DEM-based Watershed Delineation - Comparison of Different Methods and applications

Abstract:

Digital elevation models (DEMs) are commonly used for large-scale watershed hydrologic and water quality modeling. With aid of the latest LiDAR technology, submeter scale DEM data are often available for many areas in the United States. Precise characterization of the detailed variations in surface microtopography using such high-resolution DEMs is crucial to the related watershed modeling. Various methods have been developed to delineate a watershed, including determination of flow directions and accumulations, identification of subbasin boundaries, and calculation of the relevant topographic parameters. The objective of this study is to examine different DEM-based watershed delineation methods by comparing their unique features and the discrepancies in their results. Not only does this study cover the traditional watershed delineation methods, but also a new puddle-based unit (PBU) delineation method. The specific topics and issues to be presented involve flow directions (D8 single flow direction vs. multi-direction methods), segmentation of stream channels, drainage systems (single “depressionless” drainage network vs. hierarchical depression-dominated drainage system), and hydrologic connectivity (static structural connectivity vs. dynamic functional connectivity). A variety of real topographic surfaces are selected and delineated by using the selected methods. Comparisons of their delineation results emphasize the importance of selection of the methods and highlight their applicability and potential impacts on watershed modeling.