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= Introduction =
In thisFMA challengeChallenge 1, a fully two-dimensional model with a nested one dimensional model has been developed to explore in and over-bank floodplain conditions. The model includes several hydraulic structures/bridges within the main stream system which impact flood elevations. Flooding of the urbanised over-bank floodplain is experinced. For interest, the requirements of the FMA challenge are provided [httphttps://www.tuflow.com/Download/TUFLOW/Demo_Models/2012_FMA_Challenge/All/FMA%20Challenge%201%20Documention.TUFLOW.pdf here]<br><br>▼
The FMA Challenge Wiki's provide example TUFLOW models submitted by BMT WBM for the Floodplain Management Association 2-Dimensional Model Challenges, 2012.
This Wiki assumes an intermediate to advanced user level so if you're just starting out or haven't already completed the tutorial models, please see this <u>[[Tutorial_Model | tutorial model]]</u> page. <br>
 
A fullyThe functional exampleFMA modelChallenge 1 (1D-2D linked) has been developed allowing you to review the model setup, run the model and review results developingimproving your skills in:▼
▲In this challenge, a fully two-dimensional model with a nested one dimensional model has been developed to explore in and over-bank floodplain conditions. The model includes several hydraulic structures/bridges within the main stream system which impact flood elevations. Flooding of the urbanised over-bank floodplain is experinced. For interest, the requirements of the FMA challenge are provided [http://www.tuflow.com/Download/TUFLOW/Demo_Models/2012_FMA_Challenge/All/FMA%20Challenge%201%20Documention.TUFLOW.pdf here]<br>
 
▲A fully functional example model has been developed allowing you to review the model setup, run the model and review results developing your skills in:
*Nested 1D/2D models;
*Understanding urban riverine conditions and over-bank floodplains;
*Using the powerful functionality of scenarios and variables to determine a suitable cell size, timestep and log output scenarios;
*Understanding the impact of data quality on DEM development;
*Understanding the influence of structures on open channel hydraulics;
*Using scenariosbc andlayers variableswith toHX, determine a suitable cell sizeXP, timestepCD and log outputCN scenariostypes; and
*UsingUnderstanding bcthe layersimpact withof HX,data XP,quality CDon andDEM CN typesdevelopment.<br><br>
 
Data for this model is provided viain ZIPa compressedvariety fileof posteddifferent onGIS compatible formats. Download the <fontdataset color="red">that internet/FTPmatches WHEREthe ISGIS THIS???</font>software foryou download.are using:
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_1_QGIS.zip QGIS Data Download]
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_1_MapInfo.zip MapInfo Data Download]
*[https://www.tuflow.com/Download/TUFLOW/Demo_Models/FMA_Challenge_Model_1_ArcGIS.zip ArcGIS Data Download]
 
=Relevant Tutorials=
Although all Tutorials are of relevance for the FMA Challanges, For FMA Challange 1, it may be useful to revisit the following:<br>
*<font color="blue"><tt>1D-2D Linking - </ttu></font>- [[Tutorial Module02Tutorial_M03|Tutorial Module 23]] </u>
*Running Scenarios - <u>[[Tutorial_M08|Tutorial Module 8]]</u>
*<font color="blue"><tt>Running Events and Scenarios</tt></font>- http://www.tuflow.com/forum/index.php?showtopic=1149&hl=scenario<br>
*Running Events - <u>[[Tutorial_M09|Tutorial Module 09]]</u>
 
=Model Setup=
This section provides an overview and discussion of the model domain setup.<br> All files required to re-run the model can be found at '''FMA_Challenge_Models/FMA_Scenario1/'''. It is at your discretion which GIS package, text editor and method of model simulation to use (batch mode or within the text editor).
All files required to setup and run the models are available within the download package. You have the choice of running with shape file or mif for usage in ArcGIS/QGIS or Mapinfo respectively.
 
==Computational Domain Assembly==
TUFLOW directly reads GIS data layers to construct models. The layers used/created for Challenge 1 are:
<ol>
<li>A DEM TIN created from the provided terrain data (2ft contours) and exported to ESRI ASCII format as a 2ft DEM grid. When TUFLOW reads this DEM it interpolates the elevations onto the 2D computation grid.</li>
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==Use of Scenarios to Modify 2d2D Grid Resolution==
To test the effect of different resolutions, simulations were made using grid resolutions of 5, 10, 15, 20 and 40 ft (Noted that only the 10 and 15ft are presented in this example).
 
To run the model with varying cell sizes from a single TCF, the use of scenarios waswere implemented with either '10ft' or '15ft' entered in the batch file using the -s commandswitch. IfImportantly, if the -s commandswitch is not used, the model will assume a default model scenario of 10ft as specified by the line <font color="blue"><tt>Model Scenario </tt></font> <font color="red"><tt>==</tt></font> <tt> 10ft </tt> within the TCF.
 
Within this example, the 2D cell size, 2D timestep and log output frequency haveare beenvariables setdependent ason the 2D Cell Size scenario. dependentThe variables are specified through an external read file (.trd). The .trd file is called from the TCF: <font color="blue"><tt>Read File </tt></font> <font color="red"><tt>==</tt></font> <tt> FMA_T1_CellSize_Commands_001.trd </tt><br>
 
When the model is initialised, the scenario value determines the 2D_CELL_SIZE, 2D_Timestep and LogInt variables. which,The variables are set using the 'Set Variable' command in the trftrd. This results in scenario dependent values of 2D_CELL_SIZE, 2D_Timestep and LogInt values. Using the << >> syntax, values within the tcf and tgc files are substituted. For example for the -s 10ft scenario:
Each variable is then placed in the TCF and TGC using the << >> syntax. For example for the 10ft scenario:
 
*Within the TCF, <<2D_Timestep>> is replaced with 1 and <<logInt>> is replaced with 30; and
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For 2D modelling, especially in flat urban areas, contours should not be used to create the DEM. If the contours were generated from a DEM, then the original DEM should be used or the original terrain data should be provided and the DEM recreated from this data. If contours are used, additional point data and/or 3D breaklines along the low and high points need to be provided to prevent the terraced effect from occurring.
 
==The Model Boundary and Terrain Extent==
The flooding in the overbank 2D domain extends to the edge of the model boundary and terrain data. The terrain data needs to be extended further afield to high ground.
 
=Conclusion=
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