1. Local Groundwater Flow Model Addendum Guadalupe Restoration Project San Luis Obispo County October 24 2002

2. Reasons for LGFM Revision Excess water entering DSA from agricultural fields to the east Drainage channel along eastern DSA identified Update layer structure to conform with new data Overall goals: more realistic water balance, enhance model reliability

3. Model Revisions Changed layer structure –Base of DSA revised throughout GOF –Top of PA conforms with Worts (1951) Included agricultural drainage channel Revised recharge and soil properties for agricultural fields Revised calibration targets and improved model calibration

4. Revisions to Layers

6. Old Layer 5 Bottom (gray) New Layer 5 Bottom (colored) Old DSA Bottom (gray) New DSA Bottom (colored)

7. Old PA Top (gray) New PA Top (colored)

9. Addition of Agricultural Drain

11. Drain Location in LGFM 3.0 Agricultural Fields DSA

13. Changes to Recharge and Soil Properties

14. Recharge Rates in LGFM 2.0 3 in/yr 8 in/yr 10.7 in/yr

15. Recharge Rates in LGFM 3.0 3 in/yr 8 in/yr 3 in/yr

16. Hydraulic Conductivities in LGFM 2.0 K h = 75 ft/day K v = 33 ft/day K h = 50 ft/day K v = 5 ft/day

17. Hydraulic Conductivities in LGFM 3.0 K h = 75 ft/day K v = 33 ft/day K h = 25 ft/day K v = 2.5 ft/day

18. Calibration

22. Recalibration Statistics

23. How Has Flow Balance Changed? Bottom Outflow Bottom Inflow Lateral Outflow Lateral Inflow Outflow to River Willows Outflow Recharge Inflow Evapotranspiration Outflow Drain Outflow

24. Flow Balance: Old vs. New

26. Conclusions Model is more realistic in several ways: –layer structure –drain and river –agricultural fields –water balance Complies better with conceptual model

27. Conclusions Model represents shared vision Will provide better predictions of groundwater flow for future characterization and remediation issues