Near real time topography change detection of Korean tidal flats using multiple satellite imagery

Abstract

Tidal flats provide various functions such as reducing damage from natural disasters such as floods and typhoons and purifying pollutants discharged from the land. As awareness of the importance of tidal flats increases, Korean tidal flats were registered as a World Natural Heritage by UNESCO on July 26, 2021. The tidal flat is constantly changing due to climate change, sea level rise, typhoons, and artificial structure construction, so it is difficult to detect changes in the rapidly changing tidal flat topography with the existing irregular long-term survey cycle. In this study, we proposed a multiple satellite-based method for monitoring tidal flat topography changes in a near real-time. For the purpose of this, 1) advance multiple satellite-based integrated tidal flat DEM generation technology, 2) to evaluate the possibility and method of detecting tidal flats topographic change using integrated DEM. This study was conducted on tidal flats(Seocheon, Gochang, Shinan, Boseong-Suncheon) listed as UNESCO World Natural Heritage among tidal flats in Korea. From January 2017 to December 2022, available multiple satellite data were collected from the Sentinel-1A, Sentinel-2A/B, and Landsat-8,9. Data extracted from various tidal levels were matched with a spatial resolution of 10m, and DEM was generated through stacking of various satellite images. The accuracy of the integrated DEM data was verified using UAV-LiDAR data. Integrated DEM was able to update the existing tidal flats topographic information through data within at least 3 to 6 months, and the verification results showed very similar characteristics to the UAV-LiDAR topographic profile data. The DoD(DEM of Difference) of multiple satellite based integrated data enabled monitoring of short-term and long-term tidal flat topographic changes on seasonal or annual time scales.