CALCULATE LAND SPILL NHD INTERSECTIONS

Summary

Calculate Land Spill NHD Intersections calculates intersections between your NetCDF release point plume simulations and NHDPlus High Resolution (HR) hydrography features. The intersection point features output by this tool serve as the starting point locations for the downstream transport modeling performed by the Hydro Trace tool. The tool also outputs polygon representations of the multidimensional raster release plumes.

To learn more about the Liquids HCA Tool in general, please see Liquids HCA Tool Frequently Asked Questions.

To learn more about the structure of the Liquids HCA Tool project geodatabase, please see Liquids HCA Tool Data Dictionary.

Usage

GeoClaw treats NHDPlus HR features as “sinks” in the GeoClaw simulation space; plume elements encountering an NHD feature in the simulation space are removed from the simulation. When a plume encounters an NHD feature, overland plume transport ceases and hydrographic transport takes over. For this reason, it is critical to know where and when to hand off from overland transport to hydrographic transport. Calculate Land Spill NHD Intersections performs that calculation; the NHD intersection points output by the tool serve as the link between overland transport and hydrographic transport. For modeling purposes, the first intersection of a given overland product plume with a given NHD feature serves as the starting point (in time and space) for subsequent hydrographic transport of the product plume.

Calculate Land Spill NHD Intersections also creates a polygon feature class in your Liquids HCA project file geodatabase, named OVERLAND_SPREAD_POLYGONS, that stores one or more polygonal representations of each release plume. For each NHDPlus HR hydrography feature intersection, the tool creates an overland spread polygon representation of the plume at that point in time. The tool also generates an overland spread polygon representation of the plume at the overland flow response time (generally the maximum extent of the plume), and a separate overland spread polygon representation of the plume at its maximum extent, if that extent differs from the plume at the overland flow response time. (This may occur for certain rapidly evaporating products.)

Calculate Land Spill NHD Intersections uses the following tool parameters:

Input Project Database – This is the Liquids HCA project file geodatabase you created with the Initialize Database tool. By default, the remaining feature-based input parameters will be sourced from your project file geodatabase, and the output NHD intersection points are written to your project file geodatabase.
Working Directory – This must be the same working directory that you used in running Create GeoClaw Cases, Run Cases on Azure, and Download Cases from Azure. The plume simulation NetCDF files used to calculate your NHDPlus HR feature intersections are stored in your Liquids HCA project working directory under their corresponding GeoClaw case folders.
Input Release Point Features – This must be a valid release point feature class created using the Create Release Points tool. By default, this parameter is populated with the OSPOINTM release point feature class in your specified project geodatabase. This tool utilizes the values of the POINT_ID release point identifier field in your release point features.
Input Route Features – This must be a valid route centerline feature class imported into your project geodatabase via the Initialize Database tool. By default, this parameter is populated with the ROUTES centerline routes feature class in your specified project geodatabase. This tool utilizes the values of the ROUTE_ID centerline route identifier field in your centerline route features.
Input Global Inputs Table – This must be a valid global inputs table in your project geodatabase populated via the Import Global Input Data or Enter Global Input Data tools. By default, this parameter is populated with the GLOBAL_INPUTS table in your specified project geodatabase. This tool utilizes the values of the HTRES_TIME hydrographic trace response time field (by route) in your global inputs table.

The following three NHDPlus HR feature classes downloaded into your project geodatabase through the use of the NHDPlus High Resolution Data Download tool are used as input to Calculate Land Spill NHD Intersections. You must ensure that you have successfully run this tool prior to running Calculate Land Spill NHD Intersections.

Input NHD Flowline Features – This must be a valid NHDPlus HR Plus flowlines feature class downloaded and imported into your project geodatabase via the NHDPlus High Resolution Data Download tool. By default, this parameter is populated with the NHDFlowline flowlines feature class in your specified project geodatabase. NHD flowline features are the polyline features that represent the flowing river/stream network in the NHDPlus HR dataset. They primarily comprise smaller rivers and streams that can be represented with simple polylines, as well as artificial linear paths delineating the flow network through larger rivers (and other hydrography features where flow is present) represented by areal polygons.
Input NHD Area Features – This must be a valid NHDPlus HR Plus areas feature class downloaded and imported into your project geodatabase via the NHDPlus High Resolution Data Download tool. By default, this parameter is populated with the NHDArea areas feature class in your specified project geodatabase. NHD areas primarily comprise the polygonal representations of larger (wider) rivers and other flowing bodies of water. Corresponding artificial flow paths in the NHD flowlines feature class define the flow network through these features.
Input NHD Waterbody Features – This must be a valid NHDPlus HR Plus waterbodies feature class downloaded and imported into your project geodatabase via the NHDPlus High Resolution Data Download tool. By default, this parameter is populated with the NHDWaterbody waterbodies feature class in your specified project geodatabase. NHD waterbodies comprise the polygonal representations of non-flowing waterbodies, such as lakes and ponds. For the sake of hydrographic network continuity, many of these nominally non-flowing waterbody features are accompanied by corresponding artificial flow paths in the NHD flowlines feature class which define the nominal flow network through these non-flowing waterbody features.
Input NHD HUC4 Boundary Features – This must be a valid NHDPlus HR Plus HUC4 boundary feature class downloaded and imported into your project geodatabase via the NHDPlus High Resolution Data Download tool. By default, this parameter is populated with the NHDHU4Boundary hydrologic unit code (HUC) boundaries feature class in your specified project geodatabase. NHD HUC4 boundaries are the polygon features that represent the boundaries of HUC4 features in the NHDPlus HR dataset.
NHD Features Search Tolerance – This parameter is a value in the linear units of your choice that defines how closely a release plume must approach an NHD feature before being counted as an intersection. Bear in mind that the USGS 3DEP elevation data is often more detailed and of more recent vintage than the elevation data used to support the creation of the NHDPlus HR dataset. Because of this, the natural drainage of the 3DEP topography data may not coincide exactly with the drainage network defined by the NHDPlus HR dataset. As a result, GeoClaw simulation plumes may approach or parallel NHD Plus HR features, but never actually intersect them. The NHD Plus HR dataset was constructed primarily from older, 10m horizontal resolution elevation data. Given the older vintage and lesser resolution of the source NHD Plus HR elevation data, the default parameter value of 30 meters provides a reasonable “fudge factor” for release plume – NHD feature intersections.
Output NHD Intersections Feature Class – This parameter allows you to specify the name and location of the output NHD intersections point features created by the tool. By default, the tool creates an output feature class named NHD_INTERSECTIONS in your specified project geodatabase. There is generally no reason to change the default name of this feature class.
Output Overland Spread Polygons Feature Class – This parameter allows you to specify the name and location of the overland spread polygons feature class output by the tool. The default value is OVERLAND_SPREAD_POLYGONS, located in your specified project geodatabase. There is generally no reason to change the default value of this parameter.
Smooth Output Overland Spread Polygon Features – This checkbox parameter allows you to specify whether to smooth the output overland spread polygons, or to leave the output polygons with jagged outlines corresponding exactly to the cell boundaries of the release plume multidimensional raster files. By default, this parameter is enabled.

