Approache to long-term modelling of the Nhat Le estuary morphology, Quang Binh Province

Abstract

The Nhat Le estuary, located on the central coast of Vietnam, is a representative example of a tide-influenced, wave-dominated estuary with a characteristic sand spit. This study developed a long-term morphological evolution model (over 5-10 years) for the Nhat Le estuary, based on the application of the Delft3D numerical modeling system combined with a morphological acceleration factor (Mf or MorFac) and the implementation of boundary condition reduction techniques for river discharge, sediment load, waves, and tides. Modeling results compared with measured bathymetric data from 2009 to 2019 indicate that the model successfully reproduces the general patterns of sedimentation and erosion, particularly at the mouth bars and estuarine channels. Notably, substantial sediment deposition is observed along the submerged sandbar at the estuary mouth due to the combined influence of river flow and wave action. The findings from this study provide scientific insights that support effective and sustainable management of the Nhat Le estuary.