To investigate humans’ impact on freshwater resources, scientists have now conducted the first global accounting of fluctuating water levels in Earth’s lakes and reservoirs – including ones previously too small to measure from space.
The research, published March 3 in the journal Nature, relied on NASA’s Ice, Cloud and land Elevation Satellite 2 (ICESat-2), launched in September 2018.
ICESat-2 sends 10,000 laser light pulses every second down to Earth. When reflected back to the satellite, those pulses deliver high-precision surface height measurements every 28 inches (70 centimeters) along the satellite’s orbit. With these trillions of data points, scientists can distinguish more features of Earth’s surface, like small lakes and ponds, and track them over time.
Scientists used these height measurements to study 227,386 water bodies over 22 months and discovered that, from season to season, the water level in Earth’s lakes and ponds fluctuates on average by about 8.6 inches (0.22 m). At the same time, the water level of human-managed reservoirs fluctuate on average by nearly quadruple that amount – about 34 inches (0.86 m).
Continue reading at NASA Goddard Space Flight Center
Image via NASA Goddard Space Flight Center
https://www.nasa.gov/feature/goddard/2021/nasa-scientists-complete-first-global-survey-of-freshwater-fluctuation
