ISIS 2D - Flood Modeller · ISIS 2D v3.7 Quick Start Guide Cost Effective, Integrated Software Solutions For further information, email [email protected] or visit ch2mhill.com/isis

Quick Start Guide

0845 094 7990ch2mhill.com/isis [email protected].

ISIS 2D

Cost effective, integrated software solutions

ISIS 2D v3.7 Quick Start Guide Cost Effective, Integrated Software Solutions

For further information, email [email protected] or visit ch2mhill.com/isis

Table of Contents

1. Starting ISIS 2D and basic concepts ..................................................................................... 1

2. How to run an ISIS 2D model ................................................................................................ 5

3. How to run an ISIS 2D 1D-2D linked model ........................................................................ 16

4. How to build a new ISIS 2D model ...................................................................................... 20

5. How to view the ISIS 2D results files ................................................................................... 32



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1. Starting ISIS 2D and basic concepts

Starting ISIS 2D

Once you have installed ISIS, you are ready to use ISIS 2D. To open the ISIS 2D interface, please go to the

‘Start’ menu, select ‘Programs’, then select the ‘ISIS’ group and click on ‘ISIS 2D’. Alternatively you can click

on the ISIS icon on your desktop and then open the ISIS 2D interface from the ‘Run’ menu. Please note

that you can also open the ISIS 2D interface by clicking on the ISIS 2D button on the toolbar of the

Network Properties window within ISIS 1D.

Principles of working with ISIS 2D

There are several phases when working with ISIS 2D models and various parts of the software.

The main phases of working with the 2D models are:

1. Pre-processing of the input files for running an ISIS 2D simulation;

2. Preparation of the ISIS 2D control XML file;

3. Running the ISIS 2D simulation;

4. Viewing ISIS 2D results files;

ISIS MAPPER can be used for pre-processing the input files required for running an ISIS 2D simulation and

for viewing ISIS 2D results files. ISIS MAPPER can be accessed by clicking the ISIS MAPPER icon or by

selecting ‘Tools’ and ‘ISIS MAPPER’ in the Network Properties window of ISIS 1D.

ISIS MAPPER is a GIS tool specially designed for carrying out the pre and post processing of ISIS 1D, ISIS

2D and TUFLOW (2D) models. Other GIS software can also be used to generate input files for ISIS 2D.

There are two ways of running the calculations using ISIS 2D models: using the command prompt or the ISIS

2D interface.

The ISIS 2D interface can be accessed by selecting ‘Run’ and ‘ISIS 2D’ in the ISIS 1D Network Properties

window. This option is described in more detail in ISIS 2D manual. The ISIS 2D interface is designed to

make the creation of ISIS 2D XML control files easier for users.

Preparation of the ISIS 2D control XML file is carried out by using both ISIS MAPPER and the ISIS 2D

interface. Additional information on this can be found within the ISIS 2D manual.

Basic Concepts

ISIS 2D is a shallow water flow model which predicts depths and velocities on a regular square grid, and can

link to an ISIS 1D model representing flows in a channel. It has been designed to model flows in coastal,

estuary and floodplain environments. At the core of ISIS 2D, there are three numerical schemes that are

specifically developed to tackle different types of hydraulic conditions: ADI (Alternating Direction Implicit),

TVD (Total Variation Diminishing) and FAST.

The ADI solver has been developed for fluvial, overland, estuarine and coastal modelling problems where the flow is not rapidly changing. It is quick, accurate and robust and is based on the long-established depth



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integrated velocities and solute transport (DIVAST) numerical engine and over two decades of academic research.

The TVD solver is a unique feature and has been developed to specifically provide accurate representation

of two-dimensional ‘shocks’ (rapid changes in water surface profile). This solver allows complex hydraulics to

be calculated more accurately; especially useful when considering dam breaks, breaches in defences or

rapid flow around buildings. It provides increased stability as TVD solutions are less prone to numerical

oscillations than other solvers.

The FAST solver allows quick assessment of flooding using simplified hydraulics. It provides results up to 1,000 times quicker when compared to traditional two-dimensional solvers, providing results in seconds or minutes as opposed to hours or days. It enables the rapid screening for many different types of flooding considerably reducing the cost of modelling. It is ideally suited to undertaking surface water flood mapping and risk assessments at local, regional, and national scales.

The main differences between the ADI and TVD solvers are listed in Table 1 below:

ADI TVD

Rapidly varying flows May not represent higher Froude number

flows correctly

Accurate representation of high Froude

number flows, shocks and jumps

Computation Times Short run times Longer run times

Time steps Long time steps possible Shorter time steps needed for model to

run

Stability Some instabilities/oscillations in the

solution may become apparent for

simulations with Froude numbers

approaching or exceeding one, or too

large a time step

Generates more stable and smoother

solutions

Mass Conservation Generates acceptable mass balance

errors for well set up 2D and linked 1D-2D

models

Can lead to larger (but still acceptable)

mass balance errors for linked 1D-2D

models

Table 1. Differences between the ADI and the TVD schemes used in ISIS 2D.



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In order to run an ISIS 2D model, the following information is required:

A geographic model domain extent: to represent an extent of the possible flooding;

Topography (ground level data and information of the locations of defences) of the area under

consideration;

Hydrological data in the form of the boundary and initial conditions: to represent the flows entering

and leaving the model extent and the water levels passed to the model as well as the initial state of

the system;

Roughness coefficients: to describe variation of roughness coefficients in different parts of the model

(can be represented by one value for all the domain extent);

Such data as duration of a simulation period, time step, grid cell size etc: to represent various run

parameters of the model;

ISIS 2D uses an XML (Extensible Mark-up Language) control file to describe the model composition. The

locations of the model input and output files and various parameters are described by an XML control file.

This control file provides all of the necessary information for running the ISIS 2D numerical engine.

The ISIS 2D interface helps the user build 2D models and carry out the pre and post processing work. ISIS

MAPPER, a GIS tool specially designed for carrying out the pre and post processing of ISIS 1D, ISIS 2D and

TUFLOW (2D) models, is supplied as part of the ISIS 2D interface at no additional cost.

Setting up an ISIS 2D model effectively means completing a valid ISIS 2D XML control file (validate against

the predefined XML schema) and preparing the associated data files.

Files

ISIS uses a range of different files to manage model data and results, including:

XML file (.xml file): this is the format in which ISIS 2D control file is written;

Comma Separated Values format (.csv file): The mass balance ISIS 2D output file, and depth, elevation, flow

or velocity at user specified points in the domain are saved in this format;

ESRI ASCII raster grid file (.asc file): model domain extents, topography, boundary & initial conditions,

roughness coefficients can be represented by an ASCII grid.

ESRI shapefile (point, polyline, and polygon) (.shp file): active computation area, boundary & initial

conditions and topography, link lines are represented by shapefiles.

2D Model Results Data file (.dat file, .2dm and .sup files): ISIS 2D model results are written in such a format

that enables them to be viewed, visualised and analysed by ISIS MAPPER. The files with the extension .dat

contain all the results of ISIS 2D simulation, the files with the extension .2dm contain the geographic

information about the 2D mesh. The .sup file, which contains a list of the .2dm and .dat files associated with

the model results, is provided for compatibility with other software which is reading this file format.



