Abstract: Mangroves are unique coastal ecosystems found in tropical and subtropical regions. Due to climate change disturbance and human activities in the coastal ecological environment, the area of mangroves in China has drastically decreased. Since the mangrove restoration projects in China, significant progress has been made in protecting and restoring mangroves, gradually increasing the areas. However, the survival rate of newly planted mangroves remains low. There are two primary reasons. (1) There is insufficient consideration of the compatibility between suitable environments and the characteristics of mangrove species, thus lacking an objective understanding of the natural laws for suitable mangrove areas. (2) Due to the long restoration of mangroves, there is a lack of an effective means to evaluate and judge the artificial intervention dynamic changes of suitable environmental elements. To further expand the suitable mangrove area and increase their survival rate, research on mangrove restoration planning based on numerical simulation was carried out from quantitative indicators related to natural mechanisms. The dynamic process of suitable environments for mangroves under the action of natural mechanism was exhibited intuitively by using numerical simulation tools. Moreover, the natural restoration effect of mangroves under artificial intervention was predicted. This makes it possible to create stable natural mangrove landscapes and build special landscape values while increasing mangroves restoration efficiency. This study conducted a numerical simulation of the natural mechanism for suitable mangrove areas in Chengcun Bay, Yangjiang, Guangdong. The mangrove restoration was judged, planned, designed, and evaluated. 
　　First, a quantitative indicator system was summarized based on the natural mechanism of suitable mangrove areas. A total of seven key factors related to natural mechanisms and mangrove growth were determined by reviewing suitable indicators corresponding to suitable habitat, including tidal level, elevation, salinity, inorganic nitrogen, active phosphorus, flow rate, and wave height, thus establishing the indicator system for natural mechanisms of suitable mangrove areas.
　　Second, the natural mechanism of suitable mangrove areas in Chengcun Bay was simulated by using a hydrodynamic module (HD), mud transport module (MT), advection-dispersion module (AD), and spectral wave module (SW) of the MIKE21 software. The indicator system for suitable mangrove areas was brought into the simulation results of a suitable environment, thus evaluating the suitable mangrove areas in Chengcun Bay comprehensively.
　　Finally, the mangrove restoration plan in Chengcun Bay was guided by the simulation results. Hydrodynamic channels, groins, or offshore breakwaters are built through the restoration strategy of "centered at natural restoration, supplemented by some artificial intervention," aiming to improve the suitable mangrove areas. The numerical simulation method was applied to supplement the full-process mangrove restoration plan, and the plan's feasibility was verified through simulations. It concluded that the suitable mangrove areas in Chengcun Bay could be improved by dredging tidal channels and constructing U-shaped offshore breakwater groups.

Key words: mangrove restoration plan, natural mechanism, suitable environment, numerical modeling, MIKE21

摘要： 为扩大红树林适生范围、提升红树林存活率。选取广东阳江程村湾红树林作为研究区域，对影响红树林适生环境的自然机制进行数值模拟，对红树林修复进行预判、规划、设计和评估。应用MIKE21模拟影响程村湾红树林生长的自然机制过程，以评估现状红树林适生区。通过“自然恢复为主，部分人工介入”的修复策略，构建水动力通道、丁坝或离岸堤以改善红树林适生环境。采用数值模拟的方法辅助全过程红树林修复规划，并对修复方案进行可行性模拟验证。研究得出疏通潮流涌道、建设U型离岸堤群组可以改善程村湾红树林适生环境的结论。

关键词: 红树林修复规划, 自然机制, 适生环境, 数值模拟, MIKE21