Research Report on 2009 Floods and Landslides Disasters Caused by Typhoons 16(Ondoy), 17(Pepeng) and 18(Sante) in the Philippines
5. Investigation in the Metro Manila area
5.1 Field Survey
1. Study Area:
Damaged areas by the 2009 Ondoy Flood were surveyed through on the spot survey and hearing from residents to clarify flooding condition, land and social environments, and flood Prevention Facilities in flood plains of the Marikina-Pasig-Laguna Lake Complex around the Metro Manila. Field survey spots are as follows;
1) Marikina River Flood plain
Damaged Area along the Marikina River: Provident Village, Mandalay etc.,
Manggahan Flood way, Rosario Weir and Napindan Gate.
2) Laguna Lake Flood plain
Damaged Area: Bay Breeze District along the Laguna Lake etc.,
Coastal Bank along the Laguna Lake, Water Gates and Pumping Stations.
3) Coastal Lowland along Manila Bay
Damaged Areas along the Pasig River.
Urban drainage channels and Pumping Stations.
4) Valley Plain along the San Juan River.
Damaged Areas along San Juan River.
2. Summary:
1) Marikina River Flood plain
In the Marikina River Flood plain, torrential downpours in excess of the design capacity of the river channel caused severe flooding. For example, in the exclusive Provident residential district of Marikina city, floodwater depths close to 7 m were recorded and there were many fatalities.
2) Coastal Lowland along Manila Bay
In the Coastal Lowland along Manila Bay which is at the downstream parts of the Pasig river basin, 70% of the floodwater from the upstream Marikina River was diverted into Laguna de Bay (Laguna Lake) by the Manggahan floodway, thus limiting the regions subjected to external overflow from the river channel. However, due to the large scale of the downpour, flood damage was caused by inner flooding on a large scale and over a wide area despite pumps being operated to drain the inner basin into the Pasig River.
3) Valley Plain along the San Juan River
Even in this downstream of the Pasig River, external flooding occurred along the San Juan river, the right bank tributary of the Pasig river, causing severe flood damage to residential regions.
4) Laguna Lake Flood plain
In Laguna Lake, which acts as a retarding reservoir for the metropolitan area that is developing out onto the downstream Manila bay coastal plain, the water level in the lake rose due to the large amount of rainfall that fell in the Laguna de Bay river basin and the flow of floodwater from the Marikina river, causing the residential areas along the shores of the lake to be flooded for a long period of time. For example, when we visited the Bay Breeze district of Tagigu city in early December, the area was still flooded and people were using boats as a means of transport. There are also many shanty dwellings along the shores of the lake that were damaged by the flooding. With regard to these floods in Manila, although operational problems were identified with the 5) Metro Manila flood control system after the technology transfer from JICA, on-site interview surveys and from discussions with experts in the field have shown that the flood mitigation projects set up with JICA's assistance played a major role in the current floods, and made a large contribution to reducing the damage caused by the disaster.
5.2. Interview Survey
1.Interviewed organizations:
National organizations: National Disaster Coordinating Council (NDCC), Office of Civil Defense(OCD), Philippine Atmospheric, Geophysical & Astronomical Services Administration (PAGASA), Mines and Geosciences Bureau (MGB)
Metro Manila organization: Metro Manila Development Authority (MMDA)
Domestic NGOs:Philippine National Red Cross (PNRC)
Bilateral cooperation organization:Japan International Cooperation Agency (JICA)
Multilateral cooperation organization: Asian Development Bank (ADB)
2.Summary:
1)The National Disaster Coordinating Council (NDCC) implemented a counterpart
to this survey in which we asked about the outline and organization of
the NDCC activities and the outline of the activities of the Office of
Civil Defense (OCD) which is the central coordinating organization. Interviews
were also held with members of the Philippine Atmospheric, Geophysical
& Astronomical Services Administration (PAGASA) and the Mines and Geosciences
Bureau (MGB), which are two other organizations associated with the NDCC,
on subjects including the details of the latest disaster and the response
of each organization.
2)At the Metro Manila Development Authority (MMDA), interviews were held
regarding the activity surrounding the disaster and the state of flood
control in Metro Manila.
3)We conducted interviews at the Rizal branch of the Philippine Red Cross
to ascertain how this NGO responded to the disaster. In particular, we
asked about the effective gathering of disaster information using mobile
phone text messages, and the rapid aid activities of trained Red Cross
volunteers in each barangay.
4)At JICA, we asked about the results of needs assessment after the disaster
as a bilateral cooperative activity.
5)At the Asian Development Bank (ADB), we asked about the disaster response
to Typhoon Ondoy as a multilateral cooperation organization, and we discussed
the overall image of this disaster in the context of our survey results.
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