Model help:CHILD: Difference between revisions

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__NOTOC__
__NOTOC__
==<big><big>{{PAGENAME}}</big></big>==
==<big><big>{{PAGENAME}}</big></big>==
<span class="remove_this_tag">~3lines that describe the module</span>
The CHILD model simulates the evolution of a topographic surface and its subjacent stratigraphy under a set of driving erosion and sedimentation processes and with a prescribed set of initial and boundary conditions.


==Model introduction==
==Model introduction==
<span class="remove_this_tag">Introduction to the module</span>
Designed to serve as a computational framework for investigating a wide range of problems in catchment geomorphology, CHILD is both a model, in the sense that it com¬prises a set of hypotheses about how nature works, and a software tool, in the sense that it provides a simulation environment for exploring the conse¬quences of different hypotheses, parameters, and boundary conditions. The model provides a general and extensible computational framework for exploring research questions related to landscape evolution. It simulates the interaction of two general types of process: “fluvial” processes, a category which encompasses erosion or deposition by runoff cascading across the landscape, and “hillslope” processes, which includes weathering, soil creep, and other slope transport processes.


<div id=CMT_MODEL_PARAMETERS>
==Model parameters==
==Model parameters==
= Input Files and Directories =
= Input Files and Directories =
Line 201: Line 200:


==Main equations==
==Main equations==
<span class="remove_this_tag">A list of the key equations. HTML format is supported; latex format will be supported in the future</span>
* Hydraulic Geometry
 
