Modeling - Field Sampling: Principles and Practices in Environmental Analysis - page 175

program during which wind could move pollution onto or off a contaminated field.
In developing and using models it is important to be aware of scaling. Some
characteristics may be different or act differently at different scales. What works at a 1-
meter scale may not work at a 100-meter scale. Sometimes it is possible to use
nondimensional representations so that the values are the same at all scales. Sometimes
the scaling problems are not readily obvious. They may even be hidden, so that they only
become apparent when the scale is applied to a larger or smaller area. This can be easily
demonstrated by filling a jar or glass full to the rim with water, placing a #10 sieve over
the mouth, and quickly flipping it upside down. The water will flow out. Repeat the
procedure using a #200 sieve, and it will be seen that the water does not flow out.
Predicting the movement of water in small pores from models using large pores will fail.