Assessment of Spatio-Temporal Changes in Water Surface Extents and Lake Surface Temperatures Using Google Earth Engine for Lakes Region, Türkiye

Abstract

This study aims to extract water surface area and lake surface water temperature (LSWT), and to present long-term spatio-temporal analysis of these variables together with meteorological parameters. Three lakes in Türkiye’s Lakes Region, namely, Lake Burdur, Egirdir, and Beysehir, were considered as test sites. The normalized difference water index (NDWI) was applied to Landsat 5 and 8 data from 2000 to 2021 to extract the water extent in the Google Earth Engine (GEE) cloud-based platform. In addition to the lake surface area, Landsat thermal images were used to examine the LSWT. The findings indicated that water pixels could be extracted rather accurately using NDWI, with an overall accuracy of 98%. Between 2000 and 2021, the water surface area value of Lake Burdur decreased by more than 22%, while Lake Egirdir has dropped by less than 4%, and Lake Beysehir has not changed noticeably. LSWT of Burdur and Egirdir Lakes increased by more than 2.13 °C and 0.32 °C, respectively, while it decreased about 1.5 °C for Beysehir Lake. The obtained results were evaluated with meteorological parameters and our findings indicated that human-induced activities were more dominant than climate effects over Lake Burdur, unlike the others.

Keywords

• lake surface water temperature (LSWT)
• normalized difference water index (NDWI)
• Google Earth Engine (GEE)
• remote sensing (RS)
• Landsat
• Türkiye