GRACE in the Murray-Darling Basin: GRACE in the Murray-Darling Basin: integrating remote sensing with field integrating remote sensing with field

monitoring to improve hydrologic model monitoring to improve hydrologic model predictionprediction

Kevin M. EllettKevin M. EllettDepartment of Civil and Environmental Engineering, University of Melbourne, Department of Civil and Environmental Engineering, University of Melbourne,

Australia and USGS WRD Sacramento, CaliforniaAustralia and USGS WRD Sacramento, California

Colleagues: Jeffrey Walker, Rodger Grayson, Adam SmithColleagues: Jeffrey Walker, Rodger Grayson, Adam Smith and Matt Rodell (NASA-GSFC)and Matt Rodell (NASA-GSFC)

OutlineOutline

Motivation for ResearchMotivation for Research Contributions from GRACEContributions from GRACE Research ApproachResearch Approach Preliminary ResultsPreliminary Results

Motivation for ResearchMotivation for Research Modeling hydrological Modeling hydrological

processes at the processes at the catchment-scalecatchment-scale

Soil moistureSoil moisture is a key is a key component in the component in the terrestrial water and terrestrial water and energy balanceenergy balance

Primary controlsPrimary controls on soil on soil moisture distributionmoisture distribution climate, soils, vegetation, climate, soils, vegetation,

topographytopography ScalingScaling of soil moisture of soil moisture

and hydrological and hydrological processes?processes?

Western and Grayson, 1998

Motivation for ResearchMotivation for Research Current policy initiatives on Current policy initiatives on

sustainable sustainable water resource water resource managementmanagement in Australia in Australia– Murray-Darling Basin Murray-Darling Basin

(MDB)(MDB) Land clearing has resulted Land clearing has resulted

in devastating impacts in devastating impacts fromfrom salinity salinity– Long-term increase in Long-term increase in

terrestrial water storageterrestrial water storage– Re-vegetation to Re-vegetation to

reverse this trendreverse this trend

GRACE Contributions in the MDBGRACE Contributions in the MDB

Measuring the trend in storage changeMeasuring the trend in storage change– Re-vegetationRe-vegetation– Limited 5 year lifespanLimited 5 year lifespan

Assessment of regional-scale hydrological modelsAssessment of regional-scale hydrological models– Water balance closureWater balance closure– Model biasModel bias

Can GRACE help to improve modeling at the Can GRACE help to improve modeling at the catchment-scale?catchment-scale?– ScalingScaling

ObjectivesObjectives

1)1) GRACE “validation” (comparison) from an GRACE “validation” (comparison) from an observational networkobservational network

2)2) Examine the utility of GRACE observations Examine the utility of GRACE observations at the catchment-scaleat the catchment-scale

DownscalingDownscaling

ApproachApproach1)1) Installation of a Installation of a ground-based measurement networkground-based measurement network for for

monitoring changes in gravity and terrestrial water monitoring changes in gravity and terrestrial water storagestorage

Nested catchment and grid-based designs provide data at 4 Nested catchment and grid-based designs provide data at 4 different scales using 46 total sitesdifferent scales using 46 total sites

2)2) Development of a Development of a modelling frameworkmodelling framework for the for the downscaling and assimilation of GRACE data into a downscaling and assimilation of GRACE data into a catchment-based land surface modelcatchment-based land surface model

3)3) Assessing the utility of GRACE by comparing model Assessing the utility of GRACE by comparing model results results with and without GRACE data assimilationwith and without GRACE data assimilation to the to the measurement networkmeasurement network

Results will depend on downscaling approach, model physics, Results will depend on downscaling approach, model physics, data assimilation, and observations- data assimilation, and observations- uncertainty in each uncertainty in each componentcomponent

a)a) Testing of Testing of alternative modelalternative model with simple water balance with simple water balance parameterization allowing automated calibrationparameterization allowing automated calibration

b)b) Testing of Testing of alternative downscaling schemesalternative downscaling schemes

Murray-Darling Basin and theMurray-Darling Basin and the Murrumbidgee Catchment Murrumbidgee Catchment

MDB and MurrumbidgeeMDB and MurrumbidgeeAverage Annual Precipitation (mm)Average Annual Precipitation (mm)

MDB and MurrumbidgeeMDB and MurrumbidgeeAnnual Actual Evapotranspiration (mm)Annual Actual Evapotranspiration (mm)

MDB and MurrumbidgeeMDB and MurrumbidgeePrecipitation minus Evapotranspiration (mm)Precipitation minus Evapotranspiration (mm)

MDB and MurrumbidgeeMDB and MurrumbidgeeSurface Water StoragesSurface Water Storages

Murrumbidgee Monitoring NetworkMurrumbidgee Monitoring Network

Irrigation Areas

Yanco Study Area (50km x 50km Grid)

Kyeamba Ck. Study Area

Monitoring Site InstrumentationMonitoring Site Instrumentation

Gravity monitoring with CG-3M on stable platform

Logger

CS616

Backfilled soil

T107

Raingauge

Piezometer (water level and neutron probe)

TDRStar pickets (2.5 m length)

Schematic diagram of instrumentation installed at monitoring sites

Gravity Network Tied to Canberra SGGravity Network Tied to Canberra SG

Preliminary ResultsPreliminary ResultsCatchment mean RZSM storage timeseries

100

150

200

1/11

/200

1

1/01

/200

2

1/03

/200

2

1/05

/200

2

1/07

/200

2

1/09

/200

2

1/11

/200

2

1/01

/200

3

1/03

/200

3

1/05

/200

3

1/07

/200

3

RZSM

Sto

rage

(mm

)

Murr_day

Murr_mon

Ky_day

Ky_mon

Kyeamba sub-catchment (upper) - RZSM loc -mean

-60

-40

-20

0

20

40

60

1/11

/200

1

1/01

/200

2

1/03

/200

2

1/05

/200

2

1/07

/200

2

1/09

/200

2

1/11

/200

2

1/01

/200

3

1/03

/200

3

1/05

/200

3

1/07

/200

3

Tota

l RZS

M S

tora

ge (m

m)

Ginn(GS)

Ginn(F)

Wait(SS)

Clark(GS)

Palm(GS)

Observed average monthly dS = 13.5 mm

Annual amplitude approx. 50 mm

ConclusionsConclusions

Murray-Darling Basin is a reasonable candidate Murray-Darling Basin is a reasonable candidate for GRACE validation/comparisonfor GRACE validation/comparison– Signal dominated by soil moisture componentSignal dominated by soil moisture component– Magnitude?Magnitude?

Modeling framework for testing the utility of Modeling framework for testing the utility of GRACE is currently being developedGRACE is currently being developed– Catchment-based LSM [Catchment-based LSM [Koster et al.Koster et al., 2000], 2000]– Assimilation scheme for GRACE and AMSR-EAssimilation scheme for GRACE and AMSR-E– Development of alternative downscaling schemes and Development of alternative downscaling schemes and

simple “bucket” model calibratedsimple “bucket” model calibrated