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Standard text file: the boundary condition file for ISIS 1D simulation (.ied file), ISIS 2D log file are saved in

this format (normally .log or as specified by the user in the ISIS 2D Control XML file) and ISIS 1D event file

(.ief file). The last file contains the information regarding the parameters and input and results file for ISIS 1D

simulation.

Example file

The "isis" folder on your machine already contains some example files. Some of these will be used

throughout this guide. The default location for your ISIS data is C:\isis\data (if ISIS is installed at a location

other than the default folder, it will be xxx\xxx\isis\data where xxx stands for where ISIS is installed). The ISIS

2D related examples are placed into ISIS 2D subfolder (e.g. C:\isis\data\examples\ISIS 2D). Some of these

files are used when describing various operations throughout this guide.



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2. How to run an ISIS 2D model

Introduction

This chapter illustrates the process of setting up a single domain ISIS 2D model.

Building an ISIS 2D model can be divided into two actions:

Preparation of the model data;

Creation of the ISIS 2D control XML file.

An ISIS 2D control XML file is a project file that tells ISIS 2D where all of the input files are, what the run

parameters are and where the output files should be placed. There are certain tags allocated for each piece

of information the file contains.

ISIS 2D control XML files can be created using ISIS MAPPER and the ISIS 2D user interface.

This chapter also explains which input files are required for the ISIS 2D simulation and the steps needed to

run the prepared file. The example files are located in ISIS 2D\Site 1 folder (XXXXX\data\examples\ISIS2D\

where XXXXX stands for the folder where ISIS has been installed i.e. c:\isis). Please note the ISIS 2D control

XML file is already prepared for the model as well as the other input files, so there is no need for users to

draw the files themselves, however they are welcome to open the files in ISIS MAPPER as described in the

section below.

Description of the steps for setting up a single domain ISIS 2D model

An ISIS 2D simulation needs geographical information (such as domain model extent, topographical data,

etc), hydrological data (boundary and initial conditions and roughness) and run parameters for a particular

model. Preparation of the model data comprises of 9 steps (described below). Steps 1-5 are related to the

preparation of the GIS files needed for the model and steps 6-9 describe the way the hydrological input data

and the parameters of the simulation and the results output are set up.

1. Setting up a ground level data. This data is in a form of an ASCII grid.

2. Setting up a shapefile that represents a computational area. This file should be an ESRI polygon

shape file. This is known as a computational area shapefile. This file can be created in ISIS

MAPPER. Alternatively, the user can supply geographic coordinates for the computational area, or

they are derived from the topography data (see below).

3. Setting up a shapefile that represents an active area (if necessary). This file should be an ESRI

polygon shape file. This is known as an active area shapefile. This file can be created in ISIS

MAPPER. This shapefile defines an area within a computational area which will be used for

calculating ISIS 2D model results. If the file is not setup and not specified in the ISIS 2D control XML

file, than the ISIS 2D model results calculations will be carried out on the computational area.

4. Setting up a shapefile that represents a line with locations for introducing flows into the 2D system

(i.e. boundary conditions). This file should be an ESRI polyline shapefile. This file is also known as

an ISIS 2D model boundary line file. This line can be created in ISIS MAPPER.



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5. Setting up a shape file that represents topographic features (defence systems). This file can be a

point, a polyline or a polygon shapefile depending on a shape of the defence system. This file is also

called a topographic feature file. This file can be created in ISIS MAPPER.

6. Setting up the boundary conditions data for the model. The boundary conditions can be represented

by a time series or a fixed value. This information can be either mentioned in the ISIS 2D XML file or

provided in an ISIS boundary conditions .ied file, which is referenced in the ISIS 2D XML file.

7. Setting up the data for roughness and for initial conditions for your model. This information can be

either mentioned in the ISIS 2D XML file or provided in an ISIS boundary conditions .ied file, which is

referenced in the ISIS 2D control XML file.

8. Setting up the run parameters for your simulation (e.g. start time and date, run time etc). This

information should be mentioned in the ISIS 2D control XML file.

9. Setting up the parameters of the results output (e.g. locations and the format of the result files).

Example data

For the purposes of illustration some of these files have already been created and have been placed to the

examples folder: C:\ isis\data\examples\ISIS2D\Site 1\GIS

The ISIS 2D control XML file (DefenceBreach.xml) has also been created and is located in the folder: C:\

isis\data\examples\ISIS2D\Site 1

If you open the example XML file in the ISIS 2D interface, you will be able to see most of the data explained

below within the different tabs. The paragraphs below will explain which tab to look at in the ISIS 2D interface

(all of the tabs mentioned are located on the ‘Domains’ tab). The interface can be opened by going to the

‘Start’ menu, selecting ‘Programs’, then selecting the ISIS group and clicking on ISIS 2D. In order to open the

file you need to go to ‘File’ and then ‘Open’ in the ISIS 2D interface. You can then select the file

DefenceBreach.xml.

Additional information can be found in ISIS 2D Manual.

Preparation of the GIS data (steps 1-5)

The chapter "Preparing Spatial Data" of the ISIS 2D Manual and chapter 4 “How to Build a New ISIS 2D

Model” of this guide provide guidelines on how to use ISIS MAPPER to create the shapefiles mentioned

above (Steps 1-5).

The data that you need now comprises of the following files:

1. An ASCII raster grid: 5M_DTM.asc (with the ground elevation data for the whole domain);

2. An ESRI polygon shapefile: River_Active_Area.shp (with the information about the active area)

3. An ESRI polyline shapefile: Defence_BC.shp (representing an ISIS 2D model boundary line)

If you load these three files (into the ISIS MAPPER interface, in the tab ‘Layer’ select ‘Add Layer’ and then

browse to the file you would like to add, select the file and click Open. Figure 1 below represents the files

mentioned above loaded into ISIS MAPPER:



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Figure 1. ISIS 2D model domain extents and the corresponding ISIS 2D model input files for the example described in Chapter 2 “How to Run an ISIS 2D Model” of this Quick Start Guide.

Please note that on the tabs "Grid Data" and "Boundary Conditions" within the ISIS 2D interface you can see

the names of some of the files mentioned at this section of the chapter. Figure 2 represents the Boundary

Conditions tab within the ISIS 2D interface (Domains tab) where the user can see the Defence_BC.shp file

mentioned in the field Boundary Filename.

Preparation of data for boundary and initial conditions and roughness (steps 6 - 7)

This section of the chapter continues to describe the ways of preparing the input data for the ISIS 2D

simulation. You need to make sure that you have the boundary conditions for your model as the boundary

condition (BC) shows how much water is entering the domain at a certain time.

