1. UGEC20102010/10/17 at Arizona State University Field-level adaptation to floods and sea level rise in coastal peri-urban areas in monsoon Asia: Comparative case studies between continental Bangkok and insular Metro Manila Yuji Hara 1 & Danai Thaitakoo 2 1: Wakayama University, Japan 2: Chulalongkorn University, Thailand hara@sys.wakayama-u.ac.jp

2. UGEC2010 Asian large cities (population > 5million); Located on continental delta / insular lowlands 2

3. UGEC2010 Purpose of this presentation To show present case studies on landform transformation (LT) in response to flooding in continental Bangkok and insular Metro Manila – Horizontal land-use changes – LT processes – LT and floods – Field-level responses to floods (by local people and government) – Toward land-use and LT integrated planning for minimizing a flood hazard 3

4. UGEC2010 0100km Built-up area Continental Bangkok Built-up area 0100km Insular Metro Manila Case study cities 4

5. UGEC2010

6. (Hara et al. 2005) Horizontal land-use change: From rice fields to townhouses 6

7. UGEC2010 Vertical LT process: From dig & fill to introduced fill (Hara et al. 2008a) 7

8. UGEC2010 Introduced fill from further areas (the rim of delta) Fill volume (Hara et al. 2008a) Production: 5.5×10 7 m 3 year −1 Input: 5.7×10 3 m 3 km −2 year −1 8

9. UGEC2010 Flood characteristics: Sheet flow and parcel-level water management Floods come gradually Water level is manageable per each parcel using private pump with gasoline engine (using RID data) 9

10. UGEC2010 Temporal adaptation to sheet flow flooding Using sandbags to build temporal banks to protect water coming in, and then releasing floodwater to the canal by pumping Using a boat, that was traditionally utilized as a main transportation mode and still kept along the canal 10

11. UGEC2010 10 – 20 years adaptation to rising water baseline due to the loss of flood retention capacity by introduced fill 11 Lifting up a pathway and a road Lifting up a floor (as their traditional house structure)

12. UGEC2010 Suggestions for spatial planning Main problem on the current planning process – No linkage between land-use plan and water management plan  Toward better planning – Zoning based on acceptable fill (water) volume that can induce field-level adaptation using inherent LT methods – Focusing not only on regulative measures but more on incentive ones (for instance bonus floor area ratio for preparing ponds) 12

13. UGEC2010 0100km Built-up area Continental Bangkok Built-up area 0100km Insular Metro Manila 13

14. UGEC2010 Coastal Plain – Central Upland – Eastern Plain 14

15. UGEC2010 Horizontal land-use change: From natural micro landform basis to LT basis (Hara et al. 2008b) 15

16. UGEC2010 Vertical LT process: Landfilling on lower landforms (Hara et al. 2008b) 16

17. UGEC2010 Flood characteristics: Flash flow Eastern plain as “flood control pond” to protect downstream central Manila (Hara et al. 2002) 17

18. UGEC2010 10 – 20 years adaptation: Individual landfilling up to the highest flood level in their experiences Adapting themselves to their own experiences without any consideration of neighbors and flood control scheme by the government 18

19. UGEC2010 It has caused changes in distribution of flood-prone areas and required temporal adaptation SPOT 1987/11/18SPOT 1997/10/26 (Hara et al. 2002) Emerging submerged areas with poor drainage surrounded by landfill corridor 19

20. UGEC2010 New threat due to infrastructural development Tropical Storm Ondoy Flooded Areas (NAMRIA 2009) 20

21. UGEC2010 New infrastructures accelerated flash flow hazard ALOS PALSAR image soon after Ondoy (Modified after NAMRIA 2009) Newly built bridges trapped a lot of debris, and functioned as temporal dam during Ondoy 21

22. UGEC2010 Failure of planning: Subdivision out of lakeshore dike It was built before the construction of lakeshore dike in 2004 (not subject to zoning code?) 22

23. UGEC2010 Suggestions for spatial planning Main problem on the current planning process – Land-use plan is based only on road network  Toward better planning – Landfill practice should be subject to micro landform to avoid poor drainage area surrounded by landfill corridor – Need to coordinate landfill material flows between suppliers and consumers – Link between infrastructures (including non flood protection ones) and land uses 23

24. UGEC2010 Summary matrix BangkokMetro Manila Landform Continental delta Homogeneous flat plain Insular lowlands Visible micro landforms Floods Sheet flow Water level is manageable per each parcel using pumping Flash flow Water level is unmanageable without public infrastructures LT methods Dig and fill development Fill from further area Landfilling using construction debris Field-level adaptation Temporal banks Changing transportation Lifting up pathway & floor Individual fill on the floor Evacuation boat Staying upper floors Similar case studies are being carried out in other Asian low-lying cities… 24