REPUBLIC OF THE PHILIPPINES DEPARTMENT OF PUBLIC WORKS AND HIGHWAYS FLOODING IN METRO MANILA (PASIG-MARIKINA RIVER)
Engr. JERRY A. FANO OIC, Project Impact Analysis and Evaluation 1 Typhoon Ulysses was preceded by three (3) typhoons that caused too much rainfall.
Typhoon Rolly Typhoon Tonyo (November 1-2, 2020) (November 8-9, 2020)
Typhoon Siony Typhoon Ulysses (November 4-6, 2020) (November 11-12, 2020) 2 2 PASIG-MARIKINA / LAGUNA DE BAY RIVER BASIN AREA: 4,678 km²
3 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 2009?
Why heavy flood didn’t occur around the Laguna Lake?
Does deforestation in the Upper Marikina Watershed contribute in the flooding? 4 Why the water level rapidly increased in Typhoon Ulysses? Rainfall in the Pasig-Marikina River Basin Item Ondoy Ulysses Period of Record September 26 – 27, 2009 (8AM- November 11 – 12, 2020 (8AM- Basin Mean Rainfall 8AM) 8AM) Period of Record 299.3mm/day 287.1mm/day Basin Mean Rainfall September 25 – 26, 2009 (8PM-8PM) November11–12, 2020 (12PM- 406.3mm/24hours 12PM) Peak Discharges and Design Discharge 302.2mm/24hours
Fig- Comparison between Ondoy and Ulysses Item Ondoy Ulysses Phase 4 35.0 0.0
Basin mean rainfall (Ondoy) Peak 3,480m3/s 3,255m3/s 2,900m3/s 30.0 Basin mean rainfall (Ulysses) 20.0 WL_St.Nino (Ondoy) Discharge WL_St.Nino (Ulysses) 25.0 40.0
20.0 60.0
rainfall (mm/hr) rainfall hourly water level level (E.L.m) water hourly
15.0 80.0
10.0 100.0
5.0 120.0
9/25 9:009/25 9/251:00 9/253:00 9/255:00 9/257:00 9/261:00 9/263:00 9/265:00 9/267:00 9/269:00 9/271:00 9/273:00 9/275:00 9/277:00 9/279:00
9/2511:00 9/2513:00 9/2515:00 9/2517:00 9/2519:00 9/2521:00 9/2523:00 9/2611:00 9/2613:00 9/2615:00 9/2617:00 9/2619:00 9/2621:00 9/2623:00 9/2711:00 9/2713:00 9/2715:00 9/2717:00 9/2719:00 9/2721:00 9/2723:00
5
11/111:00 11/113:00 11/115:00 11/117:00 11/119:00 11/121:00 11/123:00 11/125:00 11/127:00 11/129:00 11/131:00 11/133:00 11/135:00 11/137:00 11/139:00
11/1111:00 11/1113:00 11/1115:00 11/1117:00 11/1119:00 11/1121:00 11/1123:00 11/1211:00 11/1213:00 11/1215:00 11/1217:00 11/1219:00 11/1221:00 11/1223:00 11/1311:00 11/1313:00 11/1315:00 • Findings and Ways Forward Why the water level rapidly increased in Typhoon Ulysses?
