Flood volume allocation method for flood hazard mapping using river model with levee scheme

Aslam, Muhammad Hasnain; Hirabayashi, Yukiko; Yamazaki, Dai; Zhao, Gang; Kita, Yuki; Khanh, Do Ngoc

doi:10.5194/gmd-19-3709-2026

Articles | Volume 19, issue 9

https://doi.org/10.5194/gmd-19-3709-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

https://doi.org/10.5194/gmd-19-3709-2026

© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 19, issue 9

Development and technical paper

|

08 May 2026

Development and technical paper |

| 08 May 2026

Flood volume allocation method for flood hazard mapping using river model with levee scheme

Muhammad Hasnain Aslam, Yukiko Hirabayashi, Dai Yamazaki, Gang Zhao, Yuki Kita, and Do Ngoc Khanh

Supplement

https://doi.org/10.5194/gmd-19-3709-2026-supplement

Data sets

Levee-aware downscaling (code and trial data) Muhammad Hasnain Aslam https://doi.org/10.5281/zenodo.17231818

Model code and software

Levee-aware downscaling (archive) Muhammad Hasnain Aslam https://doi.org/10.5281/zenodo.17231022

Levee-aware downscaling (code and trial data) Muhammad Hasnain Aslam https://doi.org/10.5281/zenodo.17231818

global-hydrodynamics/CaMa-Flood_v4: CaMa v4.20 D. Yamazaki et al. https://doi.org/10.5281/zenodo.11091435

Short summary

We present a simple method that turns coarse flood volume estimates into local flood depth maps by using the shape of the land and mapped levee zones. Used with a large-scale river model, it keeps total water volume consistent while spreading water realistically inside and outside levees. Tests show levees often confine water and cut flood volume by about 10 %–15 % for many event sizes. The method reveals place-to-place differences in protection and yields clearer hazard maps for planning.