SAGA-GIS Module Library Documentation (v2.2.2)

Module Hypsometry

Calculates the hypsometric curve for a given DEM.

The hypsometric curve is an empirical cumulative distribution function of elevations in a catchment or of a whole planet. The module calculates both the relative (scaled from 0 to 100 percent) and absolute (minimum to maximum values) distributions. The former scales elevation and area by the maximum values. Such a non-dimensional curve allows one to asses the similarity of watersheds as differences in hypsometric curves arise from different geomorphic processes shaping a landscape.

In case the hypsometric curve should not be calculated for the whole elevation range of the input dataset, a user-specified elevation range can be specified with the classification constant area.

The output table has two attribute columns with relative height and area values, and two columns with absolute height and area values. In order to plot the non-dimensional hypsometric curve as diagram, use the relative area as x-axis values and the relative height for the y-axis. For a diagram with absolute values, use the absolute area as x-axis values and the absolute height for the y-axis.

References:
- Harlin, J.M (1978):
'Statistical moments of the hypsometric curve and its density function',
J. Int. Assoc. Math. Geol., Vol.10, p.59-72

- Luo, W. (2000):
'Quantifying groundwater-sapping landforms with a hypsometric technique',
J. of Geophysical Research, Vol.105, No.E1, p.1685-1694

Parameters

 NameTypeIdentifierDescriptionConstraints
InputElevationGrid (input)ELEVATION--
OutputHypsometryTable (output)TABLE--
OptionsNumber of ClassesIntegerCOUNTNumber of discrete intervals (bins) used for samplingMinimum: 1
Default: 100
SortChoiceSORTINGChoose how to sort the elevation dataset before samplingAvailable Choices:
[0] up
[1] down
Default: 1
Classification ConstantChoiceMETHODChoose the classification constant to useAvailable Choices:
[0] height
[1] area
Default: 1
Use Z-RangeBooleanBZRANGEUse a user-specified elevation range instead of min/max of the input datasetDefault: 0
Z-RangeValue rangeZRANGEUser specified elevation range-

Command-line

Usage: saga_cmd ta_morphometry 5 [-ELEVATION <str>] [-TABLE <str>] [-COUNT <num>] [-SORTING <str>] [-METHOD <str>] [-BZRANGE <str>] [-ZRANGE_MIN <str>] [-ZRANGE_MAX <str>]
  -ELEVATION:<str> 	Elevation
	Grid (input)
  -TABLE:<str>     	Hypsometry
	Table (output)
  -COUNT:<num>     	Number of Classes
	Integer
	Minimum: 1
	Default: 100
  -SORTING:<str>   	Sort
	Choice
	Available Choices:
	[0] up
	[1] down
	Default: 1
  -METHOD:<str>    	Classification Constant
	Choice
	Available Choices:
	[0] height
	[1] area
	Default: 1
  -BZRANGE:<str>   	Use Z-Range
	Boolean
	Default: 0
  -ZRANGE_MIN:<str>	Z-Range
	Value range
  -ZRANGE_MAX:<str>	Z-Range
	Value range