Manggahan ‘encroachment’ blamed for Marikina River swelling

Marikina City vice mayor Dr. Jose Fabian Cadiz on Wednesday pinned the blame for the excessive swelling of the Marikina River to the narrowing Manggahan Floodway.

 

The Manggahan Floodway is an artificial waterway built in 1986 to prevent the Pasig River from overflowing by diverting water from the Marikina River toward the Laguna Lake. 

 

However, the floodway's 260-meter width and 2,400-cubic-meters-per-second water capacity had been dramatically reduced by encroachments from illegal settlers residing on the floodway's banks.

 

"Maraming encroachment along Marikina River [at Manggahan Floodway portion] kaya kami ay nalulungkot at pinapayagan ito," Cadiz said in an interview on GMA News TV's News To Go.

 

"Kami ang naapektuhan... kami ang nagsasakripisyo dito. Grabe, grabe ho," the vice mayor added.

 

In comparison, the Marikina River is 100 meters wide, while the floodway's width had been reduced to just 30 meters, Cadiz said.

 

As for the depth, Cadiz said that the floodway - located in Pasig City - has also become shallower over time.

 

"Ang lalim ng ilog sa Marikina ay 4 meters average. Doon sa Manggahan, noong minsan bumisita ako doon, nabalahok ang aming outboard motor. Ako ay tumalon sa tubig, hanggang dibdib ko lang ang tubig doon," Cadiz recounted.

 

Cadiz claimed that the floodway's water-carrying capacity had been reduced around two thirds.

 

"Kung 3,000 cms ang capacity, doon sa pagkiot na iyan, baka 1,000 cms na lang. Nawala ang 70 percent water carrying capacity ng Marikina sa lugar na iyon downstream," he added.

 

"By law of nature, from the source of the river, makitid iyan pero as it recieves tributaries from other water sources, dapat lumalapad na iyan. Eh baliktad ang nangyayari. Malapad sa amin pero downstream kumitid," said Cadiz. 

 

He described a "funnel-like" scenario where water rushing down from the mountains of Rizal and into the wide Marikina River makes its way to a much narrower portion of the river where the floodway is located.

 

Cadiz said that while the water level at the Marikina River rose by as much as 8 meters due to the continuous monsoon rains, the water level at the Manggahan River only rose by a meter.

 

"Ipaglalaban namin ito. Hindi puwedeng mangyari ito. Kailangan magkaroon ng concerted effort diyan. We cannot police the entire stretch of the Marikina River. Ipaglalaban po namin ito," Cadiz insisted.

 

Aside from re-widening the Manggahan Floodway and clearing it of illegal settlers, Cadiz said dredging operations and the construction of retaining dams could also help prevent the Marikina river from excessively swelling. — DVM, GMA News