Water level instability analysis of Urmia Lake Basin in the northwest of Iran

Water level reduction of Urmia Lake Basin is the main problem in northwest of Iran during 2001–2017. Climate change and human activity have affected the water resources in this basin. In addition, continuing downward trend of water level in the Urmia Lake leads to hazard such as dust storm, lake drying, subsidence in plains, population immigration, and reduced production efficiency. Finding the causes of water level change is one of the challenges as to the unsustainability of the lake. Climate change, drought, dam construction, well drilling, land use change, land cover change, and the pattern of cultivations are inflectional here. The results of the Man-Kendall test indicate that the annual temperature (Z = 2.3, 95%) and frequency of droughts increased, and annual precipitation (Z = − 2.5, 95%) decreased. The results indicate that groundwater extraction increased from 374 to 2263.4 mcm, and the volume of dams increased from 198 to 1758 mcm (1961–2017). Surface water is reduced due to decreasing rainfall, increasing temperature, and drought frequency in the last decade. The comparison of these parameters with each other indicates high contribution of climate change and human activity in water level reduction of the subject lake. Restoration and sustainability of this lake are very important to the water management resources of Urmia Lake Basin.