals and their dredged-material levees. In coastal Louisiana wetlands, canals are constructed primarily to facilitate navigation and oil and gas recovery. The density of canals in this region is now about equal to the natural network of bayous and creeks. The primary effect of these canals and associated levees is to alter the process of flooding and drainage. The influence of canals and their levees on coastal Louisiana erosion rates are modified by local geologic, hydrologic, and biologic interactions. The empirical relationship between canals and erosion is, however, clear; land loss is directly related to canal density. Comparisons with mosquito ditches, which are smaller analogues of canals, reveal similar patterns of wetland changes and suggest management options.