Monterrazas developer: Lapses in flood control

CEBU, Philippines - The developer of Monterrazas de Cebu in the upland area of Cebu City has admitted lapses in the implementation of flood mitigating measures.

But these measures will be part of the plan which will soon take place.

During a public hearing yesterday, representatives of Genvi Development Corporation presented to the City Council a flood mitigation plan.

The measure is designed to minimize, if not prevent, the water coming from the mountains down to the lowlands.

Engineer Ting Agbisit, vice president for engineering of Genvi Development Corp and project director of Moterrazas de Cebu, admitted that the development of Monterrazas lessens the infiltration of water.

He said the water in the project area in Barangay Guadalupe was supposed to be absorbed by the soil but has found its way down.

“That’s why there are detention ponds. Even before the July 20 flooding, we have already constructed detention ponds and before that, there are temporary silt ponds,” Agbisit said.

Detention ponds or detention basins are supposed to trap the runoff caused by impenetrable surfaces such as constructed roads.

But the flood mitigation does not end in the construction of detention ponds.

Ting said the water should go to natural tributaries, in this case, to the Grand Legacy Road in Guadalupe where they plan to put a parallel drainage system.

Interceptors will be installed below detention ponds which will be connected to a parallel drainage system that will allow the water to escape to the rivers.

However, this brings to another problem as some subdivisions are not willing to allow the developer to connect to their drainage system.

Genvi believes that even if it develops the drainage system within the Monterrazas property, there is always a tendency of a runoff that may cause flooding if there are no offsite drainages to connect.

Aside from more detention ponds and temporary silt ponds, Genvi promised to implement vegetation with cocomat in certain portions of the 210-hectare lot and construct interceptor drains and swale canals.

Genvi also believes that the July 20 heavy flooding in the barangays of Guadalupe and Tisa caused not mainly by the upland development but by the natural phenomena.

Forestry Management Bureau Regional Technical Director Isabelo Montejo confirmed that the rainfall intensity last July 20 reached 300 millimeters, more than the usual 100 to 150 millimeters.

Montejo said there has been a consistent increase in the rainfall intensity due to climate change, thus flooding, aggravated by developments, is expected.

Montejo said the number one cause of flooding is land conversion where natural sinkholes were destroyed, which also disrupts the natural process of recharging of water table.

He said the city government must start reviewing its land use plan to prevent further damage to the environment.

But everything still boils down to having a Comprehensive Master Drainage Plan as a long-term solution to urban flooding.

The drainage plan must also consider the development in the upland areas which usually takes all the blame whenever flooding hits the lowland areas.

Joseph Michael Espina, dean of the College of Architecture of the University of San Carlos, said the recent flooding is caused by the limited and inadequate planning.

Espina said when the existing drainage system was constructed, developments in the upland areas were not considered.

“New subdivision developments along the foothills of Cebu may contribute more volume of drainage water downhill but the existing drainage system at the lower portions are not designed and prepared to accept the added volume. As a matter of course, it should be the responsibility of the city to provide for such drainage improvements especially if it has issued permits for these new subdivisions,” Espina said. — (FREEMAN)