Transformers in Urban Streams: Changing Stream Morphology to Maximize Ecohydrological Benefits

Principal Investigator: Professor Ting Fong May CHUI (Associate Professor of Water and Environmental Engineering from Department of Civil Engineering)

This project is showcased in the fourth exhibition – Innoation for Impacts.

About the scholar

Professor Ting Fong May CHUI

Research interests:
Sustainable water resource development and management
Interactions between surface water and groundwater
Numerical modeling of coupled hydrologic and ecologic processes

Email: maychui@hku.hk
Website: https://www.civil.hku.hk/maychui/

Project information

This research project focuses on the development of adaptive structures called “transformers” for urban streams in Hong Kong to improve water quality and ecohydrological functions. These structures dynamically change shape according to water flow, optimizing stream morphology and restoring natural processes such as complex surface water flow patterns and groundwater-surface exchange. The project has developed physical and numerical models to optimize the design of the transformers, supporting Hong Kong’s transition to sustainable urban stormwater systems.

Novelty

  • The “transformers” significantly enhance the complexity of surface water flow patterns in urban streams with limited impacts on the drainage capacities and induce significant hyporheic flows in both stream banks and streambed. 
  • The optimal designs of “transformers” (e.g., amplitudes, intervals, and angles) for maximizing the flow complexity and hyporheic flows are derived at different flow conditions. 
  • The “transformers” will automatically change their shapes to the optimal designs according to the flow characteristics such as discharge, water depth and flow velocity.
Project video
Project images
Conceptual pictures of the transformers installed in the concrete channel of Lower Lam Tsuen River
Flume experiment shows that water depth rises before the transformer while it falls around the crest of the transformer, complexing the water depths in urban streams after the installation of transformers.
The simulated velocity field of water flow derived from numerical model, which indicates a more complex flow pattern in urban streams after the installation of transformers
Contour plots of the velocity (Ux, m/s) at 1/2 water depth of low and high stream discharges (flow direction & positive value direction: from right to left)
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