Groundwater is a vital resource.  It is often fresh and available when rain and surface waters are not.  Groundwater is also a useful indicator of climatic variability, as its natural fluctuations reflect longer term hydrometeorological variability.  In the United States, groundwater storage is somewhat well monitored, and water level records are freely and easily accessible.  Outside of the U.S., groundwater often is not monitored systematically and even where it is the data are rarely centralized and made available.  Since 2002 NASA’s Gravity Recovery and Climate Experiment (GRACE) satellite mission has delivered gravity field observations which have been used to infer variations in total terrestrial water storage, including groundwater, at regional to continental scales.  Challenges to using GRACE for groundwater monitoring include its relatively coarse spatial and temporal resolutions, its inability to differentiate groundwater from other types of water on and under the land surface, and typical 2-3 month data latency.  In this presentation I will describe progress to date on overcoming these challenges and applying GRACE, together with other observations and tools, for monitoring groundwater, and what has been revealed about groundwater variability and trends in regions where only anecdotal evidence existed previously.   


About the speaker:
Matt Rodell is the chief of the Hydrological Sciences Laboratory at NASA Goddard Space Flight Center