Human alteration of global surface water storage variability.

Area of Science:

• Hydrology
• Environmental Science
• Remote Sensing

Background:

• Understanding human impact on the global hydrological cycle is crucial for freshwater sustainability.
• Limited water level data for natural water bodies hinders quantification of human influence on surface water storage variability.

Purpose of the Study:

• To quantify the extent of human influence on global surface water storage variability.
• To assess the contribution of human-managed reservoirs to seasonal surface water storage changes.
• To establish a baseline for tracking human modifications to the global hydrologic cycle using satellite data.

Main Methods:

• Utilized NASA's ICESat-2 satellite laser altimeter data for global water level measurements.
• Assembled a dataset of water level variability for 227,386 water bodies from October 2018 to July 2020.
• Compared seasonal variability between human-managed reservoirs and natural water bodies.

Main Results:

• Human-managed reservoirs account for 57% of Earth's seasonal surface water storage variability.
• Seasonal variability in reservoirs averages 0.86 meters, significantly higher than natural water bodies (0.22 meters).
• Human influence drives 67% of surface water variability globally south of 45°N, reaching nearly 100% in arid regions.

Conclusions:

• Human activities, primarily through reservoirs, significantly alter global surface water storage variability.
• Satellite remote sensing provides a powerful tool for monitoring human impacts on the hydrological cycle.
• Findings underscore the growing pressure on global water resources due to human development and climate change.