TABLE OF CONTENTS In designing the size of most drainage sewers, usually knowing the design peak discharge, Q p, suffices. Conversely, for operation, planning, stormwater quality control and design involving runoff volume (such as detention storage), the stage or discharge hydrograph of the design rainstorm is needed. For the former, Q p, traditionally simple hydrologic methods such as the rational method can be used. For the latter, the runoff hydrograph can be determined using a hydrologic or hydraulic simulation model. Hydraulic-based simulation models employ a momentum or energy equation (either Eq. (6.3) or (6.4), or any of their simplified approximations), together with the continuity equation, whereas hydrologic models do not consider momentum or energy equations.
In a sewer network the flows in the sewers and junctions interact; therefore, for reliable simulation results, they must be considered as a system. Modeling of flow in a sewer has been described in Sec. 6.8 and the hydraulics of junctions in Sec. 6.7. Linking the components of junctions and sewers for modeling of a network system has been presented in the preceding section. According to this approach, many sewer network models have been developed. Selected ones in terms of popular uses or representative of its kind are listed in Table 6.2 and will be described in the following.
With so many models available, the selection of the appropriate model that is suitable and effective for a particular sewer network flow simulation job is itself a challenging task. Listed below are...
