Calculates the percentage of floodplain area within a reporting unit classified as selected land cover classes and creates an output table.

• This tool processes all polygons in the Reporting unit feature regardless of selections set. The ability to limit calculations to only selected reporting unit polygons is not supported in this release.

• NOTE: For the most accurate results and shortest processing times, it is highly recommended that all input layers be in the same spatial reference.

• NOTE: Enabling the Parallel Processing Factor environment can improve computation time for several ATtILA tools, but we have detected, on rare occasions, doing so can lead to spurious results. As a precaution, ATtILA will disable the Parallel Processing Factor environment for this tool. We hope to return this choice to the user once the impact on operational speed and accuracy of swapping geoprocessing tools with their pairwise counterparts has been assessed.

• The Reporting unit feature is a zone dataset.

  • A zone is defined as all areas in the input that have the same value. The areas do not have to be contiguous. The term "value" in this definition refers to the unique values in the Reporting unit ID field. Therefore, all polygons with the same reporting unit ID are treated as a single zone.

  • When more than one polygon has the same reporting unit ID, the areas for each polygon are combined and metrics are reported as a single record in the Output table.

• As the Reporting unit feature is a vector dataset, ArcGIS will perform a vector to raster conversion during processing.

  • To better control the vector to raster conversion, the tool defaults the Snap raster and the Processing cell size to that of the Land cover grid. These may be changed from within the tool.

  • If the extent of the Reporting unit feature is smaller than that of the Land cover grid, the user may wish to check the Reduce land cover grid to smallest recommended size option. This creates a temporary land cover raster with the processing extent equal to that of the Reporting unit feature to avoid unnecessary processing.

• If the Reporting unit feature has overlapping features, the zonal analysis will be performed for each individual feature.

• If a feature in the Reporting unit feature zone data does not overlap any cell centers in the secondary class rasters (e.g.,Land cover grid), those zones will not get converted to the internal zone raster. As a result, those zones will not be represented in the Output table.

• The Land cover classification scheme must correspond to the Land cover grid.

  • Schemes for common land cover datasets are included with ATtILA. Supplied schemes may be designated as either "ALL" or "LAND" (e.g. NLCD 2001 ALL vs. NLCD 2001 LAND). Schemes designated as "ALL" include all land cover classes in reporting unit area calculations, while those designated as "LAND" include only terrestrial land cover classes, with non-terrestrial land cover classes such as water and snow/ice excluded. More information about each of the classification schemes supplied with ATtILA may be found in Supplied Land Cover Classification Schemas.

  • In addition to the common land cover schemes, the tool permits a user-defined land cover classification scheme to be used by specifying a Land cover classification file. Refer to Land Cover Classification for more information on how ATtILA may be customized for user-specific needs.

  • NOTE: When a classification scheme with excluded land cover classes is selected, the areas of the excluded classes are disregarded in metric calculations. For example, when selecting a "LAND" classification scheme, the tool will process individual land cover classes and calculate metrics based on the total terrestrial area they occupy within the reporting unit, rather than the percent of the total area within the reporting unit. See Values Element in ATtILA's LCC XML Document and Values Window in the Land Cover Classification Editor for more information on excluded values.

• The Floodplain raster or polygon feature will allow you to choose either a raster, or a polygon feature.

  • When choosing a raster, floodplains are defined as any non-zero grid cell. The simplest example of this is a binary raster where floodplains are coded as 1 and everything else is coded as 0, but any value or comination of values can be used to designate floodplain areas as long as non-floodplain areas are coded as 0.

  • When choosing a polygon feature, floodplains are defined as any polygon feature. This tool does not make use of any attribute or combination of attributes to select floodplain polygons. All polygons in the floodplain input layer are considered floodplain areas. If polygons exits within the layer that do not represent floodplains, they need to be edited out before using the layer as input for this tool.

• Final output is written to the location specified in the Output table parameter. The Output table may be saved as a File Geodatabase Table, or a dBASE Table.

  • NOTE: For most consistent results, it is highly recommended that tool output be saved to a file geodatabase.

  • When saving as a File Geodatabase Table, no extension is necessary for the Output table name. The output location must be a file geodatabase.

  • When saving as a dBASE Table, include the .dbf extension in the Output table name. dBASE tables may not be saved in a file geodatabase.

