Tsunami Inundation Models for the GOSFORD region

Modifying a simulation

Here we talk about how you change a simulation. Why would you need to change a simulation? Well, you might have some better elevation data, you want to run the simulation on a finer mesh in certain areas, or maybe you want to see the result for different events.

First we describe the uses of the script files you might change, then we walk through a few examples of changes you might make.

The project scripts

In the project directory are the scripts that control the simulation. These scripts are:

project.py	Defines the input data used, where to place output, etc.
build_elevation.py	Builds a PTS file of all elevation data specified by project.py
setup_model.py	Prepares the simulation before actually running it
run_model.py	Runs the simulation

project.py

This file is the heart of the simulation. The project script introduces all files that are necessary to run all accompanying scripts. By changing one of the variables in this script the output could be completely different. For further details on changing parameters see Making changes to a simulation.

build_elevation.py

This script combines all input elevation files into one PTS file. We have provided you with the PTS file used to create the outputs on this DVD. If you would like to change the elevation see Making changes to a simulation.

setup_model.py

This script is used to transform data into a specific format for run_model.py, if required, and to generate warning messages if you are missing data.

run_model.py

This script runs a tsunami inundation scenario. It relies on the parameters set in project.py as well as the PTS and STS files. An STS file has been generated for each event listed in the boundaries directory. For further details on events see Making changes to a simulation.

Making changes to a simulation

There are many parameters that you can change within the project.py script, but the following four parameters are those most commonly changed.

Tide

The tide parameter is used to change the mean stage of the simulation. When tide is set to 0 the initial water level will be at Mean Sea Level. If you increase the tide value the water level will become deeper. However land is masked out using initial conditions. Within ANUGA tide is modelled as a constant.

Events

The event_number variable contains the event number that initiates the tsunami we are modelling. You can change event_number to any event number in the anuga/boundaries directory. As we said above, a new STS file must be generated for run_model.py to work.

The event numbers correspond to a quake ID from the probabilistic tsunami hazard map of Australia.

event_number = 51436    # 1 in 10000 yr event from New Hebrides

Elevation

Elevation data can be changed in the project.py elevation script. Elevation data can be read as either a point file, comma delimited, or as an ASCII grid file (ASC) with an accompanying projection file (PRJ). All elevation input must be projected in the correct UTM zone.

A header for a CSV file has the format:

x,y,elevation

An ASC file header has the format:

ncols         868
nrows         856
xllcorner     418933.86055096
yllcorner     5151810.6668096
cellsize      250
NODATA_value  -9999

The header of a PRJ file has the format:

Projection    UTM
Zone          55
Datum         D_GDA_1994
Zunits        NO
Units         METERS
Spheroid      GRS_1980
Xshift        500000
Yshift        10000000
Parameters

The elevation filenames must be listed in either point_filenames or ascii_grid_filenames depending on their format. Point files need to have their extension shown however the ascii grid files have the .asc extension assumed:

point_filenames = ['SD100031996_jgriffin_clip.csv',
                   'tomaga_offshore_AHD_MGA_1997.csv',
                   'gosford_BBHD_MGA_1995.csv',
                   'gosford_AHD_MGA_2000.csv']

ascii_grid_filenames = ['sd100031996_p',
                        'sd100031996_p2',
                        'sd100031996_p3',
                        'sd100031996_p4']

For further information on ANUGA file formats please see the ANUGA User Manual, section 6.1.

Interior regions

The interior_regions parameter allows you to change the mesh of the model.