Breach Parameters - Revision history

Mpollei@gfnet.com at 18:35, 21 July 2023

2023-07-21T18:35:23Z

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 [[Category:Dam Breach Inundation Analysis]]
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 “Dam breach modeling can be divided into two categories, each of which has a number of models, tools, or equations, ranging from simple to advanced: (1) tools that generate the dam breach peak discharge and/or hydrograph only; and (2) tools that develop a breach hydrograph and perform downstream flood routing using a one- or two-dimensional hydraulic model.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) | Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946), FEMA, 2013]]</ref>

Mpollei@gfnet.com at 19:08, 11 July 2023

2023-07-11T19:08:20Z

← Older revision		Revision as of 19:08, 11 July 2023
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	==Best Practices Resources==		==Best Practices Resources==
	{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946), FEMA~~, 2013~~]]		{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946), FEMA]]
	{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420), USACE~~, 1997~~]]		{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420), USACE]]

	<!-- For information on notation for in text citations visit https://www.mediawiki.org/wiki/Help:Cite Or simply enclose the citation as shown <ref> citation </ref> in the location of the in text mention. Citations will automatically populate below-->		<!-- For information on notation for in text citations visit https://www.mediawiki.org/wiki/Help:Cite Or simply enclose the citation as shown <ref> citation </ref> in the location of the in text mention. Citations will automatically populate below-->

Rmanwaring at 21:12, 19 December 2022

2022-12-19T21:12:46Z

← Older revision		Revision as of 21:12, 19 December 2022
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	*"Breach side slope factor – The breach side slope is a measure of the angle of the breach sides represented as X horizontal to 1 vertical (XH:1V).		*"Breach side slope factor – The breach side slope is a measure of the angle of the breach sides represented as X horizontal to 1 vertical (XH:1V).

	“A dam breach usually occurs in two distinct phases starting with the breach initiation followed by the breach formation. During the breach initiation phase, flow through the dam is minor and the dam is not considered to have failed. It may be possible to prevent a dam breach during this phase if flow is controlled. Breach formation begins when the flow through the dam has increased and progressed from the upstream face to the downstream face of the dam, is uncontrolled, and will result in the failure of the dam.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</~~ref~~>		“A dam breach usually occurs in two distinct phases starting with the breach initiation followed by the breach formation. During the breach initiation phase, flow through the dam is minor and the dam is not considered to have failed. It may be possible to prevent a dam breach during this phase if flow is controlled. Breach formation begins when the flow through the dam has increased and progressed from the upstream face to the downstream face of the dam, is uncontrolled, and will result in the failure of the dam.” <ref name ="FEMA P-946"/>

	==Published Breach Parameter Estimation Methods==		==Published Breach Parameter Estimation Methods==

Rmanwaring at 21:12, 19 December 2022

2022-12-19T21:12:08Z

← Older revision		Revision as of 21:12, 19 December 2022
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	*“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.		*“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.
	*“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.		*“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.
	*“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</~~ref~~>		*“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape.” <ref name ="FEMA P-946"/>

	==Best Practices Resources==		==Best Practices Resources==

Rmanwaring at 21:11, 19 December 2022

2022-12-19T21:11:25Z

← Older revision		Revision as of 21:11, 19 December 2022
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	----		----
	<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->		<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->
	“Dam breach modeling can be divided into two categories, each of which has a number of models, tools, or equations, ranging from simple to advanced: (1) tools that generate the dam breach peak discharge and/or hydrograph only; and (2) tools that develop a breach hydrograph and perform downstream flood routing using a one- or two-dimensional hydraulic model.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| ~~FEMA P-946~~ Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>		“Dam breach modeling can be divided into two categories, each of which has a number of models, tools, or equations, ranging from simple to advanced: (1) tools that generate the dam breach peak discharge and/or hydrograph only; and (2) tools that develop a breach hydrograph and perform downstream flood routing using a one- or two-dimensional hydraulic model.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946), FEMA, 2013]]</ref>

	“The parameters of failure depend on the dam and the mode of failure. For flood hydrograph estimation, the breach is modeled assuming weir conditions, and the breach size, shape, and timing are the important parameters. The larger the breach opening and the shorter the time to total failure, the larger the peak outflow.” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 ~~Hydrologic Engineering Requirements for Reservoirs~~, USACE, 1997]]</ref>		“The parameters of failure depend on the dam and the mode of failure. For flood hydrograph estimation, the breach is modeled assuming weir conditions, and the breach size, shape, and timing are the important parameters. The larger the breach opening and the shorter the time to total failure, the larger the peak outflow.” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420), USACE, 1997]]</ref>

