In my last post, I blamed the flooding in Metro Manila and 25 nearby provinces to the rains brought by the storm Ondoy (Ketsana). But my rational mind simply could not put 2 and 2 together.
The weather agency said that the storm brought in 410 mm of rainfall in nine hours — more than the average monthly rainfall during the wet season. Okay. But the floods practically everywhere started in the first hour or so. Ondoy was said to have made landfall at 10AM. By ten-thirty, there were floods everywhere in Metro Manila. As I wrote in my previous post, I could not believe my cousin’s text message to me that Congressional and Mindanao avenues were flooded. That was around 10:30 am. The amount of rain that fell for the past 24 hours was not enough to make those streets impassable by cars.
I heard on TV that the actress Christine Reyes went down to the the first floor of their house to get her nephew/niece (pamangkin). When she turned around, she was shocked to see the height of the water. I heard such stories before — during the deadly tsunami that struck Indonesia, Thailand, etc. a few years ago.
A tsunami or a tidal wave can suddenly bring in gigantic amounts of water from seemingly out of nowhere. But rains? Hmmm, I thought something was not right.
OVERFLOWING RIVERS AND CREEKS
Flash floods in Metro Manila are usually caused by clogged drainage, primitive sewage system, uncollected garbage, etc. But this time, the cause of the flooding were overflowing rivers and creeks.
The Marikina river overflowed within an hour or so of Ondoy’s landfall. Pasig river must have overflowed, too. Creeks and other tributaries overflowed.
When I was told that the water in the creek near us rose over the bridge, I couldn’t believe it. The bridge was quite high. The amount of rainfall that fell up to that time was not enough to make the water rise that much. There must have been other sources of water.
STRONG CURRENT
News programs including CNN repeatedly showed a clip of people on top of a what looked like a rooftop filled with debris. This unusual raft with several people on them was speeding along Marikina river at a very fast pace. It was as fast as a speed boat. The local news show had to replay the clip in slow motion.
Can a heavy downpour increase the current of a river at least ten-fold?
A news clip also showed floods in Quezon City and elsewhere. What amazed me was the strong current of the street floods. The floodwaters could even move cars as if they were rubber boats. My friend asked me where the current came from. Offhand, I answered that it could be because of the slope of the street. The floodwaters were simply going downhill, I reasoned.
MUDDY WATERS
Why was there so much mud? Floods from rains do not carry mud.
WATER FROM THE DAMS
There have been accusations of unannounced release of water from the Angat dam and the Angat dam operators vehemently denied any wrongdoing.
The more I think about it, it appears that the most logical reason for the massive flooding all over Metro Manila and nearby provinces was the unannounced release of huge quantities of water from the massive Angat dam, the Ipo dam and the La Mesa dam.
My hypothesis is this: because of the heavy rain in the past weeks before Ondoy, the dams were already reaching critical level. With the sudden huge downpour of tyrphoon Ondoy, the dam operators panicked and let go huge amounts of water.
The raging waters caused the overflow of rivers and creeks and flooded the towns and cities. The three dams, with the help of Ondoy’s rain could very well create the havoc that happened last weekend.
I suppose much water was also released by Pantabangan dam, which caused more flooding in Central Luzon.
ANTHROPOGENIC DISASTERS
Not only is Climate Change human-made, the effects of Climate Change are exacerbated by humans. A fairly weak storm carrying huge amounts of rain can kill hundreds of people and animals as well as destroy millions of pesos worth of properties because of careless human activities.
I hope the Ondoy experience has enlightened the country’s leaders that Climate Change adaptation or disaster risk management do not mean simple evacuation and rescue operations. They mean much much more. There should be a comprehenseive water resource mangement, water basin management, land use management, hazard mapping, etc.
Most importantly, one should use Common Sense. Do not release water from dams when there is a storm around carrying lots of precipitation.