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Science and Technology for Environmental Cleanup at Hanford (2001) / Chapter Skim
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Appendix C: Scaling Issues Applicable to Environmental Systems
Pages 171-179

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From page 171...
... The site scale is at the upper limit of length scales in this analysis. Other environmental scales of interest to groundwater modeling include the vertical and horizontal extent of a lithologic unit, c and e, respectively; the vadose zone thickness, d (which is itself a complex hydrologic environment; see Chapter 6~; and the scale of individual minerals and colloids, b.
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From page 174...
... For example, for a nonreactive solute in a saturated aquifer, variations in permeability cause variations in velocity that produce spreading of contaminants relative to the bulk flow. Stochastic analyses describing the variations in velocity are used to derive the mean transport equation that represents the large-scale transport process and the transport parameters, such as macrodispersivity, appearing in the large-scale transport equation.
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From page 175...
... A disadvantage of the stochastic upscaling approach is the extensive, statistically focused data requirements; standard site characterization efforts typically do not provide the type of data required to implement this approach. Vadose zone transport processes are influenced strongly by natural heterogeneity in the subsurface environment because of the nonlinear nature of unsaturated flow (see Chapter 6~.
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From page 176...
... SCALE ISSUES AND WATERSHEDS As an environmental system, river channels also present important scaling issues, and like the subsurface environment, river channels have boundaries defined in both space and time. In analyzing these dimensional issues with reference to water quality, the primary issue is the importance of length scales, which range from microscopic to watershed scales of hundreds of kilometers.
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From page 177...
... Further, spatial and temporal scales define external factors that relate dependent to independent variables and, most importantly, cause and effect. As scales of analysis are reduced, greater numbers of environmental and water quality variables can be considered independent, leading to a better definition of cause and effect, and directing management efforts to specific actions.
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From page 178...
... 178 3 .¢ i' c' a, _ .! 3 ~ u, ~ .~ 8 a =m co ~ ~ E cn 5o 2 co ~ a ~ F ~ CL~ E ~ to {= ~ ~ I Science and Technology for Environmental Cleanup .
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From page 179...
... 2000. Vadose Zone Transport Field Study: 179 Detailed Test Plan for Simulated Leak Tests.
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Key Terms

  • water quality
  • temporal scales
  • stochastic upscaling
  • vadose zone
  • scaling issues

  • subsurface environment
  • upscaling approach
  • field scale
  • flow properties
  • cyclic time

  • time scale
  • stochastic analyses
  • stochastic approach
  • transport equation
  • subsurface flow

  • quality issues
  • solute transport
  • zone transport
  • spatial variability
  • river channels

  • scale issues
  • contaminant retardation
  • chemical processes
  • data requirements
  • geochemical heterogeneity

  • natural heterogeneity
  • length scales
  • regulating contaminant
  • complex hydrologic
  • contaminant loading


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