getting started 2d - flood modeller · getting started – 2d modelling flood modeller ... •...

$: Getting Started 2D - Flood Modeller · Getting Started – 2D Modelling Flood Modeller ... • “C:\Users\Public\Documents\Flood Modeller\Getting Started” for Windows Vista/7/8$
Getting Started – 2D Modelling Flood Modeller

1 © 2015 CH2M HILL

Getting Started – 2D Modelling This document provides a ‘quick start guide’ for new users of Flood Modeller showing how to run a 2D model and

view results.

The guide uses the example files provided with Flood Modeller. Depending on your operating system these are

located at:

• “C:\Users\Public\Documents\Flood Modeller\Getting Started” for Windows Vista/7/8 (may be accessed from

Libraries\Documents)

• “C:\Documents and Settings\All Users\ Documents\Flood Modeller\Getting Started” for Windows XP

Note that the example data are solely design to demonstrate the Flood Modeller software – they are based on

hypothetical or old data sets and should not be used in decision making.

To run a 2D model in Flood Modeller follow the steps below:

1. Start Flood Modeller and load in the GIS datasets required to define your 2D model. The procedure for

doing this is:

• Click Add GIS Data button in the Home tab of the toolbar

• Select the following layers from the “…\Getting Started\2D Model” folder:

o ASCII raster grid: 5M_DTM.asc – provides ground elevations for area to be modelled

o ESRI polygon shapefile: Active_Area.shp - active area shape file to define modelled extent

(a subset of the ground grid to make calculations more efficient)

o ESRI polyline shapefile: Defence_BC.shp - boundary line shape file to define locations of

inflow boundaries to floodplain

o Aerial photo image file: airphoto.jpg

• The layers will be listed in the Layers panel. Use the move to top / move to bottom buttons in the

Layers panel header to order the shapefiles on top of the aerial photo with the ground elevation

grid below this.

Your map should look similar to the figure below:


2 © 2015 CH2M HILL

2. Start a new 2D simulation by clicking on the “New 2D Simulation” button in the Simulation Tab of the

main ribbon. You will be prompted to specify a name and location for saving your simulation file (e.g.

“…\Getting Started\2D Model\2d model”). A 2D simulation run definition window will then appear, as

shown below.


3 © 2015 CH2M HILL

On the General tab set the Simulation Length to 10 (hours). Leave all other settings at their defaults.

3. On Domains tab, select the Domain Details sub-tab and make the following entries:

• Click on the ground grid (5M_DTM.asc) in the Layers panel of the main interface (so it is

highlighted) and then drag it across into the Topography box

• Click on the active area shape file in the Layers panel of the main interface (so it is highlighted)

and then drag it across into the Active Area box

• Click on the grid size box and type in 5 (metres) - this should be the default setting for the

example grid.

• Click on the time step box and type in 2 (seconds). With regards to the choice of time step, it is

recommended for the ADI 2D solver (the default solver and the one used for this example) that the

time step lies in the range of ½ to 1/40 of the model grid size. So in this case a time step of 2

(seconds) is 2/5 of the entered grid size of 5 (metres).


4 © 2015 CH2M HILL

4. On the Boundary Conditions sub-tab make the following entries:

• Click on the boundary line shape file (Defence_BC.shp) in the Layers panel of the main interface

(so it is highlighted) and then drag it across into the Domains Boundaries box.

• In the Domains Boundaries box, click on the Boundary Condition cell for your boundary

condition. A drop down list will be displayed. Select the vertical flow option. This type of

boundary represents a one-way inflow onto the floodplain from the adjacent river. This boundary

type can be used as a simplified representation of an overtopping river flood event. However, it is

recommended that for more accurate results a two-way boundary is defined for this type of flood

modelling, e.g. by using a 1D-2D linked model (the 1D model represents flows within the adjacent

river).

• In the Domains Boundaries box, click on the Time Series Option cell for your boundary

condition. A drop down list will be displayed. Select the user entered time series option. This

then requires you to enter data into the time vs flow table (set the ‘units of time’ to hours). Enter

the following sequence:

Time (hours) Flow (m3/s)

0 0

5 10

10 0

To add new rows, right-click on the table and select Add Row from the displayed options.

Drag grid into

here

Drag active area

into here

Enter grid

size 5m

here

Enter time

step 2s


5 © 2015 CH2M HILL

The time series data entered will also be plotted automatically in the chart adjacent to the table.

5. All 2D model settings are now defined. Click the Run button in the 2D interface to start your simulation

(click ‘yes’ to save changes if asked).

A new window is displayed showing the progress of your simulation and summarising the calculations

performed.

The example simulation should take approximately 2 minutes to complete (times will vary due to different

computer specifications). At the end of the simulation close the run progress window (press the Enter key)

and also close the 2D simulation window to return to the main Flood Modeller interface.

6. Load and view 2D model results. Your 2D simulation file will be referenced in the Simulations section of

the Project panel. It should have a solid blue triangle next to the filename to signify associated model

results are now available.

Right-click on your 2D model file and select View Result from the displayed options. This will

automatically locate the master file for your 2D results (sup file). You will be prompted (in a new window)

to select which output parameters to load – just click OK to proceed.

Drag

boundary

line shape

file into table Set time

units to

Hours

Select vertical

flow from

dropdown list

Select user

entered time

series from

dropdown list

Enter flow /

time data

into table

Symbol signifies

results are

available


6 © 2015 CH2M HILL

The time series data associated with your simulation will be loaded to your map view and will appear as a

new group in the Layers panel. The maximum flood extent time step (signified as 9999) will be selected and

displayed automatically. You can select any other time step from the simulation by clicking the Timestep

tab below the right-hand panel and selecting from the displayed list (note that time steps are only

displayed here when an appropriate 2D results file is highlighted in the Layers panel).

The 2D results data consists of a combination of scalar and vector datasets. Flood Modeller can only

display one scalar dataset (i.e. depth or water level) and/or one vector dataset (i.e. velocity or flow) at any

one time. If you switch on a different scalar/vector dataset within the same results file then the current one

will be automatically turned off first.

7. Animate 2D results. Highlight the depth parameter layer in the Layers panel. Select the Results tab in the

main toolbar and click the Single Result button (in the Animations section). The animation toolbar will be

displayed at the top of the map view, as shown below:

Timestep

tab

Maximum

flood extent

time step

2D results

added to

map as new

group


7 © 2015 CH2M HILL

Click the play button, , and the active 2D results data (i.e. those ticked in the Layers panel to make

them visible on the map) will be animated. The animation will start at time step 0 and continue until the

last real time step is reached (the maximum extent time steps are ignored). A progress bar on the map

shows the currently displayed time.

To exit the animation mode click the “X” button on the right of the animation toolbar.