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The Obstacles to and Potentials for Increasing Riverine Ecosystem Services in High-Density Asian Cities:
Hong Kong, Singapore, and Taipei
Kuei-Hsien LIAO, Ph.D. Assistant Professor
School of Architecture, Chinese University of Hong Kong
Singapore
Hong Kong
Shared characteristics of the three cities: • Economically highly developed • Dense urban development • Dominated by Chinese culture • History of colonization • Heavy western influences • Sub-tropical/tropical climate • Naturally flood-prone • Relatively short rivers
Hong Kong Special District of the People’s Republic of China
Republic of Singapore
Taipei City, Taiwan Taipei
• GDP per capita: S$38,124 • Area: 1,104 km2
• Population: 7.2 million • Overall density: 6,544 / km2
• Sewage treatment: 93%
• GDP per capita: $23,374 • Total area: 271.8 km2
• Population: 2.7 million • Density: 9,956 / km2
• Sewage treatment: 74%
• GDP per capita: $55,183 • Total area: 718.3 km2
• Population: 5.5 million • Overall density: 7,615 / km2
• Sewage treatment: 100%
Singapore Hong Kong Taipei
Backgrounds of the study cities
• Area: 1,104 km2
• Population: 7.2 million
• Overall density: 6,544 / km2
• Total area: 271.8 km2
• Population: 2.7 million
• Density: 9,956 / km2
• Total area: 718.3 km2
• Population: 5.5 million
• Overall density: 7,615 / km2
Singapore
Hong Kong
Taipei
• Total area: 15,826 km2
• Population: 2.27 million
• Density: 143 / km2
Brisbane
Hong Kong Built-up area: 23.7% Density: 27,670/km2
Singapore Taipei Built-up area: 60% Density: 12,721/km2
Built-up area: 47.8% Density: 20,831/km2
Singapore Hong Kong Taipei
River management priority
Flood control Flood control Flood control
Water supply +
Current conditions of most urban streams and rivers Hong Kong
Heavily channelized, concertized, culverted
Current conditions of most urban streams and rivers Singapore
Channelized, leveed, culverted…
Current conditions of most urban streams and rivers Singapore
…and dammed at the mouth
Current conditions of most urban streams and rivers Taipei
Leveed, channelized, armored, culverted
Provisioning services Regulating services Cultural services Supporting services
Fisheries & other food production Water supply Energy generation Water storage Flood hazard mitigation Water purification Carbon and nitrogen sequestration Temperature regulation Erosion/sediment control Recreation, aesthetic, and inspiration value Habitat & biodiversity
Riverine ecosystem services
Riverine ecosystem services
Provisioning services Regulating services Cultural services Supporting services
Fisheries & other food production Water supply Energy generation Water storage Flood hazard mitigation Water purification Carbon and nitrogen sequestration Temperature regulation Erosion/sediment control Recreation, aesthetic, and inspiration value Habitat & biodiversity
Except in Singapore
??
✔
of highly modified urban streams and rivers In Hong Kong, Singapore, and Taipei
Hypothesized
Singapore Hong Kong Taipei Flood control
Additional objectives
+ Revitalizing waterbodies +
+ + Flood control Flood control
Water supply
Waterway enhancement
Riverine environment rehabilitation
Singapore Hong Kong Taipei Flood control
Additional objectives
+ Waterbody
revitalization
+ Flood control Flood control
Water supply Waterway
enhancement
Riverine environment rehabilitation
+
+
In reality, these objectives are far less important.
Singapore
• Launch in 2006 • It aims to transform the utilitarian drains, canals and
reservoirs throughout Singapore into “beautiful and clean streams, rivers and lakes with postcard-pretty community spaces for all to enjoy” (PUB 2011: 4).
The ABC Waters Programme
Stormwater Management + “Waterway Enhancement”
The ABC Waters Programme
Measures: Bio-swale, rain gardens, green roofs, cleansing biotopes, constructed wetlands, etc.
Measures: Riverbank greening, installation of decks, waterfront walkways, etc.
