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May 17, 2011

Review of Conceptual Model Used to Simulate Transient Recharge Rates to the Surficial Aquifer in East-Central Florida . May 17, 2011. By Pat Burger, SJRWMD, Palatka, FL Brian McGurk, SJRWMD, Palatka, FL Nick Sepulveda, USGS FWSC-Orlando, FL . Process Overview. Rain and Irrigation .

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May 17, 2011

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  1. Review of Conceptual Model Used to Simulate Transient Recharge Rates to the Surficial Aquiferin East-Central Florida May 17, 2011 By Pat Burger, SJRWMD, Palatka, FL Brian McGurk, SJRWMD, Palatka, FL Nick Sepulveda, USGS FWSC-Orlando, FL

  2. Process Overview Rain and Irrigation Input data Green-Ampt Infiltration with Redistribution (GAR) AET Calculation Independent Calculation Infiltration Hortonian runoff Intermediate Data Unsaturated-Zone Flow Package (UZF1) MODFLOW Processes Stream Flow Routing Package (SFR2) Lake Package (LAK7) Recharge to or Discharge from Groundwater Table Recharge to or Discharge from the ICU (Layer 2)

  3. Green-Ampt Infiltration with Redistribution (GAR) Input Variables: • Rainfall rate, r • Soil hydraulic properties • Saturated water content, s • Residual water content, r • Soil suction head • Soil saturated hydraulic conductivity, Ks • Initial soil water content, i Outputs: Infiltration rate Hortonian runoff rate Assumptions: Rectangular soil water content profile with sharp wetting fronts Initial water content is constant for each rainfall event. Brooks and Corey (1964) soil hydraulic conductivity equation

  4. Unsaturated-Zone Flow (UZF1) Package Input Variables: Stream segments and lakes that the runoff is routed to Saturated vertical hydraulic conductivity Brook-Corey epsilon of the unsaturated zone Saturated water content of the unsaturated zone Initial water content for each cell Infiltration rate at land surface for each cell ET rate for each cell ET extinction depths ET extinction water content Drainage field Outputs: Dunnian runoff routed to LAK7 and SFR2 packages Recharge or infiltration Discharges (UZET, GWET, UZSL) from UZ or water table Assumptions: Homogeneous unsaturated zone Horizontal soil water flow negligible Soil water flow is only driven by gravitational forces

  5. Lake (LAK7) Package Input Variables: Lake cells if lake covers 50% of grid cell Leakance of lakebeds Initial lake stages Precipitation rate to the lake Evaporation rate at the lake Hortonian or Dunnian runoff from watershed entering the lake Outputs: Flow through the lakebed Water surface elevation Flow leaving or entering the lake from SFR2 Assumptions: Hydraulic connection with the ICU aquifer dictated by lakebed leakance. Darcy’s Law governs seepage flow.

  6. Stream Flow Routing (SFR2) Package Input Variables: Stream networks Hortonian and Dunnian runoffs Vertical hydraulic conductivity of the streambed Initial stream stage Initial flow at most upstream reaches Slope of water surface elevation for each segment Slope of streambed elevation Outputs: Flow through the streambed Gage height Stream flow Assumptions: Constant-density stream flow Hydraulically connected to surficial aquifer through streambed.

  7. Calibration of Hydraulic Conductivity Ks in GAR Change vertical Ksin GAR Calculate lake volumes, lake stages, stream stages, stream flows, and groundwater levels Evaluate errors between simulated and observed values No OK? Yes End

  8. Recharge Calculations for Soldier Creek Basin, Gee Creek Basin,Econlockhatchee River Basin,Jesup Lake, Mills Lake, and Lake Pickett

  9. Study Area Includes: • 347 lakes • 307 stream segments • 22 UFA springs

  10. Model Development - Updates • Watersheds for each of the 210 drainage wells were delineated based on DEM values. • Hydrologic Soil Groups (A, B, C, D, A/D, B/D, or C/D) were assigned to ECFT areas that had a generic soil group by using the specific soil names associated with the grid cells. • Assignment of Lake cells in the model were restricted to those cells with at least 50% of grid cell area covered by a lake. Exceptions were single cell lakes that covered less than 50% but were gaged and specific lake shapes that would have split the lake in two. • ECFT Zones to calculate AET were reassigned based on Wetlands, depth-to-water, forest or bare soil, urban, and grass.

  11. SAS Recharge Calculations – Closed Basins Basin Delineation used to Generate the Drainage Field and Closed Basins (in green) where GA algorithm is not applied and no runoff was calculated

  12. Soil Permeabilities based on Hydrologic Soil Groups

  13. Hydrologic Soil Groups - Before

  14. Hydrologic Soil Groups - After

  15. Drainage Wells, Their Basins, and RIBS - Before Areal Extent of Drainage Well Basins (beige), Locations of Drainage Wells (red dots), and Rapid Infiltration Basins (dark green). Infiltration coefficient of 0.52 was used at drainage well basins.

  16. Drainage Wells, Their Basins, and RIBS - After Areal Extent of Drainage Well Basins (beige), Locations of Drainage Wells (red dots), and Rapid Infiltration Basins (dark green). Infiltration coefficient of 0.52 was used at drainage well basins.

  17. AET Zone Assignment AET was calculated based on multiple linear regressions based on RAIN (R) , AET, and PET (P) data collected at 6 stations from previous studies: BCM: 0.8741*P – 0.0010*R DP: 0.5697*P + 0.0905*R DF: 0.7158*P + 0.0580*R LWR: 0.3907*P + 0.0815*R LP: 0.6011*P + 0.1071*R TB: 0.6456*P + 0.0793*R At Lakes: AET = 1.0 * P

  18. Strategy to Calibrate Recharge Rates to the Water Table is Based on Water Budget Analysis

  19. Groundwater Budget Analysis in the SAS

  20. 1- Simulated NET_RECH rates, in inches per year, should be as close as possible to the rates WB_RECH derived from the water budget analysis.2- Simulated ROFF_ST rates, in inches per year, should be as close as possible to the rates WB_STRM derived from the water budget analysis. 3- Simulated SIM_ET should be less (in absolute value) than the AET rates from the water budget analysis.

  21. Stream Flows at Selected Basins Gages and of Water Surface Elevations at Selected Lakes

  22. Watersheds of Selected Watersheds

  23. Watershed of Econ River at Magnolia Branch near Bithlo, station number 02233001

  24. Watershed of Econ River near Oviedo,station number 02233484

  25. Watershed of Econ River near Chuluota,station number 02233500

  26. Watershed of Soldier Creek near Longwood,station number 02234384

  27. Watershed of Gee Creek near Longwood,station number 02234400

  28. Watershed of Lake Jesup, Lake Number 56

  29. Watershed of Mills Lake, Lake Number 77

  30. Hydrographs of SelectedRiver and Lake Gages

  31. Econ River at Magnolia Branch near Bithlo

  32. Econ River near Oviedo

  33. Econ River near Chuluota

  34. Gee Creek near Longwood

  35. Soldier Creek near Longwood

  36. Lake Jesup, Lake Number 56

  37. Mills Lake, Lake Number 77

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