REPUBLIC OF THE PHILIPPINESDEPARTMENT OF PUBLIC WORKS AND HIGHWAYSFLOODING IN METRO MANILA(PASIG-MARIKINA RIVER)

Engr. JERRY A. FANO

OIC, Project Impact Analysis and Evaluation1

Typhoon Ulysses was preceded by three (3) typhoons thatcaused too much rainfall.

Typhoon Rolly(November 1-2, 2020)

Typhoon Tonyo(November 8-9, 2020)

Typhoon Siony(November 4-6, 2020)

Typhoon Ulysses(November 11-12, 2020)

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PASIG-MARIKINA / LAGUNA DE BAY
RIVER BASIN
AREA: 4,678 km²3

FACTS, FINDINGS AND WAY FORWARD• Facts

 Water Level and Rainfall in the Pasig-Marikina Basin Peak Discharges and Design Discharge at Sto. Nino Gauging Station• Findings and Ways Forward Why did the water level increased rapidly even though Typhoon Ulysses
dumped smaller amount of rainfall compared to Typhoon Ketsana in 200
 Why heavy flood didn’t occur around the Laguna Lake?

 Does deforestation in the Upper Marikina Watershed contribute in theflooding?
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9/26 9:00

9/26 13:00
9/26 15:00
9/26 17:00
9/26 19:00
9/26 21:00
9/26 23:00
9/27 1:00
9/27 3:00
9/27 5:00

11/12 5:00
11/12 7:00
11/12 9:00
11/12 11:00
11/12 13:00
11/12 15:00
11/12 17:00
11/12 19:00
11/12 21:00

9/26 7:00

9/26 11:00

9/26 5:00
11/11 23:00

11/12 3:00

9/26 3:00
11/11 21:00

11/12 1:00

9/26 1:00

9/27 9:00
9/27 11:00
9/27 13:00
9/27 15:00
9/27 17:00
9/27 19:00
9/27 21:00
9/27 23:00

11/13 3:00
11/13 5:00
11/13 7:00
11/13 9:00
11/13 11:00
11/13 13:00
11/13 15:00

9/27 7:00

5
11/13 1:00

30.0

11/12 23:00

Ondoy
Ulysses

September 26 – 27, 2009 (8AM8AM)
November 11 – 12, 2020 (8AM8AM)

299.3mm/day
287.1mm/day

September 25 – 26, 2009 (8PM-8PM)
November11–12, 2020 (12PM12PM)

35.0

Basin mean rainfall (Ulysses)

rainfall (mm/hr)

120.0

11/11 19:00

5.0
9/25 23:00

100.0

11/11 17:00

10.0

9/25 21:00

80.0

11/11 15:00

15.0

9/25 19:00

60.0

11/11 13:00

20.0

9/25 17:00

40.0

11/11 11:00

25.0

9/25 15:00

2,900m3/s

11/11 9:00

3,255m3/s

9/25 13:00

3,480m3/s

11/11 7:00

Phase 4

11/11 5:00

Ulysses

9/25 9:00

PeakDischarge
Ondoy

9/25 11:00

Item

11/11 3:00

Peak Discharges and Design Discharge
406.3mm/24hours

9/25 7:00

Basin Mean Rainfall

11/11 1:00

Period of Record

9/25 5:00

Basin Mean Rainfall

9/25 3:00

Period of Record

9/25 1:00

Itemhourly water level (E.L.m)

Why the water level rapidly increased in Typhoon Ulysses?

Rainfall in the Pasig-Marikina River Basin

302.2mm/24hours

Fig- Comparison between Ondoy and Ulysses
0.0

Basin mean rainfall (Ondoy)

WL_St.Nino (Ondoy)

20.0

WL_St.Nino (Ulysses)

50.0

Ondoy
9/26 19:00
9/26 21:00
9/26 23:00
9/27 1:00
9/27 3:00
9/27 5:00

11/12 13:00
11/12 15:00
11/12 17:00
11/12 19:00
11/12 21:00

30.0

20.0

10.0

0.0
Ulysses

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9/27 9:00
9/27 11:00
9/27 13:00
9/27 15:00
9/27 17:00
9/27 19:00
9/27 21:00
9/27 23:00

11/13 1:00
11/13 3:00
11/13 5:00
11/13 7:00
11/13 9:00
11/13 11:00
11/13 13:00
11/13 15:00

9/27 7:00

9/26 17:00
11/12 11:00

35.0

Basin mean rainfall (Ulysses)

rainfall (mm/hr)

30.0

11/12 23:00

9/26 15:00

9/26 7:00

11/12 9:00

9/26 5:00
11/11 23:00

9/26 13:00

9/26 3:00
11/11 21:00

11/12 7:00

9/26 1:00
11/11 19:00

11/12 5:00

9/25 23:00
11/11 17:00

9/26 9:00

9/25 21:00
11/11 15:00

9/26 11:00

9/25 19:00
11/11 13:00

11/12 3:00

9/25 17:00

120.0

11/11 11:00

5.0
9/25 15:00

100.0

11/11 9:00

10.0

9/25 13:00

80.0

11/11 7:00

15.0

11/11 5:00

60.0

9/25 9:00

20.0

9/25 11:00

11/12 1:00

60.0
40.0

11/11 3:00

40.0
9/25 7:00

70.0(Upper Sto. Niño)
25.0

11/11 1:00

Ondoy: 2 Peaks
Ulysses: Constant

9/25 5:00

 Reason-1: Rainfall Pattern

9/25 3:00

9/25 1:00

Hourly Basin Mean Rainfall
hourly water level (E.L.m)• Findings and Ways Forward

Why the water level rapidly increased in Typhoon Ulysses?
Fig- Comparison between Ondoy and Ulysses
0.0

