ISIS Quick Start Guide - Halcrow

ISISQuick Start Guide3. How to Build a Single ChannelThis Chapter explains the ways of building a model representing a single channel, i.e. a reach of riverthat is not branched.A single channel contains at least four units: upstream boundary condition, downstream boundarycondition and two sections to represent a channel. Figure 15 shows a very simple channel with eightcross sections.QTBDY is shorthand for the discharge (Q) Time series BounDarY condition (for the upstream inflow tothe channel). HTBDY represents the water level time series boundary condition for the downstreamend of the channel.QTBDYHTBDYFigure 15. A schematic representation of a single channel with eight sections andtwo boundary conditionsIn order to build such a channel, we have to follow the following steps:1. Start a new (blank) model in ISIS (> File > New)2. Insert a Flow-Time Boundary (QTBDY) unit to represent an upstream boundary. To insert this unityou can either click on the Flow-Time Boundary picture button or select > Edit > Insert >Boundaries > Hydrographs > Flow/Time from the main menu. When the Node label editor dialogappears, enter the label S1 (in upper case), and click ‘OK’. Save this file with a proper name (forexample, singleChannel.DAT) and choose the location on your computer to place a copy of the file.3. Specify the data for the boundary condition. Double click on the newly inserted unit to display thedata entry screen for the boundary. Enter the flow data into the Flow-Time table. As shown by theexample below: let’s enter a simple hydrograph, peak flow 20m3/s, base flow 10 m3/s and time topeak is 12 hours. Remember to make sure that the unit of the time is hours (by default it is “seconds”).Do you have any questions or remarks? Please contact ISIS support at isis@halcrow.comor on 0845 094 7994 (+44 1793 845733 from outside the UK) www.halcrow.com/isis11