Purpose: Removing the pollutants of stormwater runoff at source
Singapore
Purpose: Making the waterway an enjoyable place for people
2/3 of Singapore = Water-supply
catchment area CBD area
Singapore
More than 100 ABC Waters projects through 2030
Singapore
Singapore
Kallang River at Bishan-Ang Mo Kio Park
Waterway enhancement • Naturalizing the
channel
Singapore Kallang River at Bishan-Ang Mo Kio Park
Riverbank greening
Waterway enhancement • Greening, or softening
the riverbanks • Installation of decks • Riverfront walkways
Installation of deck
Kolam Ayer ABC Waterfront Project
Singapore
Taipei
Riverine environment rehabilitation • Greening the
riverbanks with ecological engineering
• Riverfront walkways
Huang Creek
Taipei
Riverine environment rehabilitation • Developing riverfront
recreational space, e.g., sports field, bicycle path.
Daijia Riverside Park, Keelung River
Taipei
Riverine environment rehabilitation • Floodplain wetland
restoration
Shezidao Wetland, Keelung River
Lam Tsuen River (upstream)
Hong Kong
River rehabilitation Only occurs in the rural area.
The Kai Tak River Project
Hong Kong
Revitalizing waterbodies Greening and making recreational space
Image source: http://www.dsd.gov.hk/TC/HTML/390.html
The Kai Tak River Project
Hong Kong
Waterbody revitalization Greening and making recreational space
Image source: http://www.cedd.gov.hk/eng/whats/P20140826.html
Blue-green infrastructure Revitalizing waterbodies
ABC Waters Programme Waterway enhancement
Riverine environment rehabilitation
Integrated Flood Management
Singapore
Taipei
Taipei
• Water security • Quality of life
• Flood safety • Quality of life • Wildlife conservation
• Flood safety • Quality of life
Driver Stormwater management River restoration Catchment scale Channel scale
Blue-green infrastructure Revitalizing waterbodies
ABC Waters Programme Waterway enhancement
Riverine environment rehabilitation
Integrated Flood Management
Ecosystem services
Singapore
Taipei
Taipei
• Water security • Quality of life
• Flood safety • Quality of life • Wildlife conservation
• Flood safety • Quality of life
Driver Stormwater management River restoration Catchment scale Channel scale
Process-oriented
Specific species
River restoration objectives
(Bernhardt & Palmer 2007)
Geong Gye Cheong, Seoul
A suitable model?
Geong Gye Cheong, Seoul
Bishan - Ang Mo Kio Park
A suitable model?
Riverine ecosystem services
Provisioning services Regulating services Cultural services Supporting services
Fisheries & other food production Water supply Energy generation Water storage Flood hazard mitigation Water purification Carbon and nitrogen sequestration Temperature regulation Erosion/sediment control Recreation, aesthetic, and inspiration value Habitat & biodiversity
of highly modified urban streams and rivers In Hong Kong, Singapore, and Taipei
Except in Singapore
??
✔
Hypothesized
Riverine ecosystem services
Provisioning services Regulating services Cultural services Supporting services
Fisheries & other food production Water supply Energy generation Water storage Flood hazard mitigation Water purification Carbon and nitrogen sequestration Temperature regulation Erosion/sediment control Recreation, aesthetic, and inspiration value Habitat & biodiversity
Except in Singapore
?
✔✔
✔
✔ ✔
in Taipei in Taipei & Singapore
✔
of rehabilitated urban streams and rivers In Hong Kong, Singapore, and Taipei
Hypothesized
Obstacles to increasing riverine ecosystem services • Water quality is still a concern (Hong Kong & Taipei) • Flood control requirement • Land availability • Public perception (worries about flood risk) • Governance: river health is no one’s business
Potentials for increasing riverine ecosystem services • Increasing awareness of the role rivers and streams play in urbanism,
e.g., increasing demand for recreational opportunities in the riverfront. • Local runoff as an important source for water supply (Singapore). • High density means a project could exert greater effects