STUDY ON SALINITY INTRUSION PROCESSES INTO HAU RIVER OF VIETNAMESE MEKONG DELTA

抄録

 Field studies in the DinhAn branch of the Hau River, belonging to the Vietnam Mekong Delta, were conducted at spring tides (4 March 2018 and 21 to 22 April 2019) to examine the vertical and longitudinal salinity distribution along the DinhAn branch as well as the vertical salinity distribution at two typical cross-sections. The measured data were used to classify mixing and stratification of the DinhAn estuary during a tidal cycle. The results indicate that along the Hau River (1) the salinity intrusion length at flood tide is 15 km longer than that at ebb tide and (2) the maximum salinity appears at the river mouth and irregularly reduces toward upstream during flood tide. Moreover, at the cross-section far from the river mouth 22km, (3) the peak of salinity lags one hour after the peak of water level and (4) the maximum salinity during one tidal cycle occurs at ebb tide. Finally, all three stratification parameters, including Pritchard, Froude, and Richarson numbers show that the partial mixing and moderate stratification condition prevailed in the DinhAn branch during a tidal cycle. These results are useful in operating the salinity control gates in terms of timing and duration.