QUEZON CITY, Philippines — Satellite data from the Philippine Space Agency (PhilSA) have identified flooded areas across Regions 1 and 2, as well as parts of Abra and Zambales, following heavy rains brought by Tropical Storm Maymay and the enhanced Southwest Monsoon, or Habagat.

Sample flood extent map (one out of 25) from available satellite data covering areas of Region 1 and 2.

PhilSA said it produced flood extent maps to help authorities assess the impact of the weather systems and identify areas that may require immediate attention and response.

The flood assessment was based on Sentinel-1 Synthetic Aperture Radar (SAR) satellite imagery captured on August 6 at 5:54 a.m. Philippine Standard Time for Region 1, and on August 9 at 5:58 p.m. for Region 2.

The agency used artificial intelligence (AI)-assisted analysis involving a composite of three Sentinel-1 SAR images to detect areas potentially affected by flooding.

Satellite Technology Helps Track Flooding

According to PhilSA, SAR satellite technology is particularly useful for monitoring floods during severe weather because its signals can penetrate clouds, which frequently obscure large areas during tropical cyclones and periods of heavy rainfall.

Unlike optical satellite imagery, SAR can also capture information regardless of whether it is daytime or nighttime. This allows authorities to obtain valuable information even when cloudy skies and poor visibility make conventional satellite imagery less effective.

However, PhilSA cautioned that satellite-based flood maps have limitations.

Flooding in urban and densely vegetated areas may be underestimated because buildings, trees, and other complex surfaces can affect the radar signals, or backscatter, measured by the satellite. These conditions can reduce the accuracy of flood detection.

The agency emphasized that the flood extent maps remain subject to ground validation.

Supporting Disaster Response

PhilSA said its satellite-based analysis supports the National Disaster Risk Reduction and Management Council (NDRRMC) in monitoring flooding and other hazards and in prioritizing areas for response.

By providing wide-area coverage through satellite data, the space agency helps government agencies and other stakeholders gain a broader picture of disaster-affected areas, particularly when ground access may be difficult or limited.

The availability of near-real-time satellite information can also support informed decision-making during emergencies, including disaster assessment, response planning, and resource allocation.

PhilSA said it will continue monitoring satellite data as weather conditions and the situation require.

The agency reminded the public to continue monitoring official advisories and updates from local and national government agencies for the latest information on flooding, weather conditions and disaster response.

Where to Access the Flood Maps

PhilSA’s flood extent maps and shapefiles are available through the following links:

Region 1, including parts of Abra and Zambales:
https://tinyurl.com/Flood-20260806-S1D

Region 2:
https://tinyurl.com/Flood-20260809-S1C-Y2

This version gives the story a stronger news lead, clearer subheads, and a more accessible explanation of the satellite technology, while keeping PhilSA’s technical caveats and disaster-response context intact.

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