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68 lines
4.0 KiB
HTML
68 lines
4.0 KiB
HTML
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<head><link rel="stylesheet" type="text/css" href="help.css"/></head>
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<h1 class='module'>Move Outlets To Streams</h1>
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<div class='author'>(c) 2010 by David G. Tarboton</div>
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<div class='description'>Moves outlet points that are not aligned with a
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stream cell from a stream raster grid, downslope along the D8 flow direction
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until a stream raster cell is encountered, the "max_dist" number
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of grid cells are examined, or the flow path exits the domain (i.e. a
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"no data" value is encountered for the D8 flow direction). The
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output file is a new outlets shapefile where each point has been moved to
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coincide with the stream raster grid, if possible. A field "dist_moved"
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is added to the new outlets shapefile to indicate the changes made to each
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point. Points that are already on a stream cell are not moved and their
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"dist_moved" field is assigned a value 0. Points that are initially
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not on a stream cell are moved by sliding them downslope along the D8 flow
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direction until one of the following occurs: a) A stream raster grid cell
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is encountered before traversing the max_dist number of grid cells. In
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which case, the point is moved and the "dist_moved" field is
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assigned a value indicating how many grid cells the point was moved.
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b) More than the max_number of grid cells are traversed, or c) the traversal
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ends up going out of the domain (i.e., a "no data" D8 flow direction
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value is encountered). In which case, the point is not moved and the
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"dist_moved" field is assigned a value of -1.</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>A grid of D8 flow directions which are defined, for each cell, as
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the direction of the one of its eight adjacent or diagonal neighbors
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with the steepest downward slope. 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>This output is an indicator grid (1, 0) that indicates the location
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of streams, with a value of 1 for each of the stream cells and 0 for
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the remainder of the cells. This file is produced by several different
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tools in the "Stream Network Analysis" toolset.</dd>
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<dt>Outlets Shapefile <div class='type'>Point Shapefile</div></dt>
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<dd>A point shape file defining points of interest or outlets that
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should ideally be located on a stream, but may not be exactly on the
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stream due to the fact that the shapefile point locations may not have
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been accurately registered with respect to the stream raster grid.</dd>
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<dt>Maximum Number of Grid Cells to traverse <div class='type'>Double</div></dt>
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<dd>This input paramater is the maximum number of grid cells that the
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points in the input outlet shapefile will be moved before they are saved
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to the output outlet shapefile. Default is <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>Output Outlet Shapefile <div class='type'>Point Shapefile</div></dt>
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<dd>A point shape file defining points of interest or outlets. This file
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has one point in it for each point in the input outlet shapefile. If
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the original point was located on a stream, then the point was not moved.
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If the origianl point was not on a stream, the point was moved downslope
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according to the D8 flow direction until it reached a stream or the
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maximum distance had been reached. This file has an additional field
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"dist_moved" added to it which is the number of cells that
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the point was moved. This field is 0 if the cell was originally on a
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stream, -1 if it was not moved becuase there was not a stream within
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the maximum distance, or some positive value if it was moved.</dd>
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</dl>
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</body></html>
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