Basin mean rainfall (Ondoy)
20.0

WL_St.Nino (Ondoy)
WL_St.Nino (Ulysses)

9/25 1:00

5.0

Item

Why heavy flood didn’t occur around the Laguna Lake?
 Reason-1: The water level of Laguna Lake was low during that timeOndoy
Ulysses

Initial W/L of Laguna

September 25 (5PM): EL+12.77m
November 11 (10AM): EL+12.25m

After Typhoon Event

September 27 (6PM): EL+13.84m
November 12 (11AM): EL+13.13m
79/27 19:00
9/27 21:00
9/27 23:00

11/13 11:00
11/13 13:00
11/13 15:00

9/27 15:00
9/27 17:00

11/13 7:00
11/13 9:00

9/27 11:00
9/27 13:00

11/13 5:00

9/27 9:00

11/13 1:00
11/13 3:00

9/27 5:00
9/27 7:00

11/12 23:00• Fact11/12 21:00

9/27 1:00
9/27 3:00

11/12 19:00

9/26 23:00

11/12 15:00
11/12 17:00

9/26 19:00
9/26 21:00

11/12 11:00
11/12 13:00

9/26 15:00
9/26 17:00

11/12 9:00

9/26 13:00
11/12 7:00

11/12 5:00

9/26 9:00
9/26 11:00

11/12 1:00
11/12 3:00

9/26 5:00
9/26 7:00

11/11 21:00
11/11 23:00

9/26 1:00
9/26 3:00

11/11 19:00

9/25 23:00

11/11 15:00
11/11 17:00

9/25 19:00
9/25 21:00

11/11 11:00
11/11 13:00

9/25 15:00
9/25 17:00

11/11 7:00
11/11 9:00

9/25 11:00
9/25 13:00

11/11 5:00

9/25 9:00

EL+21.73m

11/11 1:00

EL+22.16m

11/11 3:00

Ulysses

9/25 5:00

Max. WaterLevelOndoy

9/25 7:00

Item

9/25 3:00

Water Level at Sto. Nino
hourly water level (E.L.m)

30.0

25.0

WL_St.Nino (Ondoy)
WL_St.Nino (Ulysses)

20.0

15.0

10.0

• Findings and Ways Forward

Why the water level rapidly increased in Typhoon Ulysses?
 Reason: Rapid Urbanization / Built Up Areas

81976 Flood Control Master Plan for Metro Manila

9Why heavy flood didn’t occur in the downstream areas(Manila, Mandaluyong, Makati, Pasig, Taguig)?

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• Findings and Ways Forward

Why heavy flood didn’t occur in the Pasig River (Downstream Areas) ?
Reason: Completed Phase 2 and Phase 3 of the Pasig Marikina River Channel Improvement Projectas well as Rehabilitation of Pumping Stations along Pasig River

PMRCIP, Phase II & III

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Pasig-Marikina River Channel Improvement Project, Phase IV

12

Mangahan Control Gate Structure (MCGS)

Along Pasig-Marikina River13

Parañaque Spillway Project14

The need for Marikina Dam and Paranaque Spillway
Montalban River
1,200

Montalban River
1,200
3,200

2,500

Marikina Dam
1,300

3,200

Rodriguez Bridge

Rodriguez Bridge

3,600~4,000

Marikina Bridge

1,300(*1)

NapindanChannelPasig River

1,200(*1)

MANILA BAYLower
Marikina River

2,000

1,200

NHCS0~600

2,800

Rosario Weir
(Fully Opened)

PilillaLAGUNA LAKE

Probable Water Level w/o Paranaque Spillway
Probability
200
100
503010San Juan
San Cristobal

Marikina River

Nangka River
800

Jala-jala

Maulauen

Paranaque Spillway*2: To be reviewed in the FS

Bay

Without Interventions

Bancabanca

2,100

Nangka River
800

Marikina Bridge

MCGS

2,900

Lower
Marikina River

1,400600550

San Mateo Bridge

River Improvement(Phase IV)

500
Rosario Weir

Pasig River
NHCS02,400Pililla

LAGUNA LAKE
(200~300m3/s) (*2)

Water Level
EL+14.7m+14.3
14.0
13.7
13.2

800

NapindanChannel

800~1,000San Mateo Bridge

San Juan RiverMarikina RiverMarikina
Retarding Basins

San Juan River

MANILA BAY• Findings and Ways Forward

Probable Water Level w Paranaque Spillway
Probability
200
100503010San Juan
San Cristobal

Jala-jala

Water Level
EL+14.3m+14.0
13.7
13.4
13.0
Maulauen

BayBancabanca
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Structural Interventions

Inundation Conditions for 100-year Return Period Flood
With and Without the Project- Pasig Marikina River Channel Impr. Project (Phase IV), Marikina Dam and Retarding Basin -16

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End of Presentation

Thank You!
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