LDRD 04

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Reed M. Maxwell1, Stefan J. Kollet1, Qingyun
Duan1 and Fotini K. Chow2 1Atmospheric, Earth,
and Energy Sciences Dept, Lawrence Livermore
National Lab 2Civil and Environmental Engineering
Dept, University of California, Berkeley
This work was performed under the auspices of the
U.S. Department of Energy by University of
California, Lawrence Livermore National
Laboratory under contract No. W-7405-Eng-48.
UCRL-PRES-XXXXXX
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Three talks for the price of one

• Brief overview on RC/LS/OF/GW coupled model
  project underway at LLNL
• Some details of a new coupled overland
  flow-groundwater work (Kollet and Maxwell, 2005)
• Example problem that illustrates distributed
  LS/OF/GW modeling

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Results of first coupled model study show
important gains resulting from process feedback
Coupled Model provides much more accurate
predictions of

• Runoff
• Soil moisture
• Water balance

Observations
-1
Coupled
Uncoupled
Maxwell and Miller, J. Hydromet,6(3), 2005.
Others have shown similar results.
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This project integrates four models in a unique
way
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This project integrates four models in a unique
way
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This project integrates four models in a unique
way
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This project integrates four models in a unique
way
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This project integrates four models in a unique
way
Explicitly incorporates fluxes at
air/land-surface/subsurface interfaces
Precipitation/Advection
Runoff/Routing
Moisture/heat flux
Evapotranspiration
Infiltration/Seepage
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Project tasks, details

• Run RCM over central US w/ a detailed study area
  over Little Washita watershed
• SGP/ARM site
• Data to validate all models (need lots)
• P1 run in a nested mode, RCM and GW/LS/OF models
  uncoupled (control run)
• RCM (ARPS) passes LS forcing to coupled model
• Coupled model spun up w/ obs, forced by RCM
• P2 fully couple models, re-run
• Verify that models are coupled and balancing mass
  and energy
• Look at water, heat fluxes across the LS and at
  weather and weather generating processes

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Surface contours for 1 km resolution grid,
07/08/99 12 UTC
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RCM/ARPS Results

• Norman Oklahoma sounding comparison 07/08/99, 12
  UTC

q g/kg
? K
fdegrees
U m/s
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Sacramento Model Calibration for Little Washita
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Borehole data used to create 3D geostatistical
realization of the subsurface
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Free-surface overland-flow boundary condition,
coupled groundwater overland flow

• Lots of motivation for coupled model
• Watershed modeling
• Climate
• Water quality
• Most (all?) coupled models rely on interface
  between SW and GW
• conductance concept
• Hard to find field data to support this
• Need for a more general formulation
• Desire for parallel model w/ a robust non-linear
  solver
• Integrate into ParFlow
• Take advantage of infrastructure

Kollet and Maxwell, Advances in Water Resources,
in press, 2005.
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The Conductance Concept
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New Overland Flow Boundary in ParFlow
Kollet Maxwell, 2005
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Verification Examples
2D Tilted V-Catchment 90 min rain, 90 min
recession
1D Slope 200 min rain, 100 min recession
Panday Huyakorn, 2004
Jabar Mohtar, 2004
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Simulation Examples II
Low-K slab
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Simulation Examples III
Random (Gaussian) Heterogeneity
Five Realizations
Kgeo qrain
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Scaled Parallel Efficiency
E(np,p) T(n,1) / T(np,p)
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Integrating land surface processes into ParFlow
an Example

• We add in LS processes (parts of CLM) into
  ParFlow
• Hydro, Runoff handled by PF as detailed earlier
• Fully distributed
• Fully parallel
• Use a well-resolved, large scale 2D Classic
  Example problem to investigate coupled model
  performance and behavior
• Dx100m Dz2m 40km x 0.54km domain
• Toth Problem sinusoidal topography in a large
  basin
• J. Toth, 1963. A theoretical analysis of
  groundwater flow in small drainage basins. J.
  Geophys. Research 684795-4842.
• Forced uniformly with PILPS midlatitude for one
  year

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Toth problem uses an sinusoidal topography
July Pressure
Initial Pressure
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Coupled model forced by PILPS midlatitude,
produces realistic looking hydrograph
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Averaged, Cumulative ET
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Distributed Ground Surface Temperature
Non-uniform freezing
Distribution of temps, non-uniform water content
Non-uniform thaw
Initialization
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Distributed Water and Heat Fluxes
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Summary

• We are working on lots of stuff, but have a lot
  yet to do
• Coupled RC/LS/OF/GW project in Y1/control run
  phase, soon will start dynamic coupling
• Coupled overland flow and groundwater method
  looks very promising
• Integrating LS processes into GW provides
  interesting distributed results need to compare
  to field site (Little Washita, Valdai)
• Still overall question regarding quantifying
  impacts and scale of coupled processes