1. Pampanga River Basin Flood Forecasting & Warning Center prffwc The Pampanga River Basin The 4th largest basin in the Philippines and covers an approximate aggregate area of 10,540 sq. km. (includes the allied basin of Guagua River). The basin extends over the southern slopes of the Caraballo Mountains, the western slopes of the Sierra Madre range and the major portions of the Central Plain of Luzon. It encompasses the provinces of Nueva Ecija; part of Bulacan, Tarlac and Quezon; and almost whole of Pampanga. The total length of the main river, the Pampanga River, is about 260 kilometers. The basin is drained through the Pampanga River and via the Labangan Channel into the Manila Bay. The main river is supported by several tributaries, the principal ones of which are the Penaranda and the Coronel-Santor Rivers on the eastern side of the basin and the Rio Chico River from the northwest side. The Angat River joins the Pampanga River at Calumpit in Bulacan via the Bagbag River. The Labangan channel, on the other hand, acts as a cut-off channel for the Angat River into Manila Bay. Somewhere between the middle and lower portion of the basin stands Mount Arayat, about 1,026 meters in elevation. Adjacent to Mount Arayat, across Pampanga River, just on the eastern side is the Candaba swamp, covering an area of some 300 sq. km. absorbing most of the flood flows coming from the eastern sections of the basin (western slopes of a portion of the Sierra Madre mountain range) and the overflowing of the Pampanga River via the Cabiao floodway. This area is submerged during the rainy season but is relatively dry during summer. At the lower sections of the basin, where the Pampanga delta lies, the Pampanga River system divide into relatively small branches, crisscrossed with fishponds to form a network of sluggish, tidal flats and canals, which eventually find their way to Manila Bay. The main river has a relatively low-gradient channel particularly at the middle and lower sections. With the anticipated completion of the Pampanga Delta Project (DPWH), it is expected that flood flows at the lower section of the Pampanga River will recede at a much faster rate than before. The basin experiences, on an average, at least one flooding in a year. The dry season generally occurs from December to May, and wet the rest of the year. The wettest months are from July to September. The frequency of tropical cyclone passage over the basin is about 5 in 3 years. http://prffwc.webs.com/# Compiled notes for CE 110 – Hydrology class, by Prof. Leonardo Q. Liongson, Institute of Civil Engineering, UP Diliman.

2. A view of the Candaba swamp area during flood season with Mount Arayat in the background. The Guagua River Basin The Guagua River Basin is an allied system of rivers and creeks to the Pampanga River virtually converging down with the latter close at the outlet into the Manila Bay. The basin drains an approximate area of 1,990 sq. km. It is bounded on the north partly by the Agno River Basin and on the south by the Manila Bay, on the east by the Pampanga River Basin, where an earthdike protecting the right bank of the Pampanga River separates them, and on the westby the Zambales mountain Range. The major river systems draining the basin are the Pasig-Potrero, Porac-Gumain, Abacan and Pasac-Guagua Rivers. Other small creeks and secondary rivers that significantly affect the basin are the Sapang-Maragul and Gugu creeks. The basin is vulnerable to flooding primarily because of its low elevation and flat terrain, its proximity to Manila Bay where tides impede the river and creek flow several kilometers upstream, and narrow and silted waterways brought largely by the eventful Mount Pinatubo eruption (1991). Possible contributory cause is the reported slow sinking of the delta making the area very vulnerable to instant flooding. (hth - ®)Recent Photos prffwc©2009

3. The Pampanga River Basin Map (with stations) Pampanga River Basin Flooding Map

4. Daily rainfall measurements on 24-30 September 2009, Pampanga River Basin.

5. Basin Info Pampanga River Basin Area - around 8,550 sq.km. ; 10,540 sq.km. including the allied basin of Guagua River Pampanga River Length - estimated at 260 kms. and its headwater source is at Caraballo Mt. at around 1,700 mts. elevation Number of Municipalities subjected/affected by floods – About 40 municipalities/cities in 4 Provinces for both Pampanga & Guagua River basins More than 60 towns/cities within the whole area (Pampanga-Guagua River basins) Frequency of Flooding – At least 1 to 2 floodings in a year For any questions or further inquiries, clarifications or suggestions please send e-mail to: [email_address] Above is the the old Arayat Station along the Pampanga River at relative high flows.

