fm s102 flood managament in the philippines by patrick b. gatan

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1

FLOOD MANAGEMENT IN THE PHILIPPINES:

THE METRO MANILA CASE

- December 5, 2012 -

Republic of the Philippines

Department of Public Works and Highways

Manila

1

The views expressed in this paper are the views of the authors and do not necessarily reflect the views or policies of theAsian Development Bank (ADB), or its Board of Directors, or the governments they represent. ADB does not guarantee theaccuracy of the data included in this paper and accepts no responsibility for any consequences of their use. Terminology

used may not necessarily be consistent with ADB official terms.



2

The PhilippinesFlood Disaster Data

7,107 islands

Land Area : 298,170 km2

Population : 85 Million

Annual rainfall : 2,400 mm

92.5% of disasters caused by

typhoons

Intense Rainfall Strong Winds

Overflowing of Waterways

Disrupt Normal Living

Conditions



3

18 Major River Basins

Catchment Area > 1,400 km2

421 Principal River Basins

Catchment Area > 40 km2

With intense rainfall:

overflowing of waterways

inundation and deposition of sediment in flood plains

extensive flood damages

often result.

River Basins in the Phil

ippines



4

Causes of Flooding

Denuded watersheds

Illegal loggingInformal Settlements

Inaccessible waterways

Limited channel capacity

Indiscriminate dumping of wastes



5

Marikina River water level rapidly rose 4.6 m in 6 hours at

Marikina Bridge on September 26, 2009 due to

approximately 400 mm rainfall in 6 hours.Also, Laguna Lake water level rose from Elev. 12.90 m at

9:00 AM on September 26, 2009 to Elev. 13.84 m in 24

hours.

5,000

4,150

3,500

3,000

500

1,200

Inflow:

7,000m3 /s

Sierra Madre Mountains

Flood in Pasig-Marikina-Laguna Lake Basin by “Ondoy” (Unit: m3/s)



6

Flood Condition by

“Ondoy” in Pasig-

Marikina River Area



DPWH History of Flood Control

Mitigation Efforts in Metro ManilaCompleted and On-Going Studies and Projects :

1. The first Study was undertaken after the flood in November 1942

2. The Study resumed after the Battle of Manila and covered North Manila Watershed (2,176 has) and South ManilaWatershed (2,908 has)

3. Study on the Drainage of Metro Manila and Suburbs (1954)

4. Construction of first seven (7) Pumping Stations (Completed in 1978)

5. Napindan Hydraulic Control Structure (Completed in 1983)

6. Study on Metro Manila Integrated Urban Drainage and Flood Control Master Plan (1984)

7. Mangahan Floodway Project (Completed in 1988)

8. Construction of additional five (5) Pumping Stations (Completed in 1990)

9. Study on Flood Control and Drainage Project in Metro Manila (1990)

10. Metro Manila Flood Control Project II (Completed in 1998)

11. The Study on the Existing Drainage Laterals in Metro Manila (2000)

12. Effective Flood Control Operation & Warning System (EFCOS) Project (Completed in 1993 & Rehabilitated in 2002)

13. The Study on Drainage Improvement in the Core Area of Metro Manila (2005)

14. Metro Manila Flood Control Project - West of Mangahan Floodway (Completed in 2008)15. KAMANAVA Area Flood Control and Drainage System Improvement Project, Phase I (Completed in 2012)

16. Pasig-Marikina River Channel Improvement Project, Phase II (To be Completed)

Proposed Projects:

1. Pasig-Marikina River Channel Improvement Project, Phase III (To be Started)

2. Projects under the Master Plan Study on Flood Risk Management in Metro Manila and Surrounding Areas (until 2035)



8

Boundary of

Study Area and

the River Basins

Based on river basins:

Pasig-Marikina River

Basin and Laguna Lake

Basin.

Total area: 4,354 km2

Total Population: 17.1 M

635 km2

72 km2

69 km2

169 km2

3280 km2

95 km2

15 km2

19 km2

8



9

Level-1

Low

Level-2

Medium

Level-3

High

Level-4

Very High

Total

1-4

Overflow from

Major rivers1,210 929 696 175 3,010

Around Laguna Lake 140 7 294 0 441

Flood Risk Map on Danger of Casualty-Risk Level(100-year Flood for the Rivers, and 2009 water level for Laguna Lake)

Population exposed to Flood Risk (unit:1000)

Note:

Estimated population in Flood

Risk Level-3 & 4.:773,940 in NCR

294,000 in Laguna Lake

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- Low Risk of Casualty- Medium Risk of Casualty

- High Risk of Casualty

- Very High Risk of Casualty



1010

Three Major Flooding

Occurrence:

(1) Huge volumeof watercoming fromSierra Madre

(2) Drainagecapacityconstraints incore area of Metro Manila

(3) Low lyingcommunitiesaround

Manila Bay &Laguna Lake



11

1,000

850(750**)

600

Dredging

Heightening of Wall

Small Marikina Dam

Retarding Basin

Flood Wall

Dike and Excavation

RAM & Small Wall

RAM & FPM

FPM

Flood Wall

900

2,000

1,000

Rehabiritation of

Floodway

3,600

RAM & Small Wall

Retarding Basin

1,750

2,900

3,000

1,200

800 (600*)

1,800

2,400

Dam

11

RAM – River Area Management

FPM – Flood Plain Management

Rehabilitation of

Floodway



12

Flood Condition without Project

Existing Condition

(100-year Return Period)

Flood Condition with Project

River Improvement and

Large Flood Control Dam

(100-year Return Period)

Pasig-Marikina RiverPasig-Marikina River

12



1313

Proposed Components

and Measures in

DICAMM

Rehabilitation of 15 MajorPumping Stations

Rehab. of Drainage Channel

• Removal of Obstructions

within drainage channels

with settlements• Dredging and Declogging

• Rehab. of Drainage Mains

Additional Drainage Mains /

Box Culverts



14

Laguna Lakeshore: Long-list of AlternativesPasig

Mangahan

Tanay

Sta. MariaParañaque

Zapote

P'que Spillway

Sta. RosaSta. Cruz

Pagsanjan

San Cristobal

San Juan

Im provem ent of St.