1) bankfull discharbge
::::{|
|width=500px|<math> Q_{b} = R_{b} A </math>
|width=50px align="right"|(1)
|}
2) bankfull channel width
::::{|
|width=500px|<math> W_{b} = k_{w} Q_{b} ^ \left (\omega b\right ) </math>
|width=50px align="right"|(2)
|}
3) Channel width
::::{|
|width=500px|<math> {\frac{W}{W_{b}}} = {\frac{Q^ \left ( \omega _{b} \right )}{Q_{b}}}</math>
|width=50px align="right"|(3)
|}
4) bankfull water depth
::::{|
|width=500px|<math> d_{b} = k_{d} Q_{b} ^ \left (\delta _{b} \right )</math>
|width=50px align="right"|(4)
|}
5) Water depth
::::{|
|width=500px|<math> {\frac{d}{d_{b}}} = {\frac{Q ^ \left ( \delta _{s}}{Q_{b}}}</math>
|width=50px align="right"|(5)
|}
6) Bankfull bed roughness
::::{|
|width=500px|<math> N_{b} = k_{N} Q_{b} ^ \left (\nu _{b} \right )</math>
|width=50px align="right"|(6)
|}
7) Bed roughness
::::{|
|width=500px|<math>  {\frac{N}{N_{b}}} = {\frac{Q ^ \left ( \nu _{s}}{Q_{b}}}</math>
|width=50px align="right"|(7)
|}
8) Bankfull bank roughness
::::{|
|width=500px|<math> M_{b} = k_{M} Q_{b} ^ \left (\mu _{b} \right )</math>
|width=50px align="right"|(8)
|}
9) Bed roughness
::::{|
|width=500px|<math>  {\frac{M}{M_{b}}} = {\frac{Q ^ \left ( \mu _{s}}{Q_{b}}}</math>
|width=50px align="right"|(9)
|}
* Overview of Transport, Erosion, and Deposition by Running water
1) Continuity of mass equation for the time rate of change of height at a cell
::::{|
|width=500px|<math> {\frac{dz_{i}}{dt}} = {\frac{1}{\Lambda _{i}}} \left ( -Q_{Si} + \sum\limits_{i=1}^\left (N_{i} \right ) Q_{Sj} \right ) </math>
|width=50px align="right"|(10)
|}
2) Potential erosion/deposition rate
::::{|
|width=500px|<math> \Phi _{i} = {\frac{1}{\Lambda _{i}}} \left ( -Q_{Ci} + \sum\limits_{i=1}^\left (N_{i} \right ) Q_{Sj} \right ) </math>
|width=50px align="right"|(11)
|}
3) Volumetric water-borne sediment transport rate out of the cell
::::{|
|width=500px|<math> Q_{Si} = \left\{\begin{matrix} \lambda _{i} D_{ci} & if \Phi _{i} > D_{c} \\ Q_{Ci} & otherwise \end{matrix}\right. </math>
|width=50px align="right"|(12)
|}
* Detachment-Capacity Laws
1) bed shear stress
::::{|
|width=500px|<math> \tau _{0} = K_{t} \left ({\frac{Q}{W}}\right ) ^ \left (M_{b}\right ) S^ \left (N_{b}\right ) </math>
|width=50px align="right"|(13)
|}
2) Detachment capacity
::::{|
|width=500px|<math> D _{c} = \left\{\begin{matrix} K_{br} \left ( \tau _{0} - \tau _{c} \right ) ^ \left (P_{b}\right ) & Detachment_law = 0 \\ K_{br} \left ( \tau _{0} ^ \left (P_{b} \right ) - \tau _{c} ^ \left (P_{b}\right ) & Detachment_law = 1 </math>
|width=50px align="right"|(14)
|}
* Transport Capacity Laws
1) Transport_Law = 0 (Power law formula, form 1)
::::{|
|width=500px|<math> Q_{c} = K_{f} W \left ( \tau _{0} - \tau _{c} \right ) ^ \left (P_{f} \right ) </math>
|width=50px align="right"|(15)
|}
2) Transport_Law = 1 (Power law formula, form 2)
::::{|
|width=500px|<math> Q_{c} = K_{f} W \left ( \tau _{0} ^ \left (P_{f}\right ) - \tau _{c} ^ \left (P_{f} \right ) </math>
|width=50px align="right"|(16)
|}
3) Transport_Law = 2 (Bridge-Dominic version of Bagnold formula)
::::{|
|width=500px|<math> Q_{c} = K_{f} W \left (\tau _{0} - \tau _{c} \right ) \left ( \sqrt{\tau _{0}} - \sqrt{\tau _{c}} </math>
|width=50px align="right"|(17)
|}
::::{|
|width=500px|<math> K_{f} = {\frac{a}{\rho ^ \left ({\frac{1}{2}} \left ( \delta - \rho \right ) g tan \Phi}} </math>
|width=50px align="right"|(18)
|}
4) Transport_Law = 4 (Generic power-law formula for multiple size fractions)
::::{|
|width=500px|<math> Q_{ci} = f_{i} K_{f} W \left (\tau _{0} - \tau _{ci} \right ) ^\left ( P_{f} \right ) </math>
|width=50px align="right"|(19)
|}
5) Transport_Law = 6 (Simple slope-discharge power law)
::::{|
|width=500px|<math> Q_{c} = K_{f} Q^ \left (M_{f}\right ) S^\left (N_{f}\right ) </math>
|width=50px align="right"|(20)
|}
* Soil Creep
1) volumetric sediment discharge per unit width (liner)
::::{|
|width=500px|<math> q_{c} = K_{d} \nabla z </math>
|width=50px align="right"|(21)
|}
2) volumetric sediment discharge per unit width (nonliner)
::::{|
|width=500px|<math> q_{c} = {\frac{K_{d}\nabla z}{1 - \left ( |\nabla z | / S_{c}\right )^2 }} </math>
|width=50px align="right"|(22)
|}
<div class="NavFrame collapsed" style="text-align:left">
  <div class="NavHead">Nomenclature</div>
  <div class="NavContent">
{| {{Prettytable}} class="wikitable sortable"
!Symbol!!Description!!Unit
|-
| R<sub>b</sub>
| bankfull runoff rate
| m / yr
|-
|A
| drainage area
| km<sup>2</sup>
|-
| Q<sub>b</sub>
| bankfull discharge
| m<sup>3</sup> / s
|-
| W<sub>b</sub>
| bankfull channel width
| m
|-
| k<sub>w</sub>
| hydro_wid_coefficient_Ds
| -
|-
| ω<sub>b</sub>
| hydro_wid_exp_Ds
| -
|-
| W
| channel width
| m
|-
| ω<sub>s</sub>
| hydro_wid_exp_stn
| -
|-
| d<sub>b</sub>
| bankfull water depth
| m
|-
| d
| water depth
| m
|-
| k<sub>d</sub>
| hydro_dep_coeff_ds
| -
|-
| δ<sub>b</sub>
| hydro_dep_exp_ds
| -
|-
| δ<sub>s</sub>
| hydro_dep_exp_stn
| -
|-
| N<sub>b</sub>
| bankfull bed roughness
| -
|-
| N
| bed roughness
| -
|-
| k<sub>N</sub>
| hydro_rough_coeff_ds
| -
|-
| ν<sub>b</sub>
| hydro_rough_exp_ds
| -
|-
| ν<sub>s</sub>
| hydro_rough_exp_stn
| -
|-
| M<sub>b</sub>
| bankfull bank roughness
| -
|-
| M
| bank roughness
| -
|-
| k<sub>M</sub>
| bank_rough_coeff
| -
|-
| μ<sub>b</sub>
| bank_rough_coeff
| -
|-
| μ<sub>s</sub>
| bank_rough_exp
| -
|-
| z<sub>i</sub>
| surface height at cell i
| m
|-
| Λ<sub>i</sub>
| cell's horizontal surface area
| m
|-
| Q<sub>Si</sub>
| volumetric water-borne sediment transport rate out of the cell
| L<sup>3</sup> / T
|-
| Q<sub>Sj</sub>
| the transport rate in from neighboring cell j
| L<sup>3</sup> / T
|-
| N<sub>i</sub>
| the number of neighboring cells that drain to cell i
| -
|-
| D<sub>ci</sub>
| potential detachment rate
| L / T
|-
| Φ<sub>i</sub>
| potential erosion/deposition rate
| L / T
|-
| τ<sub>0</sub>
| bed shear stress
| -
|-
| Q
| discharge
| L<sup>3</sup>
|-
| S
| gradient from cell i to its downstream neighbor
| -
|-
| K<sub>br</sub>
| rate coefficient (regolith for Detachment_Law = 0; bedrock for Detachment_Law = 1)
| -
|-
| τ<sub>c</sub>
| a threshold below which no detachment takes place
| -
|-
| P<sub>b</sub>
| a parameter
| -
|-
| K<sub>f</sub>
| transport efficiency factor
| m<sup>2</sup> / y / Pa<sup>-3/2</sup>
|-
|}
  </div>
</div>
==Notes==
==Notes==
<span class="remove_this_tag">Any notes, comments, you want to share with the user</span>  
<span class="remove_this_tag">Any notes, comments, you want to share with the user</span>  

