Matt Rodell NASA GSFC

GRACE and Human Impacts on the Water Cycle

Matt Rodell, Ph.D.

Chief, Hydrological Sciences Laboratory NASA Goddard Space Flight Center

Greenbelt, MD

Matt Rodell NASA GSFC

Soil Moisture Snow, Ice, Rainfall Snow

Vegetation Radiation

Gravity Recovery and Climate Experiment (GRACE)

Aqua: MODIS, AMSR-E, etc.

GRACE

GRACE is unique in its ability to monitor water at all levels, down to the deepest aquifer

Conventional radiation-based remote sensing technologies cannot sense water below the first few centimeters of the snow-canopy-soil column

Matt Rodell NASA GSFC

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Wat

er S

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ge, m

mSnow Water Equivalent

Top 2m Soil Moisture

Deep SM and Groundwater

Terrestrial Water Storage Variations

TWS variations are dominated by:!Soil moisture in temperate regions;!Snow in polar and alpine regions;!Surface water in the wet tropics.!

Top: 23 year time series of snow, soil moisture, and groundwater storage in Illinois, USA (right)

Updated from Rodell and Famiglietti, WRR, 2001

Matt Rodell NASA GSFC

Emerging Trends in Terrestrial Water Storage from GRACE

•  “Trends” in GRACE derived terrestrial water storage, 2002-2015. •  Best fit linear rate of change of TWS (cm/yr). •  Based on JPL/Tellus GRACE mascon land hydrology product. •  Which apparent trends are real and likely to continue?

cm/yr

Matt Rodell NASA GSFC

Terrestrial Water Storage “Trends” from GRACE

Exploitation of Water Resources

Percentage of Irrigated Area

Source: FAO and University of Frankfurt

Groundwater Depletion Rate (ca. 2000)

Equivalent height of water (mm/yr)

Wada et al. (2010)

Equivalent height of water (mm/yr)

Döll et al. (2011)

Net Consumptive Use of Ground and Surface Waters, 1998-2002

Equivalent height of water (cm/yr)

Matt Rodell NASA GSFC

•  “Trends” in GRACE derived terrestrial water storage, 2002-2015. •  Best fit linear rate of change of TWS (cm/yr). •  Based on JPL/Tellus GRACE mascon land hydrology product. •  Which apparent trends are real and likely to continue?

Matt Rodell NASA GSFC

Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L. and Linsey, K.S., 2014. Estimated use of water in the United States in 2010 (No. 1405). US Geological Survey.

Total U.S. Water Withdrawals, 2010

Matt Rodell NASA GSFC

Maupin, M.A., Kenny, J.F., Hutson, S.S., Lovelace, J.K., Barber, N.L. and Linsey, K.S., 2014. Estimated use of water in the United States in 2010 (No. 1405). US Geological Survey.

Irrigation Water Withdrawals, 2010

Matt Rodell NASA GSFC

Annual irrigation water use ca. 2000 reported by the USGS at the county level in cubic kilometers, from Ozdogan et al., J. Hydrometeor., 2010.

Irrigation Water Withdrawals, ca. 2000

Matt Rodell NASA GSFC

Increase in evapotranspiration due to irrigation, from Ozdogan et al., J. Hydrometeor., 2010. The increase in ET due to irrigation, averaged over the entire contiguous U.S., was 4% during the growing season, which is a huge impact on the water budget that also affects temperature and the energy budget.

Irrigation Impacts on Evapotranspiration