IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 35th IAHR Congress - Chengdu (2013) : THEME 5 - FLUVIAL HYDRAULICS AND RIVER MANAGEMENT : CFD and Physical Modelling for the Upper Tai Po River Design ? An Integration of Ecology and Enginee...
CFD and Physical Modelling for the Upper Tai Po River Design ? An Integration of Ecology and Engineering
Author : W.H. Luk, C.L. Leung, David Lui and Dominique Brocard
Erosion is a primary concern for rivers in upland and hilly areas. Concrete lined channel used to be the solution to cope with high velocity, but rising environmental concerns are placing demands for ecologically friendly designs using more natural substrates. The Upper Tai Po River is one such 2 typical steep river in Hong Kong. It has a total catchment area of about 7 km and average gradient of 1 in 23, leading to high flow velocity exceeding 8 m\s during heavy rainstorm events. It was a typical natural stream with insufficient hydraulic capacity but noticeable ecological value with a number of dwellings at a relatively low lying area in the close proximity. To enhance the river capacity, it was necessary to deepen and widen it, and at the same time to develop energy dissipation measures to control erosion. Stilling basins with baffle blocks have been proposed at critical locations along the river. These elements have to be specifically designed to suit the hydraulic and topographical conditions of the river and to meet the public?s expectations on environmental protection and ecological objectives. Given the lack of established design principle \ approach, Computational Fluid Dynamic (CFD) Model and Physical Model have been used to optimize the design. CFD modelling has the advantage of providing a reasonably fast assessment of design options, such as vertical or inclined drops, with different arrangement of the baffle blocks. Following this optimization, a 1:40 physical model was constructed to examine and verify the overall design of river configurations including soffit level of bridge crossings. The results revealed that combination of inclined drops with baffle blocks has the most energy dissipation efficiency. This arrangement is capable of limiting flow velocities to values that can be withstood by gabion which has been proposed for the river bed and bank habitat re-establishment. This approach exemplifies the integration of engineering with ecology through the use of advance modelling techniques.
File Size : 668,570 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 35th IAHR Congress - Chengdu (2013)
Date Published : 18/07/2016
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