• Field names in the Output table follow this naming scheme:

  • [class flcpField] or f[class Id] - The percent of the non-excluded floodplain area within a reporting unit occupied by the land cover class.

    • [class flcpField] is used if an flcpField attribute is provided in the class's element in the selected Land cover classification file.

      • (e.g., NINDEX_Flood for <class Id="NI" Name="All Natural Land Use" filter="" flcpField="NINDEX_Flood">)

    • f[class Id] - is used if an flcpField attribute is not provided.

      • (e.g., fNI for <class Id="NI" Name="All Natural Land Use" filter="">)

  • NOTE: Output field names can be altered by editing the Land cover classification file with the Land Cover Classification Editor (Refer to Classes Element in ATtILA's LCC XML Document for general information, or the individual Land cover classification file for details).

  • NOTE: The output field name for each class is shown as the second item next to the class's check box in Report metrics for these classes.

• In Additional Options, the user may elect to 'Add Quality Assurance Fields', 'Add Area Fields', and/or 'Retain Intermediate Layers Generated During Metric Processing'.

  • Add Area Fields

    • Choosing AREAFIELDS adds fields to record the raster area measurement of the selected land cover classes occuring in floodplains within each reporting unit. The field naming conventions is dependent on whether an flcpField is provided in the Land cover classification file:

      • [class flcpField]_A or f[class Id]_A - The area of the rasterized floodplain area, by reporting unit, occupied by the land use class.

  • Add Quality Assurance Fields

    • Choosing QAFIELDS adds a number of fields to the Output table to facilitate quality assurance checking.

      • FLCP_OVER - The percent overlap between the floodplain areas in each reporting unit and the Land cover grid.

      • FLCP_TOTA - The total raster floodplain area for each reporting unit (zone).

      • FLCP_EFFA - The effective raster area within a reporting unit's (zone) floodplain area after excluded classes have been removed.

      • FLCP_EXCA - The raster area of the excluded classes within a reporting unit's (zone) floodplain area based on exclusions in the Land cover classification scheme.

      • fTOTA - The percentage of the reporting unit classified as floodplain.

      • fEFFA - The percentage of the effective area in the reporting unit found in the floodplain area.

  • Retain Intermediate Layers Generated During Metric Calculation

    • Choosing INTERMEDIATES retains several of the key intermediate products (e.g., rasters, feature classes, tables) used to generate the final tool output. By examining the intermediate products, the user can gain a better understanding how the metric is calculated. The following intermediate products are listed in the general order they are generated:

      • flcp_Landcover# (raster) - Copy of the Land cover grid where non-floodplain areas (floodplain raster value = 0) are set to NULL. Produced when the Floodplain raster or polygon feature is a raster.

      • flcp\Intersect# (vector) - Intersection of the Reporting unit feature and the Floodplain raster or polygon feature. Produced when the Floodplain raster or polygon feature is a polygon feature class.

      • flcp_FldplnByRU# (vector) - Created by performing a Dissolve operation on flcp\Intersect# using the Reporting unit feature Id field as the dissolve field. The output contains multipart features. Produced when the Floodplain raster or polygon feature is a polygon feature class.

      • flcp_TabArea# (table) - A table of areas corresponding to the values in the Land cover grid occuring in floodplains within each reporting unit.

        • If the Floodplain raster or polygon feature is a polygon feature, the table is generated by performing a Tabulate Area operation using the flcp_FldplnByRU# and the copied Reporting unit feature Id field as the zone identifier and the Land cover grid as the raster to be summarized.

        • If the Floodplain raster or polygon feature is a raster, the table is generated by performing a Tabulate Area operation using the Reporting unit feature and its Reporting unit feature Id field as the zone identifier and the flcp_Landcover# as the raster to be summarized.

      • flcp_TabAreaFP# (table) - A table of floodplain (VALUE_1) and non-floodplain (VALUE_0) areas within each reporting unit. Produced when the Floodplain_raster_or_polygon_feature is a raster and QAFIELDS is selected in Additional options.

      • NOTE: To ensure unique filenames, intermediate filenames are typically generated using the CreateScratchName ArcPy function. This function provides a unique name for the intermediate product by appending a number to a filename prefix. The number starts at 0 and is incremented until a unique filename for the output workspace is found. The generated number is represented in this manual by the hashtag (#) symbol.

