Iloilo City flooding: submerged outfalls, old drainage blamed

By Rjay Zuriaga Castor

ILOILO CITY – Intense rainfall overwhelmed Iloilo City’s drainage and waterway systems Monday night, Aug. 17, with submerged outfalls, clogged waterways, aging drainage lines, and structures blocking creeks worsening floods in 65 barangays.

The rains, enhanced by the southwest monsoon, averaged 70 millimeters per hour and accumulated up to 165 millimeters within six hours, according to the Iloilo City Emergency Operations Center (OpCen).

Floodwaters had subsided in 14 barangays as of 2 p.m. Tuesday, Aug. 18, leaving 51 still inundated.

Jaro recorded the highest number of affected barangays at 25, with some areas experiencing chest-deep flooding.

Floodwaters in Barangay Calubihan reached 19 to 37 inches, while water levels in Barangay Sambag rose to as high as 50 inches.

The OpCen reported that flooding affected 1,056 families, or 3,216 individuals, in 17 barangays.

Of these, 517 families, or 1,679 individuals, evacuated.

The evacuees came from 13 barangays in Jaro and four in Mandurriao.

City Engineer Mavi Gustilo said one major problem was that drainage outfalls could not discharge water into creeks once creek levels rose above the outfalls.

Several barangays have drainage outfalls leading to creeks, but these become submerged when creek water levels rise, effectively preventing discharge, as happened in Barangay Calubihan, Gustilo said.

“The water level in the creek rose very high. For example, in Dungon Creek, the water level was so high that the outfall connecting to the barangay was submerged. As a result, water could no longer be discharged because the creek level was already high,” she explained.

For Calubihan, Gustilo said slope protection should be installed along the creek and floodgates should be placed on outfalls prone to submersion.

“The submerged outfalls should have floodgates that automatically close when the water level rises. This would prevent the outfalls from being submerged and prevent water from flowing back into the barangay,” she said.

However, she said floodgates would also require pumping systems to remove water from the barangay once the gates are closed.

“If we install floodgates, we also need to pump the water out. These are the principles we need to consider. This is the same principle we have adopted in the City Proper district and in areas with large creeks connected to the Iloilo River,” she said.

Gustilo also pointed to the large volume of garbage and tree debris in waterways as another factor contributing to the flooding.

“We are dredging waterways and declogging them because of the waste. Aside from the garbage, tree branches also need to be trimmed. We are considering requesting the Department of Public Works and Highways to deploy dredging equipment so we can address the severe flooding in Calubihan,” she said.

Gustilo said the city’s existing drainage facilities also need upgrades because they can no longer handle the volume of water generated by intense rainfall.

“Our existing drainage system needs to be upgraded because it can no longer handle the volume of water brought by intense rainfall. Our existing drainage system is no longer sufficient,” she said.

She noted that the city government already conducted declogging operations in La Paz, particularly at the junction near the La Paz Public Market, improving water flow in surrounding areas.

However, Gustilo said structures near waterways still impede water flow.

She cited informal settlers near the outfall close to Esplanade 9, as well as concrete bridges along Rizal Creek.

“The water can no longer pass through. When the water overflows, it flows back. If they had only installed a flat slab, the water would continue flowing even when it overflowed, but they put up a wall,” she said.

“That is why we saw that even after we declogged the area, the flow of water remained slow,” she added.

Gustilo said the city engineering office would discuss improvements to creek management regulations and policies with relevant government agencies.

She added that the city’s comprehensive drainage plan remains at the feasibility study stage.

Rizal Creek, one of the waterways Gustilo cited, was among the first dredged under the national Oplan Kontra Baha program, which began operations there in April. The Department of Public Works and Highways (DPWH), the city government, and the Philippine Institute of Civil Engineers Iloilo Chapter, which Gustilo heads, lead the program. She also chairs the Iloilo City Drainage Task Force.

The cost of a permanent fix has been documented for years. The 2017 Iloilo City Comprehensive Drainage Plan estimated that PHP 6.2 billion was needed to complete the city’s flood mitigation program.

Beyond that, the city needs PHP 14 billion to complete Phase II of the Japan International Cooperation Agency plan, which produced the 4.75-kilometer Jaro Floodway, and PHP 7.8 billion to fully implement the Iloilo City Comprehensive Flood Control Master Plan.

Funding has moved in the opposite direction. President Ferdinand Marcos Jr. removed allocations for 2026 flood control projects under the proposed national budget, a decision Iloilo City Lone District Rep. Julienne Baronda said cost the city roughly PHP 500 million under the National Expenditure Program.