ConnectDown

Summary

For each zone in a raster entered (e.g. HUC converted to grid) it identifies the point with largest AreaD8. This is taken to be the outlet. A OGR file is created. Using flow directions each outlet is moved downflow a specified number of grid cells which is user controllable (Default is 1). The ID of the location the point has moved to is taken as iddown. Two OGR files are created one with the initial points and one with the moved points. Both contain id, iddown and AreaD8.

Usage

Command Prompt Syntax:


					mpiexec -n <number of processes> connectdown
					-p <pfile>
					-ad8 <ad8file>
					-w <wfile>
					-o <outletfile>
					[-olyr outletlayername]
					-od <moved outletfile>
					[-odlyr moved outlet layer name]
					[-d]

Parameters:

pfile: Input flow directions grid
ad8file: Input contributing area grid
wfile: Input Watershed grid
outletfile: Output outlets file (OGR writeable dataset)
moved outletfile: Output moved outlets file (OGR writeable dataset)
outletlayername: OGR layer name in outletfile (optional)
moved outlet layer name: OGR layer name in moved outletfile (optional)
d: number of grid cells move to downstream

Parameter	Explanation	Data Type
Input_D8_Flow_Direction_Grid	Dialog Reference This input is a grid of flow directions that are encoded using the D8 method where all flow from a cells goes to a single neighboring cell in the direction of steepest descent. There is no python reference for this parameter.	Raster Layer
Input_D8Contributing_Area_Grid	Dialog Reference A grid giving the contributing area value in terms of the number of grid cells (or the summation of weights) for each cell taken as its own contribution plus the contribution from upslope neighbors that drain in to it using the D8 algorithm. This is usually the output of the "D8 Contributing Area" tool. There is no python reference for this parameter.	Raster Layer
Input_Watershed_Grid	Dialog Reference Watershed grid delineated from gage watershed function or streamreachwatershed function. Other watershed (e.g. HUC) raster also can be used as watershed grid. There is no python reference for this parameter.	Raster Layer
Input_Number_of_Grid_Cells	Dialog Reference Number of grid cells move to downstream based on flow directions. There is no python reference for this parameter.	Long
Input_Number_of_Processes	Dialog Reference This input indicates the number of stripes that the domain will be divided into and the number of MPI parallel processes that will be spawned to evaluate each piece of the domain. There is no python reference for this parameter.	Long
Output_Outlets_file	Dialog Reference This output is point a OGR file where each point is created from watershed grid having the largest contributing area for each zone. There is no python reference for this parameter.	File
Output_MovedOutlets_file	Dialog Reference This output is a point OGR file where each outlet is moved downflow a specified number of grid cells using flow directions. There is no python reference for this parameter.	File

ArcGIS Toolbox Python Syntax

ConnectDown (Input_D8_Flow_Direction_Grid, Input_D8Contributing_Area_Grid, Input_Watershed_Grid, Input_Number_of_Grid_Cells, Input_Number_of_Processes, Output_Outlets_file, Output_MovedOutlets_file)

Code Samples

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Title ConnectDown