We present a new model for unsteady flow routing through dendritic and looped river networks
based on performance graphs. The model builds upon the application of Hydraulic
Performance Graph (HPG) to unsteady flow routing introduced by Gonzalez-Castro (2000)
and adopts the Volume Performance Graph (VPG) introduced by Hoy and Schmidt (2006).
The HPG of a channel reach graphically summarizes the dynamic relation between the flow
through and the stages at the ends of the reach under gradually varied flow (GVF) conditions,
while the VPG summarizes the corresponding storage. Both, the HPG and VPG are unique to a
channel reach with a given geometry and roughness, and can be computed decoupled from unsteady
boundary conditions by solving the GVF equation for all feasible conditions in the reach.
Hence, in the proposed approach, the performance graphs can be used for different boundary
conditions without the need to recompute them. Previous models based on the performance
graph concept were formulated for routing through single channels or channels in series. The
new approach expands on the use of HPG/VPGs and adds the use of rating performance graphs
for unsteady flow routing in dentritic and looped networks. We exemplify the applicability of
the proposed model to subcritical unsteady flow routing through a looped network and contrast
its simulation results with those from the well-known unsteady HEC-RAS model. Our results
show that the present extension of application of the HPG/VPGs appears to inherit the robustness
of the HPG routing approach in Gonzalez-Castro (2000). The unsteady flow model based
on performance graphs presented here can be extended to include supercritical flows.Keywords: Looped network, Hydraulic routing, Modeling, Simulation, Unsteady flow, Dendritic network, River hydraulics, Flooding, Flow routingKeywords: Looped network, Hydraulic routing, Modeling, Simulation, Unsteady flow, Dendritic network, River hydraulics, Flooding, Flow routin
