Since the early 1990s, satellite altimetry has significantly improved our understanding of coastal and estuarine dynamics. The Casamance estuary in Senegal exemplifies a tropical microtidal system with limited instrumentation despite pressing environmental, social, and navigational concerns. This study explores the potential of SWOT satellite data to support the calibration and validation of high-resolution hydrodynamic models. Multi-source dataset of in situ measurements and altimetry observations has been combined with numerical modelling to investigate the hydrodynamics in response to physical drivers. Statistical metrics were used to quantify model performance. Results show that SWOT accurately captures water level variations in the main channel (width 800 m to 5 km), including both tidal and non-tidal contributions, with high correlation (R = 0.90) and low error (RMSE < 0.25 m). Performance decreases in tributaries (R = 0.42, RMSE up to 0.34 m), due to interpolated bathymetry and complex local dynamics. Notably, Delft3D achieves R = 0.877 at Diogué (RMSE = 0.204 m) and R = 0.843 at Carabane (RMSE = 0.225 m). These findings highlight the strategic value of SWOT for improving hydrodynamic modelling in data-scarce estuarine environments.

Since the early 1990s, satellite altimetry has significantly improved our understanding of coastal and estuarine dynamics. The Casamance estu-ary in Senegal exemplifies a tropical microtidal system with limited in-strumentation despite pressing environmental, social, and navigational concerns. This study explores the potential of SWOT satellite data to support the calibration and validation of high-resolution hydrodynamic models. Multi-source dataset of in-situ measurements and altimetry ob-servations has been combined with numerical modelling to investigate the hydrodynamics in reponse to physical drivers. Statistical metrics were used to quantify model performance. Results show that SWOT ac-curately captures water level variations in the main channel (width 800 m to 5 km), including both tidal and non-tidal contributions, with high correlation (R = 0.90) and low error (RMSE < 0.25 m). Performance decreases in tributaries (R = 0.42, RMSE up to 0.34 m), due to interpolated bathymetry and complex local dynamics. Notably, Delft3D achieves R = 0.877 at Diogué (RMSE = 0.204 m) and R = 0.843 at Carabane (RMSE = 0.225 m). These findings highlight the strategic value of SWOT for improving hydrodynamic modelling in data-scarce estuarine envi-ronments.

This study examines the evolution of wave shapes as they propagate over a beach of varying morphology, information essential for understanding coastal dynamics and supporting coastal management. Our objective was to analyze the relationship between wave shape parameters and the local slope of the beach. To achieve this, we used data from pressure sensors and topographic measurements to evaluate the shape of waves on a cross-shore profile of a low-tide terrace beach. The analysis of wave conditions revealed a pronounced modulation of the tidal signal, which is augmented during storm events. Our findings demonstrate that the asymmetry and skewness parameters are more pronounced in the reflective zone of the beach. Considering these results, it can be concluded that the non-linearity of waves is significantly affected by the beach slope. The parameterization method employed in this study effectively incorporates this factor, offering improved accuracy in comparison to the existing approaches.

This study analyses the hydro-morphodynamics of the Casamance Estuary, a tropical microtidal system where tidal forcing governs morphological evolution during the dry season. The methodology couples a digital elevation model of differences analysis based on bathymetric surveys (DoD, 2008--2023) with a process-based numerical model (Delft3D), calibrated in situ and validated using SWOT satellite data. The results highlight a hydrodynamic segmentation driven by the non-linear distortion of the tidal wave. A pivotal point, located around 16.65° W, divides the estuary into two cells: a downstream sediment import cell (flood-dominated) and an upstream export cell (ebb-dominated). This configuration generates a residual convergence zone that acts as a permanent sediment trap. Examination of the sediment dynamics and sandbank evolution reveals a pulsed mechanism. Vertical storage phases during neap tides alternate with intense horizontal migration during spring tides, where centroid displacements exceed 100 m per cycle. Whilst the mobilisation of massive volumes (10 6 m 3) maintains the mouth equilibrium, the lateral progradation of sandbanks in the middle sector directly threatens the navigation channel. This work provides an essential scientific basis to optimise the contribution of modelling to the management of dredging campaigns for the navigation channel between Dakar and Ziguinchor.

The Casamance estuary, located in West Africa (Senegal), is a unique hydrodynamic system characterized by a seasonal alternation between a classical (positive) and an inverse estuarine regime during which salinity may exceeds 40 psu. As previous studies have mainly focused on seasonal and interannual variations of surface salinity, this study presents the first measurements of the thermohaline vertical structure in the estuary, collected between 2022 and 2025 near the river mouth during 16 field campaigns conducted outside the rainy season. These observations reveal both the positive, transition and inverse phases of the estuarine regime. Density stratification in the surface layer (0–5 m) is dominated by vertical gradients of salinity accounting for 35-95% of the stratification in the positive regime and 47–100% in the inverse regime. The microtidal signal plays an important role in controlling stratification variability: stratification is more pronounced during neap tides than during spring tides, reflecting the effect of vertical mixing by bottom friction due to tidal currents. During periods of weak tidal currents, the effect of longitudinal wind on stratification becomes detectable. In the positive regime, down-estuary winds enhance stratification through axial wind straining. In the inverse regime, strong up-estuary winds promote stratification by spreading lighter oceanic waters over the denser estuarine waters. Transverse cross-sections reveal a persistent lateral salinity asymmetry, with salinities systematically higher on northern bank than on the southern bank, regardless of the prevailing estuarine regime.