Chesapeake Bay Breakwater Database Project, Section 227 Demonstration Site: Hurricane Isabel Impacts to Four Breakwater Systems

摘要

The use of breakwaters for shore protection on the Chesapeake Bay has increased over the past 15 years. A multiyear project evaluates post- construction data collected for 41 of these breakwaters and surrounding area including elevation surveys, vegetation, surveys, hydrodynamic analysis and photographs. This information is being accumulated into a database that will be available for evaluation and design reference and to aid in development of design guidance for short-fetch, shallow-water environments of the Chesapeake Bay and similar estuaries. In Fiscal Year 2003, six sites around the bay were chosen for detailed analysis. These surveys were conducted during the months of August and September. Shortly after these surveys were completed, Category 2 Hurricane Isabel hit the area on September 19, 2003. Post-hurricane surveys were immediately conducted at four of the six sites, and the data sets were included in the database. Analysis of these data sets indicates the breakwaters provided significant protection to the land in the lee of the breakwaters and that the structures experienced little or no damage. Additionally, the sand introduced into the sediment budget as a result of the storm cutting into the banks of adjacent unprotected properties may have enhanced the breakwater systems by accelerating the equilibrium beach-building process. This report presents the results of the pre- and post-hurricane breakwater evaluation.