基于能量耗散视角的红树林海岸沉积地貌学

能量耗散是海岸带沉积地貌学的重要研究方向。地貌系统中的能量耗散往往存在极值，但是关于地貌演化的能量耗散趋向是最大值还是最小值，一直存在争议。本文试图从文献梳理入手，回顾海岸带地貌过程中的能量耗散问题，并用阻抗匹配概念来解释能量耗散的极值问题：当地貌系统的机械储能效率最大而热力学耗散最小时，表现为“共振阻抗匹配”，反之则表现为“梯度阻抗匹配”。基于无量纲沉降速度Ω的海滩地貌分类体系，正是表现从“共振阻抗匹配”到“梯度阻抗匹配”的典型谱系。在此基础上，从能量耗散的视角，对红树林生态系统的沉积地貌过程进行了文献综述，总结了潮沟-潮滩-红树林界面上的阻抗匹配和能量耗散问题，讨论了界面能量耗散行为如何通过水动力学和热力学过程反馈到红树林的生长过程，指出了红树林生态系统中潮沟-潮滩三维地形结构的重要性，并建议在红树林生态修复工程中应用这种结构来更好地维持系统的稳定性。

Sedimentary geomorphology of mangrove coasts in perspective of energy dissipation

Energy dissipation has been widely studied in coastal sedimentary geomorphology. It has been assumed that thresholds in energy dissipation may exist in geomorphological evolution; however, whether energy dissipation evolves towards a minimum, maximum, or both, aroused a big debate in a long history. We summarized the previous publications to revisit the energy dissipation problem in coastal geomorphology, and proposed a concept of ‘impedance matching’ to explain the problem regarding minimum and maximum values of energy dissipation. Once the geomorphological system showed a maximal mechanical energy storage but a minimal thermal energy dissipation, it could be a ‘resonance impedance matching’ system. Otherwise, it could be a ‘gradience impedance matching’ system. The Ω classification of beaches obtained by dimensionless settling velocity was a typical example for these two ‘impedance matching’ systems. Based on the new concept, we reviewed geomorphological studies on mangrove ecosystems, and revealed the ‘impedance matching’ and the energy dissipation across the interfaces of tidal creek–tidal flat–mangrove systems. In addition, we discussed how the energy dissipation could affect the growth of mangroves through hydrodynamics and thermal dynamics, and pointed out that the three-dimensional structure of tidal creek–tidal flat is very important to maintain the stability of mangrove ecosystems and therefore should be considered in the future mangrove restoration projects.