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摘要
The expectation that wetlands can protect coastal communities has been a major topic in the effort to evaluate innovative methods of mitigating coastal impacts from storm surge. Recent investigations have shown that there is a potential flood mitigation benefit to be gained from the presence of marshes. Though the extent of that benefit is not yet clearly defined, prioritizing wetland systems for coastal protection requires a consideration of the interactions between communities at risk of storm surge damage and wetland areas of sufficient spatial scales to reliably attenuate storm surge. Here, a framework is proposed for geospatial characterization of these interactions based on numerical model results and is applied to Virginia's Chesapeake Bay region. Spatial identification of Chesapeake Bay wetlands was derived from four nationally available datasets (National Wetland Inventory, National Land Cover Dataset, Coastal Change Analysis Program, and NOAA's Wetland Potential database). Maps of maximum storm tides for four historical storms were generated based on a coupled hydrodynamic wave model (ADCIRC-SWAN), validated for those storms with a mean root mean square error of 0.44 m. Population information was extracted from US Census block data in FEMA's HAZUS Multi-Hazard geodatabase. Results from geospatial analysis of the relationships between wetland land cover, inundation, and population were used to identify where interactions with coastal populations are relevant for the study area when spatial limitations are considered. Approximately 1160 sq. km of wetlands were inundated by all four storms. Total population present in a range of proximities (200, 400, and 600 m) to flooded wetlands was used as a metric to evaluate the effect of a range of limitations on wetland size (5-50 sq. km) on potential population protected. A high level of uncertainty was seen due to wetland dataset selection (number of standard deviations from the mean ranged from 0.04 to 1.37), owing to high variability in spatial delineation/configuration of wetlands. Applying the framework to the Virginia Chesapeake Bay region yields an index of potential protection based on spatial scale limitations. For example, such an evaluation for wetlands meeting the 5 sq. km limitation (disregarding wetlands < 5 sq. km) indicates that the presence of wetlands offers a potential protection for 3.4 % of the population. An application of the index on a more local scale indicates that the interaction of the flooded wetlands with more populated localities is such that the coastal marshes in Hampton Roads and Gloucester may offer protection to nearby coastal communities. This framework demonstrates that effective surge protection from wetlands and marshes is related to a combination of the incidence of storm surge inundation, proximity to coastal communities, and the relationship of sufficient spatial scales for surge attenuation.
- 出版日期2016-1
