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Unconditional and Conditional Analysis of the Cape Cod Tracer Test

Author(s): Souheil Ezzedine; Yoram Rubin

Linked Author(s): Yoram Rubin

Keywords: No Keywords

Abstract: An analysis of the Cape Cod tracer test based on first and second order theories was presented. Theoretical models were used to explain the observed spatial moments based on parameters of the hydraulic conductivity field. Hence this study can be used to test the predictive capabilities of first order. A summary of our major finding is as follows: -The longitudinal spatial moment is modeled quite well using a two dimensional (2D) representation of the flow field, and even better when using a three di- mensional (3D) representation, since the 3D heterogeneity model introduces the effects of vertical heterogeneity. The lateral spatial moments are underes- timated using 3D approach. -We tested the effects of pore scale dispersion on the spatial moments, using the approach outlined in Fiori [1996]. We found a most significant effect on the lateral spread in the vertical plane. -Given the small variance of the logconductivity at Cape Cod, it is expected that higher order corrections to the first order solutions will not be significant. A computation of the spatial moments following Hsu et al. [1996] reveals that indeed this is the case. -The longitudinal spatial moment is not affected by conditioning on head mea- surements. The unconditional and conditional estimates of the spread are identical when considering only heads. However, the estimates of the lateral spread, which are off using unconditional estimators, are much improved when made conditional to head measurements. As a general observation, since the Cape Cod plumes are relatively large, it should not be expected that condi- tioning transport on local measurements will offer a significant improvement compared to unconditional estimates.

DOI:

Year: 1997

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