Abstract Modeling of overland flow for a depression-dominated area is a difficult task due to the spatial distribution of depressions. Particularly, the hierarchical relationships of depressions and their variable contributing areas make the hydrologic modeling more complicated. In traditional hydrologic modeling, however, digital elevation models (DEMs) that are used to represent surface topography are often edited by filling depressions before delineation, and the impacts of depressions are considered by using certain simplified and lumped approaches. Due to such flaws, these hydrologic models fail to account for the actual dynamic influences of surface depressions. The objective of this study is to improve hydrologic modeling for depression-dominated regions by developing a new modeling framework to quantify the influence of spatially distributed depressions. To achieve this objective, a new puddle-based unit (PBU) probability distributed model (PBU-PDM) is developed and coupled with the existing Soil and Water Assessment Tool (SWAT). The PBU-PDM facilitates separate simulations for non-depressional and depressional areas, and accounts for the hierarchical relationships of depressions, their filling and spilling processes, and the dynamic variations in their contributing areas. The PBU-PDM enhanced SWAT was applied to the Upper Maple River watershed in North Dakota, and calibrated and validated using the observed data. In particular, it was also compared with the original SWAT model, which demonstrated the abilities of PBU-PDM to mimic the filling-spilling overland flow dynamics and the threshold behavior. The PBU-PDM provides improved watershed-scale hydrologic modeling, especially for depression-dominated areas.

中文翻译：

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改进了低洼地区的水文建模

摘要 由于洼地的空间分布，对洼地主导地区的地表流建模是一项艰巨的任务。特别是洼地及其变量贡献区的层次关系使水文建模更加复杂。然而，在传统的水文建模中，用于表示地表地形的数字高程模型 (DEM) 通常在描绘前通过填充洼地进行编辑，并通过使用某些简化和集总的方法来考虑洼地的影响。由于存在这些缺陷，这些水文模型无法说明地表洼地的实际动态影响。本研究的目的是通过开发新的建模框架来量化空间分布洼地的影响，从而改进洼地主导地区的水文建模。为了实现这一目标，开发了一种新的基于水坑的单元 (PBU) 概率分布模型 (PBU-PDM)，并与现有的土壤和水评估工具 (SWAT) 相结合。PBU-PDM 有助于对非凹陷和凹陷区域进行单独的模拟，并解释凹陷的层次关系、它们的填充和溢出过程，以及它们贡献区域的动态变化。PBU-PDM 增强的 SWAT 应用于北达科他州的上枫河流域，并使用观测数据进行校准和验证。特别是还和原来的SWAT模型进行了对比，这证明了 PBU-PDM 模拟填充-溢出地表流动力学和阈值行为的能力。PBU-PDM 提供了改进的流域尺度水文建模，特别是对于洼地为主的地区。