**Preface to "Flow Hydrodynamic in Open Channels: Interaction with Natural or Man-Made Structures"**

Natural and man-made watercourses play a vital role in our way of life and in sustaining biodiversity. However, with population growth, increased economic activity, and climate change, waterways are under severe pressure and, thus, require consistent monitoring, proactive management, and timely remediation. Improved knowledge and further understanding of flow hydrodynamics in open channels are crucial to effectively achieving these goals.

Flow hydrodynamic structures in open channels are very complex, persistently challenging phenomena. Despite the numerous studies conducted over decades on this topic, many aspects still require improvement. Many new research dimensions on open-channel flow dynamics can be explored by exploiting today's availability of sophisticated experimental tools, advanced theoretical methods, ample data storage, and the high computational capacity of computers. This Special Issue represents an essential contribution to the state of the art of open-channel flow fields, extending our knowledge and providing valuable references for hydraulic engineers, experts, and those interested in the environment.

Many thanks are extended to all the authors who contributed to the SI, which would not have seen the light of day without their input.

> **Mouldi Ben Meftah** *Editor*