River

Ground aerial photo

Active area Boundary line

Boundary line



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There are 5 types of boundary conditions that users can choose from:

1. Total Flow BC (totalflow);

2. Flow per Unit Width BC (flowperunitwidth);

3. Vertical Flow BC (verticalflow)

4. Vertical Flow per Unit Width BC (verticalflowperunitwidth)

5. Elevation BC (elevation).

The BC can be represented by a time series or by a fixed value. The values can be "hard-coded" within the

ISIS 2D control XML file or could be taken from an ISIS boundary conditions .ied file. For this example, we

use the Vertical Flow BC and the values for this BC are shown in a flow hydrograph in the Table 2 below:

Time (second) 0 900 3600

Flow (m^3/s) 0 100 0

Table 2. Hydrograph used as a boundary condition for the Site 1\DefenceBreach model example.



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Figure 2. The Boundary Conditions Tab of the ISIS 2D user interface (Domains Tab) showing the boundary

conditions for the sample simulation

On Figure 2, the user can see the hydrograph used as a boundary condition for this model. If creating a new

model, the user can enter the BC values on the tab shown on Figure 2 of the ISIS 2D interface.

The roughness, boundary and initial conditions values for an ISIS 2D simulation can be set up in the ISIS 2D

interface, however for the purposes of this guide these values have already been set up in the ISIS 2D

control XML file (DefenceBreach.xml). Further information about using the ISIS 2D interface for setting up

these values can be found in chapter “Preparation of an ISIS 2D control XML file using the ISIS 2D

interface”.

Setting up the run parameters for your simulation (step 8)

In this example we use the ADI scheme as the numerical scheme for calculations. With regards to the choice

of time step there are some guidelines that take into account the relationship between the space step

(dimension of the grid with ground elevation data) and the time step (dt/dx): these schemes work best if dt/dx

is in the range 1/2 to 1/40 for ADI scheme and 1/10 to 1/100 for the TVD scheme.

Based on these recommendations, the time step will be set to be equal to 2 s. Please note the value for the

space step (dx) used in this example is 10 m which is shown in the Grid Size field of the Grid Data tab within

the ISIS 2D interface. The value of 10 m is one of the extent parameters for the computational area specified

when the rectangular extent computational area is drawn.



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We will set the total run time (simulation period) for this model to be 1 hour; the initial conditions for this

model are set as water level of 0 m all over the computational area ("globally" if using the terminology of the

XML file). Please note that for cells where the ground is above this water level, zero depth is used. The

roughness will be set as Manning's coefficient n=0.05 in all cells of the computational area ("globally").

Figure 3. The Run Details tab of the ISIS 2D interface showing the run parameters for the sample simulation

All of these parameters except the Manning's coefficient (roughness) can be seen on the Run Details tab of

the ISIS 2D user interface (Domains tab) as shown on Figure 3. The roughness values are set up on the Grid

Data tab of the Domains tab.

Setting up the parameters for the results output (step 9)

The user has the ability to specify such output parameters as locations and names of the result files, the

variables within the data to be contained in the result files (waterlevel, velocity, etc). Additionally, the user

can choose the period between model outputs being saved to disk. A longer period will result in smaller

output files and save disk space. These parameters can be seen on the tab "Model Outputs" of the ISIS 2D

user interface (Domain tab).



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Running the ISIS 2D simulation

Usually, after you have set up the data or made sure that it is all in place, you can start the ISIS 2D

simulation. The ISIS 2D control XML file DefenceBreach.xml has already been prepared and supplied with

the ISIS installation. See the Example Files section of the chapter “Starting ISIS 2D and basic concepts” for

more information. In order to start the ISIS 2D simulation in the ISIS 2D interface, go to the ‘Run’ menu and

select the ‘ISIS 2D Simulation’.

After the simulation has been run you will receive a command prompt message saying "Run successful -

stopping. Press return to close".

Now you should be able to see the result files in C:\isis\data\examples\ISIS 2D\Site 1 folder (the location will

vary if ISIS is installed somewhere else). The ISIS 2D model results will be stored in a new folder in

“C:\isis\data\examples\ISIS 2D\Site 1”.

The next section explains how the user can view the results of the ISIS 2D simulation.

Viewing the results files of the ISIS 2D simulation

1) Launch ISIS MAPPER and load the ground grid.

In order to view the 2D model results, launch ISIS MAPPER and load the ground grid.

ISIS MAPPER can be launched from:

within the main ISIS interface (Network Properties window) by clicking on the MAP icon located in

the upper right of the main toolbar

within the ISIS 2D interface by selecting ‘ISIS MAPPER’ from the ‘Run’ menu

The ground grid for this example is 5M_DTM.asc stored in the Site 1\GIS folder. In the main toolbar of the

ISIS MAPPER interface, select ‘Add Layer’ from the Layer tab to add a new GIS file to the map view. When

prompted, navigate to the Site 1/GIS folder and select the 5M_DTM.asc grid (see Figure 4).

Figure 4. Loading a ground grid into ISIS MAPPER.

The image (aerial photo) on Figure 1 is a file named Airphoto.jpg, which you can find in the Site 1\GIS folder.

This image file can also be loaded into your map view using the above method.

For more informaiton on how to load GIS datasets into ISIS MAPPER, please review the section "How do

Ioad a new layer" in the ISIS MAPPER manual.

2) Load the 2D model results data into ISIS MAPPER.

Loading 2D model results is initiated using the same method as loading any other layer, i.e. select Layer /

Add Layer from the main toolbar (see Figure 4 above). When prompted, browse to the 2D results folder (in



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this example this is folder: Site 1\DefenceBreach_01) and select either the 2dm or sup file that relates to the

results. The method for loading 2D results varies slightly depending on which file type is selected. These

methods are described as follows:

o sup file selected – the associated data files for the available output parameters (e.g. flow, depth, etc)

are automatically loaded into a new window, as shown in Figure 5 (a) below. The window displays

the available timesteps in the selected results (for information only). It enables the user to select the

parameters they require and then click OK to load them into the viewport.

o 2dm file selected – the user is then prompted to browse to and select which associated .dat files to

load (one for each output parameter, i.e. flow, velocity, depth and water level). The selected files are

then displayed in the 2D data selection window, as shown in Figure 5 (b) below. This is similar to

that displayed for sup files except that the user has the additional option to add or remove dat files

from the displayed list.

(a)

(b)

Figure 5 (a) and (b) Parameter selection when loading (a) sup file or (b) 2dm file for 2D model results in ISIS MAPPER

In the list entitled ‘Available Layers’ ensure all parameters have a tick alongside them (to signify they will be

loaded into the ISIS MAPPER viewport). Click OK to proceed to load this data into ISIS MAPPER (this may

take several seconds to complete).



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3) Animate the 2D results

To animate the 2D dataset select the animate option from the menu displayed when right-clicking on any of

the parameter layers of the 2D data file that are displayed in the ISIS MAPPER table of contents (TOC,

located to the left of the map view). The animation toolbar is then displayed below the map view. This offers

the controls shown in Figure 6 below:

Play

Stop

Loop

Step

back

Sliding

timescale

On map

progress bar Start

recording

Stop

recording

Switch to full

controller

Close

toolbar

Step

forward

Displayed

time format

Figure 6. Animation toolbar functionality in ISIS MAPPER

When the play button is depressed in the animation toolbar the selected 2D results will cycle through all

loaded timesteps. The scalar data, i.e. depth or water level, will be represented by solid colours. The vector

data, i.e. flow or velocity, will be represented by arrows. The appearance of these can be adjusted and you

should refer to the ISIS MAPPER user guide for details on how to do this.

