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46 lines
2.4 KiB
HTML
46 lines
2.4 KiB
HTML
<html>
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<head><link rel="stylesheet" type="text/css" href="help.css"/></head>
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<body>
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<h1 class='module'>D8 Distance To Streams</h1>
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<div class='author'>(c) 2010 by David G. Tarboton</div>
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<div class='description'>Computes the horizontal distance to stream for
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each grid cell, moving downslope according to the D8 flow model, until a
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stream grid cell is encountered.</div>
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<h2>Parameters</h2>
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<dl class='parameters'>
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<dt>Number of Processes <div class='type'>Integer</div></dt>
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<dd>The number of stripes that the domain will be divided into and the
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number of MPI parallel processes that will be spawned to evaluate each
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of the stripes.</dd>
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<dt>D8 Flow Direction Grid <div class='type'>Raster Grid</div></dt>
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<dd>This input is a grid of flow directions that are encoded using the
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D8 method where all flow from a cells goes to a single neighboring cell
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in the direction of steepest descent. This grid can be obtained as the
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output of the "D8 Flow Directions" tool.</dd>
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<dt>Stream Raster Grid <div class='type'>Raster Grid</div></dt>
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<dd>A grid indicating streams. Such a grid can be created by several
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of the tools in the "Stream Network Analysis" toolset. However,
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the tools in the "Stream Network Analysis" toolset only create
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grids with a value of 0 for no stream, or 1 for stream cells. This tool
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can also accept grids with values greater than 1, which can be used in
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conjunction with the Threshold parameter to determine the location of
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streams. This allows Contributing Area grids to be used to define streams
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as well as the normal Stream Raster grids. This grid expects integer
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(long integer) values and any non-integer values will be truncated to an
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integer before being evaluated.</dd>
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<dt>Threshold <div class='type'>Double</div></dt>
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<dd>This value acts as threshold on the Stream Raster Grid to determine
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the location of streams. Cells with a Stream Raster Grid value greater
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than or equal to the Threshold value are interpreted as streams. Default
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value <strong>50</strong>.</dd>
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</dl>
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<h2>Outputs</h2>
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<dl class='parameters'>
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<dt>Distance to Streams <div class='type'>Raster Grid</div></dt>
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<dd>A grid giving the horizontal distance along the flow path as defined
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by the D8 Flow Directions Grid to the streams in the Stream Raster Grid.</dd>
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</dl>
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</body></html>
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