landlab.components.weathering.exponential_weathering_integrated¶

Created on Fri Apr 8 08:32:48 2016.

@author: RCGlade @author: dylanward Integrated version created by D. Ward on Tue Oct 27 2020

class ExponentialWeathererIntegrated[source]¶

Bases: Component

This component implements exponential weathering of bedrock on hillslopes. Uses exponential soil production function in the style of Ahnert (1976).

Consider that w_0 is the maximum soil production rate and that d_start is the characteristic soil production depth. The soil production rate w is given as a function of the soil depth d:

w = w_0 exp(-d / d_star)

The ExponentialWeathererIntegrated uses the analytical solution for the amount of soil produced by an exponential weathering function over a timestep dt, and returns both the thickness of bedrock weathered and the thickness of soil produced. The solution accounts for the reduction in rate over the timestep due to the increasing depth. This enables accuracy over arbitrarily large timesteps, and better compatiblity with the run_one_step() interface.

Compared to ExponentialWeatherer, upon which it is based…

This maintains the field I/O behavior of the original, but adds new return fields for the weathered thickness and soil produced thickness.
Density adjustments are needed inside the integral and the density ratio is intialized on instantiation. The default value of 1.0 assumes no change in density.
Returns both weathered depth of bedrock and produced depth of soil over the timestep.
The primary soil__depth field that is input is NOT updated by the component.

This is left as an exercise for the model driver, as different applications may want to integrate soil depth and weathering in different sequences among other processes.

SHOULD maintain drop-in compatiblity with the plain ExponentialWeatherer, just import and instantiate this one instead and existing code should work with no side effects other than the creation of the two additional (zeros) output fields.

Examples

>>> import numpy as np
>>> from landlab import RasterModelGrid
>>> from landlab.components import ExponentialWeathererIntegrated
>>> mg = RasterModelGrid((5, 5))
>>> soilz = mg.add_zeros("soil__depth", at="node")
>>> soilrate = mg.add_ones("soil_production__rate", at="node")
>>> expw = ExponentialWeathererIntegrated(mg)
>>> dt = 1000
>>> expw.run_one_step(dt)
>>> np.allclose(mg.at_node["soil_production__rate"][mg.core_nodes], 1.0)
True
>>> np.allclose(
...     mg.at_node["soil_production__dt_produced_depth"][mg.core_nodes], 6.9088
... )
True

References

Required Software Citation(s) Specific to this Component

Barnhart, K., Glade, R., Shobe, C., Tucker, G. (2019). Terrainbento 1.0: a Python package for multi-model analysis in long-term drainage basin evolution. Geoscientific Model Development 12(4), 1267–1297. https://dx.doi.org/10.5194/gmd-12-1267-2019

Additional References

Ahnert, F. (1976). Brief description of a comprehensive three-dimensional process-response model of landform development Z. Geomorphol. Suppl. 25, 29 - 49.

Armstrong, A. (1976). A three dimensional simulation of slope forms. Zeitschrift für Geomorphologie 25, 20 - 28.

Parameters:

grid (ModelGrid) – Landlab ModelGrid object
soil_production__maximum_rate (float) – Maximum weathering rate for bare bedrock
soil_production__decay_depth (float) – Characteristic weathering depth
soil_production__expansion_factor (float) – Expansion ratio of regolith (from relative densities of rock and soil)

__init__(grid, soil_production__maximum_rate=1.0, soil_production__decay_depth=1.0, soil_production__expansion_factor=1.0)[source]¶

Parameters:

grid (ModelGrid) – Landlab ModelGrid object
soil_production__maximum_rate (float) – Maximum weathering rate for bare bedrock
soil_production__decay_depth (float) – Characteristic weathering depth
soil_production__expansion_factor (float) – Expansion ratio of regolith (from relative densities of rock and soil)

static __new__(cls, *args, **kwds)¶

calc_soil_prod_rate()[source]¶: Calculate soil production rate.

cite_as = '\n @article{barnhart2019terrain,\n author = {Barnhart, Katherine R and Glade, Rachel C and Shobe, Charles M\n and Tucker, Gregory E},\n title = {{Terrainbento 1.0: a Python package for multi-model analysis in\n long-term drainage basin evolution}},\n doi = {10.5194/gmd-12-1267-2019},\n pages = {1267---1297},\n number = {4},\n volume = {12},\n journal = {Geoscientific Model Development},\n year = {2019},\n }\n '¶

property coords¶: Return the coordinates of nodes on grid attached to the component.

property current_time¶

Current time.

