Fresh water is humanity’s single most critical resource. According to a recent United Nations report, stresses on water supplies aggravated by climate change are likely to cause more conflicts, and water should be considered as vital to national security as defense. The report points out that 145 countries share watersheds with neighbors and there are more than 300 transboundary aquifers from which groundwater can be extracted.
Yet, we still do not fully understand how much water is available and how it is distributed, which is a requirement for planning how to deal with changes in climate and, particularly, in rainfall. This knowledge gap is due to limitations in the relevant science and technology, the vastly insufficient number of sensors deployed around the world, especially in developing countries, and data denial by many governments due to security concerns.
Satellites, however, are dramatically changing this picture, by enabling us to measure the total mass of water on Earth and its various components, as well as to monitor how these amounts change over time. They are providing “the sole body of information that we wouldn’t otherwise have,” says Dr. Jay Famiglietti, Professor of Earth System Science and of Civil and Environmental Engineering at the University of California at Irvine and Director of the university’s Center for Hydrologic Modeling, who has been studying the subject for more than 30 years. Globally, new knowledge about water from satellites gives us insights into current conflict and future international security issues. Locally, it greatly improves the science and the practice of water resource management.