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Changes in Dependence between Drivers of Compound Flooding around the Contiguous United States Coastline
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  • Ahmed Nasr,
  • Thomas Wahl,
  • Md Mamunur Rashid,
  • Paula Camus,
  • Ivan Haigh
Ahmed Nasr
University of Central Florida

Corresponding Author:ahmed.nasr@knights.ucf.edu

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Thomas Wahl
University of Central Florida
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Md Mamunur Rashid
University of Central Florida
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Paula Camus
University of Southampton
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Ivan Haigh
University of Southampton
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Abstract

Low-lying coastal zones are prone to flooding from multiple drivers such as storm surge (oceanographic), excessive river discharge (fluvial), and/or surface runoff (pluvial). The flooding impacts can be exacerbated, depending on local characteristics, when flooding is intensified by concurrent (or successive) occurrence of multiple drivers known as ‘compound flooding’. Recently, compound flooding drivers are becoming more frequent and intense leading to more adverse impacts. In this study, we carry out a continental scale analysis for the CONUS coastline at locations with sufficiently long overlapping records to characterize the changes in dependence and co-occurrence between the compound flooding drivers over time. We also investigate the changes in dependence over time during tropical and extratropical seasons. Lastly, we assess how the dependence structure varies with time. We use observations (gauge records) for the analysis. Dependence between different pairs is assessed using co-occurrence counts and statistical measures for dependence (Kendall’s rank correlation coefficient, τ). The dependence structures (particularly the tails of bivariate distributions) are compared using Kullback–Leibler (KL) Divergence to assess if there are significant changes in tails of bivariate distributions over time. This analysis provides a comprehensive characterization of changes in compound flooding potential around the CONUS coastline. This will provide insights on where and how compound flooding potential has changed over time to be incorporated in flood risk assessments and planning.