Breach (Water Overlay): Difference between revisions

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A breach is a modification to the [[terrain height (Water Overlay)|terrain height]], with an optional in- or outflow of water for the hydrological model. This can be used to represent calamitous situations, such as a breach in a levee. Breaches can also be used to easily simulate a terrain height increase, like a levee.
A Breach area can be used to simulate a breach in a levee.


A breach can either be defined solely as a terrain height modification using its [[Breach_height_(Water_Overlay)|BREACH_HEIGHT]] attribute, or as a connection to a water body outside of the hydrological model by adding attributes related to the external water body. If the breach is only defined as a terrain height change, only water that is already created or defined in some other way in the hydrological model can flow through and from it.
A breach area can be defined via the [[Breach_height_(Water_Overlay)|BREACH_HEIGHT]] attribute. It can have an input area or external area with a water body outside of the hydrological model. Water can flow through the breach form the input (or external area) into the breach area just behind the levee and vise versa.


If the breach is given the attributes required for the external water body, water will automatically be created or removed uniformly on the breach, depending on the simulated water body "behind" the breach.
==Options==
 
* The breach can grow over time, based on its initial width and the critical speed at which water may flow, see [Breach_growth_formula_(Water_Overlay)]. If a [[Breach_width_(Water_Overlay)|BREACH_WIDTH]] is defined, the breach's polygon is intersected with a circle emanating from the centerpoint of the polygon. It is only in that intersection, dubbed the "active breach", that water will flow in from the simulated external water body. The radius of the circle defining the intersection will expand as water flows, based on the critical speed of the water as defined in the [[Breach_speed_(Water_Overlay)|BREACH_SPEED]] attribute. All cells in the active breach are considered directly adjacent to the external water body.
The breach can grow over time, based on its initial width and the critical speed at which water may flow. If a [[Breach_width_(Water_Overlay)|BREACH_WIDTH]] is defined, the breach's polygon is intersected with a circle emanating from the centerpoint of the polygon. It is only in that intersection, dubbed the "active breach", that water will flow in from the simulated external water body. The radius of the circle defining the intersection will expand as water flows, based on the critical speed of the water as defined in the [[Breach_speed_(Water_Overlay)|BREACH_SPEED]] attribute. All cells in the active breach are considered directly adjacent to the external water body.


The [[terrain height (Water Overlay)|terrain]] covered by the entire breach area is considered lowered to the height defined by its [[Breach_height_(Water_Overlay)|BREACH_HEIGHT]] attribute, even if the active breach does not extend across the entirety of the breach area.
The [[terrain height (Water Overlay)|terrain]] covered by the entire breach area is considered lowered to the height defined by its [[Breach_height_(Water_Overlay)|BREACH_HEIGHT]] attribute, even if the active breach does not extend across the entirety of the breach area.

Revision as of 08:42, 2 September 2022

A Breach area can be used to simulate a breach in a levee.

A breach area can be defined via the BREACH_HEIGHT attribute. It can have an input area or external area with a water body outside of the hydrological model. Water can flow through the breach form the input (or external area) into the breach area just behind the levee and vise versa.

Options

  • The breach can grow over time, based on its initial width and the critical speed at which water may flow, see [Breach_growth_formula_(Water_Overlay)]. If a BREACH_WIDTH is defined, the breach's polygon is intersected with a circle emanating from the centerpoint of the polygon. It is only in that intersection, dubbed the "active breach", that water will flow in from the simulated external water body. The radius of the circle defining the intersection will expand as water flows, based on the critical speed of the water as defined in the BREACH_SPEED attribute. All cells in the active breach are considered directly adjacent to the external water body.

The terrain covered by the entire breach area is considered lowered to the height defined by its BREACH_HEIGHT attribute, even if the active breach does not extend across the entirety of the breach area.

Water flowing through or across a breach will flow in the direction defined by the BREACH_ANGLE attribute, regardless of whether the water flowed onto the breach from elsewhere in the water model, or from the simulated external water body. If no BREACH_ANGLE is defined, water can flow in any direction.

If no critical speed is defined, the active breach will never grow. If no width is defined, the width is assumed to be very large, creating an intersection exactly the size of the polygon.

Icon Key Unit Range Description Default value
Waterwizard icon breach height.png BREACH_HEIGHT m + datum The new terrain height at the location of the breach. n/a
Waterwizard icon breach width.png BREACH_WIDTH m The initial width of the breach. 10000
Waterwizard icon breach angle.png BREACH_ANGLE geo angle (0-360°) -1.7976931348623157E308 to 1.7976931348623157E308 The angle at which water flows out through the breach. n/a
Waterwizard icon breach speed.png BREACH_SPEED m/s The critical speed factor in the breach width grow-formula (e.g. 0.2 for sand and 0.5 for clay). n/a
Waterwizard icon breach input area.png BREACH_INPUT_AREA ID of an Area The Area item representing the influx area for the breach. none
Waterwizard icon external surface level.png EXTERNAL_SURFACE_LEVEL m + datum The height of the bottom of the external water body behind the breach. The lowest level the external water level can lower to. 0
Waterwizard icon external water level.png EXTERNAL_WATER_LEVEL m + datum The water level of the external water body behind the breach. The initial level the water level is set to. 0
Waterwizard icon external area.png EXTERNAL_AREA m² The surface area of the external water body behind the breach. The larger the external water body, the more water can flow from it (or into it), and the smaller the effect of the inflow or outflow of water on the external water level. When provided with a second value, this key will also define a bottom area for the external water body, transforming its cross-section from a rectangle to a trapezoid. n/a

Notes

  • Water on a breach area is automatically spread across the entire breach area equally.

How-to's

Videos

Modeling breach growth

See also

Water Module
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Introduction button.png
Water Module
Benchmarks button.png
Getting started button.png
Tutorials
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Overview button.png
Overview
Benchmarks button.png
Theory button.png
Theory
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Benchmarks button.png
Benchmarks
Group
Water area
Water level • Water relative
Sewer area
Sewer storage • Sewer pump speed
Inundation area
Inundation level
Aquifer
Aquifer kd • Aquifer datum
Breach
Breach height • Breach width • Breach angle • Breach coefficient • Breach speed • Breach input area • Breach level area • External surface level • External water level • External area
Rain area
Rain m
Limitation area
Limit area
Output
Object flow output • Object height output • Object datum output a • Object datum output b • Object width output
Related
Building attributes • Hydraulic structures •  Terrain attributes • Model attributes • Results • Simulation data
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