DFC Updates and Explanatory Reports in GMA 13, Bill Hutchison

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DFC Updates and Explanatory Reports in GMA 13, Bill Hutchison

  1. 1. DFC Updates and Explanatory Reports in GAM 13 Bill Hutchison, Ph.D., P.E., P.G. TAGD Quarterly Meeting February 25, 2014
  2. 2. Topics • GMA 13 background – Geography – Groundwater Availability Model – Initial DFC • Activities to date • Overview of draft explanatory report
  3. 3. GMA 13
  4. 4. GMA 13: All or part of 17 counties
  5. 5. GMA 13: All or part of 8 GCDs
  6. 6. GMA 13: All or part of 8 GCDs + EAA
  7. 7. Groundwater Availability Model: QCSP-South • Aquifers – Sparta (Layer 1) – Queen City (Layer 3) – Carrizo-Wilcox Aquifer (Layers 5 to 8) • Confining Layers – Weches (Layer 2) – Reklaw (Layer 4)
  8. 8. 3 4 5 1 6 7 8 From pg 2-33 of GAM Report (Kelley and others, 2004) 2
  9. 9. Carrizo-Wilcox, Queen City and Sparta Aquifers • GMA 13 Adopted DFC on April 9, 2010 • DFC establishment relied on results from several model simulations – DFC expressed as GMA-wide average (23 ft) – Scenario 4 of GAM Run 09-034 • 61 year simulation • Assumed a starting point in 2000
  10. 10. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  11. 11. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  12. 12. Comparison of Actual Data with Current DFC (Task 0) • Initial task to assess current DFC • Address issues regarding use of “average” drawdown as DFCs • Key element of “Factor 1” (Aquifer Uses and Conditions)
  13. 13. DFC and GAM Run • How to compare actual data to DFC? • How to compare actual data to results from an “idealized” model run? • How to compare “average” drawdown over entire GMA (23 ft) with individual well measurements?
  14. 14. Point-by-Point Comparison • Comparisons at discrete locations • Extract predicted groundwater levels/ drawdown from model files • Compare to actual monitoring data • Limited use of averaging
  15. 15. 6,956 Wells in GMA 13 in the TWDB Database • 1,844 wells with screen top and bottom • 748 are completed in exactly one GAM layer • 92 have 10 or more groundwater elevation measurements with at least one after 2000
  16. 16. Hydrographs for 92 Wells • • • • • • • Presented in Task 0 report Pumping (in immediate area of the well) Land surface elevation Screen top and bottom elevation Actual groundwater elevation Calibrated model groundwater elevation Simulated groundwater elevation (DFC run)
  17. 17. Data Comparison Approach • DFC Drawdown minus Actual Drawdown – Positive number means that actual groundwater level is higher than DFC groundwater level • DFC drawdown = 10 ft • Actual drawdown = 8 ft • Difference = 2 ft – Negative number means that actual groundwater level is lower than DFC groundwater level
  18. 18. Data Comparison • Well-by-well drawdown comparison requires: – Groundwater elevation measurement in late 1999/early 2000 – Groundwater elevation measurement in year of interest • Task 0 report contains maps, tables, and graphs for the GMA and for each County • Only one GMA-level example shown here
  19. 19. 142 132 96 90 113 74 74 76 86 101 132 Precipitation as % Average 45
  20. 20. Observations • Actual drawdown less than DFC drawdown – In most counties and in most years, MAG was much higher than actual pumping • Exception in 2010 and 2011 – Increased use due to drought? – Increase use due to hydraulic fracturing water use? – Decreased recharge due to drought?
  21. 21. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  22. 22. Updated Pumping 2000 to 2011 • More accurate pumping estimates – Based on TWDB Water Use Survey and GCD input • Provides ability to use end of 2011 as starting point for any drawdown based DFC
  23. 23. Pumping Updates for 2000 to 2011 • WUS and GCD estimates were used as starting point – Included updated well locations in Gonzales and Caldwell Counties • “Calibrated” annual pumping on a countyaquifer basis based on groundwater elevation data from TWDB database • Technical memorandum will be provided to TWDB
  24. 24. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  25. 25. Future Pumping Estimates (2012 to 2070) • “Factor 2” (Water Supply Needs and Water Management Strategies) – TWDB MAG report associated with 2010 DFCs – DB12 data from TWDB (Sources, Demands, Water Management Strategies) – Oil and Gas Water Use Estimates (BEG study) – SAWS input (email of June 27, 2013) – GCD input
  26. 26. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  27. 27. Alternative Simulations • 59-year simulations (2012 to 2070) • Use 2011 conditions as starting point – Based on model update that covered 2000 to 2011 – Developed “Base Case” that included current MAG and input from SAWS, GCDs
  28. 28. Alternative Scenarios • • • • • • • Scenario 1 – 0.7*Base Case Scenario 2 – 0.8*Base Case Scenario 3 – 0.9*Base Case Scenario 4 – Base Case Scenario 5 – 1.1*Base Case Scenario 6 – 1.2*Base Case Scenario 7 – 1.3*Base Case
  29. 29. Simulation Output • Average Drawdown (Maps, Tables, Graphs) – – – – – – GMA County GCD Aquifer County-Aquifer GCD-Aquifer
  30. 30. Other Simulation Outputs • Maps, Tables and Graphs – Storage change – Outcrop vs. confined drawdown or storage • Individual well summaries – Groundwater elevation – Drawdown (from 2011) – Height of water above (or below) top of screen
