Estuarine hydrodynamics is the academic field concerned with the physics of water movement and mixing processes within estuaries. It investigates the complex interplay of forces such as tides, river discharge, wind stress, and density gradients, and their effects on circulation patterns, stratification, and the transport of dissolved and suspended materials, which is crucial for understanding and managing water quality, coastal ecosystems, sediment transport, and navigation in these transitional environments between rivers and the open ocean.