"Lake Urmia, the second largest saline lake in the world, is on the verge of drying up completely and creating a massive environmental disaster in the region. Several studies have suggested that the intensive irrigation activities and prolonged droughts are the main causes for the depletion, but none of them have simulated the anthropogenic activity in the watershed. In this study, streamflow simulated from a land surface model with anthropogenic impact assessment capabilities (HiGWMAT) is used, along with a high resolution land use land cover change map, to investigate the natural and human-induced changes in the hydrology of Lake Urmia basin. The overall goal of the study is to attribute the observed changes in lake volume to natural and anthropogenic factors. Analysis of the Standardized Precipitation Index (SPI) over the Lake Urmia region suggests that the on-going depletion of the lake is not solely due to prolonged droughts alone. Anthropogenic activities have also caused a significant change in land use, streamflow, and water storage within the watershed. There has been a 98% and 180% increase in the total area of agricultural land and urban areas, respectively, from 1987 to 2016, with a corresponding shrinkage of 86% in the lake area. The linear trend of the lake volume and Terrestrial Water Storage (TWS) from HiGW-MAT model suggest that the watershed is gaining water from the lake at a rate of 0.28 km3 /year, which could be because of the numerous water resources projects in operation in the watershed. Furthermore, the comparison of streamflow output of HiGW-MAT model with and without human impact showed an average reduction of 2.66 km3 /year from 1998 to 2010, further suggesting the significant role of human activities on the depletion of the lake volume."--Page ii.
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