Flood Modeller Tutorial Module02

Introduction

In this tutorial we will add a representation of a proposed development which involves adding TUFLOW 1D pipe network elements into the existing model network to represent the drainage network, which will then be linked with Flood Modeller Pro.

This will involve:

• Modification of the floodplain topography by the creation of a 3D TIN surface;
• Revising the land use;
• The addition of pipes and pits to represent an underground drainage network;
• Linking the pipe network to Flood Modeller; and
• The addition of an inflow into the pipe network.

GIS and Model Inputs

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

Define Elevations (Building a TIN)

We have provided the GIS layers necessary to modify the ground elevations to represent the proposed development. This part of the tutorial will demonstrate how a TIN is created from these GIS layers. We will also update the GIS defining the road crest level. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Define Surface Roughness

We have provided the GIS layers necessary to modify the land use areas that will change as part of the proposed development. This part of the tutorial will require populating the layer attributes to assign Manning’s n roughness values to each land use. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Define Pipe Network

This part of the module creates the GIS layers that make up a pipe network. The pits of the pipe network will be linked to the 2D domain. We will also create the pit inlet database which links the GIS layers to depth-discharge curves. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Define Boundary Conditions

This part of the module demonstrates how an inflow can be applied directly to the pits of the pipe network. A GIS layer of the inflow boundary has been provided. We will also modify the existing Boundary Conditions Database to include these new inflows. Follow the instructions below for your preferred GIS package.

• ArcGIS
• MapInfo
• QGIS

Flood Modeller 1D/1D Link

TUFLOW models can also be configured with Flood Modeller for dynamically linked 1D pipe network 2D overland flow modelling. The main driver for this feature is for Flood Modeller - TUFLOW models to utilise the powerful pipe network and manhole modelling capabilities of TUFLOW (see Section 5.12) and be able to link these networks into a Flood Modeller river model.

Flood Modeller and TUFLOW (ESTRY) nodes will be considered linked if:

1. An ESTRY node in a 1d_nwk layer, and a Flood Modeller node in a Read GIS ISIS Nodes or Read GIS ISIS Network layer are snapped.
2. The ESTRY node has a 1d_nwk Conn_1D_2D attribute of either "X1DH" or "X1DQ".

(i) If Conn_1D_2D is blank then “X1DH” is assumed.

(ii) A connector "X" channel type can be used to connect the end of the linked ESTRY channel to the ESTRY node snapped to the Flood Modeller node if the end of the ESTRY channel and the snapped Flood Modeller /ESTRY nodes are not in the same location.

(iii) Note that the upstream and downstream inverts for the ESTRY node linked to Flood Modeller should be set to -99999 unless the node is also being used to set the inverts of channels snapped to it.

3. An "X1DH" link means a Flood Modeller 1D water level is being applied at the ESTRY node (ie. Flood Modeller sends ESTRY a water level and ESTRY sends back a +/- flow to Flood Modeller).
4. An "X1DQ" link means a Flood Modeller inflow/outflow is being applied at the ESTRY node (ie. Flood Modeller sends ESTRY a +/- flow and ESTRY sends back a water level).
5. An ESTRY X1DH (the default) would be used for most Flood Modeller ESTRY links. An X1DQ might be more appropriate where a Flood Modeller model stops and flows into an ESTRY model.
   

Generally, an ESTRY timestep will be smaller than the Flood Modeller timestep. In these cases, the total volume is accumulated over all ESTRY timesteps within a Flood Modeller timestep, and applied to the Flood Modeller model as a discharge by dividing the volume by the Flood Modeller timestep. The mass balance _MB1D.csv file includes four new columns:

• X1DH V In: The volume of water in via a X1DH link.
• X1DH V Out: The volume of water out via a X1DH link.
• X1DQ V In: The volume of water in via a X1DQ link.
• X1DQ V Out: The volume of water out via a X1DQ link.

The type or existence of a connection can be checked by viewing the Conn_1D_2D attribute in the 1d_nwk_N_check layer. The _messages.mif/.shp layer contains CHECK 1393 messages at each ESTRY node linked to a Flood Modeller node.

Modify Simulation Control Files and Set-up a TUFLOW Scenario

Now that we have made all of the necessary changes to the GIS layers, we need to update our control files to include all the changes representing the proposed development.

TGC File

There have been two changes to the model that impact the TGC file:

• We have created two layers that together form a 3D TIN representing changes to the ground elevations.
• We have created two 2d_mat layers that represent changes to the land use at the location of the proposed development.

We will also be making the necessary amendments to the control files to incorporate the representation of the bridge in the 'FINB2' scenario into a final 'DEV' scenario.

1. Begin by opening FMT_M01_001.tgc in your text editor. Save the file as FMT_M02_001.tgc.