Using the micro-computer package DUFLOW for the simu1ation of onedimensiona1 unsteady flow in channe1 systems (Ref. [1]) it is very important to check the resu1ts of the very first ca1cu1ation for a new cana1 system. The first MODEL of a new network system wi11 contain one or more mistakes concerning the cross-sections, the storage area or the boundary conditions. The very first DUFLOW resu1ts of a new model have to be ana1yzed in detail, to be sure that mistakes are detected immediate1y. As is described in the DUFLOW users guide (Ref. [1]) much attention has been paid a1ready to get good output faci1ities. In 1991 a PC-program ECDUFLOW became available for systematic eva1uation ca1cu1ations which are based on DUFLOW output files. In Chapter 2 the relation between DUFLOW and ECDUFLOW is discussed. After a brief description of the additiona1 facilities ECDUFLOW is used in Chapter 3 to ana1yze the resu1ts of a specific ca1cu1ation (Ref. [2]) to i11ustrate the faci1ities and to make it c1ear that they are very comfortab1e. The new ski11s are important for a good insight concerning the physica1 performance of unsteady flow prob1ems (not on1y tida1 waves, but a1so f100d waves and e.g. "bandjirs" in rivers (Ref. [3]), unsteady flow in polders (Ref. [4]) etc.). To i11ustrate the operationa1 use of ECDUFLOW the DUFLOW resu1ts concerning the propagation of a tida1 wave in a system are considered in Chapter 3. A second i11ustration is given in Chapter 4 by means of the DUFLOW resu1ts concerning the propagation of a trans1atory wave in a canal.