Breach (Water Overlay): Difference between revisions

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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.
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.


==Options==
==Features==
* 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, 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 [[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 adjusted to the minimum height defined by its [[Breach_height_(Water_Overlay)|BREACH_HEIGHT]] attribute. This is to prevent the terrain height from interfering with the flow.


Water flowing through or across a breach will flow in the direction defined by the [[Breach_angle_(Water_Overlay)|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_(Water_Overlay)|BREACH_ANGLE]] is defined, water can flow in any direction.
* Water flowing through or across a breach will flow in the direction defined by the [[Breach_angle_(Water_Overlay)|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_(Water_Overlay)|BREACH_ANGLE]] is defined, water can flow in any direction. Adding this attribute with also convert the breach advection speed (m/s) into the 2D cell of the breach area. It is recommended to always use this attribute for optimal flow.


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.
* If no [[Breach_speed_(Water_Overlay)|BREACH_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.


{{Overlay keys|suppresscategory=true|
{{Overlay keys|suppresscategory=true|

Revision as of 08:47, 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.

Features

  • 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 adjusted to the minimum height defined by its BREACH_HEIGHT attribute. This is to prevent the terrain height from interfering with the flow.
  • 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. Adding this attribute with also convert the breach advection speed (m/s) into the 2D cell of the breach area. It is recommended to always use this attribute for optimal flow.
  • If no BREACH_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.