1. Reed M. Maxwell 1, Stefan J. Kollet 1, Qingyun Duan 1 and Fotini K. Chow 2 1 Atmospheric, Earth, and Energy Sciences Dept, Lawrence Livermore National Lab 2 Civil 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 A dynamically-coupled groundwater, land surface and regional climate model to predict seasonal watershed flow and groundwater response

2. 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

3. Results of first coupled* model study show important gains resulting from process feedback Runoff Soil moisture Water balance Observations Coupled Coupled Model provides much more accurate predictions of: Uncoupled *Maxwell and Miller, J. Hydromet,6(3), 2005. Others have shown similar results.

4. This project integrates four models in a unique way Land surface model

5. This project integrates four models in a unique way Groundwater model Land surface model

6. This project integrates four models in a unique way Groundwater model Land surface model Overland flow

7. This project integrates four models in a unique way Groundwater model Land surface model Overland flow Land surface model Overland flow Regional climate model

8. This project integrates four models in a unique way Groundwater model Land surface model Overland flow Land surface model Overland flow Regional climate model Explicitly incorporates fluxes at air/land- surface/subsurface interfaces Moisture/heat flux Evapotranspiration Infiltration/Seepage Precipitation/Advection Runoff/Routing

9. 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

10. Surface contours for 1 km resolution grid, 07/08/99 12 UTC

11. RCM/ARPS Results Norman Oklahoma sounding comparison 07/08/99, 12 UTC θ [K] U [m/s] φ[degrees] q [g/kg]

12. Sacramento Model Calibration for Little Washita

13. Borehole data used to create 3D geostatistical realization of the subsurface

14. 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.

15. The Conductance Concept

16. New Overland Flow Boundary in ParFlow Kollet & Maxwell, 2005

17. Verification Examples Panday & Huyakorn, 2004 2D Tilted V-Catchment: 90 min rain, 90 min recession 1D Slope: 200 min rain, 100 min recession Jabar & Mohtar, 2004

18. Simulation Examples II Low-K slab

19. Simulation Examples III Random (Gaussian) Heterogeneity Five Realizations K geo = q rain

20. Scaled Parallel Efficiency E(np,p) = T(n,1) / T(np,p)

21. 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 –Dx=100m; Dz=2m; 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 68:4795-4842. Forced uniformly with PILPS midlatitude for one year

22. Toth problem uses an sinusoidal topography Initial Pressure July Pressure

23. Coupled model forced by PILPS midlatitude, produces realistic looking hydrograph

24. Averaged, Cumulative ET

25. Distributed Ground Surface Temperature Initialization Non-uniform thaw Distribution of temps, non-uniform water content Non-uniform freezing

26. Distributed Water and Heat Fluxes

27. 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