Coupled modeling of storm surge and coastal inundation: A case study in New York City during Hurricane Sandy

Jie Yin,Ning Lin,Dapeng Yu

doi:10.1002/2016wr019102

Jie Yin, Ning Lin + Show 1 more

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https://doi.org/10.1002/2016wr019102

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Abstract

AbstractIn this paper, we describe a new method of modeling coastal inundation arising from storm surge by coupling a widely used storm surge model (ADCIRC) and an urban flood inundation model (FloodMap). This is the first time the coupling of such models is implemented and tested using real events. The method offers a flexible and efficient procedure for applying detailed ADCIRC storm surge modeling results along the coastal boundary (with typical resolution of ∼100 m) to FloodMap for fine resolution inundation modeling (<5 m). The coastal inundation during Hurricane Sandy was simulated at both the city (New York City) and subregional (lower Manhattan) scales with various resolutions. Results obtained from the ADCIRC and coupled ADCIRC‐FloodMap simulations were compared with the recorded (high water marks) and derived (inundation extent based on the planar method) data from FEMA. At the city scale, coupled ADCIRC‐FloodMap modeling demonstrates improved prediction over ADCIRC modeling alone for both the extent and depth of inundation. The advantage of the coupled model is further illustrated in the subregional modeling, using a mesh resolution of 3 m which is substantially finer than the inland mesh resolution used by ADCIRC (>70 m). In further testing, we explored the effects of mesh resolution and roughness specification. Results agree with previous studies that fine resolution is essential for capturing intricate flow paths and connectivity in urban topography. While the specification of roughness is more challenging for urban environments, it may be empirically optimized. The successful coupling of ADCIRC and FloodMap models for fine resolution coastal inundation modeling unlocks the potential for undertaking large numbers of probabilistically based synthetic surge events for street‐level risk analysis.

Highlights

Coastal flooding is among the most frequent and devastating natural hazards, resulting in significant casualties, losses, and impacts in many coastal low-lying areas around the world
This study demonstrated the integration of a widely used storm surge model (ADCIRC) and a 2-D hydrodynamic flood model (FloodMap) for flood inundation modeling in the highly urban environment of New York City
We cross-compare the predictions of ADCIRC and FloodMap for inland inundation using USGS high water marks (HWMs) observation and an inundation map derived by FEMA from the HWMs using a static planar method

Summary

Introduction

Coastal flooding is among the most frequent and devastating natural hazards, resulting in significant casualties, losses, and impacts in many coastal low-lying areas around the world. Rapid urbanization in coastal zones is set to continue in the foreseeable future [Hallegatte et al, 2013; Jongman et al, 2012], and to increase social and economic exposure. Anthropogenic changes such as land subsidence, reduced permeability, and wetland loss further exacerbate the hydrologic regime of flood responses in coastal cities [e.g., Wu et al, 2012; Yin et al, 2015]. It is widely recognized that climatic change has significant negative impacts on many regions through raising sea level and possibly enhancing storminess, which in turn amplify coastal flood events [IPCC, 2013, 2014]. Due to the combined effects of sea level rise and storm climatology change, the 10 year flood height in New York Harbor has increased by nearly 0.72 6 0.25 m since the mid1800s [Talke et al, 2014], and the present 100 year flood is projected to occur every 3–20 years by the end of the 21st century [Lin et al, 2012]

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