Advances in digital watershed features extracting based on DEM

Digital elevation models(DEMs) can be considered as a digital representation of landscape topographic properties.Construction of a DEM-based digital model for a drainage network and extraction of hydrological attributes of the drainage network are important premises for simulation of distributed hydrological processes in a catchment.Usually,the quality and efficiency of the extraction of hydrological characteristics of a river basin from DEM data are affected by treatment of the closed depressions and flat areas in DEM,determination of flow directions,and selection DEM resolutions.In this paper,fundamental principles,methods and algorithms for extraction of the features of drainage networks and watersheds are reviewed;research progresses on the methods for treatment of flat areas and depressions and for determination of flow directions are discussed;the progress on software design and development for extractions from different types of DEM data are introduced;the effects of different scales and resolutions of DEM on the extraction of drainage network and watershed features are explored.Furthermore,the research progresses on the extraction of the features of drainage networks in flat areas and plain region are summarized.