Dear, GH, and others:

Space distecrization (dividing soil profile into number of layers) is
crucial for numerical as well as simple soil water flow models whether
these models have a time step of a day or less or more. Some available
numerical models have been programmed in way that their space and time
steps automatically change with the prevailing conditions. So the bottom
line is that the space distecrization must be maintained as is even if the
whole soil profile is homogenous. Making the output layers similar to the
input layers is a different issue! It may be addressed by some kind of
averaging.

Having said the above, I should mention that I have been doing some
research on getting the same results of soil water flow using different
space distecrization. What I found was that 1) we can not just use any user
suggested space distecrization, we will have to have some constraints, and
2) changing space distecrization require an addition of a new coefficient
into the model whether it is evaporation or drainage.

Regards,

Ayman
Ayman Suleiman, PhD
Assistant Professor
Center for Atmospheric Sciences
Hampton University
23 Tyler Street
Hampton, VA 23668