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51 lines
2.7 KiB
HTML
51 lines
2.7 KiB
HTML
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<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'>D-Infinity Upslope Dependence</h1>
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<div class='author'>(c) 2010 by David G. Tarboton</div>
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<div class='description'>The D-Infinity Upslope Dependence tool quantifies
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the amount each grid cell in the domain contributes to a destination set
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of grid cells. D-Infinity flow directions proportion flow from each grid
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cell between multiple downslope grid cells. Following this flow field
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downslope the amount of flow originating at each grid cell that reaches
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the destination zone is defined. Upslope influence is evaluated using a
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downslope recursion, examining grid cells downslope from each grid cell,
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so that the map produced identifies the area upslope where flow through
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the destination zone originates, or the area it depends on, for its flow.</div>
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<div class='description'>The figures below illustrate the amount each
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source point in the domain <tt>x</tt> (blue) contributes to the destination
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point or zone <tt>y</tt> (red). If the indicator weighted contributing area
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function is denoted <tt>I(y; x)</tt> giving the weighted contribution using
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a unit value (1) from specific grid cells <tt>y</tt> to grid cells <tt>x</tt>,
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then the upslope dependence is: <tt>D(x; y) = I(y; x)</tt>.</div>
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<p align="center"><img src="img/dependence.gif"></img></p>
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<div class='description'>This is useful for example to track where flow
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or a flow related substance or contaminant that enters a destination area
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may come from.</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>D-Infinity Flow Direction Grid <div class='type'>Raster Grid</div></dt>
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<dd>A grid giving flow direction by the D-Infinity method where the
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flow direction angle is determined as the direction of the steepest
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downward slope on the eight triangular facets formed in a 3 x 3 grid
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cell window centered on the grid cell of interest. This grid can be
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produced using the "D-Infinity Flow Direction" tool.</dd>
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<dt>Destination Grid <div class='type'>Raster Grid</div></dt>
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<dd>A grid that encodes the destination zone that may receive flow from
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upslope. This grid must be 1 inside the zone y and 0 over the rest of
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the domain.</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>Upslope Dependence Grid <div class='type'>Raster Grid</div></dt>
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<dd>A grid quantifing the amount each source point in the domain contributes
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to the zone defined by the destination grid.</dd>
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</dl>
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</body></html>
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