Yuen Long Barrage and Nullah Improvement Schemes, Hong Kong

Project summary

The Yuen Long Barrage and Nullah Improvement Schemes are part of a landmark flood protection initiative designed to safeguard Yuen Long’s city centre against extreme weather and rising sea levels. The schemes feature an automated tidal barrier alongside a high-capacity stormwater pumping station, which currently stands as the largest of its type in Asia. Beyond technical upgrades such as flood walls and enhanced drainage efficiency, the project revitalises the area with a green corridor, successfully balancing vital urban resilience with significant environmental and community enhancement.

The background

The Yuen Long District is a low-lying area in north-west Hong Kong that has historically faced significant flood risks due to its flat topography and the ‘pincer attack’ of heavy rainfall and tidal surges from the Shan Pui River.

Previous drainage master plans relied on traditional flood walls and storage schemes proposed under the Drainage Master Plan Review to manage its low-lying topography. Recognising the immense challenges of urban disruption and climate change, Binnies proposed a strategic shift by introducing the innovative barrage scheme as a more effective alternative. This proposal replaced the original scope with a downstream tidal barrier and pumping station, a move accepted by the Drainage Services Department (DSD) for its superior hydraulic performance, enhanced cost-effectiveness and significantly reduced public disturbance.

Due for full completion in 2030, this scheme not only addresses the immediate threat of tidal surges and extreme rainfall but also sets a new benchmark for resilient urban drainage infrastructure in Hong Kong.

The challenges

As a naturally low-lying basin, Yuen Long town centre is prone to ‘backwater’ effects, where high sea levels prevent inland rainwater from draining out. This is compounded by escalating occurrence of powerful typhoons and extreme weather conditions such as flooding incidents during Super Typhoon Hato and Super Typhoon Mangkhut in 2017 and 2018, respectively, coupled with seawater backflow from Deep Bay and extreme rainfall events, which have considerably increased the flooding risks in Yuen Long town areas.

The ongoing development of Yuen Long South and other new housing areas has increased surface run-off, putting additional pressure on the existing concrete-lined nullahs.

Beyond flooding, the traditional nullah system of drainage channels suffered from water pollution and odour issues during the dry season, highlighting the need for an integrated approach that combines flood safety with ecological revitalisation.

The solutions

Yuen Long Barrage Scheme
At the heart of the scheme is a stormwater pumping station and tidal barrier designed to prevent tidal backflow and ensure proper drainage during high tide. With a capacity of 300 m³ per second, the pumping station is the largest of its kind in the region. Advanced hydraulic modelling was used to analyse various operational scenarios, ensuring system robustness under both current and future climate conditions.

Improvement of Yuen Long town nullah (town centre section)
The introduction of a dry weather flow interception (DWFI) system captures polluted run-off (e.g., street cleansing) during non-storm conditions and diverts it to the sewerage network for treatment. This significantly improves water quality in the nullah and enhances the surrounding environment.

Smart monitoring and adaptability
A digital twin platform enables real-time monitoring and predictive flood management based on hydrological forecasts using historical rainfall and tidal records aiming to optimise the operation of the barrage scheme. The DWFI system also features automated controls based on water quality index (WQI) (e.g., pollutant levels) and flow rates, ensuring the cost-effectiveness of the downstream treatment while ensuring adequacy of ecological flow in the nullah.

Ecological enhancement and river revitalisation
The project transforms the nullah into a blue-green corridor with riparian planting, re-naturalised sections and public amenities such as riverside walkways and educational features. These enhancements not only promote biodiversity, urban cooling and community engagement but also strengthen climate resilience.

The impact

The Yuen Long Barrage Scheme sets a new global benchmark for water management as Hong Kong’s first large-scale tidal barrier project. By replacing traditional flood walls with Binnies’ innovative downstream design, the project demonstrates that climate-resilient water infrastructure can deliver beyond flood protection, enhancing water quality, biodiversity and urban liveability. The project offers a comprehensive approach that responds effectively to both immediate climate shocks and longer-term environmental challenges. Through predictive modelling, scalable design and ecological integration, the project sets a precedent for adaptive and multifunctional urban water infrastructure.

For the local community, the project transforms a historical flood-prone zone into a secure and vibrant urban hub. Beyond enhancing flood resilience, it replaces concrete nullahs with a scenic blue-green corridor. The integration of riverside promenades and a DWFI system eliminates odour issues, turning a former utility channel into a public space for leisure and social connection.

Environmental sustainability is at the heart of the scheme, which champions the ‘Sponge City’ philosophy. By revitalising the river ecosystem and introducing nature-based solutions, the project enhances local biodiversity, which proves that essential flood defence can coexist with and even enhance the natural landscape.