Investigating the equilibrium profile of a sandy beach is important to evaluate the beach response to natural forces. Empirical or semi-empirical relationships among beach states, wave climates and sediments properties have been established in various studies. In this study, detailed physical insights of hydrodynamics and sediment transport patterns on a quasi-equilibrium beach profile are provided using a process-based model. Model results show that during the beach profile transition to equilibrium, both the magnitude and the cross-shore gradient of sediment transport rate decrease. The total net sediment transport in surfzone is mainly affected by the balance/imbalance between offshore-directed current-related suspended sediment transport and onshore-directed bedload transport, both of which showing a decreasing tendency during the transition to equilibrium. The former is due to the decreasing undertow velocity and sediment concentration, and the latter is due to the decrease of peak bedload transport rate near the intra-wave crest phase. The wave-related suspended sediment transport is relatively small compared to the other two transport components. Based on the entropy concept, a dimensionless parameter representing the spatial uniformity of wave energy dissipation rate is proposed as an indicator of the equilibrium degree of a beach profile. Results suggest that a quantitative relationship can be established between this parameter and the overall characteristics of sediment transport on a beach profile.

研究沙滩的平衡剖面对于评估沙滩对自然力的响应很重要。在各种研究中已经建立了海滩状态，波浪气候和沉积物特性之间的经验或半经验关系。在这项研究中，使用基于过程的模型提供了准平衡海滩剖面上水动力和泥沙输送模式的详细物理见解。模型结果表明，在海滩剖面过渡到平衡的过程中，泥沙输送速率的大小和跨岸坡度都减小了。海浪区的总净泥沙输送量主要受海上定向流相关的悬浮泥沙输送与陆上定向床荷输送之间的平衡/失衡的影响，在过渡到平衡过程中，两者都呈现出下降的趋势。前者是由于拖曳速度和沉积物浓度的降低，而后者是由于波内波峰相附近的峰值床层输运速率的降低。与波有关的悬浮沉积物的输送相对于其他两个输送成分而言相对较小。基于熵的概念，提出了表示波浪能量耗散率空间均匀性的无量纲参数，作为海滩剖面平衡度的指标。结果表明，可以在该参数与海滩剖面上泥沙输送的总体特征之间建立定量关系。后者是由于波内波峰相附近的峰值床载输运速率降低所致。与波有关的悬浮沉积物的输送相对于其他两个输送成分而言相对较小。基于熵的概念，提出了表示波浪能量耗散率空间均匀性的无量纲参数，作为海滩剖面平衡度的指标。结果表明，可以在该参数与海滩剖面上泥沙输送的总体特征之间建立定量关系。后者是由于波内波峰相附近的峰值床载输运速率降低所致。与波有关的悬浮沉积物的输送相对于其他两个输送成分而言相对较小。基于熵的概念，提出了表示波浪能量耗散率空间均匀性的无量纲参数，作为海滩剖面平衡度的指标。结果表明，可以在该参数与海滩剖面上泥沙输送的总体特征之间建立定量关系。提出了表示波浪能量耗散率空间均匀性的无量纲参数，作为海滩剖面平衡度的指标。结果表明，可以在该参数与海滩剖面上泥沙输送的总体特征之间建立定量关系。提出了表示波浪能量耗散率空间均匀性的无量纲参数，作为海滩剖面平衡度的指标。结果表明，可以在该参数与海滩剖面上泥沙输送的总体特征之间建立定量关系。