MANHATTAN — Satellites have revealed widespread loss of water storage in the Earth’s large lakes since the early 1990s, and much of the decline is attributable to climate change and human consumption, according to a study involving a Kansas State University researcher.
The research team — which included collaborators from the University of Colorado Boulder; Kansas State University; France’s space agency, CNES; King Abdullah University of Science and Technology; and the International Institute for Applied Systems Analysis — published “Satellites reveal widespread decline in global lake water storage” in Science, a journal published by the American Association for Advancement of Science. Jida Wang, associate professor of geography and geospatial sciences in K-State’s College of Arts and Sciences, contributed to the study.
Wang, who specializes in surface hydrology — particularly lakes, reservoirs and wetlands — analyzed lake water storage variability and trends and explored change patterns of varying lake types and conditions.
Lakes store 87% of the Earth’s liquid surface fresh water. Volume changes have profound ramifications on water sustainability, food security, waterbird habitats, carbon and nutrient cycling, and recreation.
Using three decades of satellite observations, the researchers analyzed approximately 2,000 of Earth’s largest lakes. They found significant storage declines, 53% of them between 1992 and 2020. This record of multiple decades of water storage variations is one of the study’s major contributions.
“We computed the trends of water volume, not surface area only, and then we unfolded the stories behind each in relation to major human and climatic drivers,” said Wang.
The researchers determined through climate data and hydrological models that in natural lakes, the net water loss was primarily due to climate warming, increased potential evapotranspiration and human consumption. In reservoirs, the main cause was sedimentation.
According to the study’s lead author, Fangfang Yao, a climate fellow at the University of Virginia and visiting fellow at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, and a former doctoral student at Kansas State University, this comprehensive method of tracking lake water storage trends and the reasons behind them allows scientists to help water managers and communities better protect critical water sources.
“We estimated that roughly one-quarter of the global population resides in basins with significant lake water loss,” said Wang. “Effects can range from freshwater decline to environmental degradation, such as increased salt dust exposure, to hydropower reduction. These cautionary findings highlight the importance of accounting for climate change and sedimentation impacts when planning water policies to combat lake water declines.”
In fact, the research team found an example of this type of success. Lake Sevan, in Armenia, has experienced an increase in water storage over the past two decades, which the researchers linked to enforcement of conservation laws.
“While our results are specific to the large lakes we studied, we hope the findings motivate people to continue investigating the dynamics of important smaller lakes as well,” said Wang.
For more information about the study, read the University of Colorado Boulder’s story.