Multi-channel estuaries such as the Mekong Delta in Vietnam and the Scheldt in the Netherlands have characteristics of both the river and the sea forming a unique environment influenced by tidal movements of the sea and freshwater flow of the river. This study addresses a number of knowledge gaps in multi-channel estuaries by developing a predictive analytical approach for salinity intrusion and discharge estimate in multi-channel estuaries. The new approach agrees well with 1-D hydrodynamic models and observations indicating its applicability in practice. Most importantly the study has successfully developed a new theory and a new equation to quantify tidal pumping due to ebb-flood channel residual circulation and the related salt dispersion. . Language: English