Environmental scientists from the University of the Philippines convened a special meeting yesterday at the National Science Complex to do an initial post mortem of the Ondoy (Ketsana) disaster.
Our team of scientists included climatologists, meteorologists, a geological hazards specialist, ecologists and a hydrologist.
Several points were assessed
1) Comparisons with Hurricane Katrina
Ketsana and Katrina are two different tropical cyclones. Ketsana hit Manila and Central Luzon as a tropical storm while Katrina swept through southern Louisiana as a CAT 4 cyclone. Katrina generated a huge storm surge that broke the levees protecting New Orleans causing massive flooding. Mrs Gloria Arroyo got her facts right in saying that Katrina dumped about 280 mm of rain, although 380 mm was recorded in Slidell LA. Ondoy (Ketsana) dumped 455 mm of rain in PAGASA's Science Garden station in Diliman.
The massive flooding in Louisiana is due more to the storm surge. In the Metro Manila, the flooding was due to runoff which the river systems cannot handle.
While I have noted the similarities between Katrina and Ketsana, the only point of comparison between the Louisiana disaster and the one we have here is that people NEVER REALIZED NOR WERE PREPARED THAT SUCH FLOOD CAN HAPPEN IN THEIR CITIES.
2) Flooding in Metro Manila
Residents of Marikina, Cainta and Pasig (all part of the Marikina River Valley and floodplain) have experience of floods inundating their homes. My mother grew up in Malinao, Pasig and she has childhood memories of the church plaza being under waist deep of water for a month or so in the 1940s. However what struck the Marikina valley residents is that the water rose up to 3 meters or more within 15-20 minutes. This just shows how the surrounding environment was unable to hold the water.
On the Quezon City plateau, residents near the creeks that drain into the San Juan River have experience of minor flooding. Only the very low Tatalon area experiences worse floods each year. We lived in Kamias district for 30 years and I only recall one instance of flood when I was 4. In the same neighbourhood on K7 street the water rose to 4 meters in 30 minutes. In front of the barber shop I still go, the water rose to 2.5 meters. These areas are 200 meters away from Diliman creek.
In West and Timog Avenues several areas had water up to 1.8 meters deep. Once believed unsinkable UP Diliman had 1 meter of water at the amphitheater (where commencement rites are held). In front of the UP Elementary School the street was flooded 0.5 meters deep.
The same tale is told. Quezon City residents never thought that the water can rise to those heights in 20 minutes or less.
A preliminary scientific analysis of how this happened requires geographic approaches. Prof. Mahar Lagmay of the National Institute of Geological Sciences has put up a google map for people to pinpoint where the floods happened and how deep they got. It is important that people immediately document their experiences before time (and the stress!) makes them forget.
Prof. Trina Listanco of the UP Geography Department made a study (2004-2005) of Manila's flood risk. She predicted the flood heights that could happen as related to the channeling and loss of esteros. She also noted that a philosophical shift in how people viewed these waterways happened right after WWII. Whereas before, the waterways were considered more as a routes for transport (hence the need to keep these dredged and clear of obstructions) now they are merely considered as storm drains.
It is a good idea to know if her model predictions were validated. Ondoy certainly provided the opportunity.
Hazards specialists think that the disaster is largely due in fact to Metro Manila's unregulated urban sprawl. We looked at satellite maps (2007) of Metro Manila and noted that in many areas subdivision roads were aligned with permanent and intermittent watercourses. Thus in a deluge like what we had last Saturday, streets became parallel rivers (Note my whitewater account on Quezon City's Aurora Blvd) with water seeking the natural watercourses but its flow was blocked by houses and buildings. The streets became intermittent streams or as the Arabs would call it "wadis". People living in deserts are much aware of the dangers that wadis can bring.
There is likely a need to revisit our land use planning schemes. The mandatory 20 m setback from a watercourse (which is almost never followed) will have to be rethought.
Hydrological assessments of how much water can city streets carry needs to be done ASAP. Professor Listanco's 2005 study is valuable here.
3) Historical approaches
The Ondoy deluge is not that unusual in Manila's ecological history. Perhaps the most historically documented is the November 1943 flood that sank Manila. All Manila resident memoirs about the Japanese occupation have this and even my grandfather's diary (which I saved from the Ondoy deluge that flooded my QC house). My grandpa's diary survived six floods, 1956, 1962, 1971, 1972, 1987 and 2009! Grandpa mentions that their Cubao residence (near what is now E Rodriguez Avenue) flooded.
Dr Benito Legarda's wartime memoirs even documents the fall of their Faura barometer and has estimates of how deep the water got. Mr Jack Garcia's (now Sydney based) memoirs of WWII on Taft Avenue mentions the water being more than a meter deep. Another San Juan resident mentions the doctor and nurse who were swept by raging waters near where UERM is now today.
It is obvious that Greater Manila went underwater then. But UST Rector Father Juan Labrador mentions in his wartime diary that Intramuros did not sink. This is interesting.
Historian Ambeth Ocampo writes that even Blair and Robertson is a mine of climate related information. Climate scientists will have to do ecological history before concluding that human induced climate change is to blame!
4) Is it really climate change?
Since climate is always changing, then the answer is yes. But we have to recall that the popular view equates natural climate change with human induced climate change. Scientists will have to figure out if the current events deviate from model predictions made from long term data. We don't have a clear answer yet.
Climate change has now become a significant issue that attracts advocacy and science research money. Scientists will have to walk the thin rope on being objective and scientific and pandering to the NGO gallery! However based on what I saw on the NDCC TV press cons, our top scientists seem to be pandering to the NGO gallery!
However some disturbing trends can be noted in the climate/oceanographic data. The South China Sea has been unusually warm and may contribute to enhanced rainfall.
5) The social science story
What I find interesting is that Filipinos seem to have weathered the disaster quite well as compared to the Louisianians. Since I saw how Katrina did New Orleans in, I know how society becomes unraveled in a disaster. This is aptly documented in Douglas Brinkley's "The Great Deluge". This should be interesting material for our top social scientists some of which are PDI and Star columnists who have specialized too much in political science!
6) The disaster response
The centralized nature of our governance has made disaster response more effective than in the Federal System that is the USA. Brinkley's book tells how because of State Sovereignty, then US President GW Bush had to ask if the then Louisiana Governor Katherine Babineux-Blanco would allow federalization of the Louisiana National Guard. Bush had the powers to bypass Blanco but chose not to. The disaster sank Blanco's chances for a second term and Bush got a lot of undeserved flak (although his administration also carries some of the blame). So Pinoy Federalists take note!
The problem is that we don't have many disaster response assets, like rubber boats, helicopters, dinghies etc. But Congress can easily remedy that by fiat.
A centralized authority with expanded powers for disaster response for Metro Manila is needed. While the MMDA has some powers in clearing obstructions in national roads, it surely isn't enough.
7) PAGASA.... hopeless?
PAGASA was able to forecast the approach of the storm quite well but does not have the capability at present to forecast HOW MUCH RAIN will fall. Nathaniel Cruz has said on DZMM that while PAGASA has the Doppler radars needed, they still are in the process of installing them and training of people to operate then is on going. Dr Prisco Nilo said that they targetted December 2009 for operation. But then as Ondoy has it, it is too late.
Also our typhoon warning system is based on wind velocities. With Doppler radar forecasts, rain density can be assessed and people can decide on precautions to be taken based on two kinds of information. Then the days of the joke still reiterated in the media
"Signal number 2 na pero uma-araw!"
will be a thing of the past.
PAGASA can take comfort that it has Climate Change to share the blame with!
SOURCE: Philippine Commentary