Taipei MRT protection measures Typhoon Nari lessens and responses

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1 Taipei MRT protection measures Typhoon Nari lessens and responses Tsang-Jung Chang and Tsung-Yi Pan Hydrotech Research Institute, Center for Weather Climate and Disaster Research, National Taiwan University

2 Outline The flood by Typhoon Nari in 2001 Flood analysis The protection for MRT after the flood

3 The flood by Typhoon Nari in 2001

4 Typhoon Nari in 2001 an unusually long-lived category 3 typhoon which took an erratic, two week track near Taiwan during September 2001

5 Cumulative rainfall of Typhoon Nari between Sep Daily cumulative rainfall of Taipei rain gauge is 425mm on Sep 17, It s a 400-yr return-period flood. CR Typhoon rainfall record of Taiwan rainfall record Rank mm inche year name Morakot Nari Flossie Herb Lynn Saola Carla Sinlaku Haitang Aere Rainfall of Typhoon Nari in 2001

6 The typhoon Nari event in 2001 Sunchun Shihlin Taipei Chungcheng Bridge Yunghon

7 The typhoon Nari event in 2001 Tachih Neihu Nankang Shinyi Mucha

8 Drainage systems of Taipei

9 The typhoon Nari event in 2001

10 The typhoon Nari event in 2001

11 The typhoon Nari event in 2001

12 The typhoon Nari event in 2001

13 What happened to MRT Observed flood area of Taipei

14 What happened to MRT Observed flood area of Taipei

15 What happened to MRT Taipei Main Station was reopen on Nov. 28.

16 Flood analysis

17 Flood Design Criteria of the Taipei MRT System Flood Design Considerations Flood Prevention Facilities

18 Flood Design Considerations Taipei MRT adopted an estimated flood level in a return period of 200 years plus an additional 50cm. Based on this criterion, all entrances to stations, structural openings, and depots were designed to this level to prevent water intrusion.

19 Flood Prevention Facilities Flood prevention facilities for entrances on the Taipei MRT can be summarized as follows: 1.All entrances shall be a minimum of 15cm above the flood level with a return period of 100 years, and also meet the requirement of a minimum cm above the adjacent ground level. 2. All entrances shall be provided with floodgates 50cm above the flood level in a return period of 200 years.

20 The Taipei MRT System

21 Flood Prevention Facilities 45cm 60cm 75cm 60cm

22 Flood Prevention Facilities Ground level Floodgates cm floodgates 50cm above the flood level in a return period of 200 years a minimum of 15cm above the flood level with a return period of 100 years

23 Flood simulation of Typhoon Nari 2001 Pumping station failure Levee broken

24 The typhoon Nari event in 2001 No. The recorded and failing time pumping stations in downtown Taipei during the typhoon Nari event. design capacity (cms) failing time recorded simulated 09/16 09/16 23:23 23:26 09/17 09/17 00:19 00:14 09/17 09/17 04:00 03:53 09/17 09/17 08:00 08:02 09/17 09/17 09:00 08:56

25 The typhoon Nari event in 2001 The pumped and water volumes in subway systems in downtown Taipei during the typhoon Nari event. System Pumped Water Vol. (x 10 3 m 3 ) Simulated Flood Water Vol. (x 10 3 m 3 ) TRTS & MRTS Red Line MRTS Blue Line

26 The typhoon Nari event in 水位 (m) 月 16 日 12 時 9 月 16 日 18 時 9 月 17 日 00 時 9 月 17 日 06 時 9 月 17 日 12 時 9 月 17 日 18 時 Discharge(cms) Broken levee 溢流量 (cms) 月 16 日 12 時 9 月 16 日 15 時 9 月 16 日 18 時 9 月 16 日 21 時 9 月 17 日 00 時 9 月 17 日 03 時 Water level (m) 9 月 17 日 06 時 9 月 17 日 09 時 9 月 17 日 12 時 9 月 17 日 15 時 9 月 17 日 18 時 9 月 17 日 21 時 9 月 18 日 00 時

27 The typhoon Nari event in 2001

28 The protection for the MRT after the flood

29 Upgrading Flood Protection Criteria After the disaster of Typhoon Nari in 2001, an overall review of the flood prevention systems for the Taipei MRT was carried out, and enhancement measures were adopted as follows: 1. The flood prevention standard on the longterm Taipei MRT network is now set at a return period of 200 years plus an additional 110cm (original: 50cm), or the level of flooding recorded during Typhoon Nari plus additional height.

30 Upgrading Flood Protection Criteria 2. Watertight doors shall be considered for installation on sidewalks connecting to the Taipei MRT, in joint development buildings and at underground connections with other transportation facilities. 3. Gaps between vital mechanical & electrical facility rooms and conduits & pipes shall be filled with watertight materials.

31 Upgrading Flood Protection Criteria 4. Assessment of the installation of full dimension floodgates on the daylighting sections and interchange stations where interfaces with tunnels exist and on both sides where lines cross rivers and faults. 5. Existing flood prevention facilities shall be improved or floodgates shall be heightened at stations on the initial network, in accordance with the flooding height recorded during Typhoon Nari. Moreover, movable flood barriers are installed for all underground stations.

32 Upgrading Flood Protection Criteria Ground level Floodgates cm floodgates 110cm above the flood level in a return period of 200 years a minimum of 15cm above the flood level with a return period of 100 years

33 Emergency response in 1 min

34 Emergency response in 1 min

35 What should we do in the future? Non-engineering Approaches 1. More accurate urban flood inundation simulations 2. Efficient pluvial flooding early warning 3. Resilience city strategies and new regulations for flood prevention

36 What should we do in the future? STEP 1 Typhoon Track Observation and Forecast STEP 2 Precipitation Observation and Forecast STEP 3 River Water Level Observation and Forecast STEP 6 Waterlogging Disaster Forecast and Warning STEP 5 Waterlogging Disaster Assessment System STEP 4 Sewer Water Level Observation and Forecast

37 Thank You for your attention