Issues include coverage gaps, delays, measurement continuity and consistency, data format and QC, political restrictions

Transcription

1 Satellite-based Estimates of Groundwater Depletion, Ph.D. Chief, Hydrological Sciences Laboratory NASA Goddard Space Flight Center Greenbelt, MD

2 Groundwater Monitoring

3 Inadequacy of Surface Observations Global Telecommunication System meteorological stations. Air temperature, precipitation, solar radiation, wind speed, and humidity only. Eight countries make groundwater data publicly available through the Global Groundwater Monitoring Network. River flow observations from the Global Runoff Data Centre. Lighter circles indicate greater latency in the data record. USGS Groundwater Climate Response Network. Issues include coverage gaps, delays, measurement continuity and consistency, data format and QC, political restrictions

4 NASA Earth Science Missions Current & Planned Highly relevant to hydrology

5 Gravity Recovery and Climate Experiment (GRACE) Soil Moisture Snow, Ice, Rainfall Radiation Vegetation Snow Aqua: MODIS, AMSR-E, etc. Traditional radiation-based remote sensing technologies cannot sense water below the first few centimeters of the snowcanopy-soil column

6 Gravity Recovery and Climate Experiment (GRACE) Soil Moisture Snow, Ice, Rainfall Radiation Vegetation Snow Aqua: MODIS, AMSR-E, etc. GRACE GRACE is unique in its ability to monitor water at all levels, down to the deepest aquifer

7 Gravity Recovery and Climate Experiment (GRACE) Two identical satellites flying in tandem, near-polar orbit, ~200 km apart, 500 km initial altitude Distance between satellites tracked by K-band microwave ranging system Launched 17 March 2002

8 Terrestrial Water Storage Variations Water Storage, mm Snow Water Equivalent 450 Top 2mSoil Moisture Deep SM and Groundwater Updated from Rodell and Famiglietti, WRR, 2001 Jan-8 83 Jan-8 84 Jan-8 85 Jan-8 86 Jan-8 87 Jan-8 88 Jan-8 89 Jan-9 90 Jan-9 91 Jan-9 92 Jan-9 93 Jan-9 94 Jan-9 95 Jan-9 96 Jan-9 97 Jan-9 98 Jan-9 99 Jan-0 00 Jan-0 01 Jan-0 02 Jan-0 03 Jan-0 04 Jan-0 05 Top: 23 year time series es of snow, soil moisture, and groundwater storage in Illinois, USA (right) TWS variations are dominated by: Soil moisture in temperate regions; Snow in polar and alpine regions; Surface water in wetlands.

9 GRACE Terrestrial Water Storage Anomalies, Top: Monthly terrestrial water storage anomalies (equivalent height of water in cm), derived from GRACE CSR RL05 data with 300 km smoothing (unscaled), available from (Landerer and Swenson, Wat. Resour. Res.,, 2012). Bottom: Same as top, with seasonal cycle removed.

10 Emerging Trends in Terrestrial Water Storage from GRACE cm/yr Trends in GRACE derived terrestrial water storage, Best fit linear rate of change of TWS (cm/yr). Based on land hydrology product from GRACE Tellus (CSR RL05). Which apparent trends are real and likely to continue?

11 Exploitation of Water Resources Percentage of Irrigated Area Net Consumptive Use of Ground and Surface Waters, Source: FAO and University of Frankfurt Döll et al. (2011) Equivalent height of water (mm/yr) Groundwater Depletion Rate (ca. 2000) Terrestrial Water Storage Trends from GRACE Wada et al. (2010) Equivalent height of water (mm/yr) Equivalent height of water (cm/yr)

12 Groundwater Depletion in Northern India Water Sto orage Anomaly (cm) Total Terrestrial Water Soil Water Groundwater Groundwater Trend -30 Apr-02 Apr-03 Apr-04 Apr-05 Apr-06 Apr-07 Apr-08 Apr-09 Apr-10 Apr-11 Apr-12 Apr-13 Apr-14 Date GW = TWS SM SWE Groundwater continues to be depleted in the Indian states of Rajasthan, Punjab, and Haryana by about 16.0 km 3 /yr, reduced slightly from our previous ( ) estimate of 17.7 ±4.5 km 3 /yr (Rodell, Velicogna, and Famiglietti, 2009).

13 Growth of Irrigation in Saudi Arabia Rate of change of water storage (cm/yr) Landsat images prepared by Aries Keck, NASA/GSFC

14 Groundwater Depletion in Saudi Arabia Water Storag ge Anomaly (cm m) Total Terrestrial Water Soil Water Groundwater Groundwater Trend -10 Mar-03 Mar-04 Mar-05 Mar-06 Mar-07 Mar-08 Mar-09 Mar-10 Mar-11 Mar-12 Date Preliminary estimate of groundwater depletion rate: 2.6 km 3 /yr. This includes the impact of a persistent drought in the region, as indicated by the soil water time series.