Some components may keep track of the current time. In this case, the current_time attribute is incremented. Otherwise it is set to None.

Return type:: current_time

definitions = (('soil__depth', 'Depth of soil or weathered bedrock'), ('soil_production__dt_produced_depth', 'thickness of soil produced at nodes over time dt'), ('soil_production__dt_weathered_depth', 'thickness of bedrock weathered at nodes over time dt'), ('soil_production__rate', 'rate of soil production at nodes'))¶

classmethod from_path(grid, path)¶

Create a component from an input file.

Parameters:

grid (ModelGrid) – A landlab grid.
path (str or file_like) – Path to a parameter file, contents of a parameter file, or a file-like object.

Returns:

A newly-created component.

Return type:

Component

property grid¶: Return the grid attached to the component.

initialize_optional_output_fields()¶

Create fields for a component based on its optional field outputs, if declared in _optional_var_names.

This method will create new fields (without overwrite) for any fields output by the component as optional. New fields are initialized to zero. New fields are created as arrays of floats, unless the component also contains the specifying property _var_type.

initialize_output_fields(values_per_element=None)¶

Create fields for a component based on its input and output var names.

This method will create new fields (without overwrite) for any fields output by, but not supplied to, the component. New fields are initialized to zero. Ignores optional fields. New fields are created as arrays of floats, unless the component specifies the variable type.

Parameters:: values_per_element (int (optional)) – On occasion, it is necessary to create a field that is of size (n_grid_elements, values_per_element) instead of the default size (n_grid_elements,). Use this keyword argument to acomplish this task.

input_var_names = ('soil__depth',)¶

property maximum_weathering_rate¶: Maximum rate of weathering (m/yr).

name = 'ExponentialWeathererIntegrated'¶

optional_var_names = ()¶

output_var_names = ('soil_production__dt_produced_depth', 'soil_production__dt_weathered_depth', 'soil_production__rate')¶

run_one_step(dt=0)[source]¶

Parameters:: dt (float) – Used only for compatibility with standard run_one_step. If dt is not provided, the default of zero maintains backward compatibility

property shape¶: Return the grid shape attached to the component, if defined.

unit_agnostic = True¶

units = (('soil__depth', 'm'), ('soil_production__dt_produced_depth', 'm'), ('soil_production__dt_weathered_depth', 'm'), ('soil_production__rate', 'm/yr'))¶

classmethod var_definition(name)¶

Get a description of a particular field.

Parameters:: name (str) – A field name.
Returns:: A description of each field.
Return type:: tuple of (name, *description*)

classmethod var_help(name)¶

Print a help message for a particular field.

Parameters:: name (str) – A field name.

classmethod var_loc(name)¶

Location where a particular variable is defined.

Parameters:: name (str) – A field name.
Returns:: The location (‘node’, ‘link’, etc.) where a variable is defined.
Return type:: str

var_mapping = (('soil__depth', 'node'), ('soil_production__dt_produced_depth', 'node'), ('soil_production__dt_weathered_depth', 'node'), ('soil_production__rate', 'node'))¶

classmethod var_type(name)¶

Returns the dtype of a field (float, int, bool, str…).

Parameters:: name (str) – A field name.
Returns:: The dtype of the field.
Return type:: dtype

classmethod var_units(name)¶

Get the units of a particular field.

Parameters:: name (str) – A field name.
Returns:: Units for the given field.
Return type:: str