Open-Channel Flow Control by Vegetation and Artificial Roughness and Hydraulic Design of Multi-Function Channels

近期，河流整治规划应细化河流的各个功能方面，如防洪、更有效的水资源利用、河流的娱乐或休闲利用、良好的生态状况、水生栖息地等。而要实现这一多功能，就必须在水力学和输沙力学的基础上对水流和河流形态进行更巧妙的管理或控制。本文重点研究了斜向排列的带状粗糙度对细胞运动的控制和植被带排列对细胞横向扩散的促进。细胞运动有助于船只和独木舟的直线航行，或通过二次流运动清除积雪块，或收集漂浮的垃圾以清除它们。此外，它甚至改变了主速度剖面。流型鱼的方式就是后者的一个例子。而促进的横向扩散通过将主河道的浊度捕获到植被带而降低了浊度。在这项研究中，采用了多种方法：实验室实验，现场测量和数值分析以及对现象的简化水力理解。在河床和/或侧壁上斜排列的条状粗糙度和植被带促进横向扩散形成细胞运动的机制已经在几个层面上得到了理解。实验提供了经验关系，并得到了数值分析的支持。同时，对多功能水系的水力设计也有一定的参考价值。

Recently, river improvement should be planned to refine various functional aspects of rivers such as flood control, more efficient water resources utilization, recreational or leisure usage of rivers, well-conserved ecological situation, aquatic habitat and so on. And to achieve such multi-functions, the flow and river morphology should be more skillfully managed or controlled based on hydraulics and mechanics of sediment transport.In this study, control of cellular motion by oblique arrangements of strip roughness and promotion of lateral diffusion by arrangement of vegetation zone have been focused. Cellular motion helps straight navigation of boat and canoe, or removed snow lumps by secondary flow motion, or it gathers floating garbage to remove them by side overflow. Furthermore, it even changes the primary velocity profile. Stream-type fish way is an example of the latter. While, the promoted lateral diffusion works to decrease the turbidity of the main channel by trapping it to the vegetation zone.In this study, various types of approaches have been employed : laboratory experiments, field measurements and numerical analysis as well as simplified hydraulic understanding of the phenomena. The mechanism of formation of cellular motion by obliquely arranged strip roughness on bed and/or side walls and promotion of lateral diffusion by vegetation zone have been understood at several levels. The experiment has provided empirical relations and they have been supported by numerical analysis. And, they must be useful for hydraulic design of multi-functional streams.