Landslide Hazards along River Corridors - Lowland fans

Metadata also available as - [Outline]

Frequently-anticipated questions:

What does this data set describe?

Title: Landslide Hazards along River Corridors - Lowland fans
Depositional fans are formed when sediment moving down a steep channel is deposited where the channel gradient abruptly decreases, for example where a steep valley-wall tributary reaches the valley floor. Sediment can be carried down such a steep channel in flow-type landslides (debris flows, debris floods) or as sediment can be carried by streamflow. Fans are subject to a range of hazards depending which of the preceding processes are active.
No simple metric was identified in the literature that could be used to screen lowland basins and identify those most likely to be inundated by such debris flows. A review of sites with known recent debris flows or debris floods in the Puget Lowland areas of King County suggests that they share some characteristics in common: (1) all of the recent incidents reviewed entailed discharge from ravines with steep side slopes, typically > 60 percent slopes; (2) all discharged onto well-defined, preexisting fans, and these flows were often initiated by a sudden release of water, and in a number of recent cases this has been the result of failure of an upstream beaver dam; (3) where the channel gradient above the fan was steep, in excess of a 15 percent slope, the discharge was in the form of a debris flow; and (4) where the channel gradient was less than a 15 percent slope, the discharge took the form of a debris flood. These observations are based on a small number of recent incidents, which is not enough to develop robust screening criteria. Based on the characteristics above, DNRP geologists used LiDAR imagery and closely spaced contour lines to map depositional fans in the Puget Lowland areas.
  1. How should this data set be cited?

    County, King, 20160816, Landslide Hazards along River Corridors - Lowland fans: King County, King County, WA.

    Online Links:

    Other_Citation_Details: None

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -122.232072
    East_Bounding_Coordinate: -121.654819
    North_Bounding_Coordinate: 47.778487
    South_Bounding_Coordinate: 47.143908

  3. What does it look like?

    <> (JPG)
    JPG File of layer overlain on base of WA counties or local cities

  4. Does the data set describe conditions during a particular time period?

    Calendar_Date: 20-Jun-2016
    Currentness_Reference: publication date

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set. It contains the following vector data types (SDTS terminology):

      • GT-polygon composed of chains (372)

    2. What coordinate system is used to represent geographic features?

      The map projection used is NAD 1983 HARN StatePlane Washington North FIPS 4601 Feet.

      Projection parameters:
      Standard_Parallel: 47.5
      Standard_Parallel: 48.73333333333333
      Longitude_of_Central_Meridian: -120.8333333333333
      Latitude_of_Projection_Origin: 47.0
      False_Easting: 1640416.666666667
      False_Northing: 0.0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.00032808333333333333
      Ordinates (y-coordinates) are specified to the nearest 0.00032808333333333333
      Planar coordinates are specified in foot_us

      The horizontal datum used is D North American 1983 HARN.
      The ellipsoid used is GRS 1980.
      The semi-major axis of the ellipsoid used is 6378137.0.
      The flattening of the ellipsoid used is 1/298.257222101.

  7. How does the data set describe geographic features?

    Lowland fans
    area data table (Source: King County)

    Internal feature number. (Source: Esri)

    Sequential unique whole numbers that are automatically generated.

    Author of mapped shapes (Source: King County)


    Date Author completed mapping (Source: King County)


    Description of fan (Source: King County)

    Puget Lowland fan 

    Method to map depositional fans (Source: King County)


    Source LiDAR imagery and date imagery data sent to Author (Source: King County)

    KC GIS 2016-06 

    Feature geometry. (Source: Esri)

    Coordinates defining the features.



    Entity_and_Attribute_Detail_Citation: King County

Who produced the data set?

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  2. Who also contributed to the data set?

  3. To whom should users address questions about the data?

    King County King County Dept of Natural Resources and Parks, Water and Lands Resource Division
    c/o Ken Rauscher
    GIS Analyst
    201 S Jackson St, Suite 706
    Seattle, WA 98104

    206-477-4414 (voice)

Why was the data set created?

Suitable for general reference and analyses. Identifies only depositional fans in Puget Lowland areas along the river corridor within the study limits in King County.

How was the data set created?

  1. From what previous works were the data drawn?

  2. How were the data generated, processed, and modified?

  3. What similar or related data should the user be aware of?

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How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Access Constraint: Data is not available on GIS Data Portal, it may be available via a custom data request
Use Constraint: King County data are made available with the understanding that they shall be used exclusively by the obtainer or his/her authorized agents. Digital products may not be reproduced or redistributed in any form or by any means without the express written authorization of King County.

  1. Who distributes the data set? (Distributor 1 of 1)

    KCGIS Center
    c/o Cheryl Wilder
    Data Sales Coordinator
    201 S Jackson St, Suite 706
    Seattle, WA 98104

    206-477-4421 (voice)

  2. What's the catalog number I need to order this data set?


  3. What legal disclaimers am I supposed to read?

    Distribution Liability: King County disclaims any warranty of use of any digital product or data beyond that for which it was designed.

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 13-Oct-2016
Metadata author:
King County King County Dept of Natural Resources and Parks, Water and Lands Resource Division
c/o Ken Rauscher
GIS Analyst
201 S Jackson St, Suite 706
Seattle, WA 98104

206-477-4414 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

Generated by mp version 2.8.24 on Tue Nov 14 16:00:49 2023