Topographic Effect on Wind Distribution in Hong Kong

Project: Research

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Researcher(s)

  • Kam Tim TSE (Principal Investigator / Project Coordinator)
  • Cheong Chuen Edmund CHOI (Co-Investigator)
  • Hing-yim MOK (Co-Investigator)

Description

Hong Kong is a unique place that is situated in an active typhoon region with high wind speeds and the majority of its landmass covered by mountainous terrains. Seventy-five percent of its landmass is characterized as complex topography, including hills, ridges, escarpments, and valleys, and this topography displays sharp and frequent spatial variations within a short distance. Such complex topographical features are known to cause significant changes in mean and gust wind speeds, most markedly by accelerating flow over the crests of hills or escarpments and shelter effects in valleys and the lees of hills or ridges. This has a significant impact on the engineering design of buildings, environmental planning, ventilation and pollution studies.Several wind loading codes of practice, including the Code of Practice on Wind Effects in Hong Kong 2004 (CPWEHK-2004), attempt to make use of simple guidelines to quantify the effects of topographical features on design wind speeds. These guidelines generally use parametric equations to predict the speed-up effects that are analytically/empirically derived by considering an isolated hill with an idealized shape/slope. Unfortunately, the parametric equation for the prediction of topographical factors in CPWEHK-2004 can only cater for local topographical effects. There is no provision for the topographical factor prediction of wind flow patterns over a large landscape of mountains and/or valleys. In practice, particularly in Hong Kong, hills or escarpments are unlikely to be isolated. The effects of the surrounding topography must be considered as a big picture and not as isolated local effects.The primary goal of this research project is to develop a wind map of Hong Kong that highlights district-level design wind speeds and airflow directions for application to a wide range of subjects, such as the safety of structures, the extraction of wind energy, pollutant dispersion, and air ventilation assessment. This is to be achieved by the integration of wind data collected from Hong Kong Observatory weather stations with the state-of-the-art wind tunnel modelling techniques of wind flow fields over the complex, hilly terrain of Hong Kong. The major benefits of the research will be the refinement of the single design wind speed for the entire territory to a more detailed district-level design wind speed and direction. This will also have long-term impact on the general well-being of the public with regard to air ventilation and pollution and safety and economic of building construction by having more refined wind information.

Detail(s)

Project number9041338
Grant typeGRF
StatusFinished
Effective start/end date1/10/0810/01/11