By default, the animation will cycle through all timesteps in order. However, if the toolbar is expanded to

show the full animation controller then there is an additional option to move straight to a specific timestep.

The displayed timestep is shown in the time bar displayed in the lower right corner of the map, as shown in

Figure 7 below.



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Figure 7. Animation of 2D results (depth and flow) at different time steps using ISIS MAPPER

For more information regarding animating 2D results and also loading 2D data please refer to the section

‘How do I load and animate 2D model results data’ in the ISIS MAPPER manual.

In addition to viewing your results data animated, ISIS MAPPER offers a number of other options for

customising your map view. Figure 7 above highlights some of these, which are:

Only showing a subset of vector data – showing vector arrows from all cells can clutter your view. In

the above example only every other arrow is visible.

Applying a size factor to vector data – the vector arrows in Figure 7 have been enlarged by a factor 2

to make them appear more clearly on the map.

Apply a colour ramp to vector data to highlight areas of faster moving flows (in red in Figure 7)

Display a selected colour ramp overlaid on your map – in the control tab of the table of contents tick

the display colour ramp box next to the selected layer (2D modelled depths in Figure 7)

Further information on the available custom settings, which are mainly accessed via each layer’s ‘Properties’

window, can be found in the ISIS MAPPER manual.



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In addition to the map view of your results data, other analysis options, including creation of a point time

series plot, creation of a cross section plot, generation of a flood map outline, etc are described in chapter 5

“How to view the ISIS 2D results files”.



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3. How to run an ISIS 2D 1D-2D linked model

This chapter illustrates an example of running an existing linked ISIS 1D and ISIS 2D model using the ISIS

2D interface. ISIS 1D-2D linked models combine the advantages of 1D modelling in the channel and 2D

floodplain modelling. In a linked model, the 2D model will represent complex flow paths and the 1D river

model will represent channel conveyance and the hydraulic structures in a river. Having the ability to link

models, you can now reuse your 1D channel models and let ISIS 1D do what it is best at (modelling of

channel flow and flow through various structures) and let ISIS 2D show its strength at representing out of

bank flows on the floodplain.

Running an existing ISIS 1D-2D model using the ISIS 2D interface

Basic information about the files needed for the ISIS 2D simulation

As discussed in chapter 1 "Starting ISIS 2D and basic concepts" of this guide, ISIS 2D simulations require

several files. The figure below shows the domain extents (computational area) of this model as well as some

other input files which are required for starting an ISIS 2D simulation. The example files used for this chapter

are the Site 1 model files located in the folder C:\isis\data\examples\ISIS 2D\Site 1 (the location will vary if

ISIS is installed somewhere else). The files shown in the figure below are located in this folder as well.

On the figure above the polygon marked by points (active area) is the ISIS 2D active area; alongside the 2D

active area there is a polyline (link line) showing the locations where the 1D and 2D models are linked.



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The active area shapefile and the link line shapefile have already been prepared. These files are

River_Active_Area.[.shp,.dbf and shx] and Link [.shp,.dbf and .shx] respectively. The above figure also

shows the river sections and the river centre line, which are not currently in any of the shapefiles provided,

however they represent the cross sections from Linked1D2D.ief file located in C:\isis\data\examples\ISIS

2D\Site 1\ISIS (the location will vary if ISIS is installed somewhere else). Please note that the Linked1D2D.ief

file is not a georeferenced model and therefore it is not possible to create a shapefile with the river nodes,

but the locations of these river nodes are provided in the shapefile CS_Centres. [.shp, .dbf,.shx]. The files

provided enable the running of an ISIS 2D 1D-2D linked simulation as specified and allow the user to obtain

the results.

There is a ground data file available for this model called 5M_DTM.asc. This file can be loaded into ISIS

MAPPER to view the computational area of the model. In order to load a grid or a shapefile into the ISIS

MAPPER user interface, Select Add ‘Layer’ from the ‘Layer’ tab of the main toolbar and then browse to the

required file.

The link line is a HX line which describes linking between ISIS 1D model and ISIS 2D model. When the

models are linked using an HX line, the 2D model takes the water level information from the 1D model and

returns the information about the flows back to the 1D model.

1. Open the ISIS 2D interface

Open the ISIS 2D interface by going to the ‘Start’ menu, selecting ‘Programs’, then select the ISIS group and

click on ISIS 2D.

2. Load an ISIS 2D control XML file for a sample ISIS 2D 1D-2D linked model

Please load the prepared ISIS control XML file Linked1D2D.xml which is available at

C:\isis\data\examples\ISIS 2D\Site 1 (the location will vary if ISIS is installed somewhere else) into the ISIS

2D interface by going to menu, selecting ‘File’ and then ‘Open’

The sample file which is loaded into the ISIS 2D interface is shown in the figure below:



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3. Start the ISIS 2D simulation

In order to start the ISIS 2D simulation, please go to the ‘Run’ menu and select ‘ISIS 2D Simulation’. After

the simulation has been run, you should receive a window saying "Successfully ran the ISIS model file".

If successful, you should be able to see the results in C:\isis\data\examples\ISIS 2D\Site 1 folder (the

location will vary if ISIS is installed somewhere else).

The ISIS 2D linked model simulation generates the following files:

Two .csv files with mass balance information for the 1D and 2D models. You can view this file either

using a normal text editor or Microsoft Excel. For this example the files generated are:

Linked1D2D_MB1D.csv (for 1D model) and Linked1D2D_MB2D.csv (for 2D model). The file is

saved in the same folder as where the ISIS 2D control XML file is located.

ISIS 2D model results. These can be viewed using ISIS MAPPER. For this example, the files

generated are located in a separate folder called Linked1D2D_01. The files: 01_depth.dat,

01_flow.dat, 01_velocity.dat and 01_waterlevel.dat are stored in this folder.

ISIS 1D model results: ISIS binary format (.zzn files) and can be viewed using ISIS or ISIS MAPPER

(if the cross sections in your .dat file are georeferenced).



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For more information about viewing .zzn files in ISIS, please refer to the ISIS manual. For more information

about viewing georeferenced .zzn files in ISIS MAPPER, please refer to the ISIS MAPPER manual. The ISIS

1D model results will be saved in ISIS sub-folder of the Site 1 folder mentioned above.

Viewing ISIS 2D model results

The ISIS 2D model results of the ISIS 2D linked simulation can be viewed in the same manner as described

in Chapter 2. More details about this can be found in Chapter 5 “How to view the ISIS 2D results files” of this

guide. For details on viewing ISIS 1D model results, please refer to the ISIS Manual.



