IGW-Desktop SW Tutorial 1 - Modeling simple channel flow

This video demonstrates using IGW-Desktop to model channel flow. One of four benchmark problems presented in MacDonald et al. [1] are selected to test against 1D channel flow model in IGW. Analytical solutions to this test case for the steady state flow is available for comparison. 1 Access the ‘Model Scale and Basemap’, and set the extent of the modeling workspace. X0=0.0; Y0=0.0; Xlength=1000m; Ylength=100m 2 a. Access ‘Display options’, uncheck the ‘Horizontal Scale Bar’ and ‘Vertical Scale Bar’ boxes, then: b.Select the ‘Create Zone/Assign Properties’ icon, and enter the following coordinates in the ‘Input Vertex Coordinates’ text box: 0,0 1000,0 1000,100 0,100,end Each pair of (x,y) must be followed with an ‘enter’ keystroke, and the text box must be cleared before entering the next set vertex coordinate. The ‘end’ following the last coordinate pair closes the polygon by connecting a line between the last and first vertex coordinates. 3 The channel is represented as a polyline, or a series of vertex coordinates forming a channel link. There are multiple ways to create the channel links:  inputting vertex one by one vertex using the 'Input Vertex Coordinates' text box  loading a channel configuration file directly by double click 'Input Vertex Coordinates'  Importing from 'GIS Importer' if a shapefile is available In this example, vertex coordinates are stored in a channel configuration file: - select the ‘Create Polyline/Assign Properties’ icon - double click 'Input Vertex Coordinates' - browse to the configuration file: ..\data\ ChannelConfig_IV.txt 4 Select the channel polyline (Pline) that was just created in ‘Attributes Explorer’, and select ‘Two way’ in the ‘Head Dependent Flux’ tab. Then, click on the ‘… ‘ icon to bring up the attribute table for the channel polyline. Specify the boundary conditions at the first and last node: Flow rate is given at the first node. In the ‘NType’ column, double-click the first cell (first row) and change the value from ‘1’ to ‘2’. Hit enter, and the ‘Define Q-H’ window appears. Click on the ‘edit’ icon, and change the flow rate to 20 m3/s (make sure you have the correct units). Then, click on the ‘Save Edits’ icon, then select ‘Ok’. The initial water depth in channel at the first node is 1.2m. In the 'chnDepth' column, double-click the first cell (first row) and change the value from ‘1’ to ‘1.2’. The last node of this channel link is modeled as outlet node: NType=999. In the ‘NType’ column, double-click the first cell (first row) and change the value from ‘1’ to ‘999’. Note that other parameters such as channel width (‘chWidth’) and the manning roughness coefficient (‘chRough’) can be edited for any node in the channel link. In this example, the channel cross section is a trapezoid and the channel slope is variable along the length of the channel. A file that specifies the shape and elevation of the cross-section at each node is available and needs to be imported. In 'CrossSection File' box, click 'Load' to load the cross section file: CS_IV.txt. To finish editing the channel, click ‘Ok’ in the ‘Edit Polyline Attributes’ window. 5 In ‘Attribute Explorer’ - layer1 , select ‘Surface Water Channel’. The ‘Surface Water More Options’ window will open. Check the 'Channel/Stream' box, then check 'Solver' and select 'Diffusive Wave' in the solver options box. Then select ‘OK’. 6 Select the ‘Set Simulation Time Parameters’ icon from the icon toolbar. Select 'Transient State' (top of window) and enter time step =6 sec in the text box (This means the SW time step is: 6/60 s). 7 Select ‘Deep Discretization’ from the icon toolbar, and assign NX=60. Water depth of flow at the outlet: check the ‘M/Wells’ box in the window in the bottom-left corner of ‘Attributes Explorer’. monitoring and click on the ‘Options’ icon in the ‘Monitoring Well’ box. A window will appear; check the ‘SW’ box and then select 'SW_h' (Surface Water Depth) or 'SW_Q' (Hydrograph). Before running the model, click 'on/off Channel CS' at bottom panel. Run the model forward until the solution reaches the channel outlet; show the surface water depth at the outlet well and the SW Channel Cross Section for different nodes along the channel (move the cursor along the channel). Stop the model; draw a profile along the channel using the ‘Draw Cross-section’ icon in the icon toolbar. The profile should run from left to right across the center of the channel. In the ‘Profiles Display for Cross-section ...’ window that appears, check 'SW_depth' box and uncheck the ‘Head’ box. 8 Run the model until the state-state solution is reached PAUSE --- Move along channel to show CS view again 9 Go to ‘File' - 'Export Model Results' -- 'Export SW Model Results(txt). This will save information on each node in the entire channels as a txt file with the format: X,Z,h,q,v The file is saved in the following location: C:\temp\SWResults https://www.magnet4water.net/GW_home.aspx