基于河床透视技术的山区河流河床结构演变机理研究

Fluvial process in mountain rivers is one of the key drivers for natural hazards such as flash flood, debris flow and landslide and thus, further understanding to the mechanism of this natural process will contribute significantly to disaster prevention and mitigation. However, the complex boundary conditions in riverbed owing to development of multiple bed structures lead to no satisfactory theory in mechanism and prediction of sediment transport in mountain rivers in the last century. Further understanding towards the evolution mechanism of bed structures contributes to possible breakthroughs. The evolution of bed structure in mountain rivers is not only affected by flow driving forces, but also influenced by the granular interactions. Therefore, the interior and exterior granular structural variation and information of flow and grain transport during the evolution of bed structures needs to be acquired by measurement under complex and dynamic bed surface conditions. The riverbed perspective technique based on refractive index matching (RIM) procedure will be applied in well-controlled flume experiments to measure the interior and exterior granular structure, flow field and grain movement of bed structures in the present project. The interior and exterior variation of bed structures, and interaction between bed structures and bedload will be explored. The evolution mechanism of bed structures will be studied combining both fluid and granular effect.

山区河流河床演变是山洪、泥石流、滑坡等多种山地灾害重要诱发因素，加深演变机理认识将极大推进防灾减灾工作。然而，因多种河床结构形成及演变，河道边界条件极为复杂，致使山区河流泥沙运动机制及预报一个多世纪以来都未能有效解决，深入认识河床结构演变规律有助于突破这一难题。山区河流河床结构演变同时受水流和颗粒相互作用影响，获取演变过程中全面的内外结构变化、水流及颗粒运动信息是寻求突破的前提条件，必须解决复杂动态床面条件下水沙观测难题。本项目拟通过精细控制的水槽试验并使用基于折射率匹配（RIM）技术的河床透视技术对河床结构内部外部颗粒结构特征及水沙运动展开测量，探究河床结构演变过程全面的内部外部变化规律及与推移质运动相互作用特点，综合水流和颗粒作用研究山区河流河床结构演变机理。

山区河流河床演变是山洪泥石流等多种山地灾害的重要诱发因素，加深演变机理认识是推进防灾减灾工作的重要科学基础。然而因河床结构形成、河道边界条件极为复杂，致使山区河流泥沙运动机制和预测始终未能有效解决，深入认识河床结构演变规律有助于突破这一难题。本研究的主要目的为开发完善基于折射率匹配（RIM）技术的河床透视技术并以此为基础探究河床结构地貌-水力相互作用特点，揭示其演变机理。主要研究成果包括：. （1）开发了具有凸弧面的透明固体折射率的测量方法及装置、多层透明球床的最优折射率测量方法、高时空分辨率的推移质输沙率测量方法及装置、多孔介质内部固液运动测量方法及装置等一系列基于折射率匹配的观测方法，建立了完整的河床透视观测技术体系。. （2）通过系统测试完善透水摄影测量技术在获取山区河流床面水下三维地形的应用流程。建立融合摄影测量和计算流体力学模拟技术的混合模拟方法，成功实现典型河床结构阶梯-深潭的高分辨率三维水动力特性，揭示水力-地貌耦合演变细观机理，为类似复杂河床结构发育条件下的山区河流河床演变研究提供技术参考。. （3）基于阶梯-深潭的地貌-水力耦合演变机理出发建立了基于单元尺度的多级人工阶梯-深潭系统设计方法。该设计方法使用开放性模块化架构、允许非均匀几何设计尺寸，实现人工阶梯-深潭系统的水力地貌特性预测和稳定性定量评估。. 在本项目的支持下，总计发表期刊论文4篇，全部为SCI论文，申请国家发明专利4项、实用新型专利3项，会议报告2次，项目资助出站博士后1名、在读博士生3名。