Guide to Marikina River’s alarm level system

(Editor’s Note: This story was first published on September 12, 2017.)

MANILA, Philippines – When heavy rain hits Metro Manila, the water level along the Marikina River is one of the things closely monitored by local officials.

In the past, the bursting of the river banks not only caused massive flooding in Marikina City and other parts of Metro Manila but also displaced hundreds of families living near the river.

According to the Metropolitan Manila Development Authority (MMDA), water from the Marikina River flows to the Pasig River and Laguna de Bay when it rains. When areas around the Marikina River experience flooding, the floodwater also flows to other parts of Metro Manila.

To prevent heavy flooding in Metro Manila, the MMDA would directly divert water to the Laguna de Bay through the Manggahan Floodway. 

Marikina City has a three-stage alarm level system for the Marikina River, based on the depth of water in the river below the Sto. Niño Bridge:

• Alarm Level 1: when the water is 15 meters above sea level, means “prepare”
• Alarm Level 2: when the water is 16 meters above sea level, means “evacuate”
• Alarm Level 3: when the water is 18 meters above sea level, means “forced evacuation”

Monitoring

There are at least two river monitoring sensors from the Department of Science Technology along the Marikina River to forecast and monitor flooding. The sensors are installed at the Tumana Bridge and the Sto. Niño Bridge. These sensors are able to “accurately measure and determine the floodwaters in real time.”

When the river’s water level rises, the local disaster risk reduction and management office in Marikina uses a siren to alert surrounding communities of the current alarm level. 

The 27-kilometer river connects to a number of tributary waterways which drain into four municipalities and one city in Rizal province, and three cities in Metro Manila. – Laurice Angeles/Rappler.com