Diskussionsbeitrag zur Fließwider-standsparametrisierung zur Simulation der Oberflächenabflüsse bei Starkregen

Oberle, Peter; Kron, Andreas; Kerlin, Tim; Nestmann, Franz; Rodriguez, Ernesto Ruiz

doi:10.1007/s35147-021-0811-x

Cited by 3 publications

(9 citation statements)

References 2 publications

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“…The sensitivity analysis carried out shows that the determination of the laminar flow depth in a value range of 4-10 cm has an influence on the model results. This agrees with the information from [14] and recommendations from [13]. The simulated thin-layer runoff needs to be adapted and checked in relation to the implemented roughness approaches and basic flow characteristics [13].…”

Section: Criteria For the Selection Of Suitable Model Configurationssupporting

confidence: 71%

“…This agrees with the information from [14] and recommendations from [13]. The simulated thin-layer runoff needs to be adapted and checked in relation to the implemented roughness approaches and basic flow characteristics [13].…”

Section: Criteria For the Selection Of Suitable Model Configurationssupporting

confidence: 71%

“…The correct selection of the roughness values cannot be considered separately from the flow characteristics (laminar/turbulent) and the implemented surface roughness equation. Therefore, a further review and discussion of the adaption or general applicability of the Manning's equation is recommended in [14] or [13]. The results of the sensitivity analysis in this study only relate to the current loss approach, which is implemented in the model calculation routine.…”

Section: Manning's N Roughness Valuesmentioning

confidence: 99%

“…The problem of the application of 2D hydrodynamic models for the use of catchment hydrology and the determination of shallow overland flow is that the model is applied in ways for which it was not originally developed. However, the flow behavior of the thinlayer runoff differs greatly from the flow process in a 'normal' river, due to the very low flow depths [13,14]. The model user must consider this different way of application and need to take care of a suitable model parametrization.…”

Section: Introduction Motivation and Research Gapmentioning

confidence: 99%

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A Systematic Analysis of the Interaction between Rain-on-Grid-Simulations and Spatial Resolution in 2D Hydrodynamic Modeling

David

Schmalz

2021

Water

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A large number of 2D models were originally developed as 1a models for the calculation of water levels along the main course of a river. Due to their development as 2D distributed models, the majority have added precipitation as a source term. The models can now be used as quasi-2D hydrodynamic rainfall–runoff models (‘HDRRM’). Within the direct rainfall method (‘DRM’), there is an approach, referred to as ‘rain-on-grid’, in which input precipitation is applied to the entire catchment area. The study contains a systematic analysis of the model behavior of HEC-RAS (‘Hydrologic Engineering Center—River Analysis System’) with a special focus on spatial resolution. The rain-on-grid approach is applied in a small, ungauged, low-mountain-range study area (Messbach catchment, 2.13 km2) in Central Germany. Suitable model settings and recommendations on model discretization and parametrization are derived therefrom. The sensitivity analysis focuses on the influence of the mesh resolution’s interaction with the spatial resolution of the underlying terrain model (‘subgrid’). Furthermore, the sensitivity of the parameters interplaying with spatial resolution, like the height of the laminar depth, surface roughness, model specific filter-settings and the precipitation input-data temporal distribution, is analyzed. The results are evaluated against a high-resolution benchmark run, and further criteria, such as 1. Nash–Sutcliffe efficiency, 2. water-surface elevation, 3. flooded area, 4. volume deficit, 5. volume balance and 6. computational time. The investigation showed that, based on the chosen criteria for this size and type of catchment, a mesh resolution between 3 m to 5 m, in combination with a DEM resolution from 0.25 m to 1 m, are recommendable. Furthermore, we show considerable scale effects on flooded areas for coarser meshing, due to low water levels in relation to topographic height.

