Knowledge of wave climate is essential for efficient management of the world's coastal areas. Senegal is a relevant case given its high coastal vulnerability to energetic wave conditions. This study investigates wave climates along the coastal zone of Senegal based on a new high-resolution hindcast covering the period 1980-2021. This study evaluates the average, seasonal and extreme values for the wave significant heights (Hs), periods (Tm02/Tp) and mean directions (DIR). In boreal Winter, the wave climate is dominated by swells coming from the North-Atlantic lows, while in boreal Summer, the Southern Coast (from Dakar to Casamance) is exposed to swells generated in the South-Atlantic Ocean. Throughout their refraction around Dakar Peninsula, NW swells rotate by ~100° from NW to SW, while their Hs is roughly halved when reaching the Southern Coast of Senegal. Over the studied period, trends in Hs are weak (~0.6 cm.decade-1) on the Northern Coast, double on the Southern coast (~1.2 cm.decade-1), mostly due to an increase during boreal Summer (2 cm.decade-1). The wave periods show weak trends (~0.05 s.decade-1) and DIRs show weak counterclockwise rotation (-1°.decade-1). These trends are explained by the main climate modes of the Atlantic Ocean (NAO/EA during Winter, SAM during Summer) and are important for future research and long-term monitoring of the Senegalese Coast.

Very complex aquatic ecosystem, the mangrove forest colonizes coastal lagoons, estuaries and deltas in tropical and subtropical zones. This study investigates the impact of mangrove vegetation on tidal propagation in the Somone Coastal Lagoon, located on the Senegalese small coast. The analysis of new field data is complemented with the application of a 3D circulation model accounting for vegetation. The analysis of well-reproduced water levels and currents over the whole lagoon make it possible to spatially study the amplitudes of the main tidal harmonics, semi-diurnal (M₂), diurnal (K₁) and the major overtide (M₄). The comparison between our baseline model accounting for vegetation and a configuration without vegetation reveals firstly that the mangrove strongly attenuates tidal propagation in the lagoon, whit a stronger impact on semi-diurnal waves than diurnal waves. Tidal currents are also strongly reduced when the mangrove is accounted for, even close to the inlet mouth, far away from vegetation areas. The mangrove also enhances tidal asymmetry and promotes ebb dominance, both in terms of duration (ebbs last from 0.5 up to 3 h more than floods) and current magnitude (ebb currents are about 50% stronger). Spring tides accentuate ebb-dominance compared to neap tides, where tidal asymmetry is weaker.