M aria River

Im provem ent of

Pagsanhan River

Spillway to P acific

O cean by Tunnel

Im provem ent of Sta.

C ruz R iver


Rosa River

Parañaque River

Im provem ent


Rosa River

Parañaque River

Im provem ent

Im provem ent of San

Fuan

Ring R oad D ike

Parañaque Spillway

:Partial Land Reclamation

Dredging

Partial Lake S hore D ike &Land Rising

Im provem ent of Tanay

River

14

Improvement of San

Juan River

Improvement of Sta.

Maria River



15

Options for the Lakeshore Area from Taguig to Muntinlupa

Option-1: Image of Lakeshore Dikewith Road

Option-2: Image of Raising Lakeshore Landwith Road and Future Developments



16

Short-listed Structural Mitigation Measures (1/3)No. Item High-

est

Flood

Risk

Level

Target

Flood

Safety

(R.P.)

Total

Cost

(Mil.

Pesos)

EIRR Resettle

ment

(1000

person)

Benefici

ary

(1000

person)

Preliminary

Environmental

Assess. (except

negative impact

of resettlement)

1(VH)

Pasig-Marikina

River

Improvement (RI)

+ Dam

4 100-y 198,435 16.4% 331 1,593 Moderate due

to some

negative social

impact by dam

(possible)

2(H)

Meycauayan RI 3 50-y 14,040 22.9% 35 199 Positive due to

improve. envir.

(recommended)

3(H)

Malabon-Tullahan

RI

3 50-y 21,635 22.3% 39 298 Positive due to

improve. envir.

(recommended)

4(M)

South Parañaque –

Las Piñas RI

3 30-y 17,335 12.2% 30 104 Positive due to

improve. envir.

(recommended)

5(H)

East Mangahan

Floodway (Cainta

& Taytay RIs)

3 30-y 25,901 26.8% 25 227 Positive due to

improve. envir.

(recommended)

Priority (Tentative) VH: Very High, H: High, M: Marginal



17

Short-listed Structural Mitigation Measures (2/3)

No. Item High-

est

Flood

Risk Level

Target

Flood

Safety

(R.P.)

Total

Cost

(Mil.

Pesos)

EIRR Resettle

ment

(1000

person)

Benefici

ary

(1000

person)

Preliminary

Environmental

Assess. (except

negative impactof resettlement)

6(VH)

West Laguna

Lakeshore Land

Raising

3 60-y 25,185 17.2% 114 114 Positive due to

improvement of

environment

and potential

of development

(recommended)

7(H)

Land Raising for

Small Cities around

Laguna Lakeshore

3 60-y 7,158 17.2% 8.8 8.8 Positive (same

as 6)

(recommended

and to be

studied more)

8(H)

Improvement of the

Inflow Rivers to

Laguna Lake

3 30-y 637 N.A. N.A. N.A. Positive due to

improve. of

environment

(recommended

and to be

studied more)

Priority (Tentative) VH: Very High, H: High, M: Marginal



18

Short-listed Structural Mitigation Measures (3/3)

No. Item High-

est

Flood

Risk Level

Target

Flood

Safety

(R.P.)

Total

Cost

(Mil.

Pesos)

EIRR Resettle

ment

(1000

person)

Benefici

ary

(1000

person)

Preliminary

Environmental

Assess. (except

negative impactof resettlement)

9(H)

Manila Core Area

Drainage

Improvement

2 10-y 27,257 19.1% 24 270 Positive due to

improvement of

environment

(recommended)

10(M) West MangahanArea Drainage

Improvement

2 5-y 5,522 11.1% 3.2 25.6 Positive due toimprovement of

environment

(recommended)

11 Valenzuela,

Obando and

Meycauayan

(VOM) Improve.(to

be studied further)

8,613

(Est.

only)

TOTAL 351,718

(1) Priority (Tentative) VH: Very High, H: High, M: Marginal

(2) Priority is set by considering 1) severity of floods or flood risk level, 2) cost and economic efficiency

(EIRR≧15%), and 3) social and natural impacts and preliminary environmental assessment.



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Proposed Non-Structural Measures

1. Strengthening of the Flood Information and Warning System (FIWS)

• Effective Flood Control Operation and Warning System (EFCOS)

improvement

• New telemetric rainfall and water level gauging stations

2. Capacity Building for Strengthening Community-based FRM

• Update and implement Information and Education Campaign (IEC)

programs• Rainfall and water level monitoring by Barangay Disaster Risk Reduction

and Management Councils (BDRRMCs)

• Construction of evacuation routes and temporary evacuation centers

3. Improvement of Management Information System (MIS) for Disaster Risk

Management

• Improvement and development of MIS

• Capacity building

4. Reforestation and Watershed Management

19



20

MarikinaDam

LagunaLakeshore

Raising/Road Dike

Inflow:

7,000m3 /s

5,000

Sierra Madre Mountains

L A G U N A L A K E

Flood in Pasig-Marikina-Laguna Lake Basin w/ Interventions in-placed



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End of Presentation

21



23

Linked Slides



Pandacan, Aviles, Quiapo, Valencia, Tripa de Gallina, Sta.

Clara and Paco



Libertad, Makati, Binondo, Balete and Escolta



Vitas, Balut and San Andres

fm s102 flood managament in the philippines by patrick b. gatan

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