Environmental Modeling Community of Practice

EPA On-line Tools for Site Assessment Calculation

Module Home Objectives Table of Contents Previous < Next >

57 of 45

Although Gelhar cautioned against using the tabulated data for estimating dispersivity, this is exactly what's often done:

Gelhar et al., 1992 Dispersivity Data Tabulation, with estimation equations plotted.

This drawing shows two functions plotted over the data

a = 0.1 x scale

Why is this not recommended? Because

the tabulated data does not represent a measurement at your site,
dispersivity depends on site specific heterogeneity, and
there are orders-of-magnitude variation at a given scale.

The calculated values give some guidance on what might be an appropriate value of dispersivity, but do not replace site specific measurements nor calibrated parameter sets.

Previous Top ^ Next