Drought and climate change are frequent environmental disasters. Large saline lakes across the world have experienced lake-level decline and this problem needs to be investigated accurately for water resources and environmental management. Therefore, the current paper aimed to study drought severity and frequency and their spatial-temporal distribution over the Lake Urmia basin, the second largest saline lake on earth, during the vegetation growing season, from May to September, for 2003-2019 using remote sensing tools based on the Normalized Difference Vegetation Index (NDVI) anomaly. In this study, also, remote sensing tools are used to acquire the Land Surface Temperature (LST) and the precipitation datasets as hydroclimatological factors to study their spatial-temporal correlation with the NDVI anomaly, and, also, potential trends in their time-series. The results showed that the basin has suffered from mild drought in almost all of the years. Also, more than 80% of the total area has experienced more than 7 years of mild drought and the basin has been affected in 9 years of the 17 years. The basin has just non-drought and mild drought conditions and it did not experience severe droughts. The correlation analysis indicates that the reasons for the drought can be traced to climate factors and the main reason for the long-term mild drought over the basin is temperature anomaly. The Mann-Kendall trend test, also, was applied to study the potential trends in the LST, precipitation, and the lake-level time-series. The results indicated that there was no meaningful trend in precipitation dataset, but a statistically significant positive trend in LST time-series. It is concluded that the increasing temperature is an important reason for the lake-level decline.
Anahtar Kelimeler: Drought, Climate change, Remote sensing, Trend test, Saline lakes, Lake Urmia
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