Estimation of Bedform Friction Factor Directly from Bathymetry Data

Abstract

We present a procedure to systematically estimate the form friction factor through the analysis of spatial data obtained by acoustic Doppler current profiler. The form friction factor is related to the geometric characteristics of the bedform. The zero-crossing method was used to determine the geometric parameters of the bedform, which were then utilized to construct the probability density function for Chezy coefficients. Subsequently, Chezy coefficients were generated from the probability density function and assigned to each grid cell of a numerical model. To evaluate the performance of the presented friction factor estimation method, it was applied to the numerical simulation for the Nakdong River in South Korea. Sensitivity tests were performed to address the potential influence of random extraction from the probability density function, filtering length, and different form predictors during the estimation process. The proposed method showed more robust and accurate results compared to those with Manning's n value.