16 Aug 2023
 | 16 Aug 2023
Status: this preprint is currently under review for the journal HESS.

Technical Note: Resolution Enhancement of Flood Inundation Grids

Seth Bryant, Guy Schumann, Heiko Apel, Heidi Kreibich, and Bruno Merz

Abstract. High-resolution flood maps are needed for more effective flood risk assessment and management. Producing these directly with hydrodynamic models is slow and computationally prohibitive at large scales. Here we demonstrate a new algorithm for post-processing low-resolution inundation layers by using high-resolution terrain models to disaggregate or downscale. The new algorithm is roughly eight times faster than current state-of-the-art algorithms, shows a slight improvement in accuracy when evaluated against observations of a recent flood, and is open source. The algorithm developed here can be applied in conjunction with a low-resolution hydrodynamic model and a high-resolution DEM to rapidly produce high-resolution inundation maps. For example, in our case study with a river reach of 20 km, the proposed algorithm generated a 4 m resolution inundation map from 32 m hydrodynamic model outputs in 33 seconds, compared to a 4 m hydrodynamic model runtime of 34 minutes. This 60-fold improvement in runtime is associated with a 25 % increase in RMSE when compared against the 4 m hydrodynamic model results and observations of a recent flood. Substituting downscaling into flood risk model chains for high-resolution modelling has the potential to drastically improve the efficiency of inundation map production and increase the lead time of impact-based forecasts, helping more at-risk communities prepare for and mitigate flood damages.

Seth Bryant et al.

Status: open (until 11 Oct 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-156', Anonymous Referee #1, 07 Sep 2023 reply
  • RC2: 'Comment on hess-2023-156', Anonymous Referee #2, 12 Sep 2023 reply

Seth Bryant et al.

Seth Bryant et al.


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Short summary
A new algorithm has been developed to quickly produce high-resolution flood maps. It is faster and more accurate than current methods and is available as open source. This can help communities better prepare for and mitigate flood damages.