Shaltop simulation from rasters.

We show here how Shaltop simulations can be set-up using a raster with the topography and a raster for the initial mass

Import required packages:

import os

# Read an write rasters
import tilupy.raster

# Functions to download examples of elevation and initial mass rasters
import tilupy.download_data

# Submodule used to prepare Shaltop simulations
import tilupy.models.shaltop.initsimus as shinit

Import rasters from github. You can skip this step if you cloned the github repository, ad just copy/past the files in base_folder.

base_folder = "."  # You may want to change base_folder.
folder_data = os.path.join(base_folder, "rasters")
os.makedirs(folder_data, exist_ok=True)
# raster_topo and raster_mass are the paths to the topography and initial mass
# rasters
raster_topo = tilupy.download_data.import_frankslide_dem(folder_out=folder_data)
raster_mass = tilupy.download_data.import_frankslide_pile(folder_out=folder_data)

Create folder for shaltop simulations

folder_simus = os.path.join(base_folder, "shaltop")
os.makedirs(folder_simus, exist_ok=True)

Read topo and mass

shinit.raster_to_shaltop_txtfile(
    raster_topo, os.path.join(folder_simus, "topography.d")
)
axes_props = shinit.raster_to_shaltop_txtfile(
    raster_mass, os.path.join(folder_simus, "init_mass.d")
)

Initiate simulations parameters (names are the same as in Shaltop parameter file)

params = dict(
    nx=axes_props["nx"],
    ny=axes_props["ny"],
    per=axes_props["nx"] * axes_props["dx"],
    pery=axes_props["ny"] * axes_props["dy"],
    tmax=100,  # Simulation maximum time in seconds (not comutation time)
    dt_im=10,  # Time interval (s) between snapshots recordings
    file_z_init="topography.d",  # Name of topography input file
    file_m_init="init_mass.d",  # name of init mass input file
    initz=0,  # Topography is read from file
    ipr=0,  # Initial mass is read from file
    hinit_vert=1,  # Initial is given as vertical thicknesses and
    # must be converted to thicknesses normal to topography
    eps0=1e-13,  # Minimum value for thicknesses and velocities
    icomp=1,  # choice of rheology (Coulomb with constant basal friction)
    x0=1000,  # Min x value (used for plots after simulation is over)
    y0=2000,
)  # Min y value (used for plots after simulation is over)

Prepare simulations with a constant Coulomb friction coefficient and different values of the friction coefficient (15°, 20° and 25°)

deltas = [15, 20, 25]
for delta in deltas:
    params_txt = "delta_{:05.2f}".format(delta).replace(".", "p")  # e.g. "delta_15p00"
    params["folder_output"] = params_txt  # Specify folder where outputs are stored
    params["delta1"] = delta  # Specify the friction coefficient
    # Write parameter file
    shinit.write_params_file(
        params, directory=folder_simus, file_name=params_txt + ".txt"
    )
    # Create folder for results (not done by shlatop!)
    os.makedirs(os.path.join(folder_simus, params_txt), exist_ok=True)

To run simulations, execute in the following lines in a prompt in the base_folder:

shaltop "" delta_15p00.txt
shaltop "" delta_20p00.txt
shaltop "" delta_25p00.txt