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Hurricane Katrina (August 23-30, 2005) was one of the costliest and deadliest hurricanes to ever strike the United States, impacting low-lying coastal plains particularly vulnerable to storm surge flooding. Maximum storm surges, overland flow depths, and inundation distances were measured along the Gulf Coast of Florida, Alabama, Mississippi, and Louisiana. The vehicle-based survey was complemented by inspections with the reconnaissance boat along the Gulf Coast and the Mississippi Barrier Islands. The survey covered both the impact on the built and the natural environments. The storm surge peaked to the east of Katrina's path exceeding 10 m in several locations along the Mississippi coastline. The storm surge measurements show that the lower floors of specially designed buildings were damaged by the surge of seawater and associated wave action, while the upper floors sustained minimal wind damage. The storm surge measurements along New Orleans Lakeshore allowed the investigators to exclude overtopping as failure mechanism for the 17th Street outfall canal levee. Hurricane Katrina's storm surge distribution (Category 3 at landfall) is compared against Hurricane Camille's storm surge distribution (Category 5 at landfall). The land loss on the barrier islands and the increased vulnerability of the US Gulf Coast to future hurricane storm surges is discussed. CE Database subject headings: Hurricanes; Storm surges; Florida; Alabama; Mississippi; Louisiana; Reconnaissance; Surveys.

Embankment weirs, often found in engineering applications with a side slope 1V:2H, are considered in this paper. For free overflow, the discharge coefficient is determined in terms of relative crest length for long broad-crested, broad-crested, short-crested, and thin-crested weirs. A considerable increase of capacity is noted when compared to broad-crested weirs with vertical faces. For submerged overflow, four regimes are identified: (1) A-jump: (2) plunging jet; (3) surface wave; and (4) surface jet. Particular attention is focused on plunging jets and surface waves. The flow regimes are discussed in terms of submergence, crest length, and modular limit. A description is given of the forward and backward (recirculation) zones with indications of typical lengths. Also, the entire velocity field is described, including the maximum forward and backward velocities, and the velocity distribution in arbitrary sections of the tailwater region. It is found that plunging jets and surface jets are hydraulically similar, and that the profile of one regime can be transformed into the other profile by inversion about the median. All results are generalized and can be directly applied.

A process is described for computation of bathymetry in and near the surf zone, from spatially varying celerity and breakpoint location data. The procedure involves the use of three submodels: (1) a wave shoaling model (outside of the surf zone); (2) a wave breaking model (defining the offshore boundary of the surf zone); and (3) a wave dissipation model (inside the surf zone). Influence of wave amplitude on the wave dispersion relation and celerity is included. Output includes wave height and water depth throughout the domain. In the application described here, oblique digital video served as the initial data source, although the model could be applied to data derived from other sources. Results are compared with data recorded by in situ sensors and beach profile survey data acquired by traditional means. Results suggest that water depths can be computed within 15% normalized error (equally, less than 0.1 m in biased depth error) for in and near the surf zone characterized by high wave nonlinearity. [ABSTRACT FROM AUTHOR]