Sunday, September 29, 2013

Angat Dam break simulation study, inaccurate?

MALOLOS CITY—Inaccuracies in the conduct of feasibility study in Angat Dam could result in catastrophic event.

This is part of the of a Bulakenyo dam safety expert who conducted analysis on the six month feasibility study conducted by an international consultant for the P5.7-Billion rehabilitation of the Angat Dam.

The bidding for the rehabilitation of the dam is likely to be held before the end of the year.

Engineer Roderick Dela Cruz cited simulation conducted by Tonkin and Taylor International on possible dam break.

He said that simulation showed that towns of Pulilan, Plaridel, Baliag, Calumpit and the City of Malolos will be inundated by five to 10 meters deep flood, while in Hagonoy and Paombong, a meter deep flood will inundate both towns.

Comparing said data in two flood events in Bulacan, Dela Cruz said that the simulation on possible dam break is inaccurate.

He said that in 2011, over a meter deep flood inundated Hagonoy when Angat Dam release about 1,000 cubic meters per second (cms) of water into Angat River at the height of typhoon Pedring.

In October 1978, Hagonoy town was inundated by at six to seven feet deep flood inundated  Bulacan when Angat Dan released 5,000 cms at the height of typhoon Kading.

Based on records, Angat Dam have the capacity to store at least 800-Million cubic meters of water.

Dela Cruz said that in case of a dam break, all that water could rush out and it will not only cause five to 10 meters deep flood in the towns of Plaridel, Pulilan Calumpit and Malolos.

Based on his estimates, the Tonkin and Taylor simulation study have a 20 meter plus or minus inaccuracy.

“Its good if the outcome will result into minus 20 meter inaccuracy, but what if it is on the plus 20 meter inaccuracy,” he said noting that abovementioned town will be inundated by at 25 to 30 meter deep flood.

As a dam safety expert managing 82 dams in the United States, Dela Cruz stressed that providing accurate data in preparation for disaster is crucial.

This is due to the fact that people depends on information government by officials, and prepare themselves based on it.

“What if people prepare for a 10 meter deep flood, when a 20 meter flood is coming, they will have nowhere to go,” he said.

Dela Cruz also scored the lack of site specific seismic study on the Angat Dam.

“I understand their situation, they were given six months to conduct a feasibility study,” he said noting that the time given is just not enough for a more comprehensive study on the dam.

With regards to country’s preparedness on possible dam break, he said that the country still have no national dam safety program or an approve dam safety law.

He said that the Philippines is the only country in Southeast Asia that still do not have a dam safety legislation.

Earlier this year, Vietnam passed their own version of dam safety law.

Dela Cruz said that lack a national dam safety program increases risk of dam failure in the country.

This is due to the absence of available financing for the maintenance, upgrades and repairs of dam structures, along with lack of single accountable authority on dam safety.

He also said that it also entails lack of emergency preparedness and public awareness on how to deal with possibilities  dam break.  Dino Balabo