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Simulations

Main user interface

The main interface contains the elements described below.

Run definition

Corresponds to the choice of the case study area (as defined during data importation). The available data appear in the dropdown list. If the data that have just been entered are not displayed, then it is necessary to update the interface to include them (View > update).


Options:
  1. The study area: the name of the study area.

  2. The rivers layer: corresponds to the rivers mask (pixels with a contributing area above the threshold limit). It is only used to select corresponding buffers (for debris flows source areas).

  3. The run name: a name attributed to resulting folders. It is necessary to give a run name to activate the "run" button.

Source areas

This section defines the datasets and the criteria to be considered for the source identification.


The source area delineation uses an index based approach. Input datasets can represent different types of spatial information, and are handled with user-defined parameters. Accordingly, grid cells of each input dataset are classified as (1) favourable, when initiation is possible, (2) excluded when initiation is unlikely, or (3) ignored when no decision can be taken on this parameter (see Horton et al., 2013). Datasets are combined according to the following rule: a cell is a source area if it was at least once selected as favourable, but never excluded. Alternatively, the user can directly import source areas which have been generated by another (GIS-based) approach.

The user can chose up to 6 different datasets by selecting from the dropdown list. The datasets are those listed in the file parameters\sources\_input_grids_type.xml. The second dropdown list is the area for which this type of data is available. The third one lists the criteria used to identify the source areas. These criteria are described in the xml files of the folder parameters\sources and can be modified (see FAQ).

Propagation

The activation of the propagation calculations and the choice of algorithms are available in this section.


Options:
  1. The first option is to activate / deactivate the propagation calculation.

  2. Additional results: one can also save the sum of the probability/susceptibility values of the different propagations in addition to the maximum. This option requires simulating every propagation entirely, which can turn into a lengthy process.

  3. Sources triggering as connected areas: it allows triggering together the source cells that are connected to each other. This option should spare some time when distinct areas can be identified.

  4. Calculation method: there are 3 different calculation methods that require more or less time:
    • Overview: only superior source areas > An automatic identification allows to extract the highest sources in each buffer. During this synopsis, only these superior sources are triggered. The results are generally good, but rarely complete.
    • Quick: energy based discrimination > As for the preceding option, superior sources are triggered first. Then the other source areas are considered and if, during the spreading calculation, another propagation has taken the same trajectory with a similar of superior energy, the calculations of the current propagation will stop since it will be redundant. This selection according to energy is very efficient; it can save a lot of time and produces results quasi similar to the full simulation for each source. This option is highly recommended.
    • Complete: simulation of all propagations > Each source cell is propagated without conditions. This can be extremely time consuming, but is required if ones want the sum of the probability/susceptibility values.

  5. Spreading algorithm: choice of the directions algorithm and the inertia (or persistence) algorithm. Different parameters can be chosen from the dropdown lists on the right. These parameters can be modified (see FAQ). See Horton and al. (2013) for the description of the algorithms.

  6. Energy calculation: The friction loss function determines the energy loss as a function of different parameters. The energy limitation introduces a superior energy threshold (in m/s). All parameters can be modified (see FAQ). See Horton and al. (2013) for the description of the algorithms.

Display options

Allow an overview of the source areas and the propagation extents. It is highly inadvisable to activate these displays during a calculation of a large area, as they would increase the calculation time considerably.