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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
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
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
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)
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