Multiprofile Discharge Estimation in the Tidal Reach of Yangtze Estuary

With the advent of acoustic Doppler current profiler (ADCP), the velocity profile method or index velocity method based on a single profile or a fixed-depth cell has been recommended for estimating discharge in tidal reaches. However, in large tidal reaches with a width of nearly 6 km and cross-sectional variability of flow, such as Yangtze Estuary, these methods are not accurate enough for the discharge estimation. Therefore, an improved method named the multiprofile method, is proposed in this paper. The method includes four main steps: (1) calculating the cross-sectional area A with stage data by considering the transverse slope; (2) calculating the depth-mean velocity u at each fixed ADCP; (3) establishing the u - U model with the multiprofile us and estimating the cross-sectional mean velocity U; (4) estimating the final discharge through U multiplied by A. The proposed method was tested at the Xuliujing section of the Yangtze Estuary. The result shows that the multiprofile method averagely improves the accuracy by approximately 5.8% relative to the single-profile method in the discharge estimation, which proves the proposed method to be valid in the discharge estimation of large tidal reach. (C) 2016 American Society of Civil Engineers.