Sensitivities: Using to Gain Insight into Problems with Model Fit and Parameter Fields

1. Sensitivities:Using to Gain Insight into Problems with Model Fit and Parameter Fields

2. Some K Fields Have ‘Bulls-eyes’ Need to carefully consider colorscale when identifying high and low K’s at individual pilot points (‘bulls-eyes’) that might be artifacts to achieve better model fit. Also, in UFA and APPZ, several locally high K features are springs. Kz2 Kh5

3. Locally High Kh3 • “Bulls-eye” of high Kh3 at a pilot point in Polk County underlying Lake Wales Ridge. • Kh3=1200 ft/day. • Surrounding 4 pilot points have K’s of 36-225 ft/day. • Look at: • Which head observations are most sensitive to this Kh3 parameter … • And would have improved fit by increasing Kh3 here. Kh3

4. At these LAYER 1 SAS wells, simulated head is too high, and increasing Kh3 decreases head, which improves fit. ridge_p_6 (99 & 03): SAS ridge_vc_9 (99 & 03): SAS lk_hatchi (03): UFA ridge_p_8 (99 & 03): SAS At ridge_p_8, simulated head is too low, so decreasing Kh3 would improve fit…

5. There are other K parameters at pilot points that ridge_p_6 and ridge_vc_9 heads are sensitive to: -kh3 of a nearby pilot point -kz2, kh5 of nearby pilot points -Many observations are sensitive to kz2 and kh5, so changing them to improve fit ridge_p_6 and ridge_vc_9 probably would worsen fit too much elsewhere. Thus, kh3 increases unrealistically instead. ridge_p_6 (99 & 03) ridge_vc_9 (99 & 03) lk_hatchi (03) ridge_p_8 (99 & 03)

6. What to do? • Increasing EVT in the ridges should reduce simulated heads in the SAS. • Lower the upper bound on Kh3 at this pilot point. ridge_p_6 (99 & 03) ridge_vc_9 (99 & 03) lk_hatchi (03) ridge_p_8 (99 & 03)

7. Model Fit: Heads too low in UFA For several UFA wells in Lake, Polk, Orange Counties where simulated head is too low, these heads are typically most sensitive to kz2 and recharge,followed by sensitivity to kh7 and kz6. Many observed heads throughout all model layers are very sensitive to kz2, so it is hard to pinpoint why kz2 does not change in a different way, so that the fit to the UFA wells is improved….

8. Model Fit: Heads too low in UFA The fit to several of these UFA wells would improve if the Kz6 of the evaporites decreased. In the current model the estimate of this Kz6 is too large. This occurs because this large value improves overall fit despite the worsening of fit at the UFA wells. We will next try: Set the upper bound on this Kz6 to be lower and/or increase the weight on the prior value.

9. Overall Sensitivities Composite Scaled Sensitivity (CSS): Measures sensitivity of all observations to one parameter. Used ‘multipliers’ to obtain the following:

10. Overall Sensitivities Used ‘multipliers’ to also obtain the following CSS for-- ghb lateral conductances by layer (g1c, g2c, g3c, …) -- ghb boundary heads by layer (g1h, g2h, g3h, …) -- recharge and evapotranspiration rates (r99,r03,e99,e03)

11. Overall Sensitivities Now, look at CSS for subgroups of the observations: heads by layer, and for the springs.

12. Sensitivity of Head Obs in Layer 1 kz2 kh5 kh1 kh7 kh3 kz6 Sensitivity of Head Obs in Layer 3 Sensitivity of Head Obs in Layer 5

13. Sensitivity of Head Obs in Layer 7 kh7 kz2 kz6 kh5 kh3 Sensitivity of Springs kz2 kh3 kh5 kz6 kh7

14. Sensitivity of Head Obs in Layer 1 rch03 evt03 ghb heads in layer: rch99 5 evt99 1 7 3 Sensitivity of Head Obs in Layer 3 Sensitivity of Head Obs in Layer 5

15. Sensitivity of Head Obs in Layer 7 kh7 kz2 kz6 7 evt03 rch03 kh5 kh3 5 rch99 evt99 3 Sensitivity of Springs kz2 kh3 kh5 kz6 kh7

16. Kh1

17. Kz2

18. Kh3

19. Kh3 Prior Values

20. Kh5

21. Kh5 Prior Values

22. Kh7

23. SAS 1999

24. SAS 2003

25. UFA 1999

26. UFA 2003

27. APPZ 1999

28. APPZ 2003