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Tracer Modeling

Explore various modeling approaches for tracer data interpretation, including 1D advection/dispersion and 3D models targeting groundwater flow calibration and residence times. Examples and case studies included.

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Tracer Modeling

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  1. Tracer Modeling Two goals: • more reasonable interpretation of tracer data in terms of travel time • Calibration target for groundwater flow and transport models

  2. Various modeling approaches • ‘lumped parameter’ models • 1- dimensional vertical or horizontal advection/ dispersion models • MODFLOW/MODPATH, no dispersion • 3D advection/dispersion models • calibration target: • concentration fields • residence time, e.g. 3H/3He ages

  3. Qin = Qout Residence time:  = V/Qin ‘Lumped parameter’ models e.g. exponential model Weighting function: t-1 exp(-t/t) Maloszewski and Zuber, 1982, 1983

  4. ‘Lumped parameter’ models Example: Exponential model Maloszewski and Zuber, 1982, 1983

  5. 1-dimensional vertical or horizontal advection/dispersion models v=1 m/y Schlosser et al., 1989; Solomon and Sudicky, 1991, Solomon et al., 1993; Ekwurzel et al., 1994, Stute et al., 1997

  6. Example: Sturgeon falls Determination of: • gw recharge rate • molecular diffusion and mechanical mixing coefficient Solomon et al., WRR, 29 (1993) 2951

  7. Two tracers in comparison Delmarva peninsula 1 dimensional model Ekwurzel et al., 1994

  8. Calibration of groundwater models Targets: • hydraulic head • streamflow gain/losses • groundwater flow velocities • tracer concentration fields • residence times

  9. Sandy aquifer, Kirkwood-Cohansey formation

  10. 3H/3He Tracer data Szabo et al., WRR, 32 (1996) 1023

  11. 3H/3He and CFC ages Szabo et al., WRR, 32 (1996) 1023

  12. conceptual: numerical: Szabo et al., WRR, 32 (1996) 1023

  13. Szabo et al., WRR, 32 (1996) 1023

  14. Excellent agreement between model and tracer data Szabo et al., WRR, 32 (1996) 1023

  15. Locust Grove, Delmarva

  16. Reilly et al., WRR, 30 (1994) 421

  17. No dispersionnecessary! Locust Grove, Delmarva Reilly et al., WRR, 30 (1994) 421

  18. 3H/3He ages as calibration targetsExample: buried-valley aquifer, Ohio Sheets et al. WWR, 34 (1998) 1077

  19. Complexsystems La Bolle, 2006

  20. La Bolle, 2006

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