Yuen Long is situated in the downstream section of Shan Pui River. As a consequence of recurrent floods and sedimentation, Yuen Long Town Areas has turned primarily into a flatland. In the 1960s, the Government initiated extensive channelisation eorts in the downstream section of the Shan Pui River near Yuen Long New Town to mitigate flood risks. The river channel was straightened, deepened and widened accordingly, while the riverbed and banks were covered with concrete, ultimately shaping the present-day appearance of the Yuen Long Nullah.

Over the years, the Drainage Services Department (DSD) has undertaken several drainage improvements works in Yuen Long, including flow interception works, village flood protection plans and river training, which have enhanced the area’s resilience to flooding. With the escalating occurrence of powerful typhoons and extreme weather phenomena, coupled with seawater backflow from Deep Bay and extreme rainfall events, the risk of flooding in the Yuen Long Town areas is expected to increase considerably.

In addition, with the recent developments in Yuen Long, some commercial and residential buildings have incorrectly connected sewerage pipes to the stormwater drainage system, resulting in polluted water flowing into Yuen Long Nullah and causing pollution problem, which brings odour to the residents near the Nullah.

To cope with extreme weather and improve water quality of the Nullah, DSD commenced the Yuen Long Barrage and Nullah Improvement Schemes in mid-2023, aiming to fortifying resilience to extreme weather events and improve the water quality of the Nullah. Apart from flood protection, the Schemes will also improve the water quality and alleviate odour problem of Yuen Long Nullah town centre section.


Project Scope

The "Yuen Long Barrage and Nullah Improvement Schemes" is the first large-scale barrage scheme in Hong Kong, comprises Stormwater Pumping Station, Master Control Centre, Flood Barrier and Dry Weather Flow Pumping Station to enhance the flood protection level in Yuen Long Town Area. Construction works commenced in May 2023 and are expected to be completed by the end of 2029.

Yuen Long Barrage and Nullah Improvement Schemes
The scope of the project comprises–
i) provision of a barrage scheme in Yuen Long including the construction of an automatic flood barrier of about 60 metres, a stormwater pumping station, a master control centre and the associated electrical and mechanical facilities in the Yuen Long Nullah;
ii) modification of about 300 metres of the Yuen Long Nullah and drainage improvement works at the intersection of the Yuen Long Nullah and the Yuen Long Bypass Floodway;
iii) construction of drainage channels of about 200 metres;
iv) improvement of flood walls of about 3.2 kilometres along the Kam Tin River and construction of flood walls of about 0.8 kilometres along the Yuen Long Nullah and the Sham Chung River;
v) revitalisation of a section of about 1 kilometres of the Yuen Long Nullah between the Long Ping Station and the location of the proposed barrage; and
vi) carrying out ancillary works

Improvement of Yuen Long Town Nullah (Town Centre Section)
The scope of the project comprises–
i) construction of a dry weather flow (DWF) interception system including a pumping station with designed capacity of about 18,000 cubic metres per day, box culverts with DWF interceptors of about 3.6 kilometres, and construction of pipes of about 600 metres;
ii) strengthening the structure of a section of the Yuen Long Nullah (town centre section) of about 1 kilometres;
iii) revitalisation of a section of the Yuen Long Nullah of about 1 kilometres between the Long Ping Station and the Shap Pat Heung Road;
iv) carrying out ancillary works


Master Control Centre (MCC)

As the hub of “Yuen Long Barrage and Nullah Improvement Schemes”, the Master Control Centre (MCC) is responsible for collecting signals from the large Stormwater Pumping Station, Flood Barrier, and related electrical and mechanical equipment. Thus, the MCC is an essential part of the project.

The signals of related electrical and mechanical equipment and real-time supervision of water levels of this scheme will be transmitted to The Supervisory Control and Data Acquisition (SCADA) System of MCC. The system will automatically perform the corresponding operations. Staff of the Drainage Services Department will monitor and manage the barrage operations remotely round the clock. Also, relevant E&M equipment are equipped with dual power supply. In the event of an unstable signal from one of the power supplies, these facilities will still remain in operation.

In terms of construction, part of the MCC structure adopts a DfMA (Design for Manufacturing and Assembly) unit, utilizing prefabricated building components assembled on-site. DfMA considers the design for assembly of components, selecting manufacturing and assembly methods that facilitate the construction and installation processes at the site. This simplifies on-site construction and installation procedures, thereby enhancing construction efficiency, optimizing workflows, improving safety, and reducing impact on the surrounding environment. Adopting DfMA not only shortens construction time but also reduces carbon dioxide emissions, making it safe and environmentally friendly.


Innovative Construction Methods

Welding Robots
The traditional method of welding capping plates is time-consuming and requires workers to lie on the ground to perform overhead welding, which is both inefficient and poses safety risks. To address this, the site has introduced two welding robots to take over this task, eliminating the need for manual overhead welding. Each robot is operated by a trained technician, and together they are tasked with welding a total of 120 capping plates, primarily in the Discharge Channel area. To ensure all work meets quality standards, full visual inspection and magnetic particle testing are conducted on-site by a HOKLAS-accredited laboratory for acceptance.

The Modular Excavation and Lateral Support (M-ELS) System
Moving away from conventional methods, the project team has adopted the modular excavation and lateral support system (M-ELS). By utilising off-site prefabricated components delivered and installed on-site, this approach significantly minimises on-site construction processes, elevates construction quality and ensures high safety standards.

Centralized Management Platform
The platform collects and manages data related to the safety of site workers, and machinery to enhance efficiency and ensure safety during construction. It functions as an integrated management system that leverages data analytics to support decision-making in the construction process. Additionally, it enables precise monitoring for safety management, including a mobile plant tracking system.


Work Progress

The first phase of the project is currently underway. The project team is constructing the approximately 60-meter-long automatic flood barrier, a stormwater pumping station, and the master control center at the Yuen Long Nullah. The main structure of the flood barrier is expected to be completed in 2029. The dry weather flow interception system is scheduled for completion in 2028. As for the Yuen Long Nullah itself, preliminary preparations and river channel improvements are being rolled out in stages.

The second phase of the project, which covers the main works for the revitalization of the nullah, is currently in the planning and design stage. The Drainage Services Department has completed a series of public community activities and is further refining the detailed design of the revitalization based on the feedback collected.




Source of Information and Pictures: “Yuen Long Barrage and Nullah Improvement Schemes” Website of Drainage Services Department