The paper consists of two main parts. The first part is concerned with diff
erent aspects of mathematical modeling of material flow systems for the lin
ear static case. The problems considered are the description of the model c
lass, data reconciliation, identification of subsystems and the analysis of
system properties relevant e.g. for simulation. In the second part an appl
ication of the modeling tools proposed in the first part to a study on the
metabolism of phosphorus in an Austrian region is given.