A Catchment Based Study On Streamflow Data Assimilation

Christoph Rüdigera, Jeffrey P. Walkera, Jetse D. Kalmab, Garry R. Willgoosec

and Paul R. Houserd

a Dept. of Civil & Env. Eng., University of Melbourne, Australia

b School of Engineering, University of Newcastle, Australia

c School of Geography, University of Leeds, United Kingdom

d Hydrological Sciences Branch, NASA GSFC, USA

Christoph Rüdiger

AGU May 2004

Koster et al., JHM, 2000

Christoph Rüdiger

AGU May 2004

Christoph Rüdiger

AGU May 2004

Goulburn Catchment

Melbourne

NewcastleSydney

1000km0km

Christoph Rüdiger

AGU May 2004

Goulburn Catchment

Streamgauge

Soil Moisture

Climate

www.civenv.unimelb.edu.au/~jwalker/data/oznet/

Christoph Rüdiger

AGU May 2004

Catchment Land Surface Model

Koster et al., JGR, 2000Saturation

Depth

Water Table

Eq. profile

Moisture Deficit

Prognostic variables:

•Catchment Deficit

•Surface Moisture Excess

•Root Zone Excess

Christoph Rüdiger

AGU May 2004

Internal routing

Travel time TpiVelocity weight v-1

Christoph Rüdiger

AGU May 2004

• “Truth”:– 10yr spin up– 1yr full run

• “Experiment 1”:– One month only– Degraded soil moisture values (low catchment deficit)

• “Experiment 2”:– “Openloop 1” and changed forcing (33% lower radiation

and 20% higher precipitation)

Synthetic ExperimentVariational Data Assimilation

• NLFIT (Kuczera, WRR, 1982)

Christoph Rüdiger

AGU May 2004

Results from assimilation with "true" forcing (runoff)

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Results “Experiment 1”

Discharge Soil Moisture

Christoph Rüdiger

AGU May 2004

Results form assimilation with "wrong" forcing data (runoff)

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Results “Experiment 2”

Discharge Soil Moisture

Christoph Rüdiger

AGU May 2004

Results “Experiment 2”

Root Zone Soil Moisture Surface Soil Moisture

Christoph Rüdiger

AGU May 2004

Summary of Results

• Results show that runoff has information about soil moisture states

• Problems in semi-arid regions, when overestimation of water input due to degraded forcing data

• Monthly assimilation windows have positive impact, reduction of assimilation window should improve results further

Christoph Rüdiger

AGU May 2004

• Including changed soil parameters to simulate the uncertainties involved in land surface modelling

• Assimilation of surface soil moisture data (as available) to further constrain surface soil moisture values

• Multi-catchment study for nested catchments

• Use of real data from intensive field experiment

Future Tasks

Christoph Rüdiger

AGU May 2004

Acknowledgments• Australian Research Council (ARC-DP grant

0209724)• Hydrological Sciences Branch, National

Aeronautics and Space Administration (NASA), USA

• University of Melbourne – Melbourne International Fee Remission

Scholarship (MIFRS)– Postgraduate Overseas Research Experience

Scholarship (PORES)