ALTHOUGH Davao City has passed an ordinance on land use plan and zoning, which has now become a basis for granting permits for developments, either for residential, industrial, or commercial, damage has been done.
The developments' ill effects, caused by poor planning and management in the past, are now being reaped by the Dabawenyos. Even with sudden but brief heavy downpours, the city's streets already get soaked and some barangays are submerged in flood waters.
Environmental and Urban Planner Lemuel Manalo said among the reasons why this is so is because the drainage systems that were designed and constructed were not compatible or did not have the same capacity to hold the huge volume of water as the natural wetlands or marshlands before.
"In this case, no matter how much drainage improvement works, it wouldn't solve the flooding problem," Manalo said on the Jade Valley flooding incident.
The City Disaster Risk Reduction Management Office (CDRRMO) has also observed that areas in Davao City that are not usually flooded have, most likely, become a small catch basin, which is why they experienced severe floodings when the recent heavy downpour occurred.
CDRRMO Operations Assistant Ezzra James Fernandez said that barangays in the city that experienced urban and street flooding are Matina Aplaya, Talomo Proper, Bago Gallera, Maa, Catalunan Pequeño, Baliok, and Sto. Nino, while areas affected by street flooding are Matina Crossing, along McArthur Highway, Dumoy, Barangay Bucana, and Matina Aplaya.
Another urban planner and world-renowned architect Felino "Jun" A. Palafox, Jr. reiterated Manalo's findings during his company's 35th anniversary celebration and launching of its architecture, design, and planning advocacy principle — “Philippines 2050: A First-World Country, A First-World Economy.”
"Because the city's drainage system is undersized; 75% of our drainage system is undersized," he said during a media interview after the event, adding that most of the country's drainage system and flood control system was designed mostly for 25 typhoons when the Philippines now is already being visited by more than 100 typhoons.
"Because it seems drainage systems and flood-control management are not the priority of our government," Palafox observed.
He added that there should also be a ridge-to-reef plan.
"From the top of the mountains, the highlands, the middle lands, the low lands, and the coastlines, the reef, what is happening now is subdivisions have been approved in the hillside of the mountains, so the forests are denuded, there's more run off of floodwaters that are going to the cities and our drainage system has become more silted," he said.
He also shared Manalo's idea that the grassy portions of Davao City are now concreted, which greatly contributed to the flooding
In 2022, SunStar Davao reported that a major flood-control project to help address the persistent flooding problem in the La Verna Hills Subdivision in Buhangin District and its surrounding areas was being constructed.
Department of Public Works and Highways-Davao spokesperson Dean Ortiz said during that time that the retarding basin being constructed at the La Verna Outfall section would be a long-term solution to the flooding.
“This is what we have thought of as the best solution for the problem. If not to address the problem, at least to minimize the incident of flooding, not only didto sa (in) Diversion Road but didto sa (also its) immediate areas niya,” Ortiz said.
A retarding basin is described as an open-pit infrastructure that is used to "temporarily store rainwater run-off during heavy rainfall, to absorb and contain flooding during the event of heavy rains, which will be later released at a regulated flow rate".
The size of the retarding basin in La Verna is larger than a basketball court, according to the same report and the initial cost of the construction of the project was P297 million.
This project is part of the City Government’s P2-billion infrastructure investment to address the flooding problem in various areas in Davao City, which includes a P507-million flood-control project in Sasa Creek Drainage Area that is proposed funding by the Japan International Cooperation Agency (Jica).
However, the DPWH has yet to give updates on this project. It can be noted that according to its contract, the project should have been completed 545 days from the date of contract signing between the DPWH and the construction firm, which was in April of 2022.
Giving wetlands priority
Meantime, both the urban planners agree that nothing's too late for Davao City. For Manalo, reviving wetlands in Davao City, no matter how challenging it may be, is one that he sees as the most effective way to mitigate floods.
He compared Davao City to Singapore where the state city put extra priority on reviving its wetlands, even crafting a so-called "Rejuvenating Wetlands" program, to focus its fund allocation more on the program.
When asked if it's possible in Davao city, Manalo said: "Yes! Possible kaayo kay pag-secure lang sa wetlands gamay lang ang gastuson kay sa pag improve sa drainage system (Yes, it's very possible because the cost of securing wetlands in the city would be much lesser compared to improving our drainage system)."
He said buying the property titles of the existing wetlands in the city from their owners would be cheaper than the cost of reconstructing the drainage system to an ideal one.
He revealed that there are still a lot of undeveloped properties that are found to be wetlands with existing ecosystems thriving in the city and these are threatened to be developed if the government does not move fast.
"Kung ma-preserve ni nga mga wetlands and kalutan pa sila aron maka-store pa sila'g mas daghang water, aron ma-delay nila ang water nga mag-pass through sa baba, then dili kaayo unta ta bahaon (If these wetlands would be preserved and excavated even deeper so that they could store more water to delay the water to pass to low lying areas, then we may not experience flooding)," he said.
He added that the city government could also use wetlands as parks.
"Additional siya nga green space para sa recreational use (It's an additional green space for recreational use), we call that flood parks," he said explaining that these kind of parks are usually flooded when there is continuous rain, but can also be utilized for other purposes during dry season.
In Davao City's Comprehensive Land Use Plan for 2019-2028 - Zoning Ordinance, the city is divided into zones or districts where mangroves, rivers, creeks, and lakes, and wetlands belong to the Protection Water Sub-Zone.
Palafox, however, did not discuss the city's rivers as he admitted that he doesn't know much about them. Still, he advised that rivers should always be included in engineering, transportation, drainage system studies, and flood-control management studies, among others, and they are willing to be commissioned for these.
When asked if there is a concrete solution to the flooding problem in Davao City, Palafox wittily answered: "They know the problems, they would know the solutions!" CEA