A do-it-yourself flood-warning system

MANILA – It is possible for ordinary citizens to predict oncoming floods using a low-cost, do-it-yourself gadget.

This is according to Dr. Carlos Arcilla, Director of the National Institute for Geological Sciences (NIGS) at the University of the Philippines- Diliman.

Arcilla appeared in a Senate Hearing on Wednesday to discuss how citizens can construct a simple rain gauge that can help them determine whether there is a likelihood of floods or landslides in their area, based on the amount of rainfall during a specific period of time (rain rate).

The rain gauge is essentially made up of a measuring stick placed inside a cylindrical tube that is propped up by 3 metal legs so it will not tip over easily.

The measuring stick is used to measure, in millimeters, the volume of rain collected inside the tube at a certain period of time, ranging from 30 minutes to 1 hour. Arcilla said people can even use a sardine can as a rain gauge.

“The important thing is to know the concept of rain rate,” Arcilla said in an interview on ANC’s On The Scene on Wednesday.

Essentially, if the tube or can fills up with a lot of water too fast, this is a warning that citizens need to evacuate.

A high amount of rainfall in a short period of time means that water in the soil (watershed), dams, and rivers may overflow, hence, causing floods.

Arcilla said that tropical storm Ondoy, for example, brought 600 millimeters of rain in “a very short period of time.” This is equivalent to one month of rain volume falling in just one day.

“So even if there were no dams, even if there were no trees, even if there were no ‘esteros’, the watershed drainage basin (an area of land that contributes water to a stream or river) can only accommodate so much rain, so it will really flood,” Arcilla said.

Empowering

Dr. Carlos Arcilla sits next to a simple rain gauge on ANC’s On The Scene.

Since there is a time gap between the onset of rain and resulting floods, an early-warning system like the rain gauge can give people time to evacuate.

“I’m confident you can have at least 1 to 3 hours, maybe even more, depending on where you are in the area. It saves you hours and hours, and that’s important in a flood situation,” he said.

“In fact, my colleague Dr. [Carlos Primo] David said it was 5 to 6 hours before big water came in during ‘Ondoy.’ If people were instructed on [the rain gauge], then they could have left before the flood rose,” Arcilla added.

Improved rain gauges can also feature transparent tubes so that the rise in water is easy to see.

People can even place a small colored ball on the surface of the water to gauge how fast the water rises inside the tube.

Arcilla said the beauty of the rain gauge is that it is very cheap and easy to use.

NIGS professors are reportedly willing to issue instructions on how to build and use a rain gauge for interested citizens, local government units, or non-government organizations.

Arcilla said people can also be educated on how to tell whether a certain amount of rain will cause a landslide or flood.

There are different amounts of rain that have proven to cause landslides or floods called “threshold values.”

These approximate threshold values, developed through years of studies, also vary according to how prone an area is to landslides or floods.

Still need advanced equipment

The UP NIGS has also developed other low-cost flood-warning systems like a device that can send flood warnings to cellphones. (See story “UP scientists inventing flood warning systems”)

Despite the ability of Filipino scientists to develop cheaper disaster-warning systems, Arcilla said the country still needs expensive equipment like doppler radars because they serve as “first-line defenses.”

“Doppler radars are extremely necessary because we need to see the amount of rain that they bring. The rain gauge covers a small area. But the doppler covers a big area,” he said.

Arcilla also said the Philippines needs more updated topographical data, which can help scientists predict the movement and occurrence of floods through computer software.

These, however, are expensive to produce.

For now, Arcilla said the public could do well with do-it-yourself flood-warning devices like the rain gauge. “Additional information never hurt anyone,” he said. –Kristine Servando, abs-cbnNEWS.com/Newsbreak