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Thursday, August 16, 2012

Metro Manila threatened by 220 million swimming pools of floodwaters

By Tony Lopez

Like history, nature repeats itself. The massive flooding of Sept. 26, 2009 brought about by typhoon Ondoy (Ketsana) was the worst to hit Luzon in 80 years. On that day, a Saturday, nearly, one month’s volume of rainfall – more than 400mm per hour—poured in just six hours on Metro Manila and nearby provinces. Damage caused: More than P207 billion.

Experts predicted Ondoy would repeat itself. Indeed, it did, so soon, this year, last August 6, 7 and 8, 2012.

Habagat, southwest monsoon, was not a typhoon. But it poured rainfall equivalent to a month’s volume of rain—323 mm in the first 24 hours alone, from August 6 (Monday) to August 7 (Tuesday).

A reporter in the morning of August 7 asked President Aquino about the fact that 50 percent of Metro Manila was already flooded. The President bristled at the hapless reporter for being negative.

As it turns out, not just 50 percent, but 80 percent of Metro Manila was flooded. And not just the national capital was inundated.

Region III (Central Luzon) and Region IV-A (Southern Luzon) were equally flooded. Habagat also devastated Northern Luzon.

In sum, Habagat affected 3.74 million people or 825,018 families in 173 towns, 36 cities, in 16 provinces and six regions – Regions I (Ilocos), III (Central Luzon), IV-A (Southern Luzon), IV-B (Mindoro), VI (Western Visayas), and NCR. Almost a million were evacuated. At least 95 died. A total of 8,709 houses were damaged – 3,000 of them totally. About 41 cities/towns are in state of calamity. For three days, schools, businesses, and the government ground to a halt.

As of Aug. 14, according to the National Disaster Risk Reduction and Management Center (NDRRMC), 11 roads and three bridges remain impassable to all types of vehicles in Regions I, III, IV-A and CAR (Cordillera) due to flooding, landslide, and road cut.

As of Aug 13 8 pm., five dams – Angat, Ipo, Ambuklao, Binga and San Roque continued to spill overflow water, inundating ten towns in Pangasinan, as well as areas near Angat, Ipo, Ambuklao, Binga and San Roque.

Total damage to infra and agriculture in Regions I, III, IV-A, IV-B and the NCR: P2.263 billion – P639 million to infra and P1.624 billion to agriculture. Metro Manila and 16 provinces ground to a halt with the closure of schools and businesses and even government offices for three days.

Metro Manila and Southern Luzon accounts for 66 percent of the country’s production of goods and services or GDP. Our GDP is P10 trillion. Divide that by 365 and you get a daily GDP of P27.39 million.

Multiply that by three days and you get P82 billion damage. Multiply P82 billion by .66 and you get P54 billion caused by Habagat for just three days in Metro Manila and Southern Luzon.

Typhoon Ondoy devastated basically the same regions in just one day. Total damage eventually in Ondoy 2009, according to the World Bank: P207 billion.

The irony was that there was not even a typhoon this August. There was only the southwest monsoon (Habagat) whose rains were hauled in and enhanced by typhoon Haikui as it left the Philippines and roared toward eastern China.

In Metro Manila and nearby provinces, more than 400mm of rain per hour fell in 24 hours, from 8 am of August 7 to 8 am of August 8. By the third day, rainfall of more than 1,200 mm had accumulated in places like Sangley Point in Cavite, west of Manila. The result was massive flooding.

“It was Ondoy all over again,” cried businessman Rudy Pua, whose Wonder Island resort lies in the middle of 90,000-hectare Laguna Lake.

“The waters rose more than 12 feet,” Pua said. In the 2009 inundation, he recalls, “the lake water rose more than 13 feet and took three months until December to normalize.” This time, Pua sees a worsening “because we are entering the typhoon season.”

The mayor of a coastal Pam-panga town said “the flood was worse than Ondoy.” With more than 500,000 displaced, entire Pampanga was in a state of calamity, as were Bataan, Zam-bales, Bulacan and Laguna.

The national capital and provinces in Luzon north of Manila, like Bulacan and Pampanga, are hemmed in by two large bodies of water—Manila Bay in the west and Laguna Lake east of the bay. In turn, 19 rivers drain water into Laguna Lake. They are connected by just one large river, Pasig River, which in turn is linked to Marikina River.

When Laguna Lake overflows, floodwaters, in theory, should flow to Manila Bay. Laguna Lake used to be more than 10 meters deep. It is the largest inland body of water in the Philippines. Its watershed spans 14 cities and 47 towns located in the whole province of Laguna and Rizal, and in parts of Batangas, Cavite and Quezon and Metro Manila.

With an area of 90,000 hectares, it used to be that Laguna Lake could take ten billion cubic meters of water.

Today, the lake is only 2.5 meters deep. At a depth of 2.5 meters, the lake could hold just a fourth of its potential capacity, 2.25 billion cubic meters.

In heavy rainfall, especially in a short span of time, the water does not rush to Manila Bay. Instead, it stays put in Laguna Lake and then spills into Pasig River and Marikina River and has nowhere to go.

Think of more than 7 billion cubic meters of water—the equivalent of 220 million swimming pools—swirling around an area bigger than the size of Singapore, for two to three days. That is the flood situation created by Ondoy 2009 and Habagat August 2012.

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