  31. 31. Status of GAM Simulations • Scenarios 1 to 7 presented to GMA 13 on October 9, 2013 • Requested input regarding changes by December 31, 2013 – Two GCDs requested modifications to future pumping • Gonzales UWCD • Guadalupe County GCD
  32. 32. Status of GAM Simulations • Made changes and completed Scenario 8 – Presented preliminary results to Guadalupe on February 13, 2014 • Complete summary report before next GMA 13 meeting (March 13, 2014) • Discuss results at GMA 13 meeting – Accept as basis for proposed DFC – Make additional revisions • Discuss level of detail of DFC expression
  33. 33. Summary of Activities: Fall 2012 to Date • Comparison of actual data with current DFC (Task 0) • Extended GAM with updated pumping estimates from 2000 to 2011 • Updated future pumping • Completed alternative simulations • Completed draft of explanatory report
  34. 34. Explanatory Report • Statute requires that GMA 13 consider the nine factors (and the balancing) prior to adopting a “proposed” DFC • An “explanatory” report is required when submitting “final” DFC to TWDB, and must include documentation of these factors – “Explanatory” report not required for “proposed” DFC
  35. 35. GMA 13 Approach • “Preliminary” explanatory report – Document factor review for “proposed” DFC – Useful documentation for GCDs during public review period after “proposed” DFC is adopted
  36. 36. Initial Draft of Explanatory Report • Covers elements required by statute and rule – Generally follows outline suggested by TWDB • Main text • Appendices
  37. 37. 1.0 Groundwater Management Area 13 • Overview of GMA 13 Geography and GCDs
  38. 38. 2.0 Proposed Desired Future Condition • To be completed after “Proposed” DFC adoption • Draft resolution is Appendix A (no signature block yet)
  39. 39. 3.0 Policy Justification • Lists nine factors • Includes balancing language • To be completed after “Proposed” DFC is adopted
  40. 40. 4.0 Technical Justification • Discusses GAM used and its limitations
  41. 41. 5.0 Factor Consideration • Discussion of nine factors required by statute
  42. 42. 5.1 Aquifer Uses and Conditions • Pumping estimates (Appendix B) – 1999 Pumping from GAM – 2000 to 2008 TWDB Water Use Survey estimates – Gonzales UWCD estimates – Plum Creek CD estimates • Also references and includes Task 0 report as Appendix C
  43. 43. 5.2 Water Supply Needs and Water Management Strategies • Included in Appendix D – DB12 data from TWDB (Sources, Demands, Water Management Strategies) – Oil and Gas Water Use Estimates (BEG study) – SAWS input (email of June 27, 2013) – GCD input – TWDB MAG report associated with 2010 DFCs
  44. 44. 5.3 Hydrologic Conditions • 5.3.1 – Storage (from TWDB) – Included as Appendix E • 5.3.2 – Recharge, Inflows and Discharge (Appendix F) – Table of Average Historic Water Budget (from February 19, 2010 GMA 13 meeting) with a column for proposed DFC (pending GMA 13 action) – More detailed water budget data from GAM Run 09-034
  45. 45. 5.4 Other Environmental Impacts • Spring flow and groundwater-surface water interactions • Covered in water budget discussion in Section 5.3.2 and data in Appendix F
  46. 46. 5.5 Subsidence • Not applicable
  47. 47. 5.6 Socioeconomic Impacts • State Water Plan strategies are an important foundation for this DFC • Included Region K, L, and M socioeconomic reports completed by TWDB in 2010 in Appendix G – Assesses impacts of not meeting water needs
  48. 48. 5.7 Impact on Private Property Rights • Balancing discussion – Existing well impacts vs. impacts to property owners who “conserved” groundwater • Will include maps of well specific impacts based on Task 0 wells – Feet of water above/below top of screen – Feet of water above/below bottom of screen
  49. 49. 5.8 Feasibility of Achieving DFC • Monitoring discussion • Recommendation for analyses similar to Task 0 evaluation • Discussion on updates every five years
  50. 50. 5.9 Other Information • Included James Bene paper and presentation to GMA 13 as Appendix H • Include comparison of model output to simple Darcian approach forwarded by Bill Klempt
  51. 51. 6.0 Discussion of Other DFCs Considered • To be completed • Drawn from alternative simulations
  52. 52. 7.0 Discussion of Other Recommendations • To be completed once public hearings are held (i.e. part of final explanatory report)
  53. 53. 8.0 References • References cited in report
  54. 54. Appendices • • • • • • • • A – DFC Resolution B – Historic use Estimates C – Task 0 report D – Various future pumping projections E – TWDB storage report F – Water budget estimates G – Socioeconomic reports H – Other information
  55. 55. TWDB Review • TWDB staff developed a checklist of required elements • Initiated a review of the draft • All elements were found in draft (10/25/2013 email)
  56. 56. Summary • GMA 13 has reviewed and compared current DFC and actual data (resulted in extended GAM – pumping through 2011) • GMA 13 has considered the relevant factors to “propose” a new DFC • GMA 13 has completed alternative GAM simulations (more to be completed?) • GMA 13 is reviewing draft of explanatory report • Next GMA 13 meeting is March 13, 2014
  57. 57. Questions? Bill Hutchison 512-745-0599 billhutch@texasgw.com

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