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Combined modelling of US fluvial, pluvial and coastal flood hazard under current and future climates
  • +26
  • Paul D Bates,
  • Niall Quinn,
  • Christopher C Sampson,
  • Andrew M Smith,
  • Oliver E J Wing,
  • Jeison Sosa,
  • James Savage,
  • Gaia Olcese,
  • Guy Jean-Pierre Schumann,
  • Laura Giustarini,
  • Gemma Coxon,
  • Jeffrey Charles Neal,
  • Jeremy R. Porter,
  • Mike F. Amodeo,
  • Ziyan Chu,
  • Sharai Lewis-Gruss,
  • Neil Freeman,
  • Trevor Houser,
  • Michael Delgado,
  • Ali Hamidi,
  • Ian Wesley Bolliger,
  • Kelly E McCusker,
  • Kerry A. Emanuel,
  • Celso M Ferreira,
  • Arslaan Khalid,
  • Ivan D Haigh,
  • Anais Couasnon,
  • Robert E Kopp,
  • Solomon Hsiang
Paul D Bates
University of Bristol

Corresponding Author:[email protected]

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Niall Quinn
Fathom Global Ltd.
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Christopher C Sampson
SSBN Ltd
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Andrew M Smith
University of Bristol
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Oliver E J Wing
University of Bristol
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Jeison Sosa
University of Bristol
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James Savage
Fathom
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Gaia Olcese
Fathom
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Guy Jean-Pierre Schumann
University of Bristol
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Laura Giustarini
Luxembourg Institute of Science and Technology
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Gemma Coxon
University of Bristol
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Jeffrey Charles Neal
University of Bristol
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Jeremy R. Porter
First Street Foundation
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Mike F. Amodeo
First Street Foundation
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Ziyan Chu
First Street Foundation
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Sharai Lewis-Gruss
First Street Foundation
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Neil Freeman
First Street Foundation
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Trevor Houser
Rhodium Group
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Michael Delgado
Rhodium Grouo
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Ali Hamidi
Rhodium Group
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Ian Wesley Bolliger
Rhodium Group
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Kelly E McCusker
Rhodium Group, Seattle, WA
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Kerry A. Emanuel
Massachusetts Institute of Technology
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Celso M Ferreira
George Mason University
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Arslaan Khalid
George Mason University
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Ivan D Haigh
University of Southampton
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Anais Couasnon
Vrije Universiteit Amsterdam
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Robert E Kopp
Rutgers University
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Solomon Hsiang
UC Berkeley
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Abstract

This paper reports a new and significantly enhanced analysis of US flood hazard at 30m spatial resolution. Specific improvements include updated hydrography data, new methods to determine channel depth, more rigorous flood frequency analysis, output downscaling to property tract level and inclusion of the impact of local interventions in the flooding system. For the first time we consider pluvial, fluvial and coastal flood hazards within the same framework and provide projections for both current (rather than historic average) conditions and for future time periods centred on 2035 and 2050 under the RCP4.5 emissions pathway. Validation against high quality local models and the entire catalogue of FEMA 1% annual probability flood maps yielded Critical Success Index values in the range 0.69-0.82. Significant improvements over a previous pluvial/fluvial model version are shown for high frequency events and coastal zones, along with minor improvements in areas where model performance was already good. The result is the first comprehensive and consistent national scale analysis of flood hazard for the conterminous US for both current and future conditions. Even though we consider a stabilization emissions scenario and a near future time horizon we project clear patterns of changing flood hazard (-3.8 to +16% changes in 100yr inundated area at 1° scale), that are significant when considered as a proportion of the land area where human use is possible or in terms of the currently protected land area where the standard of flood defence protection may become compromised by this time.
Feb 2021Published in Water Resources Research volume 57 issue 2. 10.1029/2020WR028673