Revision as of 14:54, 13 May 2011

The CSDMS Help System

CHILD

The CHILD model simulates the evolution of a topographic surface and its subjacent stratigraphy under a set of driving erosion and sedimentation processes and with a prescribed set of initial and boundary conditions.

Model introduction

Designed to serve as a computational framework for investigating a wide range of problems in catchment geomorphology, CHILD is both a model, in the sense that it com¬prises a set of hypotheses about how nature works, and a software tool, in the sense that it provides a simulation environment for exploring the conse¬quences of different hypotheses, parameters, and boundary conditions. The model provides a general and extensible computational framework for exploring research questions related to landscape evolution. It simulates the interaction of two general types of process: “fluvial” processes, a category which encompasses erosion or deposition by runoff cascading across the landscape, and “hillslope” processes, which includes weathering, soil creep, and other slope transport processes.

Model parameters

Parameter Description Unit
Input directory Paths to input files -
Site prefix Site prefix for input/output files -
Case prefix Case prefix for input/output files -
Parameter Description Unit
Run duraction simulation run time years
Parameter Description Unit
Type of uplift 0 = none; 1 = uniform; 2 = block -
Duration of uplift years
Uplift rate m / yr
Subsidence rate m / yr
Position of fault m
Parameter Description Unit
SubaqueousErosion port use the SubaqueousErosion provides port -
Parameter Description Unit
Width of grid in x-direction m
Width of grid in y-direction m
Mean distance between grid nodes m
Parameter Description Unit
Output directory path to output grid files -
Interval between output files -
File format format for output files -
elevation file output file prefix for variable -
erosion file output file prefix for variable -
discharge file output file prefix for variable -
sediment file output file prefix for variable -
Parameter Description Unit
Output directory path to output grid files -
Interval between output files -
File format format for output files -
Cellelevation file output file prefix for variable -
Cellerosion file output file prefix for variable -
Celldischarge file output file prefix for variable -
Cellsediment file output file prefix for variable -
Parameter Description Unit
Model name name of the model -
Author name name of the model author -

Uses ports

This will be something that the CSDMS facility will add

Provides ports

This will be something that the CSDMS facility will add

Main equations

  • Hydraulic Geometry

1) bankfull discharbge

[math]\displaystyle{ Q_{b} = R_{b} A }[/math] (1)

2) bankfull channel width

[math]\displaystyle{ W_{b} = k_{w} Q_{b} ^ \left (\omega b\right ) }[/math] (2)

3) Channel width

[math]\displaystyle{ {\frac{W}{W_{b}}} = {\frac{Q^ \left ( \omega _{b} \right )}{Q_{b}}} }[/math] (3)

4) bankfull water depth

[math]\displaystyle{ d_{b} = k_{d} Q_{b} ^ \left (\delta _{b} \right ) }[/math] (4)

5) Water depth

[math]\displaystyle{ {\frac{d}{d_{b}}} = {\frac{Q ^ \left ( \delta _{s}}{Q_{b}}} }[/math] (5)

