Flooding in Metro Manila (Pasig-Marikina River)
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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? in Typhoon increased rapidly level thewater Why Discharge Peak Item RainfallBasinMean of Record Period RainfallBasinMean of Record Period Item Peak Discharges and Design Discharge Peak in thePasig Rainfall 3,480m3/s Ondoy September September 25 September September 26 - Marikina Marikina Basin River 3,255m3/s 406.3mm/24hours Ulysses 299.3mm/day Ondoy – 8AM) 26, 26, 2009 (8PM – 27, 27, 2009 (8AM 2,900m3/s Phase 4 Phase - 8PM) - November 11 November11 302.2mm/24hours 287.1mm/day Fig- Comparison between Ondoy and Ulysses 35.0 0.0 Ulysses Basin mean rainfall (Ondoy) 12PM) 8AM) 30.0 Basin mean rainfall (Ulysses) 20.0 – – WL_St.Nino (Ondoy) 12, 12, 2020 (12PM WL_St.Nino (Ulysses) 12, 12, 2020 (8AM 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 5 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 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 the water level rapidly increased in Typhoon Ulysses? in Typhoon increased rapidly level water the Why Findings and Ways Forward Ways andFindings Ondoy: Reason Ulysses: Ulysses: Constant 2 - 1: Peaks Rainfall Pattern Rainfall Hourly Basin Mean Rainfall (Upper Sto. Niño) 70.0 60.0 Fig- Comparison between Ondoy and Ulysses 35.0 0.0 50.0 Basin mean rainfall (Ondoy) 30.0 Basin mean rainfall (Ulysses) 20.0 40.0 WL_St.Nino (Ondoy) WL_St.Nino (Ulysses) 25.0 40.0 30.0 20.0 60.0 20.0 (mm/hr) rainfall hourly water level level (E.L.m) water hourly 15.0 80.0 6 10.0 0.0 10.0 100.0 Ondoy Ulysses 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 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 Level Water Max. Item Water at Level Water • After Typhoon Event After Typhoon InitialW/L of Laguna Item Why heavy flood didn’t occur around the Laguna Lake? Laguna the didn’t flood around occur heavy Why Fact Reason - 1: The water level level water EL+22.16m Ondoy Sto . Nino September 27 (6PM): 27 (6PM): September EL+12.77m 25 (5PM): September of Laguna Lake was was Lake Lagunaof EL+21.73m Ulysses Fig- Comparison between Ondoy and Ulysses Ondoy 35.0 30.0 low EL+13.84m WL_St.Nino (Ondoy) 25.0 during that time during that WL_St.Nino (Ulysses) 20.0 hourly water level level (E.L.m) water hourly 15.0 November 12 (11AM): November 12 EL+13.13m (11AM): November 11 (10AM): 10.0 5.0 Ulysses 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 EL+12.25m 7 • 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! 17.