Horton statistics

Dialog box

The Horton Statistics operation calculates for each (Strahler) stream order number and for each merged catchment:

the number of streams,
the average stream length, and
the average area of catchments, and
expected values for these by means of a least squares fit.

The output is stored in a table which can be used to construct so-called Horton plots. Horton plots enable you to inspect the regularity of your extracted stream network and may serve as a quality control indicator for the entire stream network extraction process.

As input is required:

the output of a previous Catchment extraction operation,
the output of a previous Catchment merge operation,
the output of a previous Drainage network ordering operation.

Dialog box options:

Catchment map:	Select an input raster map that is the result of a previous Catchment extraction operation. Open the list box and select the desired input map, or drag a raster map directly from a Catalog into this box.
Merged catchment map:
	Select an input raster map that is the result of a previous Catchment merge operation. The map may contain a single merged catchment but may also contain multiple merged output catchments. For more information, see also Catchment merge : functionality.
Drainage network ordering map:
	Select an input raster map that is the result of a previous Drainage network ordering operation. For more information, see also Drainage network ordering : functionality.
Output table:	Type the name of the output table.
Description:	Optionally, type a description for the output table. The description will appear in the status bar of the Main window when moving the mouse pointer over the table in a Catalog, and in the title bar of a table window when the output table is displayed. If no description is supplied, the output table will use its own definition as description.

When you click the Show button, the dependent output table will be defined, calculated and shown. When you click the Define button, the dependent output table will only be defined; if necessary, the table will be calculated later, for instance when the table is opened to be displayed.

Furthermore, a new ID domain will created for the output table. The domain will obtain the same name as the output table and it will contain the Strahler order numbers as IDs.