Matthew Christopher Halso

Last Name

Halso

First Name

Matthew Christopher

ORCID

0000-0002-9845-3627

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03820 - Boes, Robert / Boes, Robert

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Publications1 - 10 of 14

Spatial breaching of homogeneous and zoned embankment dams
Halso, Matthew Christopher (2024)
Effect of grain size distribution in non-cohesive spatial dam breach: hydraulic model investigation and systematic calibration of 2D numerical model
Halso, Matthew Christopher; Evers, Frederic M.; Vetsch, David F.; et al. (2025)
Journal of Hydraulic Research
The breaching of earthen embankment dams can result in uncontrolled release of immense volumes of water, which can be catastrophic to downstream settlements, infrastructure, and ecosystems. The spatial dam breach process depends on the embankment sediment grain size distribution (GSD), a dependence that is investigated here with an experimental hydraulic model in combination with a numerical model. Experimental results indicate that breach development is faster, and therefore a larger flood discharge is expected, for dams made of sediment with wider GSDs. The numerical model was set up to reproduce the experiments, by applying a single-grain morphodynamic solver that was systematically calibrated to the two dominant morphodynamic processes. The model reproduced the rates of breach growth, breach discharge, and sediment erosion for the uniform-sediment dam, as well as the faster breach growth in dams made of wider-GSD sediment. However, the breach growth rate was overestimated for dams with wider sediment GSDs.
Spatial Breaching of Homogeneous and Zoned Embankment Dams
Halso, Matthew Christopher (2024)
VAW-Mitteilungen
The failure of dams and dikes can result in uncontrolled release of immense volumes of water, which can be catastrophic to downstream settlements, infrastructure, and environment. Forecasting the potential extents and timing of a flood due to dam or dike failure, and assessment of the risk associated with the existence and operation of the structure, requires a comprehensive understanding of the failure process. For embankment dams and dikes, which are constructed of erodible materials, failure is commonly driven by overtopping. An overtopping flow with sufficient intensity can erode the embankment material, and given sufficient duration of overtopping, the erosion can progress into formation of a breach. Despite numerous studies on homogeneous embankment breaching, there remains substantial uncertainty related to the effect of embankment material parameters on breach growth rate. For breaching of zoned embankments, research is less advanced, and knowledge gaps remain related to the processes and parameters controlling failure of the different zones. Thisresearchbeganwithanexperimentalinvestigationofhomogeneousembankmentbreaching, in which nineteen laboratory experiments were conducted at three scales. Results from test series showed that breach growth was faster for embankments with wider sediment gradations, less sediment compaction, and constant reservoir head. Next, the sediment gradation test series was simulated with numerical modeling, which showed that the effect of sediment gradation on homogeneous embankment breaching can be reproduced numerically. That test series was subsequently numerically extended in space, time, and parameter space, thus producing synthetically-generated experimental data through composite modeling. Results from the laboratory experiments and composite modeling were used in development of two new models for simulation of homogeneous embankment breaching: an empirical-analytical model and a parametric model. These models were successfully applied to simulation of laboratory experiments and historical dam breach events. The focus of this research then shifted to zoned embankment breaching, which was investigated with ten additional laboratory experiments performed at two scales. The observed failure processes for the outer zones (shell and filter) were progressive surface erosion and slope failure. Results from test series showed that erosion of the outer zones was slower for embankments without a filter zone and with lower shell water content. The observed failure processes for the core zone were cracking due to bending followed by detachment due to cantilever rotation. Results from test series showed that core strength increased for denser and thicker cores. Findings from these experiments were used in the development of a new parametric model for the simulation of zoned embankment breaching. This model accurately reproduced breaching of laboratory experiments, and was applied to simulation of a recent prototype zoned dam failure. This study adds to the knowledge of spatial breaching for both homogeneous and zoned embankments. Experimental and composite modeling results provide valuable data for calibration of models and guidance for future experimental investigations. The newly developed methods for parametric simulation of embankment breaching are valuable tools for engineers and practitioners for use in breach analyses, allowing for improved emergency management protocols and more refined assessment of risk.
Composite Modeling to Detect Scale Effects in Embankment Dam Breaching due to Overtopping
Halso, Matthew Christopher; Knüsel, C.L.; Vetsch, David F.; et al. (2024)
Proceedings of the 10th International Symposium on Hydraulic Structures (ISHS 2024)
