The numbers we deal with everyday can range from the simple to the staggering. When confronted with issues concerning very large numbers, images and analogies become important tools for people to grasp and understand the issue at hand.

Recently, we brought forth the analogy of using balikbayan boxes to visualize the volume of water that fell over Northern Luzon and Pangasinan during Typhoon Pepeng. The idea of comparing the volume to a balikbayan box came in the light of giving the reporter a picture of those figures being presented.

What is 5000 cubic meters per second to a layman? As a geologist, I seek for ways to let other people understand the jargon or figures I am telling by helping them visualize these terms or processes. A balikbayan box is something that most of us are familiar with and this would help in understanding the scale of the rainfall volume and the water release at the San Roque dam.

To imagine a one cubic meter per second is to imagine approximately one balikbayan box-size of water per second. I know at the back of my mind that this was less than the actual and therefore in the more conservative side of estimating the volume. It is better to underestimate the total water volume rather than to overstate it. As such, I believe it is better than having no picture at all, especially during times when people need to visualize how huge that volume of water was. Surprisingly, some people commented that this underestimation is actually being “highly sensational.”

The example was done not to hype the amount of water that was released from the dam and the consequences of this large amount of volume, but was to help the untrained mind to imagine the volume of that water. When we talk about flooding, it is the water volume that is of interest. If that volume is too high then you can drown and your house will be flooded.

Estimation is often used in scientific practice and should not be misconstrued as being inaccurate. Lacking actual volume measurements of all the nooks and crannies of the valley and rain gauge measurements over the total period in time, one can only estimate it to the same order of magnitude. In this case, the calculation was within the same order of magnitude (a billion) and leaned toward the conservative side of things.

The figure of about a billion balikbayan boxes of water filling up Pangasinan have already shown to readers the magnitude of the event. Coupled together with the high rate of water release of the dams during its peak, it made people realize the enormity of the disaster. There were some who made an actual comparison (as compared to an order of magnitude estimation) of the actual size of a balikbayan box and the water released from the dam and ended up with around 30,000 boxes per second—something that has more “shock value” to readers.

“Tumbling down like balikbayan boxes” is actually an understatement of how water flows out of an outlet at 5000 cubic meters per second. At this rate, water does not simply “flow” calmly (laminar flow, low Reynolds number). Fluids at this high volume flow rate would be rampaging down in what is technically (and figuratively) called turbulent flow. One can actually see this with your faucet at home (if water pressure is enough). If you turn your faucet on slightly, water flows smoothly and laminar. Turn it up to its full, water would spray out turbulently.

Turbulent flow (at high Rey-nolds number) would produce random eddies, vortices and other flow instabilities. At large flow rates and at the scale of a large river such as the Agno, water would definitely be tumbling around much like balikbayan boxes falling down when 5000 cubic meters per second flows through it in addition to the contribution of the surrounding areas. One can indeed describe the river flow by “swirling floodwaters” as we noted in an earlier interview.

The question of why National Power Corp. and San Roque Power Corp. waited later in the week to release water from the dam is still relevant. Visualizing the size of the disaster whether using balikbayan boxes or other means would make us ask the correct questions and seek the correct solutions. The physical truth like the water the volume of a billion (or more) balikbayan boxes tumbling down turbulently along a river would become a political matter until we can get a clear sense of what or who failed during that time.