River Revitalisation for the Good of Water
"Laozi" said: "The highest goodness is like water. Water benefits all things without struggle.” Water, nourishing all things, is an indispensable element of life; water, being non-competitive in nature, embodies the quality of versatility that allow it to adapt to variety of environments. Aspiring to emulate water in recent years, DSD has been actively developing new ideas, optimising our works in flood prevention and sewage treatment to enhance the quality of life of the public and adopting different innovative technologies to follow the nature and integrate the drainage facilities into the community. When designing river channels, we promote the concept of revitalisation of water bodies to make good use of water’s character. Recently completed river improvement projects that incorporated such concepts include Ho Chung River in Sai Kung and Upper Lam Tsuen River in Tai Po, as well as the Kai Tak River Improvement Works which will be completed in 2018. Going beyond the fundamental purpose of drainage, these projects aim to increase river biodiversity and integrate the river into the surrounding environment by introducing green elements and beautifying the scenery so as to foster water-friendly culture and promote Hong Kong’s sustainability development to cope with the huge threats brought by climate change.
Innovative Ideas for River Revitalisation
Drainage facilities built in early years were mainly designed for flood prevention. As times change, the public is gradually concerned with the importance of protecting water ecology and effective use of urban space. In response, we have been following the recommendations put forward in the 2015 Policy Address. In both large-scale drainage improvement works and the planning of drainage networks for New Development Areas, we have actively introduced innovative ideas for revitalising water bodies in nullahs and river channels.
While employing cost-effective and ecologically responsible methods to optimise drainage services, we introduce sustainable drainage systems with green and eco-conservation elements, including planting a variety of vegetation and creating natural stream environments. These measures can preserve river ecosystems and promote wildlife growth to increase river biodiversity. In a nutshell, other than achieving effective river drainage, we aim to revitalise rivers, introduce green elements, beautify the scenery, as well as promote biodiversity and water-friendly activities so as to develop sustainable drainage facilities for creating a more liveable environment.
River Revitalisation Elements
River sections are now undergoing detailed planning that ties in with their unique features, aiming to ensure full integration of drainage facilities with other land uses and strengthen community connectivity. This multi-purpose land use concept can create a better living environment. The examples below outline the concepts, designs and effectiveness of our river revitalisation initiatives.
Ho Chung River and Upper Lam Tsuen River Improvement Works
DSD completed Ho Chung River and Upper Lam Tsuen River Improvement Works in 2007 and 2012 respectively, thus alleviating the flood risk in the regions considerably. Ho Chung River in Sai Kung and Lam Tsuen River in Tai Po are of great ecological significance. Myriads of wildlife, including bird, fish and dragonfly species, inhabit in the two rivers. During construction, we did our utmost to minimise environmental and ecological impacts of our works and keep the land uptake during the river widening works to a minimum in order to preserve the original characters of the rivers.
Ho Chung River and Upper Lam Tsuen River before and after the improvement works
Our engineers also enhanced biodiversity by introducing eco-conservatory elements to the natural stream habits for fish and other aquatic wild life. In Lam Tsuen River, for example, plants that flourished on the gabion banks and natural riverbed have sustained both the original water quality and biodiversity of the water body. After completion of the Upper Lam Tsuen River Improvement Works, ecology professionals appointed by DSD conducted four years of ecological monitoring. In 2017, the study found that the numbers of bird, fish and dragonfly species were restored to pre-construction levels. In particular, the population of one rare species in Lam Tsuen River ― Hong Kong Newt ― exceeds the previous level from just over 200 recorded by pre-construction baseline monitoring to more than 600 recently. All these encouraging results stand witness to the project team’s stellar performance in nature conservation.
Eco-conservation Elements in Rivers
Creating natural stream environment with natural riverbed
The rip-rap base of Upper Lam Tsuen River is restored with irregular cobbles and boulders of original riverbed materials, replacing the riverbed made of reinforced concrete. This type of riverbed simulates the original natural stream environment with pools and shallow shoals, providing ideal habitats for native fish species of all sizes to establish and thrive.
Randomly placed boulders and cobbles on the riverbed to form fish ladders to create more ripples, pools, and irregular flow patterns, hence simulating a natural stream flow environment and maintaining river flow continuity to allow river organisms to cross sections of the stream.
Holes in the splash zone of the river wall, both isolated and sets of interconnected ones inside the bank wall, provide refuge for fish and other aquatic animals during times of high tide and rapid flow.
The deflectors in Ho Chung River are formed by strips of rocks aligned obliquely along the river wall. Their lengths vary from two to about four metres, aiming to induce variations in flow direction and velocity, as well as create zones of different water depths. All these give rise to micro-habitats and diversity in the riparian zone for various species to establish.
Gabion banks help promote vegetation
Both banks are lined with gabions instead of reinforced concrete to encourage plant growth in the cracks.
Extensive planting for riverside greening
Selected plants are planted extensively on channel sides to improve the scenery, biodiversity and river greening.
