Experimental study on the restoration and protection of mangrove tidal ecosystems flat located in a high wave area

Mangrove forests perform several essential functions, including organic carbon sequestration, wave energy dissipation, beach stabilization, and coastal protection against marine hazards. Establishing a favorable environment for developing mangrove tidal flats in estuaries with high wave activity requires targeted wave dissipation and beach stabilization measures. This study focuses on the restoration of mangrove tidal flats in the Huangmaohai Sea (HMHS), located on the western coast of the Pearl River Estuary (PRE), China. To dissipation wave impacts and enhance tidal flat stability, various combinations of bamboo rafts, artificial reefs, pine piles, and ecological oyster reefs were evaluated. Using cross-sectional experiments utilizing a physical model simulating wave dynamics and sediment transport, this study analyzes erosion and deposition patterns affecting mangrove seedlings under different wave recurrence intervals. The results indicate that under a 5 yr recurrence interval, the combinations of bamboo poles with artificial reefs and pine piles with ecological oyster reefs exhibit significant anti-erosion effects. Minor erosion was observed within the initial 1–2 m of the restored beach surface, with a maximum erosion depth of approximately 0.21 m. In contrast, the combination of pine piles and bamboo rows experienced more extensive erosion, with a maximum reach of 17.5 m and an erosion depth of 0.65 m. Erosion patterns under 30 and 50 yr recurrence intervals were also analyzed. The beach surface within the mangrove restoration area exhibits significant erosion, impairing its ability to maintain its original condition. A comparative analysis of the impact of varying bamboo row configurations on soil erosion and deposition in mangrove planting areas reveals that protection is afforded by both the bamboo rows themselves and the planted mangroves within a distance of up to 5 m from the rows. However, this protective effect diminishes with increasing distance. These findings provide a scientific foundation for the protection, restoration, and sustainable management of mangrove tidal flats in high wave areas.