Preprints
https://doi.org/10.5194/egusphere-2023-1969
https://doi.org/10.5194/egusphere-2023-1969
31 Aug 2023
 | 31 Aug 2023

To What Extent Do Extreme Storm Events Change Future Flood Hazards?

Mariam Khanam, Giulia Sofia, and Emmanouil N. Anagnostou

Abstract. Due to global climate change, flooding is predicted to become more frequent in the coming decades. Recent literature has highlighted the importance of river morphodynamics in controlling flood hazards at the local scale. Abrupt and short-term geomorphic changes can occur after major storms. However, our ability to foresee where and when substantial changes will happen is still limited, hindering our understanding of their ramifications on future flood hazards. This study sought to understand the implications of major storm events for future flood hazards. For this purpose, we developed self-organizing maps (SOMs) to predict post-storm changes in stage‐discharge relationships, based on storm characteristics and watershed properties at 3,101 stream gages across the continental United States (CONUS). We tested and verified a machine learning (ML) model and its feasibility for (1) mapping the variability of geomorphic impacts of extreme storm events and (2) representing the effects of these changes on stage‐discharge relationships at gaged sites as a proxy for changes in flood hazard. The established model allows us to select rivers with stage-discharge relationships that are more prone to change after severe storms, for which flood frequency analysis should be revised on a regular basis so that hazard assessment can be up to date with the changing conditions. Results from the model show that, even though post-storm changes in channel conveyance are widespread, the impacts on flood hazard vary across CONUS. The influence of channel conveyance variability on flood risk depends on various parameters characterizing a particular landscape or storm. The proposed framework can serve as a basis for incorporating channel conveyance adjustments into flood hazard assessment.

Mariam Khanam, Giulia Sofia, and Emmanouil N. Anagnostou

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on egusphere-2023-1969', Dean Gesch, 05 Oct 2023
    • AC1: 'Reply on CC1', Giulia Sofia, 20 Nov 2023
    • AC5: 'Reply on CC1', Giulia Sofia, 20 Nov 2023
  • RC1: 'Comment on egusphere-2023-1969', Anonymous Referee #1, 14 Oct 2023
    • AC2: 'Reply on RC1', Giulia Sofia, 20 Nov 2023
  • RC2: 'Comment on egusphere-2023-1969', Anonymous Referee #2, 19 Oct 2023
    • AC3: 'Reply on RC2', Giulia Sofia, 20 Nov 2023
  • RC3: 'Comment on egusphere-2023-1969', Anonymous Referee #3, 19 Oct 2023
    • AC4: 'Reply on RC3', Giulia Sofia, 20 Nov 2023
Mariam Khanam, Giulia Sofia, and Emmanouil N. Anagnostou
Mariam Khanam, Giulia Sofia, and Emmanouil N. Anagnostou

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Short summary
Due to climate change, flooding is expected to become more frequent globally in the coming decades. Locally, storm-induced channel geometry changes can drastically affect flood hazards, yet rivers are mostly treated as static elements in flood studies. This study tried to gain an understanding of the effects of major storm events on future flood hazards, promoting a framework for incorporating channel conveyance adjustments into flood hazard assessment.