A numerical study of storm surge and inundation in the Croatan-Albemarle-Pamlico Estuary SystemIntroductionModel configuration in the CAPESWinds and experimental settingsHurricane tracks and structureResultsCases 1-5: northward moving hurricanesCases 6-10: northeastward moving hurricanesSensitivity experimentsSensitivity to hurricane MCP and RMWSensitivity to hurricane translation speedHurricane Emily (1993)ConclusionsAcknowledgementsReferencesA numerical study of storm surge and inundation inthe CroataneAlbemarleePamlico Estuary SystemMachuan Peng, Lian Xie), Leonard J. PietrafesaDepartment of Marine, Earth and Atmospheric Sciences, North Carolina State University, Box 8206, Raleigh, NC 27695-8208, USAReceived 5 July 2002; accepted 31 July 2003AbstractAn integrated storm surge and inundation modeling system is used to simulate the storm surge and inundation in theCroataneAlbemarleePamlico Estuary System in eastern North Carolina under the influence of 10 hypothetical Category 2 and 3hurricanes representing typical historical hurricane scenarios in the study region. The integrated storm surge and inundationmodeling system is numerically stable in the complex and shallow CAPES environment under hurricane forcing conditions. For anassumed northward or northeastward moving Category 3 hurricane with a translation speed of 25 km/h, the peak storm surgeoccurs along the western Pamlico Sound and western Albemarle Sound. The most severe flooding as measured by inundation area isin the Pamlico River mouth region where the flooding area reached 500 km2. In general, a more intense or larger hurricane (lowerminimum central pressure, MCP or larger radius of maximum wind, RMW) produces higher storm surge and a larger inundationarea in the entire region. For the cases considered in this study, the storm surge height and inundation area are more sensitive toMCP than to RMW. Slower translation speed produces higher storm surge, and thus larger inundation area, but the sensitivity ofstorm surge to storm translation speed can be vastly different for different storms.Ó 2003 Elsevier Ltd. All rights reserved.Keywords: storm surge; inundation; numerical modeling; coastal flooding; hurricane1. IntroductionThe CroataneAlbemarleePamlico Estuary System(CAPES) (Fig. 1) in eastern North Carolina is thelargest lagoon system and the second largest estuary(next to Chesapeake Bay) in the United States (Pietrafesaet al., 1986). It covers a total area of approximately 5500km2. The CAPES comprises primarily two major bodiesof water, Pamlico Sound (w120 km ! 40 km) andAlbemarle Sound (w70 km!20 km), which are linkedby the relatively small Croatan and Roanoke Sounds(Pietrafesa et al., 1986). The average water depth of theCAPES is only 4.5 m, though the water depth rangesfrom 2 m around the perimeter or near the shoals toapproximately 7 m in the deepest basin. The CAPES isseparated from the Atlantic Ocean by the Outer Banks,a chain of emergent bar-built islands on their east sides.Three narrow inlets, Oregon, Hatteras and OcracokeInlets, along the Outer Banks, contribute to the waterexchange between the CAPES and the Atlantic Ocean.The CAPES faces frequent threats from tropi cal andextra-tropical cyclones. Damages associated with thesecyclones derive from strong winds, storm surge, and in-land flooding. As a function of the combination of envir-onmental factors and the socioecono mic structure of theregion impacted, the impact can vary tremendou sly.However, amongst the above suite of factors, coastaland inland flooding is known as the most dangerous tohuman life and property. The purpose of this study is toinvestigate the feasibility of modeling hurricane-inducedcurrents, storm surge and inundation in the CAPESusing a three-dimensional computer model and to im-prove our understanding of the hydrodynamic responsesof the CAPES to the passages of hurricanes.Numerical studies of hurricane-induced storm surgeand circulation in the CAPES began in the mid-1970s.These studies were mainly published in technicalreports (Amein and Airan, 1976; Pietrafesa et al.,)Corresponding author.E-mail address: [email protected] (L. Xie).Estuarine, Coastal and Shelf Science 59 (2004) 121e1370272-7714/03/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.doi:10.1016/j.ecss.2003.07.0101986) and student theses (e.g., Lin, 1992). Amein andAiran (1976) constructed a two-dimensional (depthaveraged) model for the Pamlico Sound. Pietrafesa et al.(1986) developed a three-dimensional linear shallow-water model for the Pamlico Sound, which was laterconfigured for the Albemarle Sound by Lin (1992).While the efforts of Pietrafesa et al. and Lin showedthat the earlier 2-D models underestimated the stormsurges in the Pamlico Sound, and the 3-D modelagreed much better with actual point observations ofhigh water, their model did not include interactivecoupling with the coastal ocean and thus could not beused to study estuaryeocean water mass exchange.Moreover, Pietrafesa et al. (1986) and Lin (1992) didnot include nonlinear advection terms and thermody-namic equations in the 3-D shallow-water model. Thus,their model could not be used to study the densitydriven circulation in the system. To overcome thesedrawbacks, Xie and Pietrafesa (1999) configured thenonlinear, three-dimensional Princeton Ocean Model(POM) for the entire CAPES and its adjacent coastalshelf, and studied the water mass exchange between theCAPES and the coastal ocean.A major limitation for all the hydrodynamic modelsconfigured for the CAPES is that they were not designedto simulate inundation and retreat or wetting and drying,respectively. Without a proper mathematical treatmentof the physics of the inundation and drying processes,hydrodynamic models can become computationallyunstable in shallow estuarine environments under strongwind and tidal forcing conditions. These limitationshampered the application of hydrodynamic models tothe CAPES under severe weather conditions, such asduring hurricanes.Hubbert and McInnes (1999) introduced an inunda-tion and drying scheme (hereafter referred to as the HMscheme) and incorpora ted it into a two-dimensionalstorm surge model. They simulated the storm surge andinundation produced by a tropical cyclone and twoseparate cold fronts on the Australian coast and foundthat the model results were realistic, and mathematicallywell-behaved for moderate variations in grid resolution.Xie et al. (2003) introduced a modified version of