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Suitable for general reference and analyses.

Identifies only rock fall potential along the river corridor within the study limits in King County.

Rock fall is a type of landslide that occurs in bedrock where single or multiple rocks are dislodged and fall from steep cliff faces.

In a typical alpine setting, cliffs are located on the upper slopes of a mountain with a talus below, extending to the base of the mountain.

The talus is composed of rocks that have fallen from the cliff face and accumulate below the cliff.

The talus marks the limit of most rock fall from the cliff, but a few boulders that fall from the cliff travel beyond the toe of the talus.

It is these outliers that can pose a hazard to adjacent development (see figure "b" below).

Rock fall can be triggered by earthquakes, freeze-thaw cycles, or severe weather.

Tumbling boulders falling from a cliff face are fast moving and can level virtually anything in their path.

Layer Name	lsr_rf_rockfallpotential_area
Subject Category	Environment
Title	Landslide Hazards along River Corridors - Rock fall potential
Feature Count	150
Feature Type	Polygon
Next Update	None planned
Spatial reference	EPSG:2926
Control ID	2564
Place Keywords	Pacific NW, King County, WA, Washington State
Theme Keywords	Enviro, Pacific NW, King County WA, Washington State, Landslide, Slide, Mass Movement, Landslide Hazard Mapping, Debris Slides, Shallow Landslides, Shallow Landsliding, Debris Sliding
Supplemental Information	The CONEFALL software program was used to implements this approach in a GIS environment to map areas where rock fall could propagate downslope from a source. As a starting point for the CONEFALL program, cliff-faces were identified to delineate the line representing the base-of-cliff/top-of-talus. Within the study limits, these lines were mapped based on professional judgement using a variety of tools in a GIS environment including vertical orthophotography, oblique photography, and slope mapping. Slopes inclined at more than 200 percent were especially identified.

OBJECTID From Esri	Description Internal feature number. Domain Sequential unique whole numbers that are automatically generated.
LiDAR_Sour From King County	Description Source LiDAR imagery and date imagery data sent to Author Domain KC GIS 2015
MapDate From King County	Description Date Author completed mapping Domain 2015
MapMethod From King County	Description Method to map rock fall potential Domain CONEFALL method
MapBy From King County	Description Author of mapped shapes Domain KC_DNRP
Shape From Esri	Description Feature geometry. Domain Coordinates defining the features.
Shape.STArea() From SQL Server	Description Returns the area of a geometry instance in square units, based on the spatial reference identifier (SRID) of the geometry. Domain Double
Shape.STLength() From SQL Server	Description Returns the total length of the elements in a geometry instance. Domain Double

Maintained by	DNRP - Water and Land Resources
Primary	Harkeerat Kang Harkeerat.Kang@kingcounty.gov

License	Terms of use and copyright

Links How to use in ArcGIS Pro
Sharing Status	Public