	“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams.” <ref name ="EM 1110-2-1420"/>		“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams.” <ref name ="EM 1110-2-1420"/>

Rmanwaring at 21:10, 19 December 2022

2022-12-19T21:10:43Z

← Older revision		Revision as of 21:10, 19 December 2022
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	==Best Practices Resources==		==Best Practices Resources==
	{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946)\|Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) ~~(Federal Emergency Management Agency)~~]]		{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946), FEMA, 2013]]
	{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420)\|Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) ~~(U.S. Army Corps of Engineers)~~]]		{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420), USACE, 1997]]

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Grichards at 22:40, 13 December 2022

2022-12-13T22:40:22Z

← Older revision		Revision as of 22:40, 13 December 2022
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	==Published Breach Parameter Estimation Methods==		==Published Breach Parameter Estimation Methods==
	“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.		*“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.
			*“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.
	“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.		*“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>

	“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>

	==Best Practices Resources==		==Best Practices Resources==

Grichards at 22:39, 13 December 2022

2022-12-13T22:39:37Z

← Older revision		Revision as of 22:39, 13 December 2022
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	<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->		<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->
	~~“Performing~~ a ~~dam breach model involves prediction~~ of the dam breach hydrograph and ~~the routing of~~ that hydrograph downstream. ~~A number~~ of ~~modeling tools are available to perform dam breach modeling~~, ~~ranging from simple methods to complex models. With advancements in GIS-based modeling~~, ~~many models can interface with digital terrain data to produce automated dam breach inundation zone delineations.~~		“Dam breach modeling can be divided into two categories, each of which has a number of models, tools, or equations, ranging from simple to advanced: (1) tools that generate the dam breach peak discharge and/or hydrograph only; and (2) tools that develop a breach hydrograph and perform downstream flood routing using a one- or two-dimensional hydraulic model.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>

	~~“Dam breach modeling can be divided into two categories, each~~ of ~~which has a number~~ of ~~models~~, ~~tools~~, ~~or equations, ranging from simple to advanced: (1) tools that generate~~ the ~~dam~~ breach ~~peak discharge~~ and~~/or hydrograph only; and (2) tools that develop a~~ breach ~~hydrograph~~ and ~~perform downstream flood routing using a one- or two-dimensional hydraulic model”~~ <ref name ="~~FEMA P~~-~~946~~">[[~~Federal Guidelines~~ for ~~Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures~~ (~~FEMA P~~-~~946~~) \| ~~FEMA P~~-~~946 Federal Guidelines~~ for ~~Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures~~, ~~FEMA~~, ~~2013~~]]</ref>.		“The parameters of failure depend on the dam and the mode of failure. For flood hydrograph estimation, the breach is modeled assuming weir conditions, and the breach size, shape, and timing are the important parameters. The larger the breach opening and the shorter the time to total failure, the larger the peak outflow.” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>

	“The ~~parameters of failure depend on~~ the dam ~~and~~ the ~~mode~~ of failure, ~~For flood hydrograph estimation~~, the ~~breach is modeled assuming weir conditions,~~ and ~~the breach size, shape,~~ and ~~timing are the important parameters~~. The ~~larger the breach opening~~ and ~~the shorter the time to total failure, the larger the peak outflow”~~ <ref name ="EM 1110-2-1420"~~>[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]<~~/~~ref~~>.		“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams.” <ref name ="EM 1110-2-1420"/>

	==Breach Parameter Definitions==		==Breach Parameter Definitions==

	“The following definitions are commonly accepted for use in evaluating and selecting dam breach parameters:		“The following definitions are commonly accepted for use in evaluating and selecting dam breach parameters:
	* Breach formation time (also time-to-failure) – The duration of time between the first breaching of the upstream face of the dam (breach initiation) and when the breach has reached its full geometry.		*"Breach formation time (also time-to-failure) – The duration of time between the first breaching of the upstream face of the dam (breach initiation) and when the breach has reached its full geometry.
	* Breach depth (also breach height) – The breach depth is the vertical extent of the breach measured from a specific elevation to the invert of the dam breach.		*"Breach depth (also breach height) – The breach depth is the vertical extent of the breach measured from a specific elevation to the invert of the dam breach.
	* Breach width – The breach width is the average of the final breach width, typically measured at the vertical center of the breach.		*"Breach width – The breach width is the average of the final breach width, typically measured at the vertical center of the breach.
	* Breach side slope factor – ~~the~~ breach side slope is a measure of the angle of the breach sides represented as X horizontal to 1 vertical (XH: 1V).		*"Breach side slope factor – The breach side slope is a measure of the angle of the breach sides represented as X horizontal to 1 vertical (XH:1V).