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Section: Criteria For the Selection Of Suitable Model Configurationssupporting

confidence: 71%

Section: Criteria For the Selection Of Suitable Model Configurationssupporting

confidence: 71%

Section: Manning's N Roughness Valuesmentioning

confidence: 99%

Section: Introduction Motivation and Research Gapmentioning

confidence: 99%

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A Systematic Analysis of the Interaction between Rain-on-Grid-Simulations and Spatial Resolution in 2D Hydrodynamic Modeling

David

Schmalz

2021

Water

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“…All data are shown in terms of relative submergence (h/h veg ). The experiments of Ruiz Rodriguez and Trost [58,59] with artificial grass are comparable to the surface used in this study. Accordingly, the data points largely agree with the measurements of this study.…”

Section: Analyses and Evaluation Of Experimental Resultsmentioning

confidence: 63%

Influence of Water Depth and Slope on Roughness—Experiments and Roughness Approach for Rain-on-Grid Modeling

Hinsberger

Biehler²,

Yörük³

2022

Water

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Two-dimensional (2D) models have become a well-established tool for channel flow, as well as rain-induced overland flow simulations. In channel flow simulations, slopes are usually less than a few percent and water depths are over several meters, while overland flow simulations show steep slopes and flow of a few centimeters. Despite these discrepancies, modelers transfer roughness coefficients, validated for channel flow, to overland flow. One purpose of this study is to verify whether roughness values from the literature are also valid for overland flow simulations. Laboratory experiments with different degrees of bed roughness, various discharges and a range of experimental flume slopes were carried out. For a given discharge, water depth was measured, and bed roughness was derived. Experimental results reveal that roughness shows no clear dependence on slope but is strongly dependent on water depth for vegetated surfaces. To verify the influence of different roughness approaches, they were implemented in a 2D model. A comparison of different simulation results indicates differences in the hydrograph. Here, consideration of water depth-related roughness coefficients leads to retention and translation effects. With the results of this study, modelers may enhance the precision of the hydraulic component in overland flow simulations.

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Investigation of Different Roughness Approaches and Vegetation Height Effects on rain-induced overland flow

Masoodi,

Kraft

2024

Preprint

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Abstract. Overland flow is a critical aspect of the hydrological cycle, and understanding its dynamics is crucial for managing water-related issues such as flooding and soil erosion. This paper investigates the impact of various roughness estimation methods on simulating overland flow during intense rain events, with a specific focus on the influence of vegetation. The study assesses various approaches to vary roughness as a function of water sheet thickness and vegetation height, including two different constant Manning's coefficients, a linear approach, an exponential function, a power law function, an empirical formula, and a physics-based approach. The investigation emphasizes the importance of accurate roughness estimation for improving the reliability of hydrological models and enhancing flood prediction capabilities. Experimental data from artificial rainfall experiments on 22 different natural hillslopes in Germany are used to calibrate the OpenLISEM hydrological model, adjusting parameters such as saturated hydraulic conductivity and soil suction at the wetting front. Subsequently, various Manning's coefficient estimation methods are applied, and the model's performance is evaluated numerically. Preliminary results indicate satisfactory calibration outcomes, with NSE values ranging from 0.75 to 0.95 in most cases for various sites. To validate the models, 100 different experimental rainfall events are used for each roughness method. Validation findings suggest that the physics-based approach, the linear function, and constant Manning roughness, demonstrate the best performance based on NSE values. According to our results, areas with more vegetation coverage demonstrate higher saturated hydraulic conductivity value, indicating that, for two sites with the same soil type, the locations with dense vegetation exhibit higher infiltration parameters. Consequently, it is crucial to evaluate the influence of vegetation on runoff, considering not only its effects on Manning's coefficient but also on saturated hydraulic conductivity.

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Diskussionsbeitrag zur Fließwider-standsparametrisierung zur Simulation der Oberflächenabflüsse bei Starkregen

Cited by 3 publications

References 2 publications

A Systematic Analysis of the Interaction between Rain-on-Grid-Simulations and Spatial Resolution in 2D Hydrodynamic Modeling

A Systematic Analysis of the Interaction between Rain-on-Grid-Simulations and Spatial Resolution in 2D Hydrodynamic Modeling

Influence of Water Depth and Slope on Roughness—Experiments and Roughness Approach for Rain-on-Grid Modeling

Investigation of Different Roughness Approaches and Vegetation Height Effects on rain-induced overland flow

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