Terrestrial water storage can be defined as the summation of all water on the land surface and in the subsurface. It includes surface soil moisture, root zone soil moisture, groundwater, snow, ice, water stored in the vegetation, river and lake water. Gravity Recovery and Climate Experiment has provided an unprecedented view of the terrestrial water storage variations at large scales. Extremes in water storage often are associated with droughts and flooding events because they are driven by the surplus or deficit of water. Water is a key prerequisite for human development. But only 0.5 per cent of water on Earth is usable and available as freshwater. Observing and understanding the water cycle and changes in the water cycle are essential to protect this life-enabling resource both now and in the future.