The failure of a dam can have catastrophic consequences for populations and infrastructure downstream. The processes of dam failure are typically studied with small to medium scale laboratory physical model investigations. Findings from laboratory scale studies should inform decision making for prototype scale dams, but upscaling introduces uncertainties and complexity. Detailed numerical models can simulate complex breach processes and depict larger dams, allowing for investigations at larger scale. But with increasing detail and numerical refinement comes increasing computational cost, making modeling of prototype systems potentially prohibitive. Parametric numerical models allow for efficient simulation at prototype scale, but with simplified geometries and limited erosion processes. These numerical options could connect findings from smaller scale studies to prototype scale, if the effect of scale in each method is accounted for. In this study, the effect of scale is investigated with medium laboratory scale (dam height = 0.5 m) and large laboratory scale (dam height = 1.0 m) breach modeling. Laboratory experiments, detailed numerical modeling, and parametric numerical modeling (with the Macchione and Peter methods) are performed at both scales. During initial breach formation (while reservoir head was constant), the laboratory experiments showed no effect of scale. Later, as the reservoir head fell, a faster increase in breach discharge occurred at large scale, leading to an earlier peak discharge. Detailed numerical modeling showed the effect of scale on breach growth, but with limited reproduction of the effect on breach discharge. Both parametric methods replicated the discharge hydrographs well, but only the Peter model adequately reproduced the effect of scale on timing of peak discharge.
Composite Modeling of the Effect of Material Composition on Spatial Dam Breaching due to Overtopping
Halso, Matthew Christopher; Evers, Frederic M.; Vetsch, David F.; et al. (2022)
Proceedings 39th IAHR World Congress
The overtopping of embankment dams and levees often causes erosion of embankment material, and can result in failure of the structure by breaching. The breaching process is affected by numerous characteristics of the embankment and reservoir system, including embankment geometry, material composition, and hydraulic conditions. The effects of these parameters are generally investigated by physical model experiments. The extent to which a parameter is investigated is often limited by the amount of time required for physical model setup, experimentation, and data post-processing. This study proposes a composite modeling strategy for more efficient modeling of embankment dam breaching due to overtopping. First, an embankment dam breach is modeled with physical experiments. Second, a corresponding numerical model is set up, with the same geometry, material composition, and hydraulic inputs as the physical model. Next, important findings from the physical modeling are implemented in the numerical model. Lastly, the numerical model is validated with results from the physical modeling. The composite modeling strategy was applied to an investigation of the effect of material grain size on dam breaching. The composite modeling strategy showed the ability to represent numerous effects of material grain size, including erosion rates and timing of peak outflow, as confirmed by separate physical modeling of the same system. Preliminary results indicate that the composite modeling strategy is a viable option for modeling dam breaching to investigate effects of various parameters on the breach process, allowing for greater efficiency and larger test series than with physical modeling by itself.
Composite modelling of non-cohesive homogeneous spatial dam breaches with varied grain size distributions
Halso, Matthew Christopher; Evers, Frederic M.; Boes, Robert; et al. (2025)
Journal of Hydraulic Research
The failure of embankment dams due to overtopping can produce floods that inundate vast downstream regions. Flooding extents are related to the breach formation process, which depends on numerous properties of the dam-reservoir system, including the embankment material grain size distribution (GSD). The effect of GSD on spatial breaching in non-cohesive homogeneous dams is studied here through composite modelling. A numerical model that applies a multi-grain morphodynamic solver was systematically calibrated using a previous laboratory hydraulic model parameter investigation of constant-head overtopping with mixed-size sediment dams with varying GSDs. The numerical model is applied to extend the parameter investigation by simulating longer dams with larger reservoirs, and two additional dams with different GSDs. Dimensionless equations for breach evolution, and a proposed empirical-analytical model for estimating breach discharge and sediment erosion, show good agreement with experimental results. Relations are proposed for determining the hydraulic roughness coefficient and the number of grain classes needed for multi-grain morphodynamic numerical modelling, as a function of GSD.
Experimental investigation of the overtopping failure of a zoned embankment dam
Halso, Matthew Christopher; Evers, Frederic M.; Vetsch, David F.; et al. (2023)
Role of Dams and Reservoirs in a Successful Energy Transition
The failure of dams poses an immense risk to settlements and infrastructure throughout the world. As extreme flood events become more likely in many parts of the world, dams become increasingly vulnerable to overtopping. Earthen embankment dams are made of erodible materials, and are therefore susceptible to erosion by an overtopping flow. Erosion of a dam to the point of uncontrolled outflow constitutes a dam breach. The erosive processes that lead to breaching depend on the type of dam. Zoned earthen dams with a mineral core erode differently than homogeneous earthen dams, due to the core material’s resistance to entrainment by the overtopping flow. The process of breaching a zoned dam by overtopping has been scarcely observed at laboratory, field, or prototype scales. In this study, we perform a laboratory experiment to investigate the breaching due to overtopping of a zoned earthen embankment dam. A prototype-scale zoned dam was designed based on multiple large zoned earthen dams in Switzerland, with particular focus on the Jonenbach Dam in Affoltern am Albis. The prototype dam, which includes shell, filter, and core zones, was reduced to laboratory scale for experimentation. The laboratory-scale dam was breached by overtopping, and the failure processes of each zone were observed. The breaching process began with formation of a breach channel on the downstream