Automatic watershed delineation in the Tibetan endorheic basin: A lake-oriented approach based on digital elevation models

Abstract

Watershed delineation from digital elevation models (DEMs) is an essential prerequisite for land-surface hydrology studies. Although existing automatic methods perform well in exorheic basins, finding a suitable watershed delineation approach in endorheic basins is still challenging. This study develops a lake-oriented approach given that lakes are important hydrological components in the Tibetan endorheic basin. The designed workflow of the proposed approach contains four steps: flow direction calculation, hydrological structure features extractions, classification of lake types, and watershed labeling. The experiments are conducted on a sub-region of the inner Tibetan Plateau, with an area of 119,055 km2. Extraction results prove that the proposed strategies, i.e., elevation-profile judgment and overflow-point-control correction can support the accurate delineation of watershed boundaries. In addition, the proposed approach can achieve two-level watershed boundaries in which the independences of all the endorheic basins can be maintained, meanwhile, further delineation within extracted exorheic basins satisfies various application requirements at different spatial scales. Unlike manual processing and existing datasets (e.g., HydroSHEDS), the proposed approach can fully explore the advantages of high-quality DEMs and can be expanded to much larger regions to handle scientific and engineering issues.