Two Stories of Flooding

in Hong Kong

Ir Raymond L H WOON, Senior Engineer, DSD

29 June 2019

Story 1……Rainwater

2

Water is the source of life水是生命之源

Flash Flood and Savage Beast

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Those were the days……Central on 8.5.1992

4

5

Annual Rainfall in Asia Pacific Region

Santiago 300

Beijing

600

Tokyo 1500

Seoul

1300

San Francisco 600

Vancouver 1200

Bangkok 1500

Sydney

1200

Manila 2200

Jakarta 1700

Taipei 2100

Hong Kong

2400

Singapore

2200

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3 Pronged Approach for Flood Prevention

Storage

3 Pronged Approach for Flood Prevention

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Interception

Storage

Pipeline Upgrading

Hong Kong West

Drainage Tunnel

Happy Valley Underground

Stormwater Storage Scheme

Interception : Hong Kong West Drainage Tunnel

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Storage : Happy Valley Underground Storage Tank

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Flood Prevention Asset

Since 1989

Total Project Cost

~HKD 30 billion

~2400 km Storm Drains

~360 km River

Channels

~ 21 km Drainage Tunnels (4 nos.)

4 nos. Stormwater

Storage Tanks

27 nos. Village Polder

Schemes

0

20

40

60

80

100

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019

Major Blackspots Medium, Small or Minor Blackspots

Number of Flooding Blackspots

水 浸 黑 點 數 目

Flooding Blackspots

11

90

6

1995 2019

12

6

2

13

4

5

1. Shek Wu Wai, San Tin

2. Lam Tsuen Valley Basin

3. Ting Kok Road -Shuen Wan Chim Uk to Wong Yue Tan

4. Chatham Road South- Granville Road to Austin Avenue

5. Pok Fu Lam Village

6. Morrison Hill Road -J/O Lap Tak Lane

Flooding Blackspots

Record breaking rainfall intensity

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Source:

Hong Kong Observatory

Climate Change

Rainfall Increase in Hong Kong

+10.4% by mid 21st Century

+13.8% by end 21st Century

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15

Extreme Weather

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BLUERivers and water bodies

Greening andbiodiversity

Blue Green Infrastructure 藍綠建設

滯Detain

蓄Store

淨Purify

用Reuse

排Discharge

滲Infiltrate

Sponge City

海綿城市

Infiltrate more to reduce runoff

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Drainage Master Plan Studies

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Conclude Story 1

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Plan ahead 未雨綢繆

Story 2……Seawater

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Water can bear the boat but also swallows it

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水能載舟亦能覆舟

Wanda 溫黛 1.9.1962

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Hagupit黑格比 23.9.2008

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Hato天鴿 23.8.2017

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Mangkhut 山竹 16.9.2018

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Climate Change – Sea Level Rise

Sea Level Rise

More Serious Storm Surge

Projected Sea Level Risein Hong Kong

+0.23m by mid 21st Century

+0.49m by end 21st Century

More Extreme Weather Events

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2018 Mangkhut3.88mCD

20?? Durian ??

4 ? 5 ? 6mCD ?

2017 Hato

3.57mCD

Enhance Flood Resilience!

Flap Valve - prevent backflow of water

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Demountable Flood Barrier

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Tai O Lei Yue Mun

Flood Proofing Measures- Carpark Entrance and Lift Lobby

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Sand Bags

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Non-structural Measure- Early Alert System for Storm Surge

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Storm Surge Spots Alert Level

Tai O 大澳 3.3 mCD

Luen On San Tsuen 聯安新村 (屯門) 2.7 mCD

Kar Wo Lei 嘉和里 (屯門) 3.0 mCD

Sham Tseng San Tsuen 深井新村 3.0 mCD

Lei Yue Mun 鯉魚門 2.7 mCD

Sai Kung Nam Wai 西貢南圍 2.7 mCD

Yuen Long North West 元朗西北沿岸低窪地區 3.5 mCD

Overtopping Wave Spots Alert Level

Heng Fa Chuen 杏花邨 3.5 mCD

South Horizons 海怡半島 3.5 mCD

Tseung Kwan O South 將軍澳南

3.5 mCD

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1

7

32

4

5

6

1. Tai O

2. Luen On San Tsuen, Tuen Mun

3. Kar Wo Lei, Tuen Mun

4. Sham Tseng San Tsuen

5. Lei Yue Mun

6. Nam Wai, Sai Kung

7. Yuen Long North West

Storm Surge Spots 風暴潮點

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2

1

3

1. Tseung Kwan O South

2. Heng Fa Chuen

3. South Horizons

Overtopping Wave Spots 越堤浪點

Existing Tide Stations

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New Gauging Stations

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Real Time Monitoring

Hydrometric Information System (HIS)

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Evacuation Public Education

Emergency Preparedness

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Emergency Preparedness Meeting Collaboration

Safer Living 2.0 – Public Education

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Staff Gauge - Enhance Public Awareness

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Collaboration with Industry and Academics

R&D Forum Academic Gathering

Smart City ∙ Innovative Stormwater Management

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Connection with Oversea Cities

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International Water AssociationASPIRE 2019 at Hong Kong

Melbourne

Visit us at:www.iwaaspire2019.org

Let’s join hands to enhance the

Flood Resilience of our liveable city

Thank You !

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Hong Kong……Our Home……Our Story

風雨同行