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4. How to build a new ISIS 2D model

This chapter explains how to build a new ISIS 2D model using the ISIS 2D specific tools provided within ISIS

MAPPER. The chapter is divided into sub-sections, each one covering a different ISIS 2D input file. This

chapter contains general instructions and is not based on a particular example file, however the DEM grid

used is from Site 1 example contained in C:\isis\data\examples\ISIS 2D\Site 1. Most of the files mentioned in

this chapter have to be drawn by the user using the recommendations mentioned in this chapter.

1. Launch ISIS MAPPER

ISIS MAPPER can be launched from:

within the main ISIS 1D interface (Network Properties window) by clicking on the MAP icon

located in the upper right of the main toolbar

within the ISIS 2D interface by selecting ISIS MAPPER from the ‘Run’ menu

The ISIS MAPPER Graphical User Interface (GUI) will then be launched with no data visible in either the

viewport or table of contents, as shown below:

2. Load DEM into viewport

Click on the ‘Add Layer’ button in the ‘Layer’ tab of the main ISIS MAPPER toolbar.

GIS viewport (map view)

Table of contents (TOC)

Modelling Toolbox



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The Load Layer window is then displayed:

Browse to the location of your DEM, highlight the appropriate file and click the Open button to load the data

into the map view. The DEM should appear in the ISIS MAPPER viewport and the DEM filename will be

visible in the TOC.



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The colours used to display the ground data can be changed by editing the colour legend. Right click on the

layer in the TOC and select Properties from the displayed menu (or just double-click on the layer in the

TOC). On the Properties window access the Symbology > Colour Ramp tab to edit the colours used to

display the dataset in the map view.

Furthermore, if a georeferenced image file, e.g. aerial photo, is available it can be draped over the grid to

produce a more real world 3D display. Details of how this is done are provided in the ISIS MAPPER User

Manual.

3. Define ISIS 2D computational area

In ISIS 2D the computational area defines the extent of your model. It is defined by a series of parameters,

i.e. lower left corner coordinates, grid cell size, number of rows and columns and grid orientation angle. In a

GIS environment these parameters define a rectangular grid. The size of the grid needs to encompass the

entire area that is expected to be affected by flooding. The selected grid size will affect the resolution of the

model and also the runtime. A very small grid size will ensure all flow pathways are included (and not

averaged out by adjacent features, e.g. buildings). However this is offset against the increased runtimes

required for fine resolutions. A grid size smaller than the underlying DEM may be required if the model needs

to represent small scale hydraulic features.

ISIS MAPPER provides a function to draw a rectangular outline to represent the computational area. This is

saved as an ESRI format polygon shapefile. The relevant parameters required by ISIS 2D are calculated by

ISIS MAPPER and saved as attributes of the shapefile.



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First load a DEM, aerial photo or map tile to define a georeferenced location for your computational area.

Then select the Create Computational Area tool from the options displayed in the 2D Model Build section of

the Modelling Toolbox.

ISIS MAPPER will prompt you to specify a filename and location for your new area shapefile and then

activate the shapefile drawing mode. The shapefile editor toolbar will be displayed above your map view, as

shown below, and an empty shapefile attribute table will be displayed over your map (this will become

populated automatically as you add features to your shapefile).

Make sure you can see the area you would like to set as your model extent on the viewport (i.e. use ISIS

MAPPER zoom and pan tools accordingly).

Activate the drawing tool by clicking on the Draw button and then selecting Draw Rectangle from the

displayed menu, as shown below:

As the key point for ISIS 2D is the lower left corner, rectangles are generated by dragging a shape out

from the desired location for this point. Left click on the viewport to locate the lower left corner then,

while holding the left mouse button down, drag the cursor up and across the screen. A rectangular

green polygon will appear on screen, as shown below. Note that for this initial drawing process the

orientation angle is fixed at zero (this can be changed later). To finish drawing the rectangle, double-

click the left mouse button.

The rectangle will remain a green colour after you stop drawing, signifying that it is a selected shapefile

feature. You can unselect the feature by accessing the Select menu in the Editor toolbar (click on the

triangle below the Select icon) and then clicking on the Accept option. Your rectangle will then be

displayed with its set polygon colour (which can be edited in the Properties window) and the attributes

of the rectangle will be added to the associated attributes table, i.e. number of rows and columns,

orientation angle, etc.

Click down arrow and then select Draw Rectangle from displayed menu



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The properties and/or the position of the rectangle can be changed after the initial draw process either by

moving the rectangle to a new location or by selecting Modify Rectangle from the Draw menu. In both cases

your rectangle must first be highlighted on the map by dragging the mouse across an edge of your rectangle

with the left mouse button depressed. If selection is successful the rectangle should then change to the

highlighted colour (i.e. the green colour shown in the image above).

Note that if you click on the rectangle parameters displayed in the attributes table then the rectangle may be

highlighted in a different colour (usually yellow). This does not mean your rectangle is highlighted for use with

the editing tools, it is just highlighting which map entity relates to the selected data in the attribute table.

Draw by dragging cursor from lower left corner

Attributes of rectangle added here automatically once drawn shape is ‘Accepted’



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The editing operations which can be performed on your rectangle are as follows:

Move Extent Polygon - Move rectangle to a new location by highlighting the rectangle, selecting the

move feature tool, , from the Editor toolbar (by clicking on it) and holding down the left mouse

button over any corner of the rectangle (cursor changes when mouse is in right position) and

dragging across the viewport. Both the old and new positions will be shown on your map view, as

shown below. After translation select the Accept option from the Select menu to apply your changes.



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Rotate Extent Polygon - Lower edge of rectangle can be orientated between 0 and 90 degrees from

the horizontal. To rotate first highlight the rectangle and select the Modify Rectangle option from the

Draw menu so that the Rectangle Params window is displayed (as shown above). Apply a rotation

by dragging the orientation angle slider and select the Accept option from the Select menu to apply

your changes (after you close the Rectangle Params window).

Resize Extent Polygon - Size of rectangle can be changed, though lower left corner will remain fixed.

To resize, open the Rectangle Params window, as described above, and un-tick the Fix rectangle

size option. Then either change the cell size or change the number of rows and columns to affect the

size of the rectangle. Click the update button to visualise the changed properties. Close the window

and select the Accept option from the Select menu to apply your changes.

Once the rectangle is completed (or at any time) your new shapefile can be saved by accessing the

Save option in the Editor menu (of the Editor Toolbar). Alternatively if you right click on the file name in

the Table of Contents you can select the Stop Edit option from the displayed menu. This will give you

an option to save your file as you exit the edit mode.

Use Save to save data to

current filename or Save As

to write data to a new file.

A new shapefile will then be generated with the ISIS 2D required parameters saved to the associated

dbf file. Note that unless set using the modify extent parameters window, ISIS MAPPER will save a

default grid cell size of 1m.

A computational area shapefile generated in ISIS MAPPER can be imported directly into the ISIS 2D

user interface. Alternatively a computational area shapefile can be included in the data that can be

exported from ISIS MAPPER to an ISIS 2D xml control file. In this case ISIS MAPPER automatically

extracts the required parameters and writes them to the xml file in the required format.

