r.droka

Calculates run-out distance of a falling rock mass

r.droka dem=string start=string ang=float red=float m=float num=integer prefix=name [n=integer] [--overwrite] [--verbose] [--quiet] [--qq] [--ui]

Example:

r.droka dem=string start=string ang=float red=0.9 m=float num=integer prefix=name

grass.script.run_command("r.droka", dem, start, ang, red=0.9, m, num, prefix, n=None, overwrite=False, verbose=False, quiet=False, superquiet=False)

Example:

gs.run_command("r.droka", dem="string", start="string", ang=float, red=0.9, m=float, num=integer, prefix="name")

Parameters

Command linePython (grass.script)

dem=string [required]
    Digital Elevation Model
start=string [required]
    Name of starting points map
ang=float [required]
    Shadow angle
red=float [required]
    Reduction value
    Allowed values: 0-1
    Default: 0.9
m=float [required]
    Value of rock mass (kg)
num=integer [required]
    Number of boulders (>=1)
prefix=name [required]
    Prefix for output raster maps
n=integer
    Buffer distance (meters)
--overwrite
    Allow output files to overwrite existing files
--help
    Print usage summary
--verbose
    Verbose module output
--quiet
    Quiet module output
--qq
    Very quiet module output
--ui
    Force launching GUI dialog

dem : str, required
    Digital Elevation Model
    Used as: input, raster
start : str, required
    Name of starting points map
    Used as: input, vector
ang : float, required
    Shadow angle
red : float, required
    Reduction value
    Allowed values: 0-1
    Default: 0.9
m : float, required
    Value of rock mass (kg)
num : int, required
    Number of boulders (>=1)
prefix : str, required
    Prefix for output raster maps
    Used as: output, raster, name
n : int, optional
    Buffer distance (meters)
overwrite: bool, optional
    Allow output files to overwrite existing files
    Default: False
verbose: bool, optional
    Verbose module output
    Default: False
quiet: bool, optional
    Quiet module output
    Default: False
superquiet: bool, optional
    Very quiet module output
    Default: False

DESCRIPTION

The intersection between the topographic profile and the line starting from the point of detachment with a certain angle to the horizontal line defines the point of maximum propagation (Evans and Hungr, 1993; Jaboyedoff and Labiouse, 2003). The angle of inclination and the line of propagation are defined as zenith angle and shadow zone. This script defines rockfall zones from a digital elevation model (DEM) and vector layer containing starting point or points.

Energy line used for the cone method from the top or the bottom of a cliff (shadow angle), according to various authors (Image from Jaboyedoff and Labiouse, 2003)

INPUT

Digital Elevation Model: Name of elevation raster map.

Starting points: Name of vector map containing rockfall source area. It can be one point or more.

Shadow angle: Angle of inclination that defines the propagation zone. It's calculated from a horizontal plane starting from a source point: highest values determine a lowest propagation.

Reduction value: Reduction multiplicator for velocity. Default value is 0.9.

Number of boulders: For each starting point can be generated other random points used in the computations. By default points are located in a radius from the starting point equal to: (cell size * number of boulders)/2. Insert 1 for use only the original starting point or points. Note that a high number of boulders can make excessively long the calculation times.

Rock mass: Value of rock mass (Kg)

Output prefix: Name of prefix used for output raster maps

Buffer distance: This value defines the radius for randomly generating boulders starting from starting point. It's in the option dialog window.

OUTPUT

r.droka generates 5 raster maps and a vector map. The names of all output maps start with the prefix defined by the parameter prefix followed by the name of map

prefix_propagation: raster map representing the area of propagation. If are used multiple source points, each pixel shows the percentage of passage (%)
prefix_vel_max: maximum rock-fall translational velocities (m/sec)
prefix_vel_med: medium rock-fall translational velocities (m/sec)
prefix_vel_max: medium kinetic energy (kJ)
prefix_en_max: maximum kinetic energy (kJ)
prefix_starting: vector map of starting points

REFERENCES

FILIPELLO A., GIULIANI A., MANDRONE G. (2010) - Rock Slopes Failure Susceptibility Analysis: From Remote Sensing Measurements to Geographic Information System Raster Modules. American Journal of Environmental Sciences 6 (6): 489-494, 2010 ISSN 1553-345X 2010 Science Publications.

JABOYEDOFF M., LABIOUSE V. (2003) - Preliminary assessment of rockfall hazard based on GIS Data. Proceeding of the 10th ISRM Congress, South African Inst. Min. Met., Johannesburg, pp: 575-578

EVANS, S.G., HUNGR O. (1993). The assessment of rock fall hazard at the base of the talus slope. Can. Geotech. J., 30: 620-636. DOI: 10.1139/t93-054

AUTHORS

Andrea Filipello, University of Turin, Italy

Daniele Strigaro, University of Milan, Italy

SOURCE CODE

Available at: r.droka source code (history)
Latest change: Thursday Mar 20 21:35:59 2025 in commit f270357