Diwata-1 micro-satellite captures images of silted Palawan areas

By Edd K. Usman

The Department of Science and Technology (DOST) released on Monday, March 6, satellite photos of the province of Palawan that seem to indicate soil erosion in some areas.

A mosaicked true-color Space-borne Multi-spectral Imager (SMI) image of Palawan

A mosaicked true-color Space-borne Multi-spectral Imager (SMI) image of Palawan

The images were captured on Dec. 21, 2016 by the country’s first satellite, the Diwata-1, according to Carlos Primo “CP” David, executive director of the DOST’s Philippine Council for Industry, Energy and Emerging Technology Research and Development (PCIEERD).

The 50-kilogram “eye in the sky” — the center of the country’s ambitious satellite program — was launched on March 23, 2016 to the International Space Station (ISS) and deployed into orbit some 400 kilometers above the Earth on April 27.

David, also the officer-in-charge of the Philippine Nuclear Research Institute (DOST-PNRI), told Newsbytes.PH that Diwata-1 is estimated to stay in its orbital path “for at least two more years.”

“These images of Palawan can only be seen using Diwata-1,” said David, noting that the province is a protected area by Unesco and under the National Integrated Protected Areas System or the NIPAS Act of 1992.

“Monitoring developments in Palawan always been a priority,” the DOST official said, adding that the micro-satellite could provide more vital information for some of the current environmental issues affecting the province.

A zoomed-in RGB image showing sedimentation along Palawan's coastal waters

A zoomed-in RGB image showing sedimentation along Palawan’s coastal waters

“Turbid sediment plumes along coastal waters near the municipalities of Brooke’s Point and Sofronio Española are noticeable in the image,” David said. The images indicated that the increased concentration of suspended sediments in the two municipalities is possibly caused by natural- or human-induced soil erosion, he said.

David explained that the Space-borne Multi-spectral Imager (SMI) onboard Diwata-1 utilizes both visible and near-infrared images to calculate the Normalized Difference Vegetation Index (NDVI), which is a widely used metric for estimating vegetation health and density.

“High NDVI values represented by colors orange to red, indicate healthy and dense vegetation cover. Conversely, green to blue colors indicate low NDVI values, which denote areas with sparse vegetation to no vegetation cover at all (e.g. bare land, water or clouds, built-up areas, shadows),” he said.

True-color and Normalized Difference Vegetation Index (NDVI) images that show a mining site in the municipality of Sofronio Española. A river system (broken lines) can also be highlighted using the NDVI image

True-color and Normalized Difference Vegetation Index (NDVI) images that show a mining site in the municipality of Sofronio Española. A river system (broken lines) can also be highlighted using the NDVI image

David said the SMI was able to take a snapshot of a nickel mining site situated in Sofronio Española, in the midst of a densely forested area. Since it is primarily bare land, the mining site has lower NDVI values compared with the surrounding thick forest cover, which has higher NDVI values.

“Moreover, other land features, such as the meandering river system and the coastline, could also be highlighted using the NDVI image. Since river systems are agents of sediment transport toward the coastal areas, it is important to look into their tracks to monitor potential sources and points of contamination,” he said

Presently, a group of Filipino engineers is designing the country’s second satellite called Diwata-2.

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