4. Other ISIS 2D datasets created by ISIS MAPPER

After the computational area has been defined you should proceed to define at least a boundary line.

Boundary lines represent a location where boundary input data, i.e. flows or levels, are applied to the

model. Boundary lines are defined by ESRI polyline shapefiles.

The following procedure enables the creation of a standard boundary polyline:

Select the Create Boundary Line option from the 2D Model Build section of the Modelling

Toolbox

Provide a filename and location for this new shapefile and click the Save button.



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The shapefile editing toolbar is activated. Click on the Draw button, , to start drawing the

new boundary.

To start drawing on the map, click on the viewport at the appropriate start location for the

boundary line. Each left click then adds a new point to the line. Right clicking on the viewport

presents a menu with options to remove the last point added or to finish drawing the line. A

double left click also ends drawing of the line. Note that the attribute fields required by ISIS 2D

will be added to your lines automatically.

A useful feature is that the zoom and pan tools can still be used while a line is actively been

drawn. Zoom is always available by using the mouse central scroll wheel (if available).

Alternative if you click on the View toolbar above the map and then click again on a zoom or

pan tool then the drawing will be paused while you change the map view. Double click on the

default cursor button in the View toolbar to restart the drawing process.

If a boundary is to be applied to just a single cell within model extent then this must still be

defined as a polyline if you use the create boundary line tool. The line must be short enough to

be confined to the relevant cell. Alternatively you can choose to create a standard point

shapefile (using the Create Layer menus) and then manually define any attributes you want

assign to the file. Note that you can assign a single time series input to a shapefile with no ISIS

2D specific attributes. Alternatively you can assign a multiple time series file (csv or ied) to a

boundary shapefile with attribute field ‘node’ used to cross reference between shapefile

features and time series headers.

To exit drawing mode click the Select button, , in the Editor toolbar (the pencil icon of the

mouse pointer will change back to a standard pointer).

When all required boundary lines are defined then save the shapefile and exit from the

shapefile editor (using the same save process as for your computational area rectangle).

ISIS MAPPER also provides functionality to define other ISIS 2D model files, which aren't covered in

this basic example. These are as follows:

Active areas - ISIS 2D allows an active area to be specified within the computational area.

During a simulation ISIS 2D will only consider cells that lie within the active area. Those outside

the area are ignored thus streamlining the model and reducing simulation run times. Active

areas are defined by an ESRI polygons shapefile.

1D / 2D Link Lines - specifies linkages between ISIS 2D model and nodes within an ISIS 1D

model, thus enabling the 1D model to provide a boundary input for the 2D model. Link lines are

defined by an ESRI polyline shapefile.

Additional topographical features - provides ISIS 2D with ground level information additional to

the DEM, e.g. could represent the addition of a flood defence wall to a model. Topographical

features are defined by ESRI shapefiles containing points, polylines or polygons.

The methods for defining these ISIS 2D model files are explained in detail in the other sections of both

the ISIS 2D and ISIS MAPPER user guides.

5. Uploading ISIS 2D datasets to ISIS 2D Interface

A number of methods are available for incorporating the ISIS 2D input files created using ISIS

MAPPER into your ISIS 2D model:



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An ISIS 2D model is defined by the ISIS 2D control XML file. This is an XML format file. The

ISIS 2D user guide describes the format of the XML schema for the ISIS 2D control XML file.

This can be utilised to generate a new control file manually using a text editor.

The ISIS 2D user interface can be used to define a new control XML file. The files generated in

ISIS MAPPER can be loaded individually into the appropriate locations in the user interface

using the user interface functionality, i.e. either by browsing to files or by dragging files into the

user interface.

The GIS components of an ISIS 2D model can be created in ISIS MAPPER and then exported

from ISIS MAPPER as references in a new ISIS 2D control XML file. Furthermore you can link

directly to the ISIS 2D Interface from ISIS MAPPER so that your new XML file opens in the

interface.

This guide considers the latter of these options. The tool used for the creation of the ISIS 2D control

XML file is accessed from Modelling Toolbox > 2D Model Build > ISIS 2D > Create ISIS 2D Project File.

A new window is then activated which displays a table listing the files currently loaded into the ISIS

MAPPER TOC that are potentially compatible with ISIS 2D (i.e. grids and shapefiles).

The table headings are:

Layer name - as it appears in the ISIS MAPPER TOC

Include tick box – a tick in a box here signifies which files to include in your ISIS 2D model. By

default all files are initially included (i.e. all files are ticked).

ISIS 2D data type - signifies how the data will be used in the ISIS 2D model. This information

defines how each dataset will be defined in your new ISIS 2D control XML file.

ISIS MAPPER automatically selects the type for the Topography (DEM), computational area and 1D/2D

link line files in your model. The remaining shapefiles are all given the type Topography (Feature) by

default. This type is correct for additional ground level data, e.g. defence lines. However, the Active

Areas and Boundary Lines in your model must be assigned the appropriate type by selecting from the

dropdown list provided for each entry in the table (in the ISIS 2D data type column). Also if you have

data loaded into the ISIS MAPPER viewport that is not required as part of your ISIS 2D model it can be

excluded from the export to ISIS 2D by un-ticking the adjacent box in the Include column.



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When the data that will define your ISIS 2D model are specified correctly in the window it is uploaded

into the ISIS 2D user interface by clicking the Launch button. You will be prompted to provide an XML

filename for ISIS MAPPER to save your data to. If the selected filename already exists then you will

have the choice to either append your new data to this file or to overwrite the existing file.

The ISIS 2D user interface will then open with your new data added to the appropriate locations within

the interface.

Note if the ISIS 2D interface is already open then the current data present within it will not be

overwritten by these new data. Instead the new data will have to be added manually from within the

ISIS 2D Interface, i.e. either by uploading individual datasets by browsing or by closing your current

ISIS 2D project and uploading your new control XML file. The latter is also the case if you choose to

save your ISIS MAPPER data to an ISIS 2D control XML file without launching ISIS 2D interface, i.e.

you select the Save XML button instead of the Launch button in ISIS MAPPER.

6. Running ISIS 2D Model

ISIS MAPPER is used to generate the GIS components of an ISIS 2D model. These in combination

with the default settings built into the ISIS 2D interface are sufficient to run a model. However, the initial

settings do not instruct ISIS 2D to produce any output data. Therefore, after uploading your data from

ISIS MAPPER, select the Domains tab at the top of the screen and then the Model Outputs tab located

within this.



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Click on the Add button to define a new results file. A new window will appear to define the name, data

frequency and data format of your model output. Type in a suitable name and click the OK button (the default

frequency and format are okay for this example).

A new row is automatically entered in the specified outputs table. Initially no parameter will be specified for

this new output. Available output parameters are: depth, elevation, flow and velocity and multiple parameters

can be selected for a single output file. For this example we will just specify elevation as an output

Click to add new model output data request



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parameter. Highlight the new row in the output table and ensure the elevation checkbox in the lower left

corner of the window is checked.

