2025 Volume 81 Issue 16 Article ID: 24-16153
The water depth profile used for flood discharge measurement is usually surveyed during normal water conditions. However, since bathymetry may change during floods, it is necessary to obtain the depth profile in addition to the surface velocity during floods for accurate discharge estimation. We propose a new method to estimate the cross-sectional profile by fitting the wave dispersion relation to the wavenumber-frequency spectrum of the water-surface variation, which is estimated from space-time images of the river water surface. We applied the proposed method to a river, and the estimated water depth profile had an error of less than 20% relative to the directly surveyed cross-sectional profile. On the other hand, the accuracy of the depth estimation depends on the resolution of the spectrum as well as the parameters used in the estimation method. The estimation error becomes large when the resolution is insufficient, and abnormal values may be obtained under high-Froude number conditions.
