Geoscience Reference
In-Depth Information
Figure 5:
Pomme de Terre subbasin illustrating for the entire subbasin the master center-
line selection method using artificial paths (left panel), and (right panel) the solution from
the centerline extraction algorithm. In the far right one sees insets of exemplar problem
areas before and after processing.
The current solution retains some limitations. The methods presented in
the paper have been tested on the Pomme de Terre subbasin. The algorithm
was tested against other NHD high-resolution subbasins from the state of
New Jersey whose centerline delineations have known discontinuities. Re-
sults from these tests indicate that the current version of the algorithm suc-
cessfully finds and fills gaps which span a single reach and which span two
successive reaches. Delineation across gaps which span three or more suc-
cessive reaches works only for stream networks where the sequencing of
reach codes demonstrates close spatial proximity. Where the sequencing
does not do so, a fourth scan of the node lists is required to generate a fully
continuous centerline. This is much slower computationally, and efforts to
speed processing are underway.
A second limitation is that the current algorithm relies on the presence of
standing water in the subbasin, that is, the existence of polygonal water
features. In dry landscapes, where there are few water polygons, centerline