The ISIS 2D model results will be placed in the folder XXXX_NN, where XXXX is the name of the ISIS 2D

Control XML file. NN represents the output name specified in the Domains Output table (as shown above). If

no output name is defined then the corresponding row number in the Domain Output table will be used

instead for NN.

The model is now ready to run. Click on the Run button to start the simulation.

For reviewing the results generated refer to Chapter 5 “How to view the ISIS 2D results files”.

New output entry added to table

CSV format requires coordinate location(s) GRID format covers entire model active area

Set parameter(s) to output



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5. How to view the ISIS 2D results files

This chapter explains the methods available for viewing and analysing the ISIS 2D model results obtained

after running the Site 1 example described in chapter 2 of this guide.

5.1 Viewing the mass balance file

It is highly recommended that after a 2D simulation has completed, you look at the mass balance files.

Problems with the model set up will often be highlighted by a mass balance error; where water is lost or

created by the model. During an ISIS 2D linked model simulation two mass balance files can be created (a

1D data file and a 2D data file). Note that the relevant options should be ticked in the ISIS 2D user interface

to request these files be generated.

The mass balance files are CSV format files with names specified within the ISIS 2D control XML file (i.e. as

defined in the ISIS 2D user interface). They can be opened in a normal text editor, Excel or other

spreadsheet software. The files are placed into the folder where the ISIS 2D control XML file is located

(unless you specify a different path in the Output Mass File field located on the Model Outputs Tab of the

ISIS 2D Interface Domains Tab). The table below shows an example mass balance data file:

The columns of the mass balance file are defined as follows:

"T" means time in seconds. The frequency for output for this column and the simulation is defined by

the user in the ISIS 2D control XML file (See the Description of the Format of the ISIS 2D Control

XML file Section of the ISIS 2D manual).



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"Q->1D" indicates the inflow into the linked 1D model (e.g. water spills from the floodplain into the

river). In the above example, the model is a pure 2D model, so "Q->1D" is zero value throughout the

model run.

"Q BC->2D" shows the 2D model boundary inflows onto the 2D domain (the values normally are the

linear interpolation of the inflow Hydrographs).

"Q BC<-2D" indicates the boundary outflows (e.g. downstream boundaries, flow out of the 2D

domains).

"2D DV/Dt" shows the rate of change of volume in the model over each time step.

"2D V" records the total water volume accumulated in the 2D domain.

"Q e" is the mass balance error, defined as:

The mass balance error indicates the amount of water created (positive value) or lost (negative value) by the

model per second.

It is important that you check the mass balance file carefully to ensure the model is producing sensible data.

The total water volume, boundary inflow, and mass balance error are a good indication of whether the model

is "healthy" or not.

After checking the mass balance file, you will likely want to view the 2D model results and perform post-

processing of the data. The following are items which modellers normally are interested in when post-

processing their ISIS 2D results data:

1. Time series plots for water level and velocity for any active cell in the domain;

2. Cross-section plots for water level and velocity, and total water volume pass the define cross-

section;

3. Animation of water levels and velocities for the entire 2D results;

4. Maximum flood extent map;

5. Event duration grids

6. Flood hazard grids

7. Maximum flows crossing a user specified line

The methods for producing some of these outputs are described in the following sections below:

5.2 Viewing a time series plot at a particular point

The output formats available from an ISIS 2D model are either grids or comma separated text files.



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The standard output is a series of grids representing different calculated parameters (e.g. depths, velocities,

etc.). However, embedded within each output grid cell is a time series of values calculated for the duration of

your simulation. These data can be extracted by post-processing in ISIS MAPPER. This is a useful function

for performing a general inspection of your model results.

Alternatively a model simulation can be configured in advance to output time series data at user defined

locations for selected parameters.

The following provides guidance on both of these methods for extracting point outputs from an ISIS 2D

model.

Extracting time series from grids

ISIS MAPPER provides a tool for extracting time series data at user specified points on a map. After

specifying a point location the tool reads time series data from all compatible datasets loaded in your map

view. This tool is compatible with ISIS 2D grid output datasets (also TUFLOW grid results and ISIS 1D

results post-processed to a water surface, i.e. a TIN file).

The following text provides a step by step guide for utilising the time series plotting tool to extract ISIS 2D

outputs from key point locations:

1. Launch ISIS MAPPER and use the ‘Add Layer’ function to load your ISIS 2D results data to your

map view (and to load any additional background layers if required).

2. Access the time series plotting tool. The tool is located in the Tools tab of the main toolbar and is

called P-Plot (point plot), as shown below:

3. The tool launches an empty x-y chart in a new window. To the left of the chart the compatible layers

with time series data available are listed. To add a dataset to the chart click the layer in the left hand

list (a tick is placed next to it). Multiple datasets can be plotted on your chart at the same time, as

shown below:

Time Series Point plotting tool



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It should be noted that the chart displays all data on the same x and y axes, thus parameter units are

ignored and all data are plotted based solely on the magnitude of values in each dataset (i.e. there is

no conversion to similar units).

4. On your map a red square with a yellow border marks the location associated to the data. The

default location when the tool opens is the current centre of your map view. You can select new

points by clicking at different locations on the map. The chart will automatically update with each

click (data updates and the chart title displays the new x-y coordinate location). Note that you must

have the default cursor active for this functionality to work.

Red square signifies location of displayed time series data



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5. The time series chart includes a menu, accessed by right-clicking on it. This offers the options shown

below, which include functionality to export your chart data to Excel, to a printer or as an image file.

The chart provides a zoom feature; zoom in by dragging a rectangle over the area of interest (by

holding down the left mouse button). The right click menu provides an option to return to show the

full chart.

6. If you wish to locate a precise coordinate within your data you can utilise a tool in ISIS MAPPER to

set this point as the centre of your map view. You can then access the plotting tool, which will open

by default with data from this centre location loaded.

The View tab of the main toolbar includes a tool entitled Map Centre, as shown below:

When this button is clicked a new window is displays prompting you to enter you require x and y

coordinate values. Once entered click the Go button and your map view will move so the specified

point is in the exact centre. Now access the time series tool to view the underlying data.

Creating time series outputs at model runtime

Specific time series datasets can be produced at run time in comma separated text file format (extension

‘.csv’). When you are preparing your model in the ISIS 2D user interface you need to specify additional

outputs using the following procedure:

1. With your ISIS 2D model loaded in the interface, access the Domain > Model Outputs tab. The

standard output is specified as a grid. Click the Add button to add an additional output for your

model:

Point locator tool (moves map centre point to specified location)



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Click to add new output file

2. A new window is displayed as shown below. Add an output name (the associated output file will take

this as part of its filename) and data frequency (in seconds) to write data to your file. Finally select

CSV as the output format (from the dropdown list provided) and click OK to return to the main ISIS

2D interface.

3. A new row is added to your Domains Output table displaying the details you have just defined. When

this row is highlighted the x-y table on this tab is also highlighted. You can type coordinate data

directly into this table to define the points where you want to generate time series outputs. In addition

you can select which parameters to write to your point output file (by ticking the required parameters

from the list of output options). An example time series output setup is shown below:



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4. If you require different output parameters at different point locations you will need to repeat point 3

above creating multiple output csv entries in the Domains Output table.

