**Lecturers: Michel Benoit**

This course is shared with ENSTA ParisTech engineer’s program

The first part of this course is devoted to ocean waves theory, their linear and non-linear dynamics, their spectral representation and their stochastic properties.

The second part focus on the coastal and near shore environment, where high quantities of non-cohesive sediments (sands) are transported under the combined action of waves and currents. This sediment transport is crucial to both the understanding of how the morphology of the sandy coasts evolves and the accurate designing of coastal protection methods (e.g., hard structures, sand nourishments). The course presents the basic hydrodynamical processes driving the coastal and near shore sand transport and the underlying physical mechanisms controlling the evolution of sandy bodies.

1. Introduction on surface waves

Monochromatic surface waves, linear swell, wave energy and power.

2. Sea state and random waves

Deep sea random waves observation, short-term statistics, spectral analysis: frequency and direction. Wind generation, nonlinear evolution, dispersion and dissipation.

3. Linear shallow-water waves

Shoaling, shallow-water transformation, wave breaking dissipation, wave induced currents, coastal and beach currents.

4. Non-linear shallow-water waves

Non-linear models of shallow-water waves, Green-Nagdi equations, surf and swash zones.

5. Offshore to coastal waves

Wave current interactions, wave evolution in finite depth. Numerical models of GLM2-RANS.

6. Introduction on nearshore morphodynamics

Wave-driven currents in the nearshore; geomorphology; patterns in the sand; sediment transport under breaking waves; sandy beach morphodynamics on timescales: days to years.

7. Modelling of nearshore morphodynamics

Forcing template and self-organization theories; linear and nonlinear stability analysis; shoreline instabilities, 3D surf zone sandbars dynamics.

8. Practical session: Development of a simple shoreline evolution model

One-line shoreline modelling; development and basic underlying assumptions; analytical solutions; numerical scheme; practical applications with nourishments and coastal structures.

9. Non-cohesive sediment transport and observation technics

Introduction to mophodynamics, sediment property and characterization, sediment transport, overview of observation technics, multi-beam echosounder, current meters.

10. Dynamics of marine sandbanks and sand dunes of the continental shelf

Characteristics of banks, dunes, megaripples; modelling and time scales, sandbanks modelling linear stability analysis, dunes and megaripples modelling.

M. Benoit (IRPHE & Ecole Centrale Marseille), B. Castelle (EPOC), M. Yates-Michelin (Saint-Venant)

**Langue du cours :** Anglais**Credits ECTS :** 4

- Teaching coordinator: Claude Basdevant