Categories of systems of equations in ODEs based hydrological systems

This is the continuation of the reservoirology topic saga.  Especially preparatory for understanding  is the Reservoirology #3 post. Here we show that the same topological structure of Petri Nets can address various physical concepts related to a hydrological system conceptualised as a set of reservoir and therefore solvable as a set of ODEs.
The main ODE system, however, does not reveal all of the system. A finer inspection can be obtained by investigating travel times and concentration of tracers (being the theoretical point of view, the first, the experimental one, the second).

To fix some concept we wrote the short presentations above. Or just click here. The pdf contains itself links to other posts and literature.