Tracking Fresh Water from Space

Stream flow is traditionally monitored with channel gauges that measure the water height. This method is costly, often not implemented in remote regions, and incapable of measuring flow on floodplains and wetlands. Without these observations, global models of climate and water management are poorly constrained. In their Perspective, Alsdorf and Lettenmaier argue that satellite observations are required to measure the spatial diversity of the water surface across the globe. Three different satellite-based methods can measure water volumes in floodplains, channels, lakes, and reservoirs. Further development of these methods should allow global, volumetric measurements of fresh water from space.