      • NOTE: The appended number may not be the same for all intermediate products saved during a tool run. Running a tool with different input options can result in different intermediate products being produced. If a tool is run more than once using the same output workspace, different number suffixes may be generated depending on the files already present in the output workspace.

FLCP (Reporting_unit_feature, Reporting_unit_ID_field, Land_cover_grid, Land_cover_classification_scheme, Land_cover_classification_file, Report_metrics_for_these_classes, Floodplain_raster_or_polygon_feature, Output_table, {Processing_cell_size}, {Snap_raster}, Select_options, {Reduce_land_cover_grid_to_smallest_recommended_size})

Floodplain Land Cover Proportions example 1 (Python window)

This example returns a table with the following fields: the proportion of the floodplain in the reporting unit zone comprised of agriculture land cover, and the proportion of the floodplain in the reporting unit zone comprised of developed land cover. The options to retain the intermediate calculation products, to add the square area values for the selected land cover classes in the floodplain, and to generate the quality assurance fields have also been selected.

NOTE: ATtILA tools that utilize the Report metrics for these classes parameter will clear all class selections when the tool is opened. This results in setting any variable set for that parameter to None when calling the tool from a script. Because of this, the standard scripting syntax (e.g. arcpy.ATtILA.LCP(variable 1, variable 2, variable 3, etc.) will fail. To overcome this idiosyncrasy, use the scripting example provided below. When using this technique, all variables are passed in as strings.

import arcpy
from arcpy.sa import *
arcpy.ImportToolbox(r"D:\Destination Folder\ATtILA v2.tbx")
from ATtILA2 import metric

Reporting_unit_feature = r"D:\pyexamples\data.gdb\Watersheds"
Reporting_unit_ID_field = "HUC_12"
Land_cover_grid = r"D:\pyexamples\data.gdb\NLCD_2016"
Land_cover_classification_scheme = "NLCD LAND"
Land_cover_classification_file = r"D:\Destination Folder\ToolboxSource\LandCoverClassifications\NLCD LAND.xml"
Report_metrics_for_these_classes = "'agr  -  [fagr]  Agriculture';'dev  -  [fdev]  Developed'"
Floodplain_raster_or_polygon_feature = r"D:\pyexamples\data.gdb\Floodplain_Raster"
Output_table = r"D:\pyexamples\results.gdb\Watersheds_FLCP"
Processing_cell_size = "30"
Snap_raster = r"D:\pyexamples\data.gdb\NLCD_2016"
Select_options = "'AREAFIELDS  -  Add Area Fields for All Land Cover Classes';'INTERMEDIATES  -  Retain Intermediate Layers Generated During Metric Calculation';'QAFIELDS  -  Add Quality Assurance Fields'"
Reduce_land_cover_grid_to_smallest_recommended_size = "false"

metric.runFloodplainLandCoverProportions(Reporting_unit_feature,
                                         Reporting_unit_ID_field,
                                         Land_cover_grid,
                                         Land_cover_classification_scheme,
                                         Land_cover_classification_file,
                                         Report_metrics_for_these_classes,
                                         Floodplain_raster_or_polygon_feature,
                                         Output_table,
                                         Processing_cell_size,
                                         Snap_raster,
                                         Select_options, 
                                         Reduce_land_cover_grid_to_smallest_recommended_size)

Floodplain Land Cover Proportions example 2 with raster floodplain input (Tool Details Messages)

This is a sample capture of the geoprocessing messages generated during a typical tool run. It is provided here to assist in the understanding of the tool's processing steps.

Start Time: Day, Month dd, yyyy hh:mm:ss AM/PM
Started: yyyy-mm-dd hh:mm:ss Setting up environment variables
Intermediates are stored in this directory: workspace path
Time: yyyy-mm-dd hh:mm:ss Generating land cover in floodplain grid...
Time: yyyy-mm-dd hh:mm:ss Save intermediate grid complete: flcp_Landcover0
Time: yyyy-mm-dd hh:mm:ss Tabulating the area of the flood plains within each reporting unit...
Time: yyyy-mm-dd hh:mm:ss Constructing the ATtILA metric output table
Time: yyyy-mm-dd hh:mm:ss Generating a zonal tabulate area table
Time: yyyy-mm-dd hh:mm:ss Processing the tabulate area table and computing metric values
Succeeded at Day, Month dd, yyyy hh:mm:ss AM/PM (Elapsed Time: ##.## units)

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