Climate change, drought, and anthropogenic effects are among the main drivers causing alterations in natural resources one of which is the lake level (LL) of large saline lakes, which are mainly located in arid and semi-arid regions. As an urgent need to manage natural resources, this study focuses on determining the significant reasons for the shrinkage problem of saltwater lakes. To this end, the long-term severity and frequency of droughts from 2003 to 2020 and their spatiotemporal distribution in the Lake Urmia Basin (the second largest saline lake on Earth) were investigated based on the normalized difference vegetation index (NDVI) anomaly. Thereafter, monthly soil moisture, evapotranspiration, land surface temperature (LST), LL, NDVI, and precipitation time series were collected, Boolean images were used to generate drought frequency maps, and Mann-Kendall trend test techniques and wavelet transform coherence (WTC) were used to determine the impacts of anthropogenic activities and climate change on the region. The results indicated that the basin had only non-drought and mild drought conditions and did not experience moderate, severe, or very severe droughts. The results indicated that the mild drought indices covered 80% of the total area and were exposed for more than seven years. Pearson correlation analysis indicated that the primary reason for the drought was temperature anomalies (r = −0.68) in the basin. The annually changing drought conditions in the basin revealed human effects on the basin. The results indicated a statistically significant positive trend in evapotranspiration time series, which was a reason for the LL decline. Thereafter, wavelet coherence was employed to delve deeper into the correlation between LL and the hydro-environmental datasets. The increasing vegetation cover in the situation that precipitation, land surface temperature, and soil moisture had stable conditions as well as common periodicities between the hydro-environmental variables, and the abrupt change points in significant periodicities revealed that anthropogenic activities in terms of agricultural expansion had increased in the basin. Besides, the annually changing condition of drought in the basin is also an indicator of anthropogenic activities that affect the environment. The differences in the spatial distribution of the NDVI maps also indicated that people living in the western, eastern, and southern regions of the basin had cultivated more land.

气候变化、干旱和人为影响是导致自然资源变化的主要驱动因素，其中之一是大型盐湖的湖水位 (LL)，主要位于干旱和半干旱地区。作为管理自然资源的迫切需要，本研究侧重于确定咸水湖泊萎缩问题的重要原因。为此，基于归一化植被指数（NDVI）异常研究了乌尔米亚湖盆地（地球上第二大盐湖）2003-2020年干旱的长期严重程度和频率及其时空分布。此后，收集每月土壤水分、蒸散量、地表温度 (LST)、LL、NDVI 和降水时间序列，使用布尔图像生成干旱频率图，和 Mann-Kendall 趋势测试技术和小波变换相干 (WTC) 被用来确定人为活动和气候变化对该地区的影响。结果表明，该流域仅有非干旱和轻度干旱条件，没有经历中度、重度和特重度干旱。结果表明，轻度干旱指数覆盖了总面积的80%，暴露时间超过7年。Pearson 相关分析表明，干旱的主要原因是流域温度异常（r = -0.68）。流域每年不断变化的干旱条件揭示了人类对流域的影响。结果表明蒸散时间序列在统计上显着正趋势，这是 LL 下降的原因。此后，小波相干性被用来深入研究 LL 和水文环境数据集之间的相关性。在降水、地表温度和土壤水分条件稳定且水文环境变量之间具有共同周期性的情况下植被盖度的增加以及显着周期性的突变点表明农业扩张方面的人为活动对盆地内增加。此外，流域干旱的逐年变化也是影响环境的人为活动的一个指标。NDVI 地图空间分布的差异也表明流域西部、东部和南部地区的人们耕种了更多的土地。