Spatially quantifying and mapping the riverbed roughness of a tropical river via acoustic Doppler current profiler (ADCP) measurements to develop a 2-D numerical model

Abstract

Field measurement of the bed roughness of tropical tidal rivers is a long and expensive process. In this study, we quantified the roughness coefficient from the acoustic Doppler current profiler (ADCP) measurements considering flow characteristics along a 240 km length of the Vu Gia Thu Bon River system, in central Vietnam. Our approach entailed the application of the logarithmic velocity distribution trend of turbulent flows to determine the bottom roughness height. Then, we applied the equation suggested by Strickler (1923) to calculate the Manning roughness coefficient. The TELEMAC-2D hydraulic model was then used to simulate the effect of the roughness coefficient on the estimated water level. Despite its uncertainty, the estimated bed roughness was sufficient for the accurate calculation of the hydraulic variables. Compared to those in previous research, the statistical indicators showed good performance in the first simulation process during both the calibration and validation periods along the river system.