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 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
- Author: (c) 2001 by O.Conrad
- Specification: grid
- Menu: Terrain Analysis|Morphometry
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | Elevation | Grid (input) | ELEVATION | - | - |
| Output | Hypsometry | Table (output) | TABLE | - | - |
| Options | Number of Classes | Integer | COUNT | Number of discrete intervals (bins) used for sampling | Minimum: 1
Default: 100 |
| Sort | Choice | SORTING | Choose how to sort the elevation dataset before sampling | Available Choices:
[0] up
[1] down
Default: 1 |
| Classification Constant | Choice | METHOD | Choose the classification constant to use | Available Choices:
[0] height
[1] area
Default: 1 |
| Use Z-Range | Boolean | BZRANGE | Use a user-specified elevation range instead of min/max of the input dataset | Default: 0 |
| Z-Range | Value range | ZRANGE | User 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