Water level changes of Hulun Lake in Inner Mongolia derived from Jason satellite data.

Water levels in lakes can reflect changes in such bodies. Therefore, there is value in identifying the variations in water levels using observations from altimetry satellites and analyzing the possible causes. In this work, the water-level changes of Hulun Lake in Inner Mongolia during the period from 2002 to 2015 are monitored by the use of Jason satellite data, the results of which are compared with historical data. Landsat TM/ETM/OLI_TRIS remote sensing images are analyzed, and the surface area of the lake extracted from them and converted to the corresponding water level to verify the values obtained from the Jason observations. The results show a downward trend after 2000 (−0.98 mm/year) and a sharp increase after 2012 (3.07 mm/year). The root mean square error (RMSE) between the two methods was 0.2369 m, and the correlation coefficient was 0.986. By analyzing the various influencing factors, we draw the conclusion that the water level of Hulun Lake is affected by both natural factors (e.g., rainfall, runoff, evapotranspiration etc.) and anthropogenic influences (e.g., water consumption in coal mining, overgrazing, etc.). These are the main causes of the decrease in the area of Hulun Lake and other lakes in the Inner Mongolia Autonomous Region. By comparing the lake storage anomalies of Hulun Lake with the terrestrial Total Water Storage anomalies (TWSA) inverted from GRACE satellite data and the Surface Water Storage anomalies (SWSA) from WaterGAP Global Hydrology Model (WGHM) within the Hulun Basin, we find that not only do Hulun Lake and basin interact with each other, but also that Hulun Lake has an important function with regards to the changes within the basin as a whole. This work therefore provides a method for monitoring the dynamic changes of lake water levels, while analyzing the influencing factors based on multi-scale data. Such a method shows potential for being applied to efforts to ensure environmental protection.