Hydrologic Systems from GRACE Data

One of the most exciting research areas we are currently involved in is applying GRACE temporal gravity data to assess water storage variability in the African watersheds. Dr. Sultan has been a member of the GRACE Science Team Mission and has been funded by this program for the past 12 years. Our results show that temporal and spatially smoothed mass variations are largely controlled by elements of the hydrologic cycle such as runoff, infiltration, and groundwater flow. These mass variations are probably modulated but not obscured by noise as previously thought. If true, our findings suggest that it is possible to use GRACE to investigate temporal local responses of a much larger suite of (smaller) hydrologic systems (watersheds, lakes, rivers, marshes, etc.) and domains (e.g., source areas, lowlands) within watersheds and sub-basins world-wide. Using temporal and spatial variations of GRACE Mascon solutions over the Nubian Sandstone Aquifer System, we demonstrated that GRACE seasonal variations could be used to identify the sources of recharge and the nature of groundwater flow (laminar versus turbulent).