16. Scientific basis and application potential of surface velocity measurement technology for hydrological stations in tidal river regions of Viet Nam

Abstract

This study evaluates the scientific basis and applicability of surface point velocity measurement technologies, including surface Doppler radar, fixed acoustic sensors, and the Large-Scale Particle Image Velocimetry (LSPIV) system, for discharge estimation in tidal rivers in Vietnam. Velocity data were collected from 17 hydrological stations within the national monitoring network in 2025. Cross-sectional mean velocities were measured and calibrated using Acoustic Doppler Current Profiler (ADCP) instruments in accordance with the recommendations of WMO [1] and USGS [3]. Based on these data, regression relationships between surface point velocity (Vs) and mean velocity (Vtb) were established. The results indicate a strong correlation between Vs and Vtb, with correlation coefficients (R) mostly exceeding 0.9. This confirms that surface point velocity can serve as a proxy for representative vertical mean velocity in discharge estimation for tidal river stations, both for currently applied stations and for potential extension to other tidal river stations in Vietnam. Furthermore, the findings highlight the potential of non-contact measurement technologies in improving automation and the reliability of hydrological observations.