5. If you have multiple coordinate pairs to enter in the x-y table then you can generate these data in

Excel. Then copy and paste the values into the ISIS 2D interface by accessing the right click menu

of the x-y table, as shown below:

6. Once your output points are configured you can proceed to run your simulation (saving your model

xml file first). The point output csv text files will be generated in the same outputs folder as the grid

data outputs (a sub-folder from the model xml file location).

5.3 Viewing a cross-section plot using ISIS MAPPER

You can also cross section plots of your ISIS 2D results data. These are snapshots of a user selected time

step. The following provides a step by step guide for generating a cross-section plot:

1. Launch ISIS MAPPER and use the Add Layer function to load your ISIS 2D results data to your map

view (and load any additional background layers if required).

2. Your cross section needs to be located using a polyline shapefile. There are three options for this:

You can draw a new polyline shapefile using the Create Layer function in ISIS MAPPER

You can use an existing shapefile (use ‘Add Layer’ to load into the ISIS MAPPER viewport)



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You can use the Measure Tool (located in the View > Analysis section of the main toolbar,

) to draw a temporary line across your data. If you access the cross section tool

with a measure line visible then the tool will automatically use this line as the cross section

location.

In this guide it is assumed that you select the draw new shapefile layer option (further information on

the other options is available in the ISIS MAPPER manual).

3. The procedure to create a new shapefile layer for your cross section is as follows:

In the ‘Layer’ tab of the main toolbar select ‘Create Layer’ > ‘Shapefile’. You are presented

with a list of shapefile types in a new window.

Select the Standard Shapefiles >. Polyline option and provide a new filename and folder

location for the new file you will create. Click OK to continue.

The shapefile editor toolbar is then activated. Click on the Draw button, , to activate the

drawing tool. The mouse icon should change to a pencil.

Left click the mouse pointer at the point on the map where you want your cross section to

begin. Then each subsequent left click will add a new point to your line, which you should

see forming on the map. Double click to stop drawing. Alternatively right-clicking displays a

menu which includes options to stop drawing and to undo the last point added.

Do not add more than one feature (i.e. line) to your cross section shapefile (although your

single line can contain multiple points, e.g. go around corners). Click the Select button in the

toolbar, , to exit drawing mode. Then click the Editor button, , to save your cross

section file and exit shapefile editing mode.

4. Access the cross section plotting tool. The tool is located in the Tools tab of the main toolbar and is

called X-Section, as shown below:

You will be prompted to select which polyline shapefile to use to locate your cross section. Select

your newly created file and click the OK button.

5. A new window will be displayed that shows an empty x-y chart and a list of datasets that are

compatible with cross section plotting, e.g. ISIS 2D results parameter datasets (.dat files) and ground

elevation grids. Click next to each dataset you wish to add to the cross section plot (placing a tick in

the adjacent box). Your data is added to the chart as shown in the example below:

Cross section plotting tool



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6. If you right click on the chart a menu is displayed which includes options to save the chart as an

image, send the chart to the printer and export the chart data to Excel (as comma separated values).

More information on the operation of this tool is provided in the ISIS MAPPER manual.

5.4 Animation of the 2D model results in ISIS MAPPER

The 2D model results can be animated in ISIS MAPPER. The following provides a step by step guide for

activating the animation function:

1. Load your 2D model results into ISIS MAPPER (using the ‘Add Layer’ function)

2. Right click on the 2D results data layer in the table of contents. Select the Animate option from the

displayed menu (you can also access this function via the Modelling Toolbox > 2D Flood Map

section). The animation toolbar is then activated at the bottom of the map view, as shown below:



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3. To start the animation, you need to click on the play button (see above). You can also click the Loop

button so that the animation sequence continuously repeats. To finish animating click on either the

Stop button or close the animation toolbar. It is possible to animate scalar data only (water levels or

depths), vector data only (flow or velocity – shown as arrows) or a combination of both scalar and

vector data. All datasets marked in the table of contents as visible on the map will be animated.

4. It is also possible to record the animation into a video file (.avi file), which can then be played back in

a compatible video player. This can be done by clicking the Start Recording button in the animation

toolbar before you start running the animation (see figure below). You may need to then specify the

video settings and specify the name of the .avi file to be created. After this just click the Run

Animation button to start the video recording and Stop Animation to then stop recording.

More details about results animation in ISIS MAPPER are described in the ISIS MAPPER Manual in the

section entitled "How Do I Load and Animate 2D Model Results Data?".

5.5 Generation of a flood extents map in ISIS MAPPER

ISIS MAPPER provides functionality to extract a flood extent map for any selected time step from your ISIS

2D model results files (you can also select the 9999 time step which represents maximum flood extents

within your active area). The flood extend map is produced as an ASCII raster grid of water depths, however

ISIS MAPPER also provides tools to convert this format to a binary grid, shapefile or Google Earth format

file. These outputs can then be viewed in ISIS MAPPER or other GIS software packages.

The following provides guidance on generating a flood extents map in ISIS MAPPER:

1. Load your 2D Model Results into ISIS MAPPER (using the Add Layer function).

2. Access the 2D Flood Calculator tool from the Tools tab of the main toolbar, as shown below:

3. The 2D Flood Calculator tool will be displayed in a new window, as shown below:

2D Flood Calculator tool



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To define the flood extent(s) to export from your results you must specify the following:

Select the 2D results parameter layer you wish to export, e.g. water depth, from the list of

loaded results datasets displayed on the left of the window

Select one or more time steps to export by clicking on the list of available time values. Each

click on this list will select an additional time step (click a second time on a time value to

unselect it). Scroll to the bottom of the list to access the ISIS 2D maximum extent time

step(s), i.e. 9999 or 9999.1.

Use the browse button, ,to specify an output filename. This will be the base name for

all your selected time step outputs. ISIS MAPPER will then add the selected time step value

to this filename automatically (i.e. filename becomes “filename_timestep.asc”).

Leave other settings as defaults, i.e. threshold ranges and output type (should be set to

“Export selected layer”). Refer to the ISIS MAPPER manual for further details on these.

4. Click the Run button to proceed to generate your flood extents. These calculations may take a few

seconds to complete. If you have placed a tick in the Load to View option the generated grids will be

automatically loaded into your map view.

5. The Layer Convertor tool can then be used to convert your ASCII raster grids to an alternative

format. This tool is located in the Modelling Toolbox > Other Tools section (refer to the ISIS

MAPPER manual for details on using this tool).

More information about using the 2D Flood Calculator are described in the ISIS MAPPER Manual in the

section entitled “How Do I Export Model Results as a Flood Map?”.

2. Select time step(s) to export

3. Define range (optional)

4. Specify flood map filename

5. Click Run to create maps

1. Select layer to export from

Documents

ISIS 2D - Flood Modeller · ISIS 2D v3.7 Quick Start Guide Cost Effective, Integrated Software Solutions For further information, email [email protected] or visit ch2mhill.com/isis