landlab

DetachmentLtdErosion: Solve stream power equations, but without stability checks

Simulate detachment limited sediment transport.

Landlab component that simulates detachment limited sediment transport is more general than the stream power component. Doesn’t require the upstream node order, links to flow receiver and flow receiver fields. Instead, takes in the discharge values on NODES calculated by the OverlandFlow class and erodes the landscape in response to the output discharge.

As of right now, this component relies on the OverlandFlow component for stability. There are no stability criteria implemented in this class. To ensure model stability, use StreamPowerEroder or FastscapeEroder components instead.

Code author: Jordan Adams

Examples

>>> import numpy as np
>>> from landlab import RasterModelGrid
>>> from landlab.components import DetachmentLtdErosion

Create a grid on which to calculate detachment ltd sediment transport.

>>> grid = RasterModelGrid((4, 5))

The grid will need some data to provide the detachment limited sediment transport component. To check the names of the fields that provide input to the detachment ltd transport component, use the input_var_names class property.

Create fields of data for each of these input variables.

>>> grid.at_node['topographic__elevation'] = np.array([
...     0., 0., 0., 0., 0.,
...     1., 1., 1., 1., 1.,
...     2., 2., 2., 2., 2.,
...     3., 3., 3., 3., 3.])

Using the set topography, now we will calculate slopes on all nodes.

>>> grid.at_node['topographic__slope'] = np.array([
...     -0.        , -0.        , -0.        , -0.        , -0,
...      0.70710678,  1.        ,  1.        ,  1.        ,  0.70710678,
...      0.70710678,  1.        ,  1.        ,  1.        ,  0.70710678,
...      0.70710678,  1.        ,  1.        ,  1.        ,  0.70710678])

Now we will arbitrarily add water discharge to each node for simplicity. >>> grid.at_node[‘surface_water__discharge’] = np.array([ ... 30., 30., 30., 30., 30., ... 20., 20., 20., 20., 20., ... 10., 10., 10., 10., 10., ... 5., 5., 5., 5., 5.])

Instantiate the DetachmentLtdErosion component to work on this grid, and run it. In this simple case, we need to pass it a time step (‘dt’)

>>> dt = 10.0
>>> dle = DetachmentLtdErosion(grid)
>>> dle.erode(dt=dt)

After calculating the erosion rate, the elevation field is updated in the grid. Use the output_var_names property to see the names of the fields that have been changed.

>>> dle.output_var_names
('topographic__elevation',)

The topographic__elevation field is defined at nodes.

>>> dle.var_loc('topographic__elevation')
'node'

Now we test to see how the topography changed as a function of the erosion rate.

>>> grid.at_node['topographic__elevation'] 
array([ 0.        ,  0.        ,  0.        ,  0.        ,  0.        ,
        0.99936754,  0.99910557,  0.99910557,  0.99910557,  0.99936754,
        1.99955279,  1.99936754,  1.99936754,  1.99936754,  1.99955279,
        2.99968377,  2.99955279,  2.99955279,  2.99955279,  2.99968377])
class DetachmentLtdErosion(grid, K_sp=2e-05, m_sp=0.5, n_sp=1.0, uplift_rate=0.0, entraiment_threshold=0.0, **kwds)[source]

Bases: landlab.core.model_component.Component

Landlab component that simulates detachment-limited river erosion.

This component calculates changes in elevation in response to vertical incision.

erode(dt, elevs='topographic__elevation', discharge_cms='surface_water__discharge', slope='topographic__slope')[source]

Erode into grid topography.

For one time step, this erodes into the grid topography using the water discharge and topographic slope.

The grid field ‘topographic__elevation’ is altered each time step.

Parameters:

dt : float

Time step.

discharge_cms : str, optional

Name of the field that represents discharge on the nodes, if from the de Almeida solution have units of cubic meters per second.

slope : str, optional

Name of the field that represent topographic slope on each node.