Stream Definition With Drop Analysis

Summary

This tool combines the function of the "Stream Drop Analysis" tool and the "Stream Definition by Threshold" tool. It applies a series of thresholds (determined from the input parameters) to the input accumulated stream source grid (*ssa) grid and outputs the results in the stream drop statistics table (*drp.txt). Then it outputs a stream raster grid, which is an indicator (1,0) grid of stream cells. Stream cells are defined as those cells where the accumulated stream source value is >= the optimal threshold as determined from the stream drop statistics. There is an option to include a mask input to replicate the functionality for using the *sca file as an edge contamination mask. The threshold logic should be: src = ((ssa >= thresh) & (mask >=0)) ? 1:0

Usage

There is no usage for this tool.

Syntax

StreamDefWithDropAnalysis (Input_Pit_Filled_Elevation_Grid, Input_D8_Flow_Direction_Grid, Input_D8_Contributing_Area_Grid, Input_Accumulated_Stream_Source_Grid, Input_Outlets, {Input_Mask_Grid}, Minimum_Threshold_Value, Maximum_Threshold_Value, Number_of_Threshold_Values, Use_logarithmic_spacing_for_threshold_values, Input_Number_of_Processes, Output_Drop_Analysis_Text_File, Output_Stream_Raster_Grid)

Parameter	Explanation	Data Type
Input_Pit_Filled_Elevation_Grid	Dialog Reference This input is a grid of elevation values. As a general rule, it is recommended that you use a grid of elevation values that have had the pits removed for this input. Pits are generally taken to be artifacts that interfere with the analysis of flow across them. This grid can be obtained as the output of the "Pit Remove" tool, in which case it contains elevation values where the pits have been filled to the point where they just drain. There is no python reference for this parameter.	Raster Layer
Input_D8_Flow_Direction_Grid	Dialog Reference A grid of D8 flow directions which are defined, for each cell, as the direction of the one of its eight adjacent or diagonal neighbors with the steepest downward slope. There is no python reference for this parameter.	Raster Layer
Input_D8_Contributing_Area_Grid	Dialog Reference A grid of contributing area values for each cell that were calculated using the D8 algorithm. The contributing area for a cell is the sum of its own contribution plus the contribution from all upslope neighbors that drain to it, measured as a number of cells or the sum of weight loadings. This grid can be obtained as the output of the "D8 Contributing Area" tool. In this tool, it is the contributing area (A) that is compared in the formula A > ML^y to determine the transition to a stream. There is no python reference for this parameter.	Raster Layer
Input_Accumulated_Stream_Source_Grid	Dialog Reference This grid nominally accumulates some characteristic or combination of characteristics of the watershed. The exact characteristic(s) varies depending on the stream network raster algorithm being used. This grid needs to have the property that grid cell values are monotonically increasing downslope along D8 flow directions, so that the resulting stream network is continuous. While this grid is often from an accumulation, other sources such as a maximum upslope function will also produce a suitable grid. There is no python reference for this parameter.	Raster Layer
Input_Outlets	Dialog Reference A point feature defining the outlets of interest. If this input file is used, only the cells upslope of these outlet cells are considered to be within the domain being evaluated. There is no python reference for this parameter.	Feature Layer
Input_Mask_Grid (Optional)	Dialog Reference This optional input is a grid that is used to mask the domain of interest and output is only provided where this grid is >= 0. A common use of this input is to use a D-Infinity contributing area grid as the mask so that the delineated stream network is constrained to areas where D-infinity contributing area is available, replicating the functionality of an edge contamination mask. There is no python reference for this parameter.	Raster Layer
Minimum_Threshold_Value	Dialog Reference This parameter is the lowest end of the range searched for possible threshold values using drop analysis. This technique looks for the smallest threshold in the range where the absolute value of the t-statistic is less than 2. For the science behind the drop analysis see Tarboton et al. (1991, 1992), Tarboton and Ames (2001). There is no python reference for this parameter.	Double
Maximum_Threshold_Value	Dialog Reference This parameter is the highest end of the range searched for possible threshold values using drop analysis. This technique looks for the smallest threshold in the range where the absolute value of the t-statistic is less than 2. For the science behind the drop analysis see Tarboton et al. (1991, 1992), Tarboton and Ames (2001). There is no python reference for this parameter.	Double
Number_of_Threshold_Values	Dialog Reference The parameter is the number of steps to divide the search range into when looking for possible threshold values using drop analysis. This technique looks for the smallest threshold in the range where the absolute value of the t-statistic is less than 2. For the science behind the drop analysis see Tarboton et al. (1991, 1992), Tarboton and Ames (2001). There is no python reference for this parameter.	Double
Use_logarithmic_spacing_for_threshold_values	Dialog Reference This checkbox indicates whether logarithmic or linear spacing should be used when looking for possible threshold values using drop analysis. There is no python reference for this parameter.	Boolean
Input_Number_of_Processes	Dialog Reference 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 of the stripes. There is no python reference for this parameter.	Long
Output_Drop_Analysis_Text_File	Dialog Reference This is a comma delimited text file with the following header line: Threshold, DrainDen, NoFirstOrd, NoHighOrd, MeanDFirstOrd, MeanDHighOrd, StdDevFirstOrd, StdDevHighOrd, T The file then contains one line of data for each threshold value examined, and then a summary line that indicates the optimum threshold value. This technique looks for the smallest threshold in the range where the absolute value of the t-statistic is less than 2. For the science behind the drop analysis, see Tarboton et al. (1991, 1992), Tarboton and Ames (2001). There is no python reference for this parameter.	File
Output_Stream_Raster_Grid	Dialog Reference This is an indicator grid (1,0) that indicates the location of streams, with a value of 1 for each of the stream cells and 0 for the remainder of the cells. There is no python reference for this parameter.	Raster Dataset

Code Samples

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Credits

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Use limitations

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