Brain Contour » Tragedy and Disaster

Flooding in Philippines as Seen Through Satellite Images

braincontour — Sat, 31 Dec 2011 01:52:27 +0000

Mindanao as seen from space.

Thanks to NASA for providing the latest satellite images of the Philippines, I was able to look into the damaged areas in Cagayan de Oro and Iligan caused by massive flooding, which was triggered by Tropical Storm Washi (known locally as Typhoon Sendong) on December 16, 2011. The Moderate Resolution Imaging Spectroradiometer (MODIS) images provided a wide look of the destruction as seen from space. Too bad the spatial resolution of MODIS is not as high as the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) — the one I used to analyze the spatial extent of the Tsunami effect on Japan. Anyhow, the NASA’s Aqua satellite images are good enough to come up with a change detection map.

The before-image was acquired on December 12th. The after-flooding image was taken on December 19, 2011. At first sight, it is obvious that the rivers that run both Cagayan de Oro and Iligan cities have expanded in width with clear presence of brown sediments after the deadly flooding. It is also evident from the December 19 image that sediments have accumulated into the sea floor.

Taken on December 12th:

Cagayan de Oro before the December 2011 flood.

Taken on December 19th:

Cagayan de Oro after the December 2011 flood.

Most of the land surface changes happened near the shoreline, near rivers and on populated areas (I encircled those changes). These are the same locations where most deaths and injuries were reported.

Changes occured near shorelines.

What is also very clear from the images, which others may have not seen, are the browning of the mountain slopes (not posted here). What have our Philippine officials been doing to stop the deforestation in the area? Denuded forest would always lead to killer floods. With Cagayan de Oro and Iligan cities situated on low-lying areas, without any doubt vulnerable to flooding, local officials must have known this beforehand. Or maybe not. Or maybe they do, but they just turned a blind eye on the issue. May this calamity awaken the minds of our public officials and, much more, agonize the conscience of those who are involved in illegal activities that have ravaged our forest!

We can never turn back time. We can never bring back to life the more than 1500 people (via Associated Press) who died in that horrific flash flood on December 16th. We can only hope that this will never happen again.

But now may not be the right time to blame. There are thousands of homeless survivors who need help. This is the moment that we Filipinos unite and share our love and care to those affected by the tragedy.

Have you already donated? Visit the Philippine Red Cross and share your blessings.

Note: I did not post the Iligan images here. Also, you can share this article and the link, but please ask my permission, through the comment section, if you intend to use the subset images and the map I made. Thanks.

Japan: Before and After Tsunami Maps

braincontour — Tue, 15 Mar 2011 22:12:48 +0000

NASA provided satellite images of Sendai, Japan before and after the 9.0 earthquake and tsunami hit and devastated the region on March 11, 2011. The images vary in spatial resolution. One set of images came from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA’s Aqua and Terra satellite. MODIS provides daily reflectance data of the entire Earth’s surface that are specifically designed for land and water applications with spatial resolutions as small as 250 m. The other set of images came from the imaging instrument Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) flying on Terra. ASTER has a much higher spatial resolution of 15 m, which means you could see more details of the earth’s surface.

NASA Image of Tsunami Damage near Ishinomaki, Japan

I used the ASTER images to map the tsunami damage near Ishinomaki, Japan, which is one of the major affected areas. Note that the classified maps below produced in this analysis are a rough estimation of the extent of flooding caused by the tsunami. The first map result was derived from the August 8, 2008 image. The classification shows water levels (blue color) under normal circumstances. The red color represents the vegetated/agricultural/forested areas, while the green represents the urban/soil areas (I combined both for simplicity).

Ishinomaki, Japan on August 8th 2008

Now here is a classified image of Ishinomaki, Japan for the March 14, 2011 data — three days after the earthquake and tsunami. Again, water is in blue, urban/soil areas in green, and vegetated/agricultural/forested areas in red.

Ishinomaki, Japan on March 14, 2011

What differences can you detect? First, water inundated the city. Days after the tsunami, water still covers what was before just flat fields. Look how water devastated the vegetated/agricultural/forested fields (spread of the green color inland) leaving just bare soil, probably dirt. According to my analysis, and based on the images, about 51 km^2 have been changed to urban/soil/dirt in 2011 from another class in 2008. Notice how the Matsushima Air Base in the lower left corner of the image has been surrounded by water.

Note: The satellite images provided cover a much bigger area, including the one in Sendai. For this analysis, I used a subset of about 304 km^2. For any of you who would want to map the same, I used ENVI software to do the analysis. You can use supervised classification by establishing the regions of interest (ROI) first.

If you have produced maps as well, kindly leave your links in the comment section. My analysis was roughly done for the sake of visualization of tsunami extent. In fact, for those who are into GIS and RS, misclassified pixels are easy to detect.

Manila Flooding worst in history

braincontour — Mon, 28 Sep 2009 02:37:55 +0000

My little brother, Jeffrey, who works in Manila, was among the thousands of people affected by the tropical storm “Ondoy” (international codename: Ketsana) that hit the Philippines this weekend. After my sister (in Illinois) and I heard about the worsening situation in Manila due to flooding caused by the torrential rains, we immediately contacted our brother, but to no avail. His phone, and all his friends’ phones, were unreachable. We posted messages on Facebook hoping other friends and relatives could somehow trace our brother’s whereabouts.

Last night, we finally got a note that my brother and some others were trapped in the second floor of a two-story house. Water on the first floor was about chest-high.

Electricity was cut off. No water running. No food supply. Appliances were submerged in the flood. My brother and his friends were waiting for rescuers to come. We relied so much for our friends in Manila to contact government agencies to send a quick rescue operation before the water would rise to the second floor. As of now, based from our contacts, the water is slowly subsiding and my brother is still in the second floor.

This latest flooding is the worst in Manila’s flooding history. The capital is not new to flooding occurences as it gets flooded every now and then when heavy rains from strong typhoons hit the city. “Ondoy” was underestimated. It brought a record of 455 millimeters of rain in 12 hours (that’s more than the 390-mm average rainfall for the whole month of September)!

As of the latest news, 95 people are dead, 29 are missing, and there are some 247,555 affected families. But these numbers are expected to increase in the coming hours. According to the Philippine Atmospheric, Geophysical and Astronomical Services Administration (Pagasa), “Ondoy” is now leaving the country but there would still be occasional rains in the next 24 hours.

The typhoon victims need help! There are many links posted by concerned citizens on Facebook for those who would want to donate.

Watch this video of a woman (a teacher still in her uniform) who climbed on top of the vehicle, trying to save her life.

There are more videos posted on YouTube.

Assistance hotline numbers:
- NDCC, Camp Aguinaldo – 911-1873; 912-5668; 911-1406; 912-2665
- DSWD Disaster Relief Operations, Monitoring and Information Center 488-3199 (24 hours)
- Crisis Intervention Unit DSWD-NCR 734-8635
- Disaster Relief Operations, Monitoring and Information Center 931-8101 to 05, local 506, 951-7119
- Red Cross 143/911-1816
- MMDA 136/869-6000
- Coast Guard 527-6136
- M-Water 1627
- Maynilad 1626
- Meralco 16211