	~~“A dam breach usually occurs in two distinct phases starting with the breach initiation followed by the breach formation.~~

	“Breach initiation: During the breach initiation phase, flow through the dam is minor and the dam is not considered to have failed. It may be possible to prevent a dam breach during this phase if flow is controlled.

	~~“Breach~~ formation: Breach formation ~~(defined above)~~ begins when the flow through the dam has increased and progressed from the upstream face to the downstream face of the dam, is uncontrolled, and will result in the failure of the ~~dam”~~ <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>.		“A dam breach usually occurs in two distinct phases starting with the breach initiation followed by the breach formation. During the breach initiation phase, flow through the dam is minor and the dam is not considered to have failed. It may be possible to prevent a dam breach during this phase if flow is controlled. Breach formation begins when the flow through the dam has increased and progressed from the upstream face to the downstream face of the dam, is uncontrolled, and will result in the failure of the dam.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>

	==Published Breach Parameter Estimation Methods==		==Published Breach Parameter Estimation Methods==

	“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.		“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.

	“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.		“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.

	“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph ~~shape”~~ <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>.		“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape.” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>

	~~==Other Relevant Quotes==~~

	“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>.

	==Best Practices Resources==		==Best Practices Resources==

Grichards at 05:10, 18 November 2022

2022-11-18T05:10:53Z

← Older revision		Revision as of 05:10, 18 November 2022
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	__NOTOC__		__NOTOC__
			[[Category:Dam Breach Inundation Analysis]]
	----		----
	<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->		<!-- Delete any sections that are not necessary to your topic. Add pictures/sections as needed -->
Line 24:		Line 25:
	==Published Breach Parameter Estimation Methods==		==Published Breach Parameter Estimation Methods==

	“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of hydraulics, sediment transport, and soil mechanics.		“Physically Based Erosion Methods – These methods predict the development of an embankment breach and the resulting breach outflows using an erosion model based on principles of [[hydraulics]], sediment transport, and soil mechanics.

	“Parametric Regression Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.		“Parametric [[Regression]] Equations – These equations, developed from case study information, are used to estimate the time-to-failure and ultimate breach geometry. The breach can then be simulated to proceed as a time-dependent linear process with the computation breach outflows using principles of hydraulics.

	“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>.		“Predictor Regression Equations – These equations estimate the dam breach peak discharge empirically based on case study data of peak discharge and hydrograph shape” <ref name ="FEMA P-946">[[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) \| FEMA P-946 Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures, FEMA, 2013]]</ref>.

Grichards at 04:24, 17 September 2022

2022-09-17T04:24:00Z

← Older revision		Revision as of 04:24, 17 September 2022
Line 34:		Line 34:
	“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>.		“The breach is the opening formed in the dam when it fails. Despite the fact that the main modes of failure have been identified as piping or overtopping, the actual failure mechanics are not well understood for either earthen or concrete dams. In previous attempts to predict downstream flooding due to dam failures, it was usually assumed that the dam failed completely and instantaneously. These assumptions of instantaneous and complete breaches were used for reasons of convenience when applying certain mathematical techniques for analyzing dam-break flood waves. The presumptions are somewhat appropriate for concrete arch-type dams, but they are not suitable for earthen dams and concrete gravity-type dams” <ref name ="EM 1110-2-1420">[[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) \| EM 1110-2-1420 Hydrologic Engineering Requirements for Reservoirs, USACE, 1997]]</ref>.

	~~==Examples==~~
	~~{{Website Icon}}~~
	==Best Practices Resources==		==Best Practices Resources==
	{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946)]]		{{Document Icon}} [[Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946)\|Federal Guidelines for Inundation Mapping of Flood Risks Associated with Dam Incidents and Failures (FEMA P-946) (Federal Emergency Management Agency)]]
	{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420)]]		{{Document Icon}} [[Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420)\|Hydrologic Engineering Requirements for Reservoirs (EM 1110-2-1420) (U.S. Army Corps of Engineers)]]
	~~==Trainings==~~
	~~{{Video Icon}}~~

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