Breach (Water Overlay)

A Breach area can be used to simulate a breach in a levee or dam. It is identified via the BREACH_HEIGHT attribute. Water flowing through the breach originates from a body of water. This body of water can be defined as an input area in the project or a conceptual external water body existing outside the project area. Water can flow through the breach from the input water body to the defined Breach area, and vice versa.

Attributes

Key	Unit	Range	Description	Default value
BREACH_HEIGHT	m + datum		The new terrain height at the location of the breach.	n/a
BREACH_WIDTH	m		The initial width of the breach.	10000
BREACH_ANGLE	geo angle (0-360°)	-1.7976931348623157E308 to 1.7976931348623157E308	The angle at which water flows out through the breach.	n/a
BREACH_COEFFICIENT	coefficient		The flow coefficient related to the shape of the breach.	1.37
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
BREACH_INPUT_AREA	ID of an Area		The Area item representing the influx area for the breach.	none
BREACH_LEVEL_AREA	ID of an Area		The Area item representing the downstream water level measurement area for the breach.	none
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
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
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

Overlay attributes

Icon	Attribute	Unit	Range	Description	Default value
	BREACH_MEASUREMENT_DISTANCE_M	m		Distance from the breach area to the automatically placed measurement point for the downstream water level of the breach, in the direction of the breach.	100