Mark Hansen

Hurricanes 2004: An Overview of Their Characteristics and Coastal Change

Four hurricanes battered the state of Florida during 2004, the most affecting any state since Texas endured four in 1884. Each of the storms changed the coast differently. Average shoreline change within the right front quadrant of hurricane force winds varied from 1 m of shoreline advance to 20 m of retreat, whereas average sand volume change varied from 11 to 66 m3 m−1 of net loss (erosion). These changes did not scale simply with hurricane intensity as described by the Saffir-Simpson Hurricane Scale. The strongest storm of the season, category 4 Hurricane Charley, had the least shoreline retreat. This was likely because of other factors like the storms rapid forward speed and small size that generated a lower storm surge than expected. Two of the storms, Hurricanes Frances and Jeanne, affected nearly the same area on the Florida east coast just 3 wk apart. The first storm, Frances, although weaker than the second, caused greater shoreline retreat and sand volume erosion. As a consequence, Hurricane Frances may have stripped away protective beach and exposed dunes to direct wave attack during Jeanne, although there was significant dune erosion during both storms. The maximum shoreline change for all four hurricanes occurred during Ivan on the coasts of eastern Alabama and the Florida Panhandle. The net volume change across a barrier island within the Ivan impact zone approached zero because of massive overwash that approximately balanced erosion of the beach. These data from the 2004 hurricane season will prove useful in developing new ways to scale and predict coastal-change effects during hurricanes.

Accelerated relative sea-level rise and rapid coastal erosion:: testing a causal relationship for the Louisiana barrier islands

Abstract The role of relative sea-level rise as a cause for the rapid erosion of Louisianas barrier island coast is investigated through a numerical implementation of a modified Bruun rule that accounts for the low percentage of sand-sized sediment in the eroding Louisiana shoreface. Shore-normal profiles from 150 km of coastline west of the Mississippi delta are derived from bathymetric surveys conducted during the 1880s, 1930s and 1980s. An RMS difference criterion is employed to test whether an equilibrium profile form is maintained between survey years. Only about half the studied profiles meet the equilibrium criterion; this represents a significant limitation on the potential applicability of the Bruun rule. The profiles meeting the equilibrium criterion, along with measured rates of relative sea-level rise, are used to hindcast shoreline retreat rates at 37 locations within the study area. Modeled and observed shoreline retreat rates show no significant correlation. Thus, in terms of the Bruun approach, relative sea-level rise has no power for hindcasting (and presumably forecasting) rates of coastal erosion for the Louisiana barrier islands.

THE IMPACT OF AN EXTREME EVENT ON THE SEDIMENT BUDGET: HURRICANE ANDREW IN THE LOUISIANA BARRIER ISLANDS

A study of alternatives including a shoreline evolution numerical modelization has been carried out in order to both diagnose the erosion problem at the beaches located between Cambrils Harbour and Pixerota delta (Tarragona, Spain) and select nourishment alternatives.

Archive of bathymetry data collected at Cape Canaveral, Florida, 2014

The Cape Canaveral Coastal System (CCCS) is a prominent feature along the Southeast U.S. coastline and is the only large cape south of Cape Fear, North Carolina. Most of the CCCS lies within the Merritt Island National Wildlife Refuge and included in its boundaries are the Cape Canaveral Air Force Station (CCAFS), NASA’s Kennedy Space Center (KSC), and a large portion of Canaveral National Seashore. The actual promontory of the modern cape falls within the jurisdictional boundaries of the CCAFS. These various agencies have ongoing concerns related to erosion hazards and vulnerability of the system including critical infrastructure, habitats, and recreational and cultural resources. The USGS conducted a bathymetric mapping survey August 18-20, 2014, in the Atlantic Ocean offshore of Cape Canaveral, Florida (USGS Field Activity Number 2014-324-FA). The study area covered an area extending south from Port Canaveral, Florida, to the northern end of the KSC property and from the shoreline to about 2.5 km offshore. Bathymetric data were collected with single-beam sonar- and lidar-based systems. Two jet skis and a 17-ft outboard motor boat equipped with the USGS SANDS hydrographic system collected precision sonar data. The sonar operations were conducted in three missions, one on each day, with the boat and jet skis operating concurrently. The USGS airborne EAARL-B mapping system flown in a twin engine plane was used to collect lidar data. The lidar operations were conducted in three missions, one in the afternoon of August 19, 2015, and two more in the morning and afternoon of August 20, 2014. The missions were synchronized such that there was some temporal and spatial overlap between the sonar and lidar operations. Additional data were collected to evaluate the actual water clarity corresponding to lidars ability to receive bathymetric returns. This dataset serves as an archive of processed single-beam and lidar bathymetry data collected at Cape Canaveral, Florida, in 2014 (in XYZ comma delimited, ASCII and shapefile format). Also included in this archive are Geographic Information System (GIS) data products: gridded map data (in ESRI binary and ASCII grid format), and a color-coded bathymetry map (in PDF format).The Cape Canaveral Coastal System (CCCS) is a prominent feature along the Southeast U.S. coastline and is the only large cape south of Cape Fear, North Carolina. Most of the CCCS lies within the Merritt Island National Wildlife Refuge and included in its boundaries are the Cape Canaveral Air Force Station (CCAFS), NASA’s Kennedy Space Center (KSC), and a large portion of Canaveral National Seashore. The actual promontory of the modern cape falls within the jurisdictional boundaries of the CCAFS. These various agencies have ongoing concerns related to erosion hazards and vulnerability of the system including critical infrastructure, habitats, and recreational and cultural resources. The USGS conducted a bathymetric mapping survey August 18-20, 2014, in the Atlantic Ocean offshore of Cape Canaveral, Florida (USGS Field Activity Number 2014-324-FA). The study area covered an area extending south from Port Canaveral, Florida, to the northern end of the KSC property and from the shoreline to about 2.5 km offshore. Bathymetric data were collected with single-beam sonar- and lidar-based systems. Two jet skis and a 17-ft outboard motor boat equipped with the USGS SANDS hydrographic system collected precision sonar data. The sonar operations were conducted in three missions, one on each day, with the boat and jet skis operating concurrently. The USGS airborne EAARL-B mapping system flown in a twin engine plane was used to collect lidar data. The lidar operations were conducted in three missions, one in the afternoon of August 19, 2015, and two more in the morning and afternoon of August 20, 2014. The missions were synchronized such that there was some temporal and spatial overlap between the sonar and lidar operations. Additional data were collected to evaluate the actual water clarity corresponding to lidars ability to receive bathymetric returns. This dataset serves as an archive of processed single-beam and lidar bathymetry data collected at Cape Canaveral, Florida, in 2014 (in XYZ comma delimited, ASCII and shapefile format). Also included in this archive are Geographic Information System (GIS) data products: gridded map data (in ESRI binary and ASCII grid format), and a color-coded bathymetry map (in PDF format).