slope of the dam. The breach channel incised downstream of the core, and expanded laterally due to mass slope failures of shell material. The filter material remained temporarily stable after departure of the supporting shell material, due to effects of apparent cohesion, but gradually failed with mass detachments. Erosion of the shell and filter zones left the core unsupported on the downstream side. The forces of water and soil pressure from upstream gradually became too large for the core to resist, causing the core to bulge, crack, and eventually break. Once the core broke, water and shell material from upstream flowed uncontrolled through the breach. Similar morphodynamic and hydrodynamic processes that occurred in this experiment would also be expected to occur during the overtopping failure of a prototype-scale zoned dam. The resistance of the core to the soil and water pressures can be a valuable output for calibration of statics calculations of core stability. Such calculations could be implemented in parametric or numerical dam breach models, for use by engineers to estimate the timing and resulting discharge of zoned earthen dam breaches.
Material Scaling for Laboratory Experiments of Zoned Dam Breaching due to Overtopping
Halso, Matthew Christopher; Evers, Frederic M.; Vetsch, David F.; et al. (2023)
Proceedings of the 40th IAHR World Congress
The overtopping of an embankment dam or dike can result in formation of a breach, which may result in a catastrophic flood. Experimental research on zoned embankment breaching has been rare, and the morphodynamic processes that lead to failure of each zone remain not well-understood. A challenge for experimental research of zoned embankment breaching is scaling from prototype to model scale. Froude scaling of material from prototype earthen embankments results in model material that may not be morphodynamically similar to that of the prototype. This can affect the rate of material erosion and may cause a model zone to fail due to a different process than the corresponding prototype zone. As a reference for this study, a prototype scale zoned earthen embankment dam has been designed. The prototype dam contains three zones: shell, filter, and core. After assessing multiple methods for scaling that have been used in previous experimental hydraulics research, a model dam was designed and constructed by scaling each material zone based on the expected failure process of the prototype zone. A laboratory overtopping breach experiment of the model dam was then performed. A unique failure process was observed for each zone, beginning with a breach channel forming through the shell due to progressive surface erosion, and ending with the core breaking due to cantilever rotation. The experiment demonstrated that the applied scaling approaches allowed for successful representation of the expected failure processes during the overtopping failure of a zoned embankment dam.
A simplified method for simulation of the overtopping failure of zoned earthen dams and dikes
Halso, Matthew Christopher; Vetsch, David F.; Evers, Frederic M.; et al. (2025)
River Flow 2024: Proceedings of the 12th International Conference on Fluvial Hydraulics, Liverpool, UK, 2nd- 6th September, 2024
The failure of earthen dams and dikes leads to rapid release of immense volumes of water. Estimation of the outflow hydrograph is crucial for emergency preparation and flood risk assessment, but currently no method is available for estimating the outflow hydrograph due to overtopping-induced failure of zoned earthen dams. Based on findings from laboratory exper iments of zoned dam overtopping failure, a method for simulating the failure of two-layer zoned earthen dams is proposed. This paper describes the simplified numerical method, designed for zoned dams that consist of a mainly non-cohesive shell and a cohesive vertical core. Erosion of the shell zone due to overtopping flow is simulated by adapting an existing parametric numerical method for progressive erosion of homogeneous earthen dams. Failure of the core zone is mod eled based on the stability of the core against the bending moment induced by upstream water and sediment pressures, which cause the core to crack and then break. The method enables simulation from initial overtopping of a low spot along the dam crest until the initial breaking of the core.
Software tool for progressive dam breach outflow estimation
Vetsch, David F.; Halso, Matthew Christopher; Seidelmann, Leonhard; et al. (2023)
Role of Dams and Reservoirs in a Successful Energy Transition
Hazard assessment due to a dam failure is an important task in risk management. Assessment of the related hazard potential is based on a dam break analysis, a multi-step workflow in which the first step includes the analysis of possible dam failure and estimation of the outflow hydrograph. For that purpose, various approaches with different level of details with regard to modelled physical processes are available. Among the simplest approaches are parameter models, which are often used due to their straightforward and efficient application. The open-source software BASEbreach provides a suite of parameter models, developed particularly for the estimation of the outflow discharge resulting from progressive dam failure. We illustrate the software capabilities by comparing different approaches for instantaneous and progressive dam failure. Further, we show that the maximum breach discharge may be overestimated or underestimated depending on the approach and the situation. Estimation of the maximum breach discharge is always associated with great uncertainties. Hence, the BASEbreach software provides access to relevant parameters for local sensitivity analysis. Also, Monte-Carlo simulations in combination with the Peter parameter models are available for uncertainty quantification. The software is a valuable tool for engineers and practitioners to estimate the potential breach outflow from progressive embankment dam failure.

Publications1 - 10 of 14

Matthew Christopher Halso

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