grace satellites monitor groundwater depletion groundwater is a vital source of fresh water. in some...
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GRACE Satellites Monitor Groundwater DepletionGRACE Satellites Monitor Groundwater Depletion
Groundwater is a vital source of fresh water. In some parts of the world it is being withdrawn for agricultural, industrial, and domestic uses faster than it is naturally recharged, causing groundwater depletion. We have used the GRACE satellites to identify regions where aquifer levels are declining and to quantify that depletion. Two such locations are northwestern India and central California.
Figure 1: Trends in groundwater storage in India during 2002-08, with decreases in red. The study region is outlined.
Matt Rodell, Code 614.3, NASA GSFC
Figure 2: Time series GRACE-estimated groundwater (with linear trend) as an equivalent height of water averaged over the study region in northwest India.
Figure 4: Time series of GRACE-estimated groundwater (with linear trend) as an equivalent height of water averaged over California’s Sacramento, San Joaquin, and Tulare Lake basins.
Hydrospheric and Biospheric Sciences Laboratory
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Figure 3: Location of the study region in central California, which consists of three drainage basins.
with contributions from Jay Famiglietti (UC Irvine), Isabella Velicogna (UC Irvine), and Sean Swenson (NCAR)
Name: Matt Rodell, Code 614.3, NASA/GSFC E-mail: [email protected]: 301-286-9143
References:Rodell, M., I. Velicogna, and J.S. Famiglietti (2009), Satellite-based estimates of groundwater depletion in India, Nature, 460, 999-1002.
Famiglietti, J.S., D.P. Chambers, R. Nerem, M. Rodell, S.C. Swenson, I. Velicogna, and J.M. Wahr (2009), Trends in river basin, groundwater, and global water storage from GRACE, Eos Trans. AGU, 90(52), Fall Meet. Suppl., Abstract H13G-03.
Data Sources: We used time series of terrestrial water storage (the sum of groundwater, soil moisture, snow, ice, and surface water) based on observations from NASA's Gravity Recovery and Climate Experiment (GRACE) and simulated soil moisture from the Global Land Data Assimilation System (GLDAS) in order to estimate groundwater storage variations.
Technical Description of Images:Figure 1: The location of the first study region, outlined in black, which consists of the Indian states of Rajasthan, Punjab, and Haryana. The background image is a qualitative map of trends in groundwater storage in India during 2002-08, with decreases in red.
Figure 2: The estimated time series of groundwater storage is plotted as an equivalent height of water (cm) averaged over the study region in northwest India. The best fit linear trend line is also shown. Groundwater is being depleted at a rate of 4.0 ±1.0 cm/yr equivalent height of water (17.7 ±4.5 km3/yr). This is equivalent to a net loss of 109 km3 of groundwater from the region between 2002 and 2008, which is triple the capacity of Lake Mead, the largest man-made reservoir in the US.
Figure 3: The location of the second study region, consisting of the Sacramento River basin, San Joaquin River basin, and the Tulare Lake basin, in central California.
Figure 4: The estimated time series of groundwater storage is plotted as an equivalent height of water (cm) averaged over the study region in central California. The best fit linear trend line is also shown. Groundwater is being depleted at a rate of 2.4 cm/yr equivalent height of water (3.7 km3/yr). This is equivalent to a net loss of 20 km3 of groundwater from the region between October 2003 and March 2009, or more than half the capacity of Lake Mead.
Scientific significance: Groundwater is a vital source of fresh water in many parts of the world. Depletion of this resource due to withdrawals for crop irrigation and other uses can have devastating impacts if it continues unabated. GRACE-type satellite gravimetry is the only remote sensing technology able to measure groundwater storage changes.
Relevance for future science and relationship to Decadal Survey: Depending on the health of its instruments, GRACE may endure until 2013. A follow-on to GRACE was recommended as a third tier mission by the Earth Science Decadal Survey. However, GRACE’s greatest capabilities, monitoring groundwater depletion and ice sheet and glacier melt rates, were not demonstrated until publication of the Decadal Survey, so there is justification for it to move up in NASA’s priority list.
Hydrospheric and Biospheric Sciences Laboratory
Lake Drummond Lake Drummond (Dismal Swamp)(Dismal Swamp)
Characterization of Surface Directional Reflectance PropertiesCharacterization of Surface Directional Reflectance Propertiesat the at the Chesapeake Bay Watershed (CBW)
Miguel O. Román, Code 614.5, NASA/GSFC; Charles K. Gatebe, Code 613.2, UMBC-GEST
2008-06-13 (ARCTAS Campaign Flight #2008)2008-06-13 (ARCTAS Campaign Flight #2008)
The measurements acquired by NASA’s Cloud Absorption Radiometer (CAR) canprovide us with insights to issues of scale-dependent uncertainties and the opportunity to examine mixed pixels from moderate resolution satellite sensors (e.g., MODIS, MISR, and POLDER). Since CAR test flights are routinely carried out at NASA’s Wallops Flight Facility, the instrument often flies over key terrestrial and maritime ecosystems (e.g., permanent wetlands, marches, swamps, and estuaries).
