Source code for terrainbento.derived_models.model_basicHy

# coding: utf8
# !/usr/env/python
"""terrainbento **BasicHy** model program.

Erosion model program using linear diffusion, stream-power-driven sediment
erosion and mass conservation, and discharge proportional to drainage area.

Landlab components used:
    1. `FlowAccumulator <https://landlab.readthedocs.io/en/master/reference/components/flow_accum.html>`_
    2. `DepressionFinderAndRouter <https://landlab.readthedocs.io/en/master/reference/components/flow_routing.html>`_ (optional)
    3. `ErosionDeposition <https://landlab.readthedocs.io/en/master/reference/components/erosion_deposition.html>`_
    4. `LinearDiffuser <https://landlab.readthedocs.io/en/master/reference/components/diffusion.html>`_
"""


from landlab.components import ErosionDeposition, LinearDiffuser
from terrainbento.base_class import ErosionModel


[docs]class BasicHy(ErosionModel): r"""**BasicHy** model program. **BasicHy** is a model program that evolves a topographic surface described by :math:`\eta` with the following governing equation: .. math:: \frac{\partial \eta}{\partial t} = \frac{V Q_s} {Q} - KQ^{m}S^{n} + D\nabla^2 \eta Q_s = \int_0^A \left((1-F_f)KQ(A)^{m}S^{n} - \frac{V Q_s}{Q(A)} \right) dA where :math:`Q` is the local stream discharge, :math:`A` is the local upstream drainage area,:math:`S` is the local slope, :math:`m` and :math:`n` are the discharge and slope exponent parameters, :math:`K` is the erodibility by water, :math:`V` is effective sediment settling velocity, :math:`Q_s` is volumetric sediment flux, :math:`r` is a runoff rate, and :math:`D` is the regolith transport efficiency. Refer to `Barnhart et al. (2019) <https://doi.org/10.5194/gmd-12-1267-2019>`_ Table 5 for full list of parameter symbols, names, and dimensions. The following at-node fields must be specified in the grid: - ``topographic__elevation`` """ _required_fields = ["topographic__elevation"]
[docs] def __init__( self, clock, grid, m_sp=0.5, n_sp=1.0, water_erodibility=0.0001, regolith_transport_parameter=0.1, settling_velocity=0.001, fraction_fines=0.5, solver="basic", **kwargs ): """ Parameters ---------- clock : terrainbento Clock instance grid : landlab model grid instance The grid must have all required fields. m_sp : float, optional Drainage area exponent (:math:`m`). Default is 0.5. n_sp : float, optional Slope exponent (:math:`n`). Default is 1.0. water_erodibility : float, optional Water erodibility (:math:`K`). Default is 0.0001. regolith_transport_parameter : float, optional Regolith transport efficiency (:math:`D`). Default is 0.1. settling_velocity : float, optional Settling velocity of entrained sediment (:math:`V`). Default is 0.001. fraction_fines : float, optional Fraction of fine sediment that is permanently detached (:math:`F_f`). Default is 0.5. solver : str, optional Solver option to pass to the Landlab `ErosionDeposition <https://landlab.readthedocs.io/en/master/reference/components/erosion_deposition.html>`__ component. Default is "basic". **kwargs : Keyword arguments to pass to :py:class:`ErosionModel`. Importantly these arguments specify the precipitator and the runoff generator that control the generation of surface water discharge (:math:`Q`). Returns ------- BasicHy : model object Examples -------- This is a minimal example to demonstrate how to construct an instance of model **BasicHy**. For more detailed examples, including steady-state test examples, see the terrainbento tutorials. To begin, import the model class. >>> from landlab import RasterModelGrid >>> from landlab.values import random >>> from terrainbento import Clock, BasicHy >>> clock = Clock(start=0, stop=100, step=1) >>> grid = RasterModelGrid((5,5)) >>> _ = random(grid, "topographic__elevation") Construct the model. >>> model = BasicHy(clock, grid) Running the model with ``model.run()`` would create output, so here we will just run it one step. >>> model.run_one_step(1.) >>> model.model_time 1.0 """ # If needed, issue warning on porosity if "sediment_porosity" in kwargs: msg = "sediment_porosity is no longer used by BasicHy." raise ValueError(msg) # Call ErosionModel"s init super().__init__(clock, grid, **kwargs) # verify correct fields are present. self._verify_fields(self._required_fields) # Get Parameters self.m = m_sp self.n = n_sp self.K = water_erodibility # Instantiate a Space component self.eroder = ErosionDeposition( self.grid, K=self.K, F_f=fraction_fines, v_s=settling_velocity, m_sp=self.m, n_sp=self.n, discharge_field="surface_water__discharge", solver=solver, ) # Instantiate a LinearDiffuser component self.diffuser = LinearDiffuser( self.grid, linear_diffusivity=regolith_transport_parameter )
[docs] def run_one_step(self, step): """Advance model **BasicHy** for one time-step of duration step. The **run_one_step** method does the following: 1. Creates rain and runoff, then directs and accumulates flow. 2. Assesses the location, if any, of flooded nodes where erosion should not occur. 3. Assesses if a :py:mod:`PrecipChanger` is an active boundary handler and if so, uses it to modify the erodibility by water. 4. Calculates erosion and deposition by water. 5. Calculates topographic change by linear diffusion. 6. Finalizes the step using the :py:mod:`ErosionModel` base class function **finalize__run_one_step**. This function updates all boundary handlers handlers by ``step`` and increments model time by ``step``. Parameters ---------- step : float Increment of time for which the model is run. """ # create and move water self.create_and_move_water(step) # Do some erosion (but not on the flooded nodes) # (if we're varying K through time, update that first) if "PrecipChanger" in self.boundary_handlers: self.eroder.K = ( self.K * self.boundary_handlers[ "PrecipChanger" ].get_erodibility_adjustment_factor() ) self.eroder.run_one_step(step) # Do some soil creep self.diffuser.run_one_step(step) # Finalize the run_one_step_method self.finalize__run_one_step(step)
[docs]def main(): # pragma: no cover """Execute model.""" import sys try: infile = sys.argv[1] except IndexError: print("Must include input file name on command line") sys.exit(1) ha = BasicHy.from_file(infile) ha.run()
if __name__ == "__main__": main()