Fig- Comparison between Ondoy and Ulysses Reason-1: Rainfall Pattern 35.0 0.0
Ondoy: 2 Peaks Basin mean rainfall (Ondoy) 30.0 Basin mean rainfall (Ulysses) 20.0 Ulysses: Constant WL_St.Nino (Ondoy) WL_St.Nino (Ulysses) 25.0 40.0
20.0 60.0
rainfall (mm/hr) rainfall hourly water level level (E.L.m) water hourly
Hourly Basin Mean Rainfall 15.0 80.0 (Upper Sto. Niño) 70.0 10.0 100.0 60.0
5.0 120.0
9/25 9:009/25 9/253:00 9/255:00 9/257:00 9/261:00 9/263:00 9/265:00 9/267:00 9/269:00 9/271:00 9/273:00 9/275:00 9/277:00 9/279:00
50.0 9/251:00
9/2511:00 9/2513:00 9/2515:00 9/2517:00 9/2519:00 9/2521:00 9/2523:00 9/2611:00 9/2613:00 9/2615:00 9/2617:00 9/2619:00 9/2621:00 9/2623:00 9/2711:00 9/2713:00 9/2715:00 9/2717:00 9/2719:00 9/2721:00 9/2723:00
11/111:00 11/113:00 11/115:00 11/117:00 11/119:00 11/121:00 11/123:00 11/125:00 11/127:00 11/129:00 11/131:00 11/133:00 11/135:00 11/137:00 11/139:00
11/1113:00 11/1115:00 11/1117:00 11/1119:00 11/1121:00 11/1123:00 11/1211:00 11/1213:00 11/1215:00 11/1217:00 11/1219:00 11/1221:00 11/1223:00 11/1311:00 11/1313:00 11/1315:00 40.0 11/1111:00
30.0
20.0
10.0
0.0 Ondoy Ulysses
6 Fig- Comparison between Ondoy and Ulysses 35.0
30.0
• Fact WL_St.Nino (Ondoy) 25.0 WL_St.Nino (Ulysses)
Water Level at Sto. Nino 20.0 hourly water level level (E.L.m) water hourly Item Ondoy Ulysses 15.0 Max. Water EL+22.16m EL+21.73m Level 10.0
5.0
9/251:00
9/253:00
9/255:00
9/257:00
9/25 9:009/25
9/261:00
9/263:00
9/265:00
9/267:00
9/269:00
9/271:00
9/273:00
9/275:00
9/277:00
9/279:00
9/2511:00
9/2513:00
9/2515:00
9/2517:00
9/2519:00
9/2521:00
9/2523:00
9/2611:00
9/2613:00
9/2615:00
9/2617:00
9/2619:00
9/2621:00
9/2623:00
9/2711:00
9/2713:00
9/2715:00
9/2717:00
9/2719:00
9/2721:00
9/2723:00
11/111:00
11/113:00
11/115:00
11/117:00
11/119:00
11/121:00
11/123:00
11/125:00
11/127:00
11/129:00
11/131:00
11/133:00
11/135:00
11/137:00
11/139:00
11/1111:00
11/1113:00
11/1115:00
11/1117:00
11/1119:00
11/1121:00
11/1123:00
11/1211:00
11/1213:00
11/1215:00
11/1217:00
11/1219:00
11/1221:00
11/1223:00
11/1311:00
11/1313:00 11/1315:00 Why heavy flood didn’t occur around the Laguna Lake? Reason-1: The water level of Laguna Lake was low during that time
Item Ondoy 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+13.13m7 • 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)?
10 • 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 Project as well as Rehabilitation of Pumping Stations along Pasig River
PMRCIP, Phase II & III 11 Pasig-Marikina River Channel Improvement Project, Phase IV
12 Mangahan Control Gate Structure (MCGS)
Along Pasig-Marikina River
13 Parañaque Spillway Project
14 • Findings and Ways Forward The need for Marikina Dam and Paranaque Spillway
Montalban River Montalban River 1,200 1,200 Marikina Dam 1,300 3,200 3,200 2,500 Rodriguez Bridge Rodriguez Bridge Marikina Retarding Basins San Mateo Bridge San Mateo Bridge 2,100 Nangka River Nangka River 800 800 800 3,600 800
~ River Marikina Marikina River Marikina 1,000 ~ Marikina Bridge Marikina Bridge 4,000 MCGS 2,900 River Improvement
Lower Lower San Juan River Juan San San Juan River Juan San Marikina River Marikina River (Phase IV) 2,000 1,300 1,200 1,200 1,400 600 550 500 (*1) (*1)
Pasig River Rosario Weir Pasig River Rosario Weir MANILA BAY MANILA MANILA BAY MANILA NHCS 2,800 (Fully Opened) NHCS 2,400 0 0 ~
*1: Discharge when Channel
Channel Napindan Napindan 600 NHCS Closed
Pililla Pililla LAGUNA LAKE LAGUNA LAKE Probable Water Level w/o Paranaque Spillway Jala-jala Paranaque Spillway Probable Water Level w Paranaque Spillway Jala-jala (200~300m3/s) (*2) Probability Water Level Probability Water Level 200 EL+14.7m 200 EL+14.3m 100 +14.3 *2: To be reviewed in the FS 100 +14.0 50 14.0 50 13.7 30 13.7 30 13.4 10 13.2 10 13.0
San Juan Maulauen Bay Bancabanca San Juan Maulauen Bay 15Bancabanca WithoutSan Cristobal Interventions StructuralSan Cristobal 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 16 End of Presentation Thank You!
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