ABSTRACT
Variables have dimensions. Whenever a new variable is introduced the dimensions will be indicated between brackets, []. e symbols used are: [L] for length, [T] for time, [M] for mass, and [F = ML/T2] for force. For practical applications the dimensions can be substituted by any consistent set of units. A logical choice would be the International Systems of Units (SI units), that is, meter (m), second (sec), kilogram (kg), and Newton (N), respectively; however, because groundwater ow is usually extremely slow oen days are used instead of seconds for the time dimension.
