Remotely sensed assessment of Urmia Lake drying up; Climate change or anthropogenic effects?!

Urmia Lake is the largest hypersaline lake in Western Asia and it is currently facing severe desiccation. Immediate action is necessary to prevent irreversible damage to the environment and economy. The lake covers the majority of the Urmia Lake watershed. This study aimed to analyze the changes in Land Surface Temperature (LST) during the day and night in the area using MODIS 1 km, 8 days, version 061 (MOD11A2) images. The study also looked at water level variations using TOPEX/POSEIDON and Jason 1, 2, and 3, and precipitation variations using CHIRPS images from the period of 2001-2023. The results indicate that the water level of Urmia Lake has significantly declined by about 10 meters in the last few decades. Approximately 95 percent of the lake has dried up. The continuous declining trend of the water level started in 2001 and has led to an increase in LST day, about 0.03 ℃/year, and a decrease in LST night, about 0.07 ℃/year. Precipitation variations did not show any significant trend during the study period. Due to the high salt content caused by the lake drying up, the area is becoming a center for salty dust that can negatively affect the surrounding habitats. The trend of precipitation variations suggests that climate is not the primary factor responsible for the lake's desiccation.