5:15 PM - 6:30 PM
[HDS08-P03] An example of using Google Earth Engine in providing and sharing information on wide-area typhoon disasters in international joint research projects
Keywords:Flood, Satellite data , Information sharing, Google Earth Engine, Philippines, Typhoon
ICHARM has been conducting the SATREPS project with Philippine research members since 2020. The project's objective is to research disaster assessment to contribute to hydrology, agriculture, and water management under climate change. However, field surveys and local activities have been restricted even by local researchers due to the pandemic of COVID-19. In these circumstances, Typhoon Ulysses hit Luzon Island in early November 2020, and heavy rainfall caused large-scale floods in various parts of the country. According to the National Disaster Risk Reduction and Management Council (NDRRMC) of the Philippines, a large number of people were forced to evacuate because so many houses were severely damaged as a result of flooding. However, the overall picture of the damage caused or to be caused by the typhoon remained unknown during the disaster.
In such a case, earth observations (EO) by satellites have been proven extremely useful. Among various current operational EO-satellites, the Sentinel series by the European Space Agency (ESA) and the Landsat series by the National Aeronautics and Space Administration (NASA) provide satellite images of different areas on the planet free of charge. Sentinel-1 synthetic aperture radar (SAR) images and Sentinel-2 optical images are frequently acquired at intervals of 5 or 6 days, respectively. Such operations are beneficial for ground monitoring.
Similar to these satellite data, the information provided by government agencies is also essential for understanding the whole picture of a disaster. Information such as the number of victims, shelters, and evacuees of each municipality is regularly released by NDRRMC through the Internet. Though such information itself is very useful, it can be even more useful to understand the entire situation if visualized on a map.
Therefore, this project used the Google Earth Engine (GEE) to share the overall picture of the disaster situation due to Typhoon Ulysses. GEE is a cloud-type mapping application provided by Google. Using global satellite data and geographic information stored on Google's server, a special computer program is applied to process such data and information to help users understand them visually while looking at the screen. In other words, the most significant merit of GEE is that it can quickly launch a system that can collect and share information anywhere in the world without depending on the area of residence or human and economic resources. And, the application can visualize information for mapping, making it ready to be shared easily by many people with user-friendly functions such as enlarging and reducing images, as long as they have an Internet environment.
The information shared among the members in this project is disaster information released by NDRRMC, inundation area estimated based on Sentinel-1 SAR images, visible images and the estimated inundation area from the Sentinel-2 optical sensor, and precipitation products from satellites. The precipitation products are hourly and cumulative precipitation distributions using the satellite global precipitation map (GSMaP) provided by the Japan Aerospace Exploration Agency (JAXA) and the Integrated Multi-satellitE Retrievals for GPM (IMERG) provided by NASA. These products were applied to the Pampanga River basin, Pasig River, Laguna Lake, Marikina River basin, and Cagayan River in the three main watersheds in northern Luzon Island.
Visualization with these GEE systems is considered to have the following significance from the viewpoint of disaster response: 1) Although the whole picture of the disaster could not be understood due to a widespread disaster, visualization of information was useful to capture a rough image of the damage distribution. To have an idea of the disaster makes it possible to predict how it may further develop or which areas need support more urgently than other areas; 2) Although, due to COVID-19, researchers from both countries could not go to the target site and meet each other, information shared among the members created a foundation for discussions on disaster response and recovery; 3) Although satellite-based visible images only offer inundation area, adding a land-use map to the inundation area map produced a useful tool for disaster response and restoration efforts; and 4) By increasing the number of information layers, the resultant map can be used not only immediately after a disaster but also at various subsequent stages, for example, to show the progress of restoration and reconstruction.
In such a case, earth observations (EO) by satellites have been proven extremely useful. Among various current operational EO-satellites, the Sentinel series by the European Space Agency (ESA) and the Landsat series by the National Aeronautics and Space Administration (NASA) provide satellite images of different areas on the planet free of charge. Sentinel-1 synthetic aperture radar (SAR) images and Sentinel-2 optical images are frequently acquired at intervals of 5 or 6 days, respectively. Such operations are beneficial for ground monitoring.
Similar to these satellite data, the information provided by government agencies is also essential for understanding the whole picture of a disaster. Information such as the number of victims, shelters, and evacuees of each municipality is regularly released by NDRRMC through the Internet. Though such information itself is very useful, it can be even more useful to understand the entire situation if visualized on a map.
Therefore, this project used the Google Earth Engine (GEE) to share the overall picture of the disaster situation due to Typhoon Ulysses. GEE is a cloud-type mapping application provided by Google. Using global satellite data and geographic information stored on Google's server, a special computer program is applied to process such data and information to help users understand them visually while looking at the screen. In other words, the most significant merit of GEE is that it can quickly launch a system that can collect and share information anywhere in the world without depending on the area of residence or human and economic resources. And, the application can visualize information for mapping, making it ready to be shared easily by many people with user-friendly functions such as enlarging and reducing images, as long as they have an Internet environment.
The information shared among the members in this project is disaster information released by NDRRMC, inundation area estimated based on Sentinel-1 SAR images, visible images and the estimated inundation area from the Sentinel-2 optical sensor, and precipitation products from satellites. The precipitation products are hourly and cumulative precipitation distributions using the satellite global precipitation map (GSMaP) provided by the Japan Aerospace Exploration Agency (JAXA) and the Integrated Multi-satellitE Retrievals for GPM (IMERG) provided by NASA. These products were applied to the Pampanga River basin, Pasig River, Laguna Lake, Marikina River basin, and Cagayan River in the three main watersheds in northern Luzon Island.
Visualization with these GEE systems is considered to have the following significance from the viewpoint of disaster response: 1) Although the whole picture of the disaster could not be understood due to a widespread disaster, visualization of information was useful to capture a rough image of the damage distribution. To have an idea of the disaster makes it possible to predict how it may further develop or which areas need support more urgently than other areas; 2) Although, due to COVID-19, researchers from both countries could not go to the target site and meet each other, information shared among the members created a foundation for discussions on disaster response and recovery; 3) Although satellite-based visible images only offer inundation area, adding a land-use map to the inundation area map produced a useful tool for disaster response and restoration efforts; and 4) By increasing the number of information layers, the resultant map can be used not only immediately after a disaster but also at various subsequent stages, for example, to show the progress of restoration and reconstruction.