Network configuration and hydrograph sensitivity to storm kinematics

This paper explores the relationship between channel network configurations and hydrograph sensitivity to storm kinematics with different storm speeds, storm directions, and storm sizes. A synthetic circular catchment is introduced, in order to prevent bias due to interaction between storm directions and catchment geometry. The drainage network of the test catchment is simulated with Gibbs' model for a given network configuration (β). The peak response of the catchment is investigated with different configurations of drainage network, combined with different conditions of storm kinematics. The results show that the relationship between storm kinematics and the peak discharge response is dependent on the network configuration. The network configuration indicates the network efficiency in terms of the total drainage time of a network. The resonance condition can be defined for a 2-D drainage network as the inverse of the averaged total sum of flow distance. The results show that the storm kinematics that produces the maximum peak discharge depends on the network configuration because the resonance condition changes with the network configuration. The investigation of 12 catchments in the Chicago area indicates that urban drainage networks, typically, are highly efficient but can also be inefficient. The results illustrate that more inefficient networks (networks with lower β) are less sensitive to rainstorm movement and produce lower peak discharge, compared with efficient networks. In contrast, an efficient network produces higher peak discharges and is more sensitive to storm kinematics, compared with an inefficient network.