Preprints
https://doi.org/10.5194/hess-2021-268
https://doi.org/10.5194/hess-2021-268

  27 May 2021

27 May 2021

Review status: this preprint is currently under review for the journal HESS.

Assessing the dependence structure between oceanographic, fluvial, and pluvial flooding drivers along the United States coastline

Ahmed A. Nasr1, Thomas Wahl1, Md Mamunur Rashid1, Paula Camus2, and Ivan D. Haigh2 Ahmed A. Nasr et al.
  • 1Civil, Environmental, and Construction Engineering & National Center for Integrated Coastal Research, University of Central Florida, 12800 Pegasus Drive, Suite 211, Orlando, FL 32816-2450, USA
  • 2School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Waterfront Campus, European Way, Southampton, SO14 3ZH, UK

Abstract. Flooding is of particular concern in low-lying coastal zones that are prone to flooding impacts from multiple drivers: oceanographic (storm surge and wave), fluvial (excessive river discharge), and/or pluvial (surface runoff). In this study, we analyse for the first time the compound flooding potential along the contiguous United States (CONUS) coastline from all flooding drivers, using observations and reanalysis datasets. We assess the overall dependence from observations by using Kendall’s rank correlation coefficient (τ) and tail (extremal) dependence (χ). Geographically, we find highest dependence between different drivers at locations in the Gulf of Mexico, southeast, and southwest coasts. Regarding different driver combinations, the highest dependence exists between surge-waves, followed by surge-precipitation, surge-discharge, waves-precipitation, and waves-discharge. We also perform a seasonal dependence analysis (tropical vs extra-tropical season), where we find higher dependence between drivers during the tropical season along the Gulf and parts of the East coast and stronger dependence during the extra-tropical season on the West coast. Finally, we compare the dependence structure of different combinations of flooding drivers using observations and reanalysis data and use the Kullback–Leibler (KL) Divergence to assess significance in the differences of the tail dependence structure. We find, for example, that models underestimate the tail dependence between surge-discharge on the East and West coasts and overestimate tail dependence between surge-precipitation on the East coast, while they underestimate it on the West coast. The comprehensive analysis presented here provides new insights on where compound flooding potential is relatively higher, which variable combinations are most likely to lead to compounding effects, during which time of the year (tropical versus extra-tropical season) compound flooding is more likely to occur, and how well reanalysis data captures the dependence structure between the different flooding drivers.

Ahmed A. Nasr et al.

Status: open (until 26 Jul 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Ahmed A. Nasr et al.

Ahmed A. Nasr et al.

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Short summary
We analyse the dependence between different flooding drivers around the contiguous US coastline. We find that the Gulf of Mexico, southeast, and southwest coasts are regions of high dependence between flooding drivers. Also, dependence is higher during tropical season in the Gulf and some location on the east coast but higher during extratropical season on the west coast. This analysis provides new insights on locations, driver combinations, and time of the year when compound flooding is likely.