The Case of the Olongapo Flooding

Author: Prof. Danny Piano

The City of Olongapo was again devastated by so much flooding... one of the worst in the city’s history. Many of the houses in low-lying areas were totally submerged, roof and all. Schools converted to evacuation centers were packed full of people, with little to eat and no fresh clothes to change to. It’s a disaster of huge proportions.

The local government and other agencies will spend humongous amounts of effort and money to try to save lives and will try to provide whatever comfort it can to those who were affected. Other government agencies like the Subic Bay Metropolitan Authority (SBMA) and non-government organizations (NGOs) will do the same. The city has, in fact, already declared the city as being in a state of calamity.

The Subic Chamber, as we have done many times in the past, again started to solicit relief goods from members. Many will respond with donations, and a good number will volunteer their time to help. We will do the best we can.

But...

Olongapo City is more than 15 meters above sea level on average. That’s relatively high. But why is it that so much flooding occurs almost every year?

Is it an unavoidable hand dealt by nature? Why is it that the Central Business District (CBD) of the Subic Bay Freeport does not have as much flooding? It is, in fact, at just about the same elevation as many areas in Olongapo City.

Oh, but we already know the answer. It’s the garbage clogging the city’s waterways... partly.

The main culprit is actually the heavily silted rivers. How much of a culprit?

From a basic satellite altitude mapping that I did earlier (see below), it is obvious that the silted mouths of the two rivers coming out of Olongapo City are about 11 meters higher than what it is at the shores just beyond the Boardwalk area of the Subic Freeport.

Of course, this means these rivers no longer have the capacity to carry heavy rains. For those who are not from this area, it started after the eruption of Mt Pinatubo when so much volcanic ash and sand were deposited to just about everywhere, which eventually ended on the rivers. But, that’s some 22 years ago!

Just dredge those rivers already.

(SBFCC Newsletter Volume 18 Issue 8)