Investigation of the Changes of Lake Surface Temperatures and Areas: Case Study of Burdur and Egirdir Lakes, Turkey

Abstract

Abstract. The world's average surface temperature has been increasing in recent decades. This situation is expected to affect aquatic systems and lakes are one of the most important aquatic systems. The main aims of this study are to examine Lake Surface Water Temperature (LSWT) and area changes of Burdur and Egirdir lakes located in the West Mediterranean Region (TR61) of Turkey for the years 1998, 2008 and 2018 using Landsat satellite images. For this purpose, initially, Normalized Difference Vegetation Index (NDVI) and Modified Normalized Difference Water Index (MNDWI) images were generated and the lake shorelines were extracted by thresholding these images. Then, the LSWT values were obtained by using Landsat thermal images. Finally, the area and LSWT changes of Burdur and Egirdir lakes between the years 1998-2008-2018 and the relationships of these parameters with each other were analysed. The obtained results showed that the lake boundaries could be semi-automatically extracted with overall accuracy values higher than 95%. In 20-year time period it was also observed that the Burdur Lake area decreased significantly, while the Egirdir Lake area decreased slightly. When the LSWT values were analysed, it can be stated that the LSWT values increased in both lakes during this time period. The amount of increase in LSWT values was about 2.2 °C for Burdur Lake, while about 1.3 °C for Egirdir Lake.

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

“…Surface temperature patterns throughout time could provide insight into how climate change is affecting the lake area. A relationship existed between the extent of lake surface area lost and the rise in LSWT measurements, according to Aslan and Koc-San [34]. LST studies commonly use Landsat images, which are among the most widely utilized types of RS data.…”

“…As a result, the year's water temperature value could not be computed. Some images were identified as outliers due to their high deviation from the mean values, which were likely In 1998, based on Aslan and Koc-San [34], Burdur Lake's area was roughly 161 km 2 , but by 2018, it had shrunk by 127 km 2 . Therefore, it has lost more than 20% of its surface area in the last two decades, while the LSWT value increased by 2.2 • C throughout the same period.…”

“…The lake lost more than 22% of its surface area during the 21-year period, indicating that the LSWT and the surface extent of the lake were found to be in a directly proportional relationship. Aslan and Koc-San [34] analyzed the relationship between the lake surface area and the change in LSWT, stating that the LSWT values increased as the lake extent decreased between 1998 and 2018. The LSWT values of Egirdir Lake rose by more than 1.3 °C and the lake's surface area reduced by less than 4 km 2 .…”

“…The LSWT values varied between 17.4 °C and 34.8 °C in the summer of 2000, while they increased between 20.9 °C and 39.00 °C in the summer of 2021 as portrayed in Figure 13b,d. In the autumn season, Aslan and Koc-San [34] analyzed the relationship between the lake surface area and the change in LSWT, stating that the LSWT values increased as the lake extent decreased between 1998 and 2018. The LSWT values of Egirdir Lake rose by more than 1.3 • C and the lake's surface area reduced by less than 4 km 2 .…”

“…Moreover, Abujayyab et al [33] collected 570 Landsat scenes from GEE for the surface area extraction of Lake Burdur during a 34-year period between 1984 and 2019, where a seasonal fluctuation in the area of water bodies was determined by combining their suggested extraction technique with NDWI. Considering the study of Aslan and Koc-San [34], the water surface area and LSWT of Burdur and Egirdir lakes were analyzed using Landsat satellite images acquired in 1998, 2008, and 2018. Thus, after a 20-year period, it was discovered that the increase in LSWT values was about 2.2 • C for Lake Burdur and approximately 1.3 • C for Lake Egirdir, and both lakes' water surface area decreased.…”