Skip to main content
U.S. flag

An official website of the United States government

Elevation-Derived Hydrography READ Rules: Artificial Path

An abstraction to facilitate hydrologic modeling through open waterbodies (Figure 33 and Figure 34).

Media
An image showing an area of land with a hill shade elevation product. In the middle is light blue polygon representing a lake
Figure 33. Diagram showing inflow and outflow points of a Lake/pond feature.

 

Media
A graphic with two images. The main image is an elevation hill shade with light blue lines and polygons representing lakes, s
Figure 34. Example of Artificial path features in Lake Fannie, Minnesota. Source data are from the NHD (U.S. Geological Survey, 2020), which is used to provide examples of hydrographic feature types but may differ in density and other characteristics of elevation-derived hydrography.

Delineation

The limit of an Artificial path feature is defined as the connection between the inflow and outflow points of an in-line polygon, the line through a head or terminal open waterbody connecting to the inflow (for terminal) or the outflow point (for head) (Figure 34).

Representation Rules

Delineate features as points, lines, or polygons based on their area or length along different axes (Table 20). 

Table 20. Artificial Path representation rules.
Kind of feature object                                       AreaShortest AxisLongest Axis
0-dimensional (point)------
1-dimensional (line)--greater than 0--
2-dimensional (polygon)------
Special Conditions
Artificial Path Features Around Islands
  • Islands smaller than 1 acre shall not be delineated unless they were in the original breaklines used for hydroflattening the DEM.
  • Group small islands into large “island areas”.
    • IfSAR
      • If islands smaller than 1 acre are present in the original breaklines, are no more than 30 meters apart, and cover more than an acre combined within the channel, treat the combined islands as an “island area” and only place Artificial path features around the group, not within them. The “island area” follows the same rules as an individual “island area”.
    • Lidar
      • If islands smaller than 1 acre are no more than 16 meters apart and cover more than a tenth of an acre combined within the channel, treat the combined islands as an “island area” and only place Artificial path features around the group and not within them. The island area would follow the same rules as an individual island area.
    • Avoid tracing Artificial path features around all the islands (Figure 35). Artificial path features through waterbodies shall follow the shortest path while connecting to all inputs and outflowing channels (Figure 36).
    • Artificial path features represent the direction of flow and shall not loop back causing some flow to go upstream around islands (Figure 37).
Media
An image of a hydrographic polygon with many orange lines representing artificial path features.
Figure 35. Too many Artificial path features around small islands in waterways.
Media
An image of a hydrographic polygon with one orange lines representing artificial path features.
Figure 36. Correct placement of Artificial path following shortest distance through waterbody, not looping around small islands, and not crossing over any islands.
Media
An image of a hydrographic polygon with several orange lines representing artificial path features. One of the artificial pat
Figure 37. Lines shall always flow downstream monotonically. This example shows an incorrectly placed segment flowing upstream.

Data Extraction

Capture Conditions

Artificial path features shall be placed in all polygons except isolated Lake/pond features. Artificial path features shall represent the shortest path from the inflow to the outflow without crossing through banks or islands.

Attribute Information

FClass 1— Hydrography feature defined within the collection criteria of the elevation-derived hydrography specifications.
FCode 55800—Artificial path (abstraction to facilitate hydrologic modeling through open waterbodies).
EClass 2— Linear feature that follows elevation surface.

Source Interpretation Guidelines

None.
 


 

Was this page helpful?