Flood Modeller Tutorial Module01

Introduction

In this module we will link an existing 2D TUFLOW domain to an existing Flood Modeller 1D model. The 2D TUFLOW domain will represent the floodplain in the study area, and the 1D Flood Modeller model will represent the watercourse and all online structures.

1D-2D linked models are able to utilise the individual benefits of 1D and 2D solution schemes. In this example, the 1D Flood Modeller scheme is used to represent the watercourses where the flow is essentially one-directional. A 2D scheme is suited to the representation of floodplains where a more detailed flow patterns may occur.

TUFLOW may be dynamically linked to 1D networks using the hydrodynamic solutions of ESTRY (TUFLOW 1D), Flood Modeller (previously ISIS), XP-SWMM and 12D Solutions’ Dynamic Drainage.

Existing Model Data

Introduction

This section of the tutorial provides a summary of the background Flood Modeller and TUFLOW model data that has been provided for the purposes of this tutorial. This tutorial builds upon the 2D TUFLOW domain that was constructed as part of Module 1 and Module 2 of the TUFLOW Tutorial Model. This TUFLOW model consists of:

• Definition of Active/In-Active Areas
• Definition of Land Use
• 1D ESTRY culverts
• 1D/2D boundary links to connect the 1D ESTRY culverts to the 2D TUFLOW domain.

The provided model differs from Module 2 in that the 2D boundary conditions (upstream inflows and downstream stage-discharge boundary) have been removed from the model. These will instead be represented in Flood Modeller as it is a more typical schematisation for a 1D/2D linked model. Hydraulic structures along the watercourse have also been removed and have been represented in the Flood Modeller 1D model. Amended versions of the TUFLOW control files and GIS files have been provided as part of this tutorial in preparation for linking to Flood Modeller.

Flood Modeller

A complete Flood Modeller 1D model of the watercourse has been provided for the purposes of this tutorial. The model data has been arranged in the following folder structure. For further information on each file type, please refer to the Flood Modeller User Manual:

• DAT: Contains the Flood Modeller 1D network file.
• IED: Contains event data of the model.
• IEF: A blank folder in which to store Flood Modeller Event Files used to simulate the model.
• RES: A blank folder in which to write the Flood Modeller result files.

For this tutorial, the floodplain of the study area will be modelled entirely in TUFLOW. The cross-sections in the Flood Modeller 1D model have been trimmed to the top of bank to ensure there is no double-counting of storage within the floodplain. Upstream and downstream boundary data is contained separately within the IED files. These will be referenced and linked to the Flood Modeller 1D model via the IEF 1D simulation file.

GIS and Model Inputs

The steps necessary to modify each of the GIS inputs are demonstrated in MapInfo, ArcGIS and QuantumGIS (QGIS). At each stage please select your GIS package to view relevant instructions.

Define the External 1D Networks

This part of the module creates the GIS layers that specify the geographic location of the Flood Modeller nodes that are to be connected to the 2D domain. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Define the 1D/2D Boundary Links

This part of the module creates the 1D/2D boundaries to link the Flood Modeller 1D component to the TUFLOW 2D domain. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Define Bank Elevations

This part of the module defines the bank elevations of the watercourse which are the elevations of the 1D/2D boundary links created in the previous section. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Deactivate 2D cells

This part of the module describes the steps to deactivate the 2D cells where the 1D model is replacing the 2D solution. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Modify Simulation Control Files

Now that we have made all of the necessary changes to the GIS layers, we need to update the TUFLOW control files and Flood Modeller Simulation Files to create a linked model.

TCF File

1. Firstly save a copy of the TUFLOW file created as a part of module 2 (M02_5m_001.tcf) as FMT_M01_001.tcf.
2. The simulation time control commands (shown below) which specify timestep, start time and end time need to be removed from the tcf.
   ! SIMULATION TIME CONTROL COMMANDS

   Timestep == 1.5 ! Specifies a 2D computational timestep of 1.5 seconds

   Start time == 0 ! Specifies a simulation start time of 0 hours

   End Time == 3 ! Specifies a simulation end time of 3 hours

   The reason for this step being completed is the information is to be moved to an IEF file
3. Delete the 1D Domain commands from the tcf. These are shown below:
   

   !1D DOMAIN COMMANDS

   Start 1D Domain ! Indicates the start of a block of 1D or ecf (Estry Control File) commands

   Output Folder == ..\results\M02\1d ! Specifies the location of the 1D output files

   Write Check Files == ..\check\1d\ ! Specifies the location of the 1D check files and prefixes them with the .tcf filename

   Output Interval (s) == 180 ! Writes the 1D output every 3 minutes. Note the (s) is required to indicate the value is in seconds Timestep == 0.75 ! Specifies a 1D computational timestep of 0.75 seconds. We will set the 1D timestep to be half the 2D timestep Read GIS Network == ..\model\gis\1d_nwk_M02_culverts_001_L.shp ! Reads the 1d_nwk GIS layer defining culverts within the model Read GIS Network == ..\model\gis\1d_nwk_M02_culverts_001_P.shp ! Reads the 1d_nwk GIS layer defining nodes used to create automatic SX 1D/2D boundaries End 1D Domain These commands should be moved to the ecf. This is however an optional step

TGC File

TBC File

Flood Modeller Simulation Files

IEF File

Run the Simulation

There are a number of different methods in which to start a Flood Modeller – TUFLOW model. Please refer to the following page for a detailed discussion on each of these methods. Using your preferred method, start the model FMT_0100F_001.ief. If the simulation fails to start, please refer to the troubleshooting guidance on this page.



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