Sediment transport is ubiquitous in nature. Solid grains are transported by different agents such as wind and water, but they can also be eroded under chemical and thermal effects. The diversity of landforms may be explained by the variety of physical processes like erosion, sedimentation, bed- or suspended-load, and their multiple combinations. Even though the phenomenon is taking place naturally, it can be exacerbated by anthropogenic factors (urban planning, industrialization, agriculture, tourism) and their resulting climate change (sea level rise, storm surge) effects.

This presentation deals with sediment transport by water in rivers, bays, estuaries and coastal zones. More specifically we will focus on actual research activities on hydraulic structures for which erosion means important damage with potential ecological impacts. For instance, failure of a submarine pipeline could generate oil spills; collapse of bridges can interrupt transport networks; dam failure may endanger population.

This will illustrate the important need to develop accurate methods and tools to predict sediment transport and to design optimized solutions to the environment. Here we present the scientific challenges in terms of a triple interaction with the fluid dynamic, the sediment transport and the structural response of constructions. As it is an interdisciplinary research topic with many non-linearity, both physical and mathematical modeling are essential for improving our basic knowledge or defining best practices for engineers. Recent development in experimental and numerical methods are presented with their new challenge.