Identification of Flow-Routing Sequence from DEMs Based on Quicksort

As most of the distributed hydrological models are based on the channel networks extracted from digital elevation models, for distributed modeling to be implemented, the channel networks must be ranked to determine a flow-routing sequence. In this paper, an algorithm identifying flow-routing sequence from DEMs by the Quicksort rank method is presented. Working recursively via a divide-and-conquer method, the Quicksort procedure will efficiently produce a chain matrix of ascending flow accumulation in which the flow-routing ordering of the channels is recorded. The flow-routing sequence information extracted by the new method can be flexibly applied in either a grid-based model or a catchment-based model. The application of a catchment-based Xinanjiang model in the Mishui study area confirms the convenience and applicability of the new method.