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Presentation on Modflow model updates for Edwards Aquifer. Review, verification, and post-audit updates for years 2001-2011. Structural features, layer elevations, recharge estimation methods, and HSPF Watershed Model results.
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Edwards Aquifer MODFLOW Model Updates Jim Winterle—EAA Modeling Supervisor Presentation to HCP Science Committee May 8, 2014
MODFLOW Model Review and Updates • Verification Analysis completed August 2013: update model inputs to include years 2001—2009 and run using existing calibration to evaluated how well model predicts a time period not used in the calibration • Post-Audit Updates to be completed by December 31, 2014: updated layer elevations and structural features to reflect current understanding and recalibrate model for years 2001—2011 • Schedule for completion: updated, calibrated model by December 31, 2014
MODFLOW Model Updates • Inputs: Pumping and recharge for years 2001—2011 • Observations/Calibration Targets: water levels and spring flows • Structural Features • Layer Top and Bottom Elevations • Hydrologic Flow Barriers (HFB Package) • Potential Model Domain changes • Revise Northern Boundary? • Remove Barton Springs Segment?
Recharge Estimation Methods • USGS (Puente, 1978, method) • HSPF Watershed Models
HSPF Watershed Models • Updates and recalibrations of all nine HSPF watershed models were completed in early 2013 by Clear Creek Solutions under a U.S. Army Corps of Engineers Feasibility Study
HSPF Watershed Model Results • HSPF models results generally lower than USGS estimates for wet periods and similar during dry periods Recharge (acre-feet)
HSPF Watershed Model Results • HSPF recharge estimates are generally lower than cumulative recharge estimated through mass balance methods, while USGS estimates are higher
Water Withdrawal Locations • Dataset improvements over original model includes detailed information on pumping locations and amounts
Water Level Observations • Approximately fourfold increase in number of observation wells for calibration targets • 423 water-level target locations from 2001-2009
With Barton Springs Segment Without Barton Springs Segment