A spaceborne multisensor approach to monitor the desiccation of Lake Urmia in Iran

Our altimetry results indicate that, on average, the lake has lost 34 ± 1 cm of its water level every year from 2002 to 2014. The results from satellite imagery reveal a loss of water extent at an average rate of 220 ± 6 km2/yr, which indicates that the lake has lost about 70% of its surface area over the last 14 years. By combining water level from altimetry, surface water extent from satellite imagery and local bathymetry, we ascertain the changes in lake volume. Results indicate that the lake volume has been decreasing at an alarming rate of 1.03 ± 0.02 km3/yr. The water volume of the lake behaves differently from the water storage of the whole basin captured by GRACE. Our results show that the onset of a drought in 2007 over this region together with an increase in the rate of groundwater depletion caused a new equilibrium level for water storage of the whole basin. Comparing the results from GRACE and the obtained water volume in the lake with in situ groundwater level data reveals the anthropogenic influences on an accelerated lake desiccation. In fact, our monitoring approach raises critical issues regarding water use in the basin and highlights the important role of spaceborne sensors for any urgent or long-term treatment plan.