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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN" "http://www.w3.org/TR/REC-html40/strict.dtd">
<html>
<head>
<style>
pre {
line-height: 1.2
}
ul {
line-height: 1.2
}
</style>
</head>
<body>
<h1>Flow Estimator - A Uniform, Steady Open Channel Flow Calculator for QGIS</h1>
<h2>Description</h2>
<p>This plugin calculates flow and velocity using the Manning equation for uniform, steady flow. <strong>If you've never heard of the Manning equation or taken a course in open channel hydraulics you won't understand what this tool is doing.</strong></p>
<p>If you are familar with open channel hydraulics and want a quick refresher check out this information from the University of Delaware:</p>
<p><a href="http://web.archive.org/web/20160305025907/udel.edu/~inamdar/EGTE215/Open_channel.pdf">http://web.archive.org/web/20160305025907/udel.edu/~inamdar/EGTE215/Open_channel.pdf</a></p>
<p>A great reference for Mannings n values can be found from the USGS here:</p>
<p><a href="http://pubs.usgs.gov/wsp/2339/report.pdf">http://pubs.usgs.gov/wsp/2339/report.pdf</a></p>
<h2>User Defined Cross Section</h2>
<p>The user defined cross section option allows loading a tab or space delimited text file without a header. The first column should contain station values and the second column should contain elevation values.</p>
<h2>Usage Considerations</h2>
<p>Make sure the steady, uniform flow assumption is valid.</p>
<p>When sampling a DEM cross-section be sure to make the cross-section perpendicular to flow at a location that is representative of the stream or drainage channel.</p>
<p>When sampling DEM cross-sections and slopes, make sure the DEM is in the same CRS as the project CRS (but you knew that already right!).</p>
<h2>Known Issues</h2>
<ul>
<li>On QGIS3 there are still occasional crashes, so remember to save your project if necessary.</li>
<br>
<li>On QGIS3 the plugin is hidden when sampling from a raster. Showing the plugin again isn't 100% reliable. If this annoys you, hide/show can be disabled by editing flow_estimator_dialog.py, around line 89. Change "True" to "False":</li>
<pre><code> if Qgis.QGIS_VERSION_INT > 29000: # Hide and show works on QGIS3, mostly... although occasionally not!<p> HIDE_ENABLED='True' # Change to False if you can't cope with the show failing every now and then.</code></pre><p>
<li>If you accidentally sample from an aerial photo you might need to wait a while!</li>
</ul>
</body></html>