Incorporating the Filling–Spilling Feature of Depressions into Hydrologic Modeling

Lan Zeng,Yali Cui,Xuefeng Chu,Haoyong Shen,Jingli Shao

doi:10.3390/w14040652

Lan Zeng, Yali Cui + Show 3 more

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https://doi.org/10.3390/w14040652

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Abstract

Surface depressions are one of the important impact factors of hydrologic processes and catchment responses. However, in many hydrologic models, the influence of depressions is often simulated in a lumped manner, which results in the insufficient characterization of the filling–spilling–merging–splitting dynamics of depressions and the threshold behavior of the overland flow. The objective of the research reported in this paper is to improve the simulation of depression-influenced hydrologic processes by capturing the threshold control of depressions. To achieve this objective, a Depression-oriented Soil and Water Assessment Tool (SWAT-D) is developed. Specifically, the intrinsic changing patterns of contributing area and depression storage are first determined and further incorporated into the SWAT to simulate the filling–spilling of depressions and depression-influenced overland flow dynamics. The SWAT-D was applied to a depression-dominated watershed in the Prairie Pothole Region to evaluate its performance and capability. The simulated and observed hydrographs at the watershed outlet showed good agreement, with only a 7% deviation between the simulated and observed volumes of discharges in 2004. The NSE values for the simulated monthly average discharges during calibration and validation periods were 0.78 and 0.71, respectively, indicating the ability of the SWAT-D in reproducing the depression-influenced catchment responses. In addition, the SWAT-D was compared with other depression-oriented modeling techniques (i.e., the lumped depression approach and probability distribution models), and the comparisons emphasized the improvement of the SWAT-D and the importance of the research reported in this paper.

Highlights

Hydrologic models have become an effective tool to explore the spatial and temporal variations of hydrologic processes, evaluate water quantity and quality, as well as provide valuable information for water resources management and planning [1,2,3,4]
In the research reported in this paper, two modeling scenarios
In the Soil and Water Assessment Tool (SWAT)-D, the intrinsic changing patterns of the contributing area and the depression storage were first determined for depressiondominated subbasins, which were further incorporated into the SWAT to track the filling

Summary

Introduction

Hydrologic models have become an effective tool to explore the spatial and temporal variations of hydrologic processes, evaluate water quantity and quality, as well as provide valuable information for water resources management and planning [1,2,3,4]. Incorporating the influences of depressions into hydrologic modeling is of significance for understanding depression-oriented hydrologic processes and estimating water resources of depression-dominated areas. The Soil and Water Assessment Tool (SWAT), which is a physically-based watershed-scale model, provides three functions (i.e., Pond, Wetland, and Pothole functions) to deal with the hydrologic impacts of depressions. In the SWAT model, a watershed is divided into a number of subbasins, each of which is further delineated into many hydrologic response units (HRUs) based on the combination of land use, soil type, and slope of the subbasin. By using the Pond/Wetland/Pothole functions, all depressions in a subbasin are aggregated as a lumped depression, and part of the subbasin area (i.e., depressional area) contributes surface runoff to the lumped depression

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Conclusion