Satellite Derived Bathymetry and Water Level Change in Beysehir Lake

Abstract

Several factors, including water level, depth, water quality, biodiversity, and tourist activities, play a crucial role in the sustainability of lakes, and therefore require constant monitoring. This study aimed to examine the water level changes of Lake Beysehir between 2015 and 2020 and determine whether there was a difference in bathymetry as the lake water level changed. To achieve this, lake water level data was first obtained from Copernicus Global Land Service, which uses satellite altimetry data to determine water level changes in Beysehir Lake. Sentinel-2 multispectral high-resolution satellite images obtained from Sentinel-Hub were then used to determine the depth of the lake. Finally, these high-resolution satellite images were processed using the open-source SNAP software developed by the European Space Agency. A decreasing trend of -9.8 ± 0.8 cm/yr in the lake water level between 2015 and 2020 was revealed by the analysis. The Empirical Satellite-Derived Bathymetry map was produced, and the maximum and average depth of the lake was determined after the required corrections were applied to the Sentinel-2 satellite images. The average depth, which was 8.44 meters in 2015, was found to have decreased to 4.06 meters in 2020. Additionally, a 0.92 correlation was found between the decrease in the lake water level and the average depth change.