NetMap's Technical Help Guide

Channel Width

Channel Width (Bankfull)
Parameter Description: Bankfull channel width predicted by statistical regressions. Users can customize their width predictions using their own regressions (Subscription only).
Data Type: Line (stream layer)
Field Name: WIDTH_M; Common Name: Bankfull width
Units: Meters
NetMap Module/Tool: Fluvial Processes/Hydrualic-Planform Geometry
Model Description:
In NetMap, statistical regressions are used to predict bankfull channel width (Figure 1). Active channel width is modeled as a power function of mean annual flow, drainage area and or precipitation; see Leopold and Maddock 1953 and Clarke et al. 2008. Channel bankfull width is used in numerous applications in NetMap, including in the prediction of fish habitat (see Aquatic Habitat Module).
Figure 1. In the Channel Width interface, users can display the width (1) using the default regression that was used (2), or users can re-calculate channel width using their own regressions (Figure 2).
Figure 2. Users have the option of customizing the prediction of channel width (1), although the form of the regression equation used must follow specific formats; the cutomization option requires a NetMap subscription. If channel width is modified, there are several other parameters that need to be recalculated, some automatially and others needing to be done manually by the user (2); for example, fish IP will be effected. An analyst inserts their own custom regressions using the equation forms provided (3). A citation can be added (4). And results can be displayed (5), Figure 3.
Precipitation data is from PRISM ( data on annual precipitation and the use of one or more regression models; refer also to Lorensen et al. (1994) and Clarke et al. (2008).
Figure 3. Channel width is important for interpreting channel types, valley confinement index (i.e., valley width/channel width) and fish habitat potential.  It is estimated in NetMap using empirical relationships between channel hydraulic geometry and flow discharge and/or average annual precipitation.
Analysts are encouraged to use landscape specific regression models or to develop their own regressions. NetMap includes a table of readily available regression models across portions of the western U. S. Click the button on the top left on the tool interface called "Get Regional Regression Data".

Made with help of Dr.Explain

Copyright TerrainWorks 2014