6. Main Operations Center Located in DOST Compound, Bgy. Maimpis, San Fernando, Pampanga 2000, Philippines Posted by prffwc on May 2, 2009

7. San Fernando main operations center A view of the operations center building of the PRBFFWC in San Fernando, Pampanga, Philippines. Posted by prffwc on May 9, 2009

8. Arayat View of Mt. Arayat from the San Agustin Bridge in Arayat, Pampanga. Posted by prffwc on May 2, 2009

9. Arayat Station The Arayat rainfall & river gauge station located along the San Agustin Bridge, Arayat, Pampanga, Philippines Posted by prffwc on May 2, 2009

10. Palali Station Palali rainfall station located in Bgy. Nazareth, Gen. Tinio, Nueva Ecija, Philippines Posted by prffwc on May 2, 2009

11. Candaba Station The Candaba rainfall and water level station located in the heart of the Candaba swamp area, Candaba, Pampanga, Philippines. Posted by prffwc on May 9, 2009

12. Mayapyap Station Mayapyap rainfall and water level station situated at the north end of Valdefuente Bridge, Cabanatuan City, Nueva Ecija, Philippines. Posted by prffwc on May 9, 2009

13. Sapang Buho Station The Sapang Buho rainfall and water level station is the uppermost river gauging station within the basin; situated at Palayan city, Nueva Ecija, Philippines. Posted by prffwc on May 9, 2009

14. Sulipan Station The rainfall and water level station of Sulipan is situated in Apalit, Pampanga, Philippines. It is the last monitoring point along the Pampanga river. Posted by prffwc on May 9, 2009

15. Zaragoza Station Situated along the Rio Chico Bridge in Zaragoza, Nueva Ecija, Philippines is the rainfall and water level station of Zaragoza. Posted by prffwc on May 9, 2009

16. San Isidro Station The rainfall and water level station of San Isidro is located along the San Isidro-Jaen Bridge in San Isidro, Nueva Ecija, Philippines. Posted by prffwc on May 9, 2009

17. Sasmuan Station Sasmuan rainfall and water level station is in Bgy. Sta. Lucia, town of Sasmuan, Pampanga Posted by prffwc on May 9, 2009

18. Sulipan Bridge Staff gage Water level gage of PDMO-Bulacan at Sulipan Bridge: Reading of 0.35m, 7:00 am, Aug 8, 2009 Posted by prffwc on Aug 8, 2009

19. PRFFWC Sulipan Station Sulipan station (7:30 am, 08 Aug 2009). Telemetry reading at 3.25m Posted by prffwc on Aug 8, 2009

20. Arayat Stn, Staff gage Staff gage reading of about 7.6m (1:00 pm, 07 Aug 2009) Posted by prffwc on Aug 8, 2009

21. Old Arayat Stn. A view of the old Arayat Station in San Agustinm Arayat, Pampanga (1:00 pm, 07 Aug 2009) Posted by prffwc on Aug 8, 2009

22. Candaba swamp area Candaba swamp at about 5.3m reading of staff gage at the station (background), 12 noon, 07 Aug 2009) Posted by prffwc on Aug 8, 2009

23. Pampanga River at San Isidro, Nueva Ecija Pampanga River at San Isidro (2:00 pm, 07 Aug 2009) Posted by prffwc on Aug 8, 2009

24. SMS NIA DAM STATION Brgy. Tingib, Pastrana, Leyte ASSESSED WATER LEVEL = 1 meter (computed by PAGASA) Automatically sends data to the Operation Center every 8:00 am and 5:00 pm during normal water level condition Automatically sends data to the Operation Center every 15 minutes water level reached the tip of the sensor The primary purpose of the system is to help lessen the vulnerability risk of the stakeholders along the Binahaan Watershed through timely exchanged of information which is to give the stakeholders advanced information of the existence of flood in their respective areas.