The Pampanga River Basin


Posted at Oct 23 2009 04:01 PM | Updated as of Oct 25 2009 09:36 AM

This is the map of tributaries and flood-prone areas around the Pampanga River basin from Pagasa’s Flood Forecast Branch. The text below the map gives general information about the Pampanga River Basin and its environs.

Fast Facts:

  • Fourth largest basin in the Philippines
  • Covers an approximate aggregate areas of 10,540 square kilometers (sq. km)
    • Includes basin of the Guagua River in Pampanga
  • Extends over southern slopes of Caraballo Mountains (in Central Luzon), Sierra Madre mountain range and the Central Plain of Luzon
  • Encompasses Nueva Ecija, Bulacan (partially), Tarlac and Quezon, almost all of Pampanga
  • Total length of main river: 260 kilometers
  • The middle and lower sections of the main river have low-gradient channels
  • Frequency of tropical cyclone passage over the Pampanga River Basin: 5 times in 3 years


  • Average of at least one flooding a year
  • Dry season: December to May
  • Wet season: June-November
    • Wettest months: July to September

Connecting water ways and mountain ranges

  • Drains via the Lanbangan Channel into Manila Bay
  • Supported by tributaries:
    • Penaranda River (Nueva Ecija)
    • Coronel-Santor River (Nueva Ecija)
      • Both are on the eastern side of the Pampanga River basin
    • Rio Chico River (Nueva Ecija)
      • Northwest side of the Pampanga River
    • Bagbag River (Bulacan)
      • This river joins the Pampanga river and Angat river
      • Labangan channel: acts as cut-off channel for the Angat River into Manila Bay
  • Mount Arayat (Pamgpanga)
    • Stands somewhere between the middle and lower portion of the basin
    • 1,206 meters in elevation
  • Candaba swamp (Pampanga)
    • Adjacent to Mount Arayat
    • Located across the Pampanga River
    • Area: 250 sq. km.
      • Absorbs most of the flood flows from the eastern sections of the Pampanga River basin or the western slopes of the Sierra Madre mountain range
      • Cabiao Floodway (Nueva Ecija): allows Candaba swamp to absorb overflow from the Pampanga River
  • Lower sections of the basin (where Pampanga delta lies):
    • Fishponds
    • Canals
    • Sluggish
    • Tidal flats
      • All lead to Manila Bay

Source: Pagasa flood forecasting branch