6) Bankfull bed roughness

[math]\displaystyle{ N_{b} = k_{N} Q_{b} ^ \left (\nu _{b} \right ) }[/math] (6)

7) Bed roughness

[math]\displaystyle{ {\frac{N}{N_{b}}} = {\frac{Q ^ \left ( \nu _{s}}{Q_{b}}} }[/math] (7)

8) Bankfull bank roughness

[math]\displaystyle{ M_{b} = k_{M} Q_{b} ^ \left (\mu _{b} \right ) }[/math] (8)

9) Bed roughness

[math]\displaystyle{ {\frac{M}{M_{b}}} = {\frac{Q ^ \left ( \mu _{s}}{Q_{b}}} }[/math] (9)
  • Overview of Transport, Erosion, and Deposition by Running water

1) Continuity of mass equation for the time rate of change of height at a cell

[math]\displaystyle{ {\frac{dz_{i}}{dt}} = {\frac{1}{\Lambda _{i}}} \left ( -Q_{Si} + \sum\limits_{i=1}^\left (N_{i} \right ) Q_{Sj} \right ) }[/math] (10)

2) Potential erosion/deposition rate

[math]\displaystyle{ \Phi _{i} = {\frac{1}{\Lambda _{i}}} \left ( -Q_{Ci} + \sum\limits_{i=1}^\left (N_{i} \right ) Q_{Sj} \right ) }[/math] (11)

3) Volumetric water-borne sediment transport rate out of the cell

[math]\displaystyle{ Q_{Si} = \left\{\begin{matrix} \lambda _{i} D_{ci} & if \Phi _{i} \gt D_{c} \\ Q_{Ci} & otherwise \end{matrix}\right. }[/math] (12)
  • Detachment-Capacity Laws

1) bed shear stress

[math]\displaystyle{ \tau _{0} = K_{t} \left ({\frac{Q}{W}}\right ) ^ \left (M_{b}\right ) S^ \left (N_{b}\right ) }[/math] (13)

2) Detachment capacity

[math]\displaystyle{ D _{c} = \left\{\begin{matrix} K_{br} \left ( \tau _{0} - \tau _{c} \right ) ^ \left (P_{b}\right ) & Detachment_law = 0 \\ K_{br} \left ( \tau _{0} ^ \left (P_{b} \right ) - \tau _{c} ^ \left (P_{b}\right ) & Detachment_law = 1 }[/math] (14)
  • Transport Capacity Laws

1) Transport_Law = 0 (Power law formula, form 1)

[math]\displaystyle{ Q_{c} = K_{f} W \left ( \tau _{0} - \tau _{c} \right ) ^ \left (P_{f} \right ) }[/math] (15)

2) Transport_Law = 1 (Power law formula, form 2)

[math]\displaystyle{ Q_{c} = K_{f} W \left ( \tau _{0} ^ \left (P_{f}\right ) - \tau _{c} ^ \left (P_{f} \right ) }[/math] (16)

3) Transport_Law = 2 (Bridge-Dominic version of Bagnold formula)

[math]\displaystyle{ Q_{c} = K_{f} W \left (\tau _{0} - \tau _{c} \right ) \left ( \sqrt{\tau _{0}} - \sqrt{\tau _{c}} }[/math] (17)
[math]\displaystyle{ K_{f} = {\frac{a}{\rho ^ \left ({\frac{1}{2}} \left ( \delta - \rho \right ) g tan \Phi}} }[/math] (18)

4) Transport_Law = 4 (Generic power-law formula for multiple size fractions)

[math]\displaystyle{ Q_{ci} = f_{i} K_{f} W \left (\tau _{0} - \tau _{ci} \right ) ^\left ( P_{f} \right ) }[/math] (19)

5) Transport_Law = 6 (Simple slope-discharge power law)

[math]\displaystyle{ Q_{c} = K_{f} Q^ \left (M_{f}\right ) S^\left (N_{f}\right ) }[/math] (20)
  • Soil Creep

1) volumetric sediment discharge per unit width (liner)

[math]\displaystyle{ q_{c} = K_{d} \nabla z }[/math] (21)

2) volumetric sediment discharge per unit width (nonliner)

[math]\displaystyle{ q_{c} = {\frac{K_{d}\nabla z}{1 - \left ( |\nabla z | / S_{c}\right )^2 }} }[/math] (22)

Notes

Any notes, comments, you want to share with the user

Numerical scheme


Examples

An example run with input parameters, BLD files, as well as a figure / movie of the output

Follow the next steps to include images / movies of simulations:

See also: Help:Images or Help:Movies

Developer(s)

Name of the module developer(s)

References

Key papers

Links

Any link, eg. to the model questionnaire, etc.