The P1-billion allocation for Nationwide Operational Assessment of Hazards (NOAH) will allow scientists to test proposed flood-control measures through computer simulations before the government commits money to construction, University of the Philippines Resilience Institute Executive Director Mahar Lagmay said Thursday.

Lagmay said the goal is to make flood-management spending more evidence-based by determining in advance how proposed infrastructure would affect water levels and whether it would deliver enough benefits to justify its cost.

“We want to simulate and find out what the results would be even before we start the project,” Lagmay said. “And that is what UPRI-NOAH can do.”

The approach comes as the Philippines grapples with recurring flooding and other hazards that are being compounded by climate change. Lagmay said the country must prepare not only for floods but also for storm surges, landslides, earthquakes, volcanic hazards, subsidence and debris flows.

“Hazards will always happen here in the Philippines, but if you are smart in handling nature, we'll be able to prevent disasters from happening,” he said.

Mapping the problem 

For NOAH, that starts with improving the country's understanding of where hazards occur.

The program plans to produce high-resolution maps of major river basins, with resolution of up to 1 meter by 1 meter. The maps will contain detailed information on waterways, floodplains, land use, infrastructure and communities.

Lagmay said the higher-resolution data would allow planners to see flooding at a much more localized level, including which roads and communities are likely to be inundated.

“You cannot find a solution if you do not understand the problem,” he said.

That detailed picture then feeds into the next step: determining what can actually be done about the risk.

The institute plans to use one- and two-dimensional hydraulic models to simulate how water moves through watersheds, including surface runoff and underground drainage. The models can be used to assess proposed pump stations, drainage systems and detention basins and their effects upstream and downstream.

Lagmay said the simulations can help agencies decide whether an intervention will reduce flood levels before construction begins.

“Para hindi nasasayang yung pera, kaya natin tingnan,” he said. “Kaya natin i-simulate so that we know our investments yield the best benefit cost ratio.”

Looking beyond a single city

Testing individual projects, however, is not enough if water is considered only within political boundaries, Lagmay said.

Floodwaters move across municipalities and cities, so flood-management plans must consider the entire watershed, from the mountains to the sea.

“Floods do not recognize administrative boundaries. If you do infrastructure in one place, the water transfers to another place,’ Lagmay said.

That principle is central to NOAH's planned work with the Department of Public Works and Highways, the Metropolitan Manila Development Authority and local governments under Oplan Kontra Baha. 

The program will combine watershed science, flood modeling, terrain data, infrastructure information and local knowledge to identify appropriate interventions.

The approach is meant to prevent a situation in which a project protects one area while worsening flooding elsewhere.

Lagmay said the institute wants proposed projects to be evaluated as part of a larger system rather than as stand-alone structures.

Concrete is not the only answer

That broader approach also changes how flood solutions are considered.

Lagmay said government should not automatically turn to dikes and other concrete structures whenever flooding occurs. Natural systems can also absorb, store or slow water, potentially reducing the pressure on built infrastructure.

The NOAH plan includes restoring wetlands and floodplains, expanding urban green spaces, using permeable surfaces and planting trees as complementary flood-management measures.

Lagmay cited detention basins as another option. In urban areas, spaces such as basketball courts could potentially be designed to temporarily hold excess water before releasing it.

“We have to be smart about these things,” he said.

The objective, he said, is not to promise that flooding can be eliminated, but to reduce its depth and impact.

“We cannot totally eradicate the floods kasi hindi tayo mas magaling sa kalikasan,” Lagmay said. “But we can lower it so that yung pasakit sa community, yung pasakit sa mga tao ay hindi ganun ka grabe.”

But even the best flood model can miss part of the picture if it does not account for waterways that have disappeared from maps.

Finding the waterways cities lost

NOAH will also map buried, diverted and undocumented waterways, which can serve as drainage paths during periods of heavy rain.

Lagmay said some of these waterways may appear insignificant or remain dry during the summer but can carry large volumes of water during the rainy season. Building over or obstructing such paths can contribute to flooding.

The institute's plan says mapping these waterways will improve flood modeling and guide urban planning, drainage improvements, infrastructure design and emergency response.

This mapping can also reveal why some areas repeatedly flood despite drainage or flood-control projects, Lagmay said.

Understanding those natural drainage pathways is particularly important as cities continue to develop and more surfaces become impermeable, reducing the amount of rainfall that can soak into the ground.

From maps to drones and AI

Producing and updating that level of detail will require more than conventional surveys.

Lagmay said half of the P1-billion allocation would be used for equipment, including LiDAR-equipped drones that can rapidly map terrain.

The equipment will be distributed to state universities and colleges, allowing them to conduct surveys and update hazard maps in their regions. The program also includes training for faculty, researchers and students.

The same technology can be used for environmental monitoring beyond flood hazards.

NOAH plans to map native trees and assess sediment erosion and delivery. The information can be used for watershed protection, ecological restoration and flood management, while sediment assessments can identify potential impacts on waterways and drainage infrastructure.

AI will be used to process the resulting large datasets and develop decision-support tools for land-use planning, infrastructure decisions and risk assessment. The plan also calls for AI-assisted benefit-cost assessments to help officials compare proposed interventions.

The technology, however, is only useful if the resulting information reaches the people making decisions — and those affected by them.

Turning science into decisions

Lagmay said the institute's work is not simply to produce scientific papers or maps but to ensure that research is incorporated into government planning.

“It is not enough that we only use science and engineering and technologies to address our problems of disasters,” he said. “We need to communicate better so that the people can understand better what the science tells us we should do.”

That means involving social scientists and communities, particularly when decisions concern land use and development.

The institute's plan calls for scientific information to be incorporated into local planning and for stakeholders to be consulted in affected communities.

For Lagmay, that is part of a larger shift in how the country approaches disasters: from trying to control nature to managing the risks it creates.

The P1-billion allocation, he said, should ultimately help government make fewer decisions based on assumptions and more decisions based on evidence.

“We can't just spend and spend and spend na tantsa lang ng tantsa,” Lagmay said. “We have to be smart about it. We have to be evidence-based. We have to use science.”