Nan flood extent surpasses 2,793 hectares across three districts
Radar images from Sentinel-1 satellites show floodwater spreading along the Nan and Nam Sa rivers, affecting Wiang Sa, Mueang Nan and Phu Phiang districts.
- Thailand's space agency, GISTDA, is using Sentinel-1 satellite data to monitor the flood situation in the northern Nan province.
- A comparison of satellite images confirmed that floodwaters from the Nan and Nam Sa rivers have spread, inundating over 2,793 hectares of low-lying land.
- The analysis identified Wiang Sa, Mueang Nan, and Phu Phiang districts as key areas affected by the spreading floodwaters.
The Ministry of Higher Education, Science, Research and Innovation, through the Geo-Informatics and Space Technology Development Agency (Public Organisation), or GISTDA, was closely monitoring and assessing the flood situation in northern Thailand on Friday (August 21, 2026).
GISTDA most recently compared radar data from the Sentinel-1D satellite, captured on Saturday (August 15), with Sentinel-1C data captured at 6am on Friday (August 21).
The comparison clearly showed standing floodwater covering more than 2,793.28 hectares.
The comparative images showed a marked increase in the volume of water, which had overflowed the banks along long stretches of the Nan and Nam Sa rivers and spread into low-lying floodplains.
The images showed the direction of flow and the volume of water inundating a wide area of Wiang Sa district.
At the same time, areas in Mueang Nan and Phu Phiang districts remained affected, with clearly more signs of standing floodwater than on Saturday (August 15, 2026).
GISTDA has provided the analytical data to relevant agencies in the area and disaster-relief agencies for use in decisions on assisting affected residents, in planning water management and in draining floodwater from the area as quickly as possible.
