CoAuthors

Mohammad Tourian (Institute of Geodesy, University of Stuttgart, Germany); Omid Elmi (Institute of Geodesy, University of Stuttgart, Germany); Shirzad Roohi (Institute of Geodesy, University of Stuttgart, Germany); Qiang Chen (Institute of Geodesy, University of Stuttgart, Germany); Balaji Devaraju (Institute of Geodesy, University of Stuttgart, Germany)

With limited availability of hydrological in situ data, spaceborne monitoring of inland waters is a prerequisite for climatological and environmental studies. A case in point is the long-term monitoring of Lake Urmia, a hypersaline lake in northwestern Iran, which is currently in an unprecedented desiccation process. We monitor the lake level evolution through satellite altimetry (Envisat and CryoSat-2) while quantifying the area within the lake's receding shorelines using satellite imagery. Knowing the bathymetry we conclude that the total lake volume went down from around 9 km^3 to less than 2 km^3 in the monitoring time frame of 10 years. We corroborate this volume loss through (1) spaceborne gravimetry from the GRACE satellite mission and (2) an analysis of hydrometeorological data over the whole Urmia lake watershed. The validation results emphasize the reliability of spaceborne sensors for monitoring the lake's watershed water cycle. Comparing the results from different sensors 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.