Understanding the factor of scale, a very complex, yet universal issue across Earth System Science disciplines is central to the validation and characterization of long-term data records and to their effective use as input to global climate, biophysical, and biogeochemical models. Airborne angular reflectance measurements are thus essential because they provide an intermediate scale between intensive field studies appropriate for modeling landscape patterns and distributions; and larger-scale and longer-term measurements appropriate for modeling the global climate system.
Figure 3: CAR Instrument Schematic
NASA-WallopsNASA-Wallops
Figure 1: Figure 1: MODIS Satellite ImageMODIS Satellite Image
Hydrospheric and Biospheric Sciences Laboratory
Figure 2: NASA P-3B Aircraft
Name: Miguel O. Román, Code 614.5, NASA/GSFC; Charles K. Gatebe, Code 613.2, UMBC-GEST E-mail: [email protected]; [email protected]: 301-614-5811; 301-614-6228
References:
Román, M.O., Gatebe, C.K., Schaaf, C.B., & King, M.D. (2010). Characterization of Surface Directional Reflectance Properties over the US Southern Great Plains during the 2007 CLASIC Experiment. Remote Sensing of Environment (Submitted).
Gatebe, C. K., M. D. King, A. I. Lyapustin, G. T. Arnold, J. Redemann, 2005: Airborne Spectral Measurements of Ocean Directional Reflectance, Journal of the Atmospheric Sciences, 62(4), 1072-1092.
Data Sources: CAR airborne datasets over the Chesapeake Bay Watershed (available at http://climate.gsfc.nasa.gov/car/data/) were acquired during the 2001 Chesapeake Lighthouse and Aircraft Measurements for Satellites field campaign (CLAMS) sponsored by CERES, MISR, MODIS-Atmospheres and the NASA/GEWEX Global Aerosol Climatology Project (GACP); and the 2008 Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) campaign sponsored by NASA's Radiation Sciences Program.
Technical Description of Image:
Figure 1: ARCTAS Flight #2007 flight track over Great Dismal Swamp (11 June 2008). Multiple clockwise circular flight patterns were taken at several heights above ground level to achieve a low noise level and an even sampling of directional space.
Figure 2: The CAR was designed to operate from a position mounted on various aircraft. Prior to 2002 the CAR flew aboard the University of Washington’s aircraft (Douglas B-23: 1983-1984, C-131A: 1985-1997 and Convair CV-580: 1998-2001). Following retirement of the UW aircraft, the CAR has been integrated on three other Aircraft platforms: South Africa Weather Service, Aerocommander 690A (wing mount, June 2005) and Sky Research inc. (USA) Jetstream 31 (nose mount, February 2006- June 2007). The CAR was integrated in the nose cone of NASA P-3B in 2008. It has 14 narrow spectral bands between 0.34 and 2.30 µm, six of which (1.5-2.3 µm) are defined on the filter wheel and share one detector. Radiometric calibration is performed at NASA Goddard calibration facility.Figure 3: CAR instrument schematic
Scientific significance: Addressing scale-dependent uncertainties from a multi-angular perspective will provide insight into the interaction of the spectral and spatial information domains; thus allowing us to answer critical questions on the orthogonality of the information content of directional reflectance data. This is particularly useful when mapping and detecting changes in seasonally exposed tundra, tropical savannas, permanent wetlands (seen here), as well as other intrinsically complex environments that are very difficult to discern with reasonable accuracy because of spectral confusion with other land cover classes
Relevance for future science and relationship to Decadal Survey: The Surface Reflectance Earth System Data Record (SR-ESDR) is used as primary input for a number of essential climate variables (ECVs), e.g., Surface albedo, LAI/FPAR, Fire disturbance, and Land cover; which are required to support the work of the UNFCCC and the IPCC. SR-ESDR is also used in various applications to detect and monitor changes on the Earth’s surface, such as variations in the extent of snow cover and flooding, the phenology of natural vegetation and agricultural crops, as well as other signatures from rapidly changing surface conditions (e.g., burning, clearing, and tilling). These activities are directly relevant to NASA's upcoming missions for delivering improved ESDRs, improved modeling of the Earth's weather, climate, and ecosystems, and will further address the ongoing need to provide a ground-truth reference for intercomparisons between long-term consistent and climate-quality products from multi-sensor platforms.
Hydrospheric and Biospheric Sciences Laboratory