A Nonlinear Synthetic Unit Hydrograph Method Based on Channel Network Classification

Abstract

Most current synthetic unit hydrograph (UH) methods either consider only very limited aspects of basin geometry or require explicit representation of the basin flow paths. None explicitly consider the channel network classification (i.e. dendritic, parallel, pinnate, rectangular, and trellis). The goal of this study is to examine whether knowledge of the network classification provides beneficial information about the network structure for synthetic UH determination. A nonlinear synthetic UH method is developed using kinematic wave travel time expressions for hillslope and channel points in the basin. The effects of the network structure are then isolated into two random variables. The distributions for these random variables are then estimated based on either the actual flows paths, the network classification, or average conditions. Overall, considering the network classification produces more accurate instantaneous UHs than neglecting the classification, and the classification results closely approximate the actual flow path results for some classifications. Keywords Spatially distributed; travel time; drainage network; network classification; kinematic wave