Automatic Algorithm for River Gradient Based on Directed Topology

Abstract

River gradient is an important aspect and also a technical difficulty in expressing water system elements in geographic mapping. There are few studies on automatic algorithm for river gradient. This paper addresses this issue by proposing a new automatic algorithm for river gradient using the tree-shaped constrained stroke. Based on the in-depth study of the data structure of directed topology, this method focuses on recognizing the patterns of estuary, constructing the tree-shaped constrained stroke, establishing river hierarchies, and studying the hierarchical gradient of the main stem and tributaries. It realizes automatic river gradient and has been tested in practice. The results show that this algorithm does not require human intervention in river network identification, estuary recognition, river stratification, and river gradient, which is highly automatic and largely improves the mapping efficiency. The gradient effect is better than manual work.