Jeffrey Walker

Australian Root Zone Soil Moisture: Assimilation of

Remote Sensing Observations1Jeffrey Walker, 2Nadia Ursino,

1Rodger Grayson and 3Paul Houser

1. Dept of Civil and Env Engg, University of Melbourne, Australia2. Dept IMAGE, University of Padova, Italy

3. Hydrological Sciences Branch, NASA-GSFC, USA

http://www.civenv.unimelb.edu.au/~jwalker

Jeffrey Walker

The SituationRemote SensingSatellite

Soil MoistureSensors

Logger Soil Moisture Model[q , D ( ), ( )] f s(z)

Stream Gauge

Jeffrey Walker

Catchment Discretisation

• Hydrologic unit is the catchment 50x50 km2

Jeffrey Walker

SMMR Soil Moisture Observations

Owe, de Jeu and Walker, TGRS 2001

79-8779-87

8686

79-8579-85

Rüdiger and Walker

Jeffrey Walker

Assimilation Results

Jeffrey Walker

Soil Moisture DataAdelaide Jan 1948 Dec 1950Alice Springs Oct 1954 Dec 1956Ballarat Jan 1976 Dec 1977Belconnen Jan 1983 Dec 1986Biloela Jan 1948 Dec 1951Borden Oct 1996 Dec 1999Brindabellas Apr 1981 Oct 1983Collie Jan 1974 May 1979Coranderrk Jan 1970 Dec 1978Dooen Jan 1988 Dec 1991Dwellingup (upslope) May 1984 Oct 1986East Beverly Jan 1992 Dec 1994Esperance Valley Nov 1986 Apr 1988Griffith Jan 1981 Dec 1984Hastings Jan 1976 Dec 1980Huon A (1934 regrowth) Jan 1976 Dec 1980Huon B (1966 regrowth) Jan 1976 Dec 1980Huon C (1975 regrowth) Jan 1976 Dec 1980Keith 1 Apr 1956 Mar 1958Keith 2 Apr 1956 Mar 1958Kojonup Jul 1995 Mar 1999Lidsdale Oct 1968 Apr 1971Lockhart Jan 1980 Dec 1983Lockyersleigh Jan 1987 Jul 1990Moura Jan 1986 Dec 1989Mt Gambier (Grass Land) Jan 1960 Dec 1965Mt Gambier (Kalangadoo Sand) Apr 1963 May 1966Mt Gambier (Young Sand) Apr 1963 May 1966Narrabri Sep 1979 Jun 1980Nerrigundah Aug 1997 Oct 1998North Maroondah (Black Spur 1) Jul 1973 Dec 1976Northfield Jan 1963 Dec 1966Old Junee Jan 1992 Jan 1998Parafield Oct 1966 Oct 1968Pingrup Oct 1996 Dec 1999Pinjarra Nov 1965 Nov 1967Point Nepean Sep 1998 Feb 2000Puckapunyal Apr 1981 Jun 1983Rutherglen Sep 1995 Dec 1999Simmonds Marsh Jan 1976 Dec 1980Sorell Jul 1991 Jul 1994Storm Hill Jan 1976 Dec 1980Tarrawarra Sep 1995 Nov 1997Three Springs (upslope) Jan 1984 Dec 1985Townsville Feb 1968 Aug 1968Trangie Jan 1982 Dec 1984Walpeup Jan 1988 Dec 1991Wongan Hills Jul 1996 Dec 1998Yanchep Jan 1982 Dec 1985Yanco Sep 1981 Jun 1984Yarralaw May 1985 Oct 1986

0

200

400

600

800

1000

0 200 400 600 800 1000

Mo

de

l Ch

an

ge

in M

ois

ture

Sto

rag

e (

mm

)

Literature Change in Moisture Storage (mm)

Jeffrey Walker

Gauged Catchments

330 catchments but mostly coastal and/or dense veg

Jeffrey Walker

NDVI Data

Jeffrey Walker

Drought of 1982/83

0.1

0.2

0.3

0.4

0.5

0.6

0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45

ND

VI (

-)

Soil Moisture (v/v)

ND

VI

(-)

Soil Texture: Wilt Pt

Jeffrey Walker

Anomalies

Jeffrey Walker

Drought of 1982/83

Jeffrey Walker

Temporal Correlation

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Conclusions• Mismatch between model output and available soil

moisture data made it difficult to draw conclusions on improvement in soil moisture predictions.

• Need to make further investigations using the runoff data for low vegetation interior catchments – assumes model has correct dependence on soil moisture.

• An increase in correlation with NDVI data – provides encouragement for pursuing assimilation of AMSR-E data and the collection of appropriate ground-based soil moisture validation data.

Jeffrey Walker