15 Groundwater Depletion in the North China Plain Water Storage Anom maly (cm) Total Terrestrial Water Soil Water Groundwater Groundwater Trend -10 Mar-03 Mar-04 Mar-05 Mar-06 Mar-07 Mar-08 Mar-09 Mar-10 Mar-1 1 Mar-12 Date Preliminary estimate of groundwater depletion rate: 4.9 km 3 /yr. Estimate likely would increase if properly scaled to account for leakage.

16 Emerging Trends in Global Freshwater Storage Trends in terrestrial water storage (cm/yr), including groundwater, soil l k d i b d b GRACE d i water, lakes, snow, and ice, as observed by GRACE during Alaska s glaciers have been melting at 84 km 3 /yr Greenland s ice sheet has been thinning at a rate of 142 km 3 /yr Russian droughts in 2010 and 2012 Groundwater is being depleted across northern India at rate of about 54 km 3 /yr due to pumping for irrigation Drought gave way to flooding in the Missouri River basin in 2011 Recent droughts in the southern U.S. Recovery from drought in the Amazon 2010 Chile earthquake and drought in southern Argentina Patagonian glacier melt The western Antarctic ice sheet has been thinning at a rate of 65 km 3 /yr Overexploitation of freshwater resources in the North China Plain Return to normal after wet years in early 2000s Drought recovery and flooding Depletion of water resources in Middle East, exacerbated by drought Return to normal in the Okavango Delta after drought ended in 2007 GRACE observes changes in water storage caused by natural variability, climate change, and human activities such as groundwater pumping

17 Land Surface Models (LSMs) LSMs solve for the interaction of energy, momentum, and mass between the surface and the atmosphere in each model element (grid cell) at each discrete time-step (~15 min) GRID SUBGRID HETEROGENEITY NEEDLELEAF TREES: 25% SHRUBS: 10% BARE SOIL: 15% GRASSLAND: 50% SURFACE VEGETATION ATMOSPHERE TRANSFER SCHEME Input - Output = Storage Change P + G in (Q + ET + G out) ) = ΔS R n -G = L e + H System of physical equations: Surface energy conservation equation Surface water conservation equation Soil water flow: Richards equation Evaporation: Penman-Monteith equation etc.

18 Input Parameters: vegetation class vegetation greenness/lai soil type elevation LSM Input and Output Fields Required Forcing Fields: total precipitation convective precipitation downward shortwave radiation downward longwave radiation near surface air temperature near surface specific humidity near surface wind speed (U & V) surface pressure Summary of Output Fields: soil moisture in each layer snow water equivalent soil temperature in each layer surface and subsurface runoff evaporation transpiration latent, sensible, and ground heat fluxes snowmelt snowfall and rainfall net shortwave and longwave radiation

19 GRACE Data Assimilation for Drought Monitoring GRACE terrestrial water storage anomalies (cm equivalent height of water) for June New process integrates data from GRACE and other satellites to produce timely information on wetness conditions at all levels in the soil column, including groundwater. For current maps and more info, see unl U.S. Drought Monitor product for 26 July Surface Soil Moisture Root Zone Soil Moisture Groundwater Drought indicators from GRACE data assimilation (wetness percentiles relative to the period 1948-present) for 26 June 2007.

20 Indicators of Drought Based on GRACE Data Assimilation

21 Summary and Future Prospects Due to the incompleteness of ground-based d observations, space-based observation of global freshwater resources is critical. NASA s GRACE satellite mission is unique in its ability to monitor all forms of water at all depths, including groundwater. Emerging trends in terrestrial water storage observed by GRACE during can be categorized as natural variations, climate change impacts, or direct consequences of human activities, particularly irrigation. The value of GRACE and other satellite data for applications such as drought monitoring can be enhanced by combining them within a land surface model. The GRACE Follow-On mission is scheduled to launch in August 2017.

22 Data, Visualization, Educational Materials t / / d ti / - GRACE educational materials -GRACE data, images, and animations - Soil Moisture Active Passive Mission - Tropical Rainfall Measurement Mission - Global Precipitation Measurement Mission - Satellite based monitoring of lake and reservoir levels - Giovanni Earth science data visualization tool National Drought Mitigation Center - NASA/GSFC Water Resources Applications Projects water html - Feature on Indian groundwater depletion detected by GRACE