针对当前已有河湖数字孪生体大多存在的三维虚拟场景精度不够高、河湖水体动态化效果欠佳及动力过程不够精确等问题,使用虚幻引擎5(UE5)作为研究平台,对河湖环境下三维虚拟场景构建与水动力过程模拟方法进行了研究。首先将地形高度图、三维环境模型等作为输入数据构建高精度河湖三维虚拟场景,再对引擎中水体模拟插件进行改进,添加摩擦源项,实现河湖水体动力过程模拟,水文参量和数据读取与计算。然后设计了验证与对比试验场景,最终形成一个具备河湖三维场景与水动力过程模拟功能的数字孪生体框架。该方法实现了河湖三维场景构建、可视化水动力过程模拟与水文参量动态获取,提高了其作为数字孪生体的模拟能力,可为河湖流域数字孪生体技术在场景构建、动态模拟及交互设计的开发提供技术参考。

[Objective] To address the problems of insufficient 3D scene accuracy, unsatisfactory dynamic water effects, and imprecise hydrodynamic process simulation in existing river-lake digital twins, this study proposes an integrated method for 3D river-lake scene construction and hydrodynamic process simulation based on Unreal Engine 5 (UE5). The proposed method aims to construct a digital twin framework that combines high-fidelity scene representation with high-accuracy hydrodynamic process simulation, and to enhance the visualization, dynamism, and interactivity of river-lake digital twins. [Methods] UE5 was used as the research platform, and a real-scene 3D hydrodynamic process simulation method for river-lake scenarios was proposed and implemented by integrating terrain construction, water body simulation, and dynamic extraction of hydrological parameters. First, high-precision 3D river-lake terrain and environmental scenes were constructed using terrain height maps and high-precision photogrammetric models. Second, the Fluid Flux water simulation plugin in UE5 was modified by incorporating bottom friction factors influenced by the Manning coefficient, as used in engineering analysis, thereby establishing a hydrodynamic process model that better conformed to engineering practice. Finally, Blueprint programs were designed to dynamically extract and compute hydrological process parameters during simulation, enabling real-time calculation and dynamic extraction of key hydrological parameters such as flow velocity, water depth, watershed area, total water volume, and river cross-sections. An interactive user interface was also developed to support parameter visualization and scene interaction. [Results] A complete river-lake digital twin framework was constructed, and its functional effectiveness was verified through multiple experiments. First, a dam-break simulation experiment in a 90° bend was constructed to simulate the diffusion process of dam-break flow. The trends of water level variations at all measurement points showed good agreement with classical experimental data, validating the reliability of the hydrodynamic model. Subsequently, inundation simulation experiments under different vegetation cover conditions were conducted. These experiments reflected the influence of vegetation density on flow resistance and inundation processes in the simulated scenarios, demonstrated the capability of surface roughness variations to affect flow simulation, and verified that the proposed method could simulate the impacts of different vegetation environments on hydrodynamic processes. Finally, a complete 3D river-lake scene integrating 3D scenarios, dynamic water simulation, real-time hydrological parameter extraction, and an interactive interface was presented. Through the interface, users could obtain hydrological parameters such as water depth, flow velocity, cross-sectional morphology, watershed area, and total water volume at any location in real time, facilitating clear data acquisition and subsequent processing. [Conclusion] This study investigates methods for 3D scene construction of rivers and lakes and for hydrodynamic process simulation within such scenes, and successfully constructs a river-lake scene framework that integrates high-precision 3D scenes with hydrodynamic process simulation using UE5. The main innovations of this study lie in clarifying the method for constructing 3D river-lake scenes in the UE5 environment, generating terrain base surfaces using the terrain system and elevation data, and introducing high-precision photogrammetric models to enrich the surface environment, thereby improving the realism of 3D river-lake scene construction. From an engineering analysis perspective, the hydrodynamic model of the Fluid Flux plugin in UE5 is improved by adding a friction term influenced by the Manning coefficient, enabling hydrodynamic process simulation in 3D scenes to more accurately reflect the influence of environmental roughness. Simulation scenarios are also designed to verify the impacts of different terrain and vegetation roughness on flow simulation. In addition, Blueprint programs are designed to dynamically extract and compute various hydrological elements during the simulation of 3D river-lake scenes, forming a complete method for hydrodynamic process simulation in 3D river-lake scenes. The proposed method provides integrated capabilities for scene construction, hydrodynamic process simulation, and hydrological parameter extraction and computation, thereby improving the efficiency of data acquisition and processing during 3D scene simulation.