NMIA Flood Mitigation Backed by Multi-Year Studies

San Miguel Aerocity Inc. (SMAI), developer of the New Manila International Airport (NMIA) in Bulacan, said the project incorporates long-term flood mitigation measures based on multi-year hydrological studies, engineering assessments and climate projections.

SMAI issued the clarification amid claims circulating online linking NMIA to recent flooding following weeks of heavy rains. The company said the claims have not been supported by hydrological data, technical analysis or identified experts establishing a direct connection between the airport project and flooding in Bulacan.

“NMIA did not cause Bulacan’s flooding. This is a problem the province has had to contend with for many generations. Our responsibility is to make sure the airport is built for these conditions, and that its development does not make flooding in the province worse,” SMAI said.

Flooding in Bulacan predates NMIA by decades and results from multiple factors, including its low-lying geography, heavy rainfall, upstream river flows, limited river capacity and land subsidence. Rising sea levels and continuing development are adding further pressure to the province’s interconnected watershed.

Studies shaped airport design

SMAI said flood mitigation studies for NMIA began as early as 2018 with Danish engineering firm DHI, which conducted hydrological modeling of surrounding rivers and coastal waters, historical typhoons and storm surges, land subsidence, and the potential effects of raising the airport site on drainage and flood levels in surrounding communities.

A 2019 DHI river flood assessment and broader Bulacan flood mitigation study identified the need for an engineered channel to improve water flow and mitigate flooding risks associated with the airport.

In 2021, UK-based engineering firm Mott MacDonald consolidated DHI’s models and baseline data to align the project with international lender requirements, including the environmental and social performance standards of the International Finance Corporation (IFC).

SMAI said long-term subsidence data and climate-change projections through 2100 led to the determination that the airport platform should be raised to between 3.85 meters and 5.50 meters above mean sea level, with higher elevations toward the center.

During the transition to construction, Dutch marine engineering firm Boskalis and DHI developed an alternative to extensive river widening, taking into account land constraints and mangrove areas.

The approach involved deepening riverbeds while narrowing their bottom width to achieve target flows in three major waterways around the airport: the Maycapiz-Taliptip or Alipit River, Santa Maria River and Meycauayan River.

SMC expands river cleanup

From 2022 to 2024, San Miguel Corporation (SMC), through its Better Rivers PH initiative, removed more than 1 million metric tons of silt and waste from the three rivers.

SMC said the work, undertaken at no cost to government, increased the capacity of waterways that had been heavily silted and shallow, improving their ability to carry upstream water toward Manila Bay.

The cleanup has since expanded across Bulacan. As of Aug. 18, 2026, SMC said it had removed more than 4.3 million metric tons of silt and waste from rivers in Bulakan, Bocaue, Guiguinto, Balagtas, Malolos, Obando, Meycauayan, Marilao and the Labangan-Angat River.

SMAI said continued maintenance of waterways around NMIA is part of its long-term commitment to government, with flood mitigation intended to protect both nearby communities and the airport, which will eventually be transferred to government ownership.

NMIA is not reclamation

SMAI also clarified that NMIA is not a reclamation project but a land development project on existing titled land in Bulakan that had historically been used as commercial fishponds.

The company said reclamation creates new land from bodies of water, while NMIA involves raising and preparing existing land for development. The Department of Environment and Natural Resources (DENR) has previously made the same distinction.

SMAI said the site’s flooding and subsidence conditions were considered in selecting Bulacan, citing the availability of a large contiguous area for a new international gateway and future expansion, its proximity to Metro Manila and major economic centers, and its potential connection to Luzon’s expressway network.

Flooding requires a broader approach

SMAI stressed that mitigating risks associated with NMIA is separate from addressing Bulacan’s much larger flooding problem.

The province is part of an interconnected river system that carries rainfall and runoff from inland areas toward Manila Bay. Upstream development and the conversion of open areas into buildings, roads and paved surfaces reduce natural water absorption and increase runoff.

Low-lying coastal areas such as Bulakan, Obando and Hagonoy also face land subsidence, high tides and rising sea levels, making drainage toward Manila Bay increasingly difficult.

“Protecting the airport and nearby areas and addressing Bulacan’s larger flooding problems are two separate challenges,” SMAI said. “We can engineer NMIA for the conditions of the site and mitigate its impact. But protecting communities across Bulacan requires looking at the whole system—from the water coming from upstream, to the rivers carrying it, to the coastal areas where it eventually has to drain.”

SMAI acknowledged that dredging alone may not be enough to address more severe rainfall events in some areas. Additional measures could include wider river channels, permanent river dikes, floodgates and pumping stations, particularly in vulnerable coastal communities.

SMAI said it would continue implementing NMIA’s environmental and flood-mitigation commitments while working with government agencies and local governments on broader measures to strengthen river capacity and flood resilience across Bulacan.