Author(s): Motohiko Umeyama; Narumi Ishikawa
Keywords: Salt intrusion; Geometric characteristics; Multi-branched estuary; Red River
Abstract: We developed a predictive flow-distribution model, considering how the energy loss by the bottom friction affects the rate of freshwater discharge in the branched channels, and a saline intrusion model, considering the salt balance by diffusion and advection. The study area is located in the Red River Delta, where the Red River and many distributaries spread out to form a large alluvial plain. The Red River Estuary System lies in the southeastern part of the delta and includes four branches: the Tra Ly, Red River, Ninh Co, and Day. The predicted result was compared with a set of observed data and with the numerical result by commercial software. The mean freshwater discharge rate was calculated accurately at junctions where the main flow separates into branches. Salinity distributions were estimated by making use of the salt intrusion model. The present models efficiently evaluate the mixing mechanism caused by the tidal flux in a multibranched estuary, where hydraulic data are not always feasible to observe in the dry season.