Our main interest here is actually devoted to the supplemental material present in MARRmoT where the Authors present the 46 models of the version 1.2. The presentation is clear and well illustrated trough the traditional use of reservoirs. Here I made an exercise for my students in transforming the MARRmoT representation into the  EPN one. EPN, as deducible from the title are  diagrams that allows to represent any Dynamical System (in mathematical or system and control science meaning) with graphics which have a one-to-one correspondence with the equations. To learn briefly how they works, please refer to  these other posts.  We wrote a couple of papers, which are cited below,  describing them and showing how to exploit some of their capabilities. 

From the educational point of view I realized that the students are quite helped and in using them they have a better understanding, and, moreover, a method, to grasp what the lumped hydrological models contains. So, anyone interested, can  find the presentation by clicking on the Figure above and my short talk in the video below.