Functionalities of Surface Depressions In Runoff Routing and Hydrologic Connectivity Modeling

Document Type

Article

Publication Date

2-1-2021

Department

Marine Science

School

Ocean Science and Engineering

Abstract

© 2020 Elsevier B.V. Hydrologic processes in depression-dominated areas are controlled by the spatial distribution of surface depressions and their dynamic hydrologic connectivity. Existing hydrologic models often utilize lumped ways to handle depressions, and hence their spatial features are lost in this simplification process. In this study, a unique watershed-scale, semi-distributed hydrologic model accounting for dynamic hydrologic connectivity (HYDROL-DC) is developed and the functionalities of depressions in runoff generation processes and hydrologic connectivity are respectively quantified by introducing two concepts of depression impact coefficient and connected area. Unlike other models, a new modeling framework is proposed in HYDROL-DC to facilitate separate modeling for the puddle-based units, off-stream channel-based units, and on-stream channel-based units of each subbasin. HYDROL-DC was applied to the Edmore Coulee watershed in North Dakota. The modeling results showed that depressions significantly influenced hydrologic processes and their impact capacities were mainly dominated by the storages and spatial distributions of depressions. In a subbasin with depressions of similar storage, depending on the spatial distribution of fully-filled depressions, hydrologic connectivity varied within a range. With the increase in depression storage, the variation of the range exhibited a progressive and hierarchical pattern. Additionally, depressions “blocked” the pathways of runoff water from the activated topographic units to the associated outlet in a subbasin, and such a “blocking” function became significant as more depressions were fully filled.

Publication Title

Journal of Hydrology

Volume

593

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