Using SAR data to monitor floods in northern Vietnam

03/10/2024

Typhoon Yagi made landfall in Vietnam on September 7, 2024. The storm's circulation caused heavy rain and severe flooding in many northern provinces of Vietnam. To monitor the current flooding situation, scientists at the Vietnam Space Center collected SAR image data provided by the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA). Extracting information from SAR satellite data showed flooded areas identified on September 10, 12 and 15, 2024 on Sentinel-1 satellite images. The flooding had the largest area on September 12.

The use of SAR images shows that if used well and with the help of satellites around the world, storm flood monitoring can be carried out with a relatively high frequency, helping to monitor flood developments and supporting timely and effective response measures.

Figure 1: Flood developments due to storms in the northern provinces on September 10, 12, 15, 2024

It is expected that with the launch of the LOTUSat-1 radar satellite with high resolution (1m), the data source will be increased and proactive, contributing to improving the ability to provide information and improving the effectiveness of disaster response. In order to determine the capabilities of LOTUSat-1, with the help of Japan (NEC Cooperation Company), ASNARO-2 images (a satellite with a similar configuration to LOTUSat-1) taken on September 12, 2024 were provided and used.

Details of flooded areas seen from ASNARO-2 and Sentinel-1 satellite images are compared through the images below (Figure 2). It can be easily seen that ASNARO-2 images with a resolution of 2m (in stripmap mode) show more detail than Sentinel-1 images. With the mastery of LOTUSat-1 image analysis technology, when satellite data is ready, a new source of detailed and reliable information will be added to increase the frequency and level of detail of flood monitoring. By using radar satellite images, this information will be collected regardless of weather conditions. Therefore, this is considered a valuable source of information to effectively overcome the consequences of natural disasters, especially floods caused by storms.