Investigation on the Sediment Resistance to Wave-Induced Lateral Erosion Under Different Mangrove Forests

Abstract

Under the effect of global climate change, the enhanced wave condition leads to lateral erosion at the mangrove vegetation edge, threatening the survival of mangrove habitat and the safety of coastal defense. By means of investigations on sediment physicochemical properties and wave flume experiments, we quantify the lateral erosion rates of mangrove sediments under waves and bridge the edge stability and vegetation with sediment properties. It is found that different mangrove species and stand ages significantly alter the physiochemical properties of sediments, and consequently affect the erosion resistance. Lateral erosion rate is positively correlated with organic matter content and negatively correlated with saturated density, which serve as two main factors that affect sediment resistance to wave forcing. Experimental datasets suggest that the sediment lateral erosion rate of Kandelia obovata reaches several times larger than that of Sonneratia apetala among different stand ages, indicating that the erosion resistance has significant differences between mangrove species. Amongst different Sonneratia apetala sites, the erosion resistance is enhanced with increasing mangrove stand age. This study sheds light on the feedbacks between geo-morphodynamics and intertidal vegetation, which provides a promising experimental approach to evaluate the ecological functions of mangrove forests with respect of resistance to external disturbance. Insights gained from this study is useful in guiding the nature-based solutions for coastal defense through proper spatial-temporal configuration of suitable saplings with higher potential in resilience.

Keywords: mangroves, lateral erosion, sediment physicochemical properties, wave flume experiment, erosion resistance