Model:Chi analysis tools

Chi analysis tools

Metadata

Also known as	Channel segment finder
Model type	Single
Model part of larger framework
Note on status model
Date note status model

Incorporated models or components:

Spatial dimensions	1.5D
Spatial extent	Regional-Scale, Landscape-Scale, Watershed-Scale
Model domain
One-line model description	Tool for examining channel profiles in chi-elevation space using the integral method of channel analysis
Extended model description	This tool is used for examining bedrock channels. The tool is based on the assumption that the stream power incision model (SPIM) adequately describes channel incision. Channels profiles are converted to chi-elevation space, where chi is a transformed longitudinal coordinate that takes drainage area into account. The tool uses a variety of statistical tests to extract the most likely series of segments with distinct steepness in chi-elevation space. It also performs statistical tests to determine the best fit m/n ratio, where m is an area (A) exponent and n is a slope (S) exponent in the SPIM with E = K A^m S^n, where E is an erosion rate and K is an 'erodibility'.

Keywords:	geomorphology, bedrock channel erosion, topographic analysis,

Name	Simon Mudd
Type of contact	Model developer
Institute / Organization	University of Edinburgh
Postal address 1	School of GeoSciences
Postal address 2	Drummond Street
Town / City	Edinburgh
Postal code	EH8 9XP
State	NO STATE
Country	United Kingdom
Email address	simon.m.mudd@ed.ac.uk
Phone	+44 (0) 131 650 2535
Fax

Name	David Milodowski
Type of contact	Model developer
Institute / Organization	University of Edinburgh
Postal address 1	School of GeoSciences
Postal address 2	Drummond Street
Town / City	Edinburgh
Postal code	EH8 9XP
State	NO STATE
Country	United Kingdom
Email address
Phone
Fax

Name	Stuart Grieve
Type of contact	Model developer
Institute / Organization	University of Edinburgh
Postal address 1	School of GeoSciences
Postal address 2	Drummond Street
Town / City	Edinburgh
Postal code	EH8 9XP
State	NO STATE
Country	United Kingdom
Email address
Phone
Fax

Name	Declan Valters
Type of contact	Model developer
Institute / Organization	University of Edinburgh
Postal address 1	School of GeoSciences
Postal address 2	Drummond Street
Town / City	Edinburgh
Postal code	EH8 9XP
State	NO STATE
Country	United Kingdom
Email address
Phone
Fax

Supported platforms	Unix, Linux
Other platform
Programming language	C++, Python
Other program language
Code optimized	Single Processor
Multiple processors implemented
Nr of distributed processors
Nr of shared processors
Start year development	2012
Does model development still take place?	Yes
If above answer is no, provide end year model development
Code development status
When did you indicate the 'code development status'?
Model availability	As code
Source code availability (Or provide future intension)	Through CSDMS repository
Source web address
Source csdms web address
Program license type	GPL v2
Program license type other
Memory requirements	Depends on the size of your DEM
Typical run time	A few minutes to several days depending on parameters and DEM size

Describe input parameters	The input is a 'channel file' and a 'driver file'. The channel file contains data on channel profiles within a channel network composed of a main stem and tributaries flowing into that main stem (that is, there are no tributaries of tributaries). The driver file contains parameters for the model run. The format of these files is described in the documentation that accompanies the model source code.
Input format	ASCII
Other input format
Describe output parameters	The outputs are i) For chi_m_over_n_analysis.exe, a .movern file that contains information about the goodness of fit of channel profiles to a series of linear segments as a function of the m/n ratio: this file is used to determine the best fit m/n ratio of a channel network. ii) For chi_get_profiles.exe, a series of .tree files which contain information about the best fit channel segments in chi-elevation space. This data can be used to infer erosion rates, tectonics, or variations in erodibility.
Output format	ASCII
Other output format
Pre-processing software needed?	Yes
Describe pre-processing software	Channel profile data must be prepared to meed the specifications of the *.chan file. The format of this file is described in the documentation provided with the source code.
Post-processing software needed?	No
Describe post-processing software
Visualization software needed?	No
If above answer is yes
Other visualization software

Describe processes represented by the model	The module performs topographic analysis but the analysis is based on the assumption that the stream power incision model is a good approximation for channel incision.
Describe key physical parameters and equations	Topographic analysis so no physical parameters as such. The main parameters fro the module are: 1) sigma: the uncertainty (in metres, or meters for you yanks), of the topographic data. 2) The target nodes: These are the number of nodes you wish to use in each subset of the channel. For details see associated documentation. This should vary between 60-140. The module partitions data and the number of partitions is a highly nonlinear function of the number of nodes so target node values of >150 will lead to compute times of many months - forever. 3) The minimum segment length: The shortest contiguous number of nodes the user is willing to consider for statistical analysis (in testing, 8-20 performed reasonably well). If you chose 2 you will be performing linear analysis on segments with 2 data points which is clearly nonsense. 4) Mean skip: See associated documentation, but the module uses a Monte Carlo sampling regime which skips nodes, analyses a subset of data, and then performs this skipping and analysis routine over a number of iterations. For SRTM and ASTER data this should be 1-2. For 10m data it can be 1-10, and for LiDAR data you could skip up to 100 nodes. Note that because of the iterative processes you will need to increase the number of iterations as you increase the skip value if you are to sample all of the data.
Describe length scale and resolution constraints	With reasonable parameter values channel networks with individual channel of ~1000 nodes will take a few to 10s of minutes to analyse. The longer the channel network, the longer the analysis.
Describe time scale and resolution constraints	Topographic analysis so no time scale constraints.
Describe any numerical limitations and issues	See documentation. The major limitation is computational time. This can be alleviated with sensible selection of module parameters. See documentation for guidance.

Describe available calibration data sets	Topographic analysis: no calibration required.
Upload calibration data sets if available:
Describe available test data sets	There are 3 datasets within this repository. One from Southwest Pennsylvania, one from the Apennines in Italy, and one from a CHILD model run. Datasets are the same as those run with the associated manuscript (available at Simon Mudd's website) so users can compare results with figures from the manuscript.
Upload test data sets if available:
Describe ideal data for testing	Any bedrock channel profile. Module is intended for use on topographic data.

Do you have current or future plans for collaborating with other researchers?	Yes.

Is there a manual available?	Yes
Upload manual if available:	Media:Chi analysis movern and profiles.pdf
Model website if any
Model forum / discussion board

Comments

This part will be filled out by CSDMS staff

OpenMI compliant	No not possible
BMI compliant	No not possible
WMT component	Not yet"Not yet" is not in the list (Yes, In progress, No but possible, No not possible) of allowed values for the "Code CMT compliant or not" property.
PyMT component
Is this a data component

Can be coupled with:

Model info

Authors

Simon Mudd

Milodowski, Grieve, Valters

Source code

View in CSDMS GitHub repository

Model citations

Nr. of publications:	1
Total citations:	144
h-index:	1
m-quotient:	0.1

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