Conservation of rare species
Hong Kong Newt, a native species occurring in Lam Tsuen River, is a near-threatened amphibian on the International Union for Conservation of Nature and Natural Resourses (IUCN) list. Prior to the Upper Lam Tsuen River Improvement Works and annual dry weather works, we captured individuals in Lam Tsuen River within site and immediately rehabilitated them in the upper part of the river unaffected by works. Upon completion of the works, as the restored channel environment was very similar to its original state and the natural riverbed was well-preserved, the Hong Kong Newts re-colonised their former habitats.
Kai Tak River Improvement Works
Known as Kai Tak Nullah in the past, the approximate 2.4km Kai Tak River is one of East Kowloon’s major drainage channels. Due to urban developments and extreme weather conditions, serious flooding occurred in Choi Hung Road during rainstorms, affecting nearby residents. As the nullah did not meet the current flood prevention standards, DSD implemented river improvement works in stages to improve the 1.1km section of the nullah in Wong Tai Sin. Before the project began, we rolled out “Building Our Kai Tak River”, a two-stage public engagement programme, jointly with the Civil Engineering and Development Department and the Planning Department and finalised the design principles of the project: prioritising flood prevention, avoiding decking the channel as far as possible, and transforming Kai Tak Nullah into the first urban green river corridor in Hong Kong ― Kai Tak River.
Construction works commenced in stages from October 2011 and are expected to be completed in 2018. The approved project estimate for the improvement works is about $2.8 billion.
Kai Tak River (Wong Tai Sin Section) before and after the improvement works
Improvement works were carried out mainly to enhance the drainage capacity of Kai Tak River. Upon completion of the works, Kai Tak River will meet the latest flood prevention design standards and be able to withstand rainstorms of a 200-year return period, alleviating the flood risks in Wong Tai Sin and San Po Kong areas.
Sectional view of Kai Tak River and its box culvert at Choi Hung Road
DSD also seized the opportunity to improve the scenery of the local urban setting and provide leisure place for the public to enhance overall living environment of the area. To this end, greening and ecological elements were included in the Kai Tak River Improvement Works to revitalise this water body into an urban green river corridor that links the river closely with the local neighbourhood.
Kai Tak River Revitalisation Elements
Draping plant Bougainvillea spectabilis is planted in the roadside planters along the river. It usually blossoms twice a year (in Spring and Autumn). The dazzling colour adds special appeal to the river.
Artificial rock planters
To simulate the bedrock of natural riverbeds, rocks made of glass fibre reinforced concrete were placed at the banks of Kai Tak River to allow plants to grow out of the rock crevices. This increases the greening area along Kai Tak River.
In wider section of the river, submerged planters, with native mangroves species, are built to imitate a wetland habitat.
Fish shelters and deflectors
Fish shelters and deflectors can change the flow direction and reduce flow speed, providing a refuge for fish to inhabit.
Preserving grantie walls
The 70-year-old granite wall along Tung Kwong Road has been preserved. We have paved the riverwall with granite tiles to match with the grantie wall.
After revitalising the Kai Tak River, we often see birds and fishes on the riverside.
In addition to integrating the river revitalisation concept into the existing drainage projects, DSD will continue to include water body revitalisation elements in New Development Area drainage plans to create better living environments for the community. Land is always precious in Hong Kong and revitalised urban channels and nullahs can create more public space where people can enjoy the waterfront and engage in water-friendly activities such as walking, jogging and cycling.
Revitalisation of Tsui Ping River
Situated right at the heart of Kwun Tong, Tsui Ping River is a nullah running along Tsui Ping Road and King Yip Street. It is set in close proximity to residential and bustling commercial and industrial areas. Given its unique waterscape, Tsui Ping River is well-positioned to become a valuable urban riverside leisure space for public enjoyment. In sync with enhancing flood prevention capacity, the project will involve turning the existing nullah into a new landmark where the public can enjoy the river view and leisure activities.
The works under the Revitalisation of Tsui Ping River comprises the following:
- Revitalisation of the existing nullah through the provision of attractive waterscape design and water features
- Provision of landscaped decks and amenity public space above the river
- Provision of walkways along/across the river to enhance connectivity in order to transform Tsui Ping River into a green river corridor in the community
- Modification of the existing footbridge across Lei Yue Mun Road; and
- Beautification of streets adjacent to Tsui Ping River
Existing View of Tsui Ping River and the Revitalisation Concept
Selecting Potential Nullahs and Rivers for Revitalisation
Meanwhile, we have reviewed and assessed the revitalisation potential of major nullahs and river channels in Hong Kong. We will select nullahs and river channels that are suitable for revitalisation. We are now conducting in-depth investigation on Tai Wai Nullah (from Heung Fan Liu to Man Lai Court), Fo Tan Nullah (from Kwai Tei New Village to Hong Kong Sports Institute), mid-stream of Tuen Mun River Channel (from Siu Hong Station to Tuen Mun Station), and Jordan Valley Nullah (from Shum Wan Shan Pumping Station to Jordan Valley Swimming Pool) to identify suitable revitalisation schemes with a view to enhancing quality of living by revitalising our water bodies.