Why Lando caused massive flooding — and why threat isn't over yet

Of 32 barangays in Cabanatuan City in Nueva Ecija, only 25 have been identified as flood-prone. The remaining seven barely experienced flooding in recent years because they are situated in an elevated area.

 

But on Sunday, residents were surprised when the city experienced massive flooding, with some areas experiencing waters almost reaching their rooftops.

 

PAGASA could not obtain the rainfall amount in Nueva Ecija since their monitoring stations in the province were also affected by the typhoon. 

 

But the tropical cyclone brought intense amounts of rain in other areas, with the state weather bureau recording about half of the normal rainfall amount for the month of October, a report on GMA-7's "24 Oras" said on Monday. 

 

Normal rainfall amount for the month of October: 

 

Lando rainfall amount from October 17, 8 a.m. - October 19, 8 a.m. 

 

According to geologist CP David, Typhoon Lando's pace had a lot to contribute to the flooding in many parts of Luzon. 

 

"The slow movement of Lando caused areas within its inner rainbands to be subjected to prolonged rain, as opposed to a fast moving typhoon where heavy rain is only experienced over three to six hours," he told GMA News Online. 

 

Aside from the amount of rainfall, Cabanatuan City's location also made it susceptible to flooding. 

 

"Cabanatuan is along the path of upstream Pampanga River and is one of the first towns after the mountainous area of Gabaldon, where a lot of rain fell," he added. 

 

This was further explained by Project NOAH executive director Dr. Mahar Lagmay in a television interview. 

 

"There was a lot of rain in the mountains of Aurora and Sierra Madre and those rains drained into the network of streams and rivers, flooding Gabaldon, Laur, Bongabon," he said. 

 

The rainwater then flowed to other parts of Nueva Ecija such as Cabanatuan City as well as Bulacan. 

 

Floods without heavy rains

 

This meant that some areas experienced severe flooding despite the fact that these places did not get heavy rains.

 

Candaba town in Pampanga saw 24 barangays flooded in the municipality, with mayor Rene Maglanque saying the waters came from Aurora, Nueva Ecija and Bulacan.

 

Among the barangays that were flooded include those around the Pampanga River and the Candaba swamp.

 

Cagayan province is also bearing the brunt of the tropical cyclone, with 15 of its 28 towns flooded, according to the Provincial Disaster Risk and Reduction Management Council, even though Lando did not hit it directly.

 

"Kami ang may pinakamaraming municipalities na lubog sa baha," said Cagayan PDRRMC officer Bon Cuartero.

 

Because of runoff water caused by heavy rains brought on by Lando over the Sierra Madre mountains, even places that usually did not flood became inundated.

 

President Benigno Aquino III, who went to Nueva Ecija to distribute relief goods, said on Monday that the effects of the typhoon will be felt for about three more days. Moreover, rainwater will likely to start to come down from higher ground.

 

"The challenge with a lot of our countrymen ‎is that, they don't seem to see the amount of rain that is pouring. They think it is safe already to go back to their communities but we are preventing them right now because the expectations from tonight and after tomorrow," Aquino added.

 

"A lot of this rainfall that fell on the northern portion of Luzon will be coming down and will be affecting all of these barangays near the major river systems." —JST, GMA News