Source code for landlab.components.weathering.exponential_weathering

#!/usr/bin/env python
"""Created on Fri Apr  8 08:32:48 2016.

@author: RCGlade

import numpy as np

from landlab import Component

[docs]class ExponentialWeatherer(Component): """Calculate exponential weathering of bedrock on hillslopes. Uses exponential soil production function in the style of Ahnert (1976). Consider that ``w0`` is the maximum soil production rate and that ``w_star`` is the characteristic soil production depth. The soil production rate ``w0`` is given as a function of the soil depth:: soil_production = w0 * exp(-soil__depth / w_star) The :class:`~.ExponentialWeatherer` only calculates soil production at core nodes. An alternative version which uses the analytical integral of production through time is available at the component :py:class:`~.ExponentialWeathererIntegrated`. Examples -------- >>> import numpy as np >>> from landlab import RasterModelGrid >>> from landlab.components import ExponentialWeatherer >>> mg = RasterModelGrid((5, 5)) >>> soilz = mg.add_zeros("soil__depth", at="node") >>> soilrate = mg.add_ones("soil_production__rate", at="node") >>> expw = ExponentialWeatherer(mg) >>> expw.calc_soil_prod_rate() >>> np.allclose(mg.at_node['soil_production__rate'], 1.) 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. **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. """ _name = "ExponentialWeatherer" _unit_agnostic = True _cite_as = """ @article{barnhart2019terrain, author = {Barnhart, Katherine R and Glade, Rachel C and Shobe, Charles M and Tucker, Gregory E}, title = {{Terrainbento 1.0: a Python package for multi-model analysis in long-term drainage basin evolution}}, doi = {10.5194/gmd-12-1267-2019}, pages = {1267---1297}, number = {4}, volume = {12}, journal = {Geoscientific Model Development}, year = {2019}, } """ _info = { "soil__depth": { "dtype": float, "intent": "in", "optional": False, "units": "m", "mapping": "node", "doc": "Depth of soil or weathered bedrock", }, "soil_production__rate": { "dtype": float, "intent": "out", "optional": False, "units": "m/yr", "mapping": "node", "doc": "rate of soil production at nodes", }, }
[docs] def __init__( self, grid, soil_production_maximum_rate=1.0, soil_production_decay_depth=1.0 ): """ Parameters ---------- grid: ModelGrid Landlab ModelGrid object soil_production_maximum_rate : float, array of float Maximum weathering rate for bare bedrock soil_production_decay_depth : float, array of float Characteristic weathering depth """ super().__init__(grid) # Store grid and parameters # soil_production_maximum_rate, value set in setter below self._w0 = None # soil_production_decay_depth, value set in setter below self._wstar = None self.maximum_weathering_rate = soil_production_maximum_rate self.decay_depth = soil_production_decay_depth # weathering rate if "soil_production__rate" not in grid.at_node: grid.add_zeros("soil_production__rate", at="node")
[docs] def calc_soil_prod_rate(self): """Calculate soil production rate.""" core = self._grid.core_nodes self.grid.at_node["soil_production__rate"][core] = self._w0[core] * np.exp( -self.grid.at_node["soil__depth"][core] / self._wstar[core] )
[docs] def run_one_step(self): """ Parameters ---------- dt: float Used only for compatibility with standard run_one_step. """ self.calc_soil_prod_rate()
@property def maximum_weathering_rate(self): """Maximum rate of weathering (m/yr).""" return self._w0 @maximum_weathering_rate.setter def maximum_weathering_rate(self, new_val): if np.any(new_val <= 0): raise ValueError("Maximum weathering rate must be positive.") self._w0 = np.broadcast_to(new_val, self.grid.number_of_nodes) @property def decay_depth(self): """Maximum rate of weathering (m/yr).""" return self._wstar @decay_depth.setter def decay_depth(self, new_val): if np.any(new_val <= 0): raise ValueError("Maximum decay depth must be positive.") self._wstar = np.broadcast_to(new_val, self.grid.number_of_nodes)