In a typical Liquids HCA Tool workflow, Calculate Land Spill NHD Intersections is run after NHDPlus High Resolution Data Download and Download Cases from Azure, and before Hydro Trace.

For visual reference on Liquids HCA Tool execution order, see Liquids HCA Tool Process Flow Diagrams.

Syntax

CalculateLandspillNHDIntersections_ (in_workspace, in_nc_data_dir, in_ospointm_features, in_route_features , in_global_inputs_table, in_nhd_flowline_features, in_nhd_area_features, in_nhd_waterbody_features, in_nhd_huc4_bnd_features, {in_nhd_search_tol}, out_nhd_intersections_features, out_os_polygon_features, {smooth_os_polygons})

Parameter	Explanation	Data Type
in_workspace	Dialog Reference Specify your input Liquids HCA project geodatabase. There is no Python reference for this parameter.	Workspace
in_nc_data_dir	Dialog Reference Specify the working directory storing your release point case folders (and the NetCDF plume simulation files contained therein). There is no Python reference for this parameter.	Workspace
in_ospointm_features	Dialog Reference Specify your input release point features from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_route_features	Dialog Reference Specify your input pipeline centerline route features on which your input release point features are located from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_global_inputs_table	Dialog Reference Select the global inputs table from your input project geodatabase. There is no Python reference for this parameter.	Table View
in_nhd_flowline_features	Dialog Reference Specify your input NHD flowline features from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_nhd_area_features	Dialog Reference Specify your input NHD area features from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_nhd_waterbody_features	Dialog Reference Specify your input NHD waterbody features from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_nhd_huc4_bnd_features	Dialog Reference Specify your input NHD HUC4 boundary features from your input project geodatabase. There is no Python reference for this parameter.	Feature Layer
in_nhd_search_tol (Optional)	Dialog Reference Specify the distance that defines how closely a release plume must approach an NHD feature before being counted as an intersection. There is no Python reference for this parameter.	Linear Unit
out_nhd_intersections_features	Dialog Reference Specify a name and destination for your output NHD Intersections feature class. There is no Python reference for this parameter.	Feature Layer
out_os_polygon_features	Dialog Reference Specify the name and destination for your output overland spread polygon features. There is no Python reference for this parameter.	Feature Layer
smooth_os_polygons	Dialog Reference Specify whether to smooth output overland spread polygons. There is no Python reference for this parameter.	Boolean

Code sample

The following script demonstrates how to use Calculate Land Spill NHD Intersections in Python:

import arcpy

arcpy.ImportToolbox(r”C:\Program Files\ArcGIS\Pro\bin\Python\envs\arcgispro-py3\Lib\site-packages\liquidshca\esri\toolboxes\LiquidsHCA.pyt”)

arcpy.env.workspace = r “C:\data\test.gdb”

in_workspace = r “C:\data\test.gdb”

netcdf_dir = “C:\data”

global_inputs = “global_inputs”

route_features = “PipelineCenterlines”

release_points = “OSPointM”

nhd_fl_features = r”C:\data\test.gdb\NWDataset\NHDFlowline”

nhd_ar_features = r”C:\data\test.gdb\NWDataset\NHDArea”

nhd_wb_features = r”C:\data\test.gdb\NWDataset\NHDWaterbody”

nhd_huc4_features = r”C:\data\test.gdb\NWDataset\NHDHU4Boundary”

nhd_int_features = r “C:\data\test.gdb\NHD_Intersections”

buffer_dist = “30 Meters”

out_os_polygons = r “C:\data\test.gdb\OVERLAND_SPREAD_POLYGONS”

smooth_os_polys = TRUE

arcpy.liquidshca.CalculateLandspillNHDIntersections(in_workspace, netcdf_dir, release_points, route_features, global_inputs, nhd_fl_features, nhd_ar_features, nhd_wb_features, nhd_huc4_features, buffer_dist, nhd_int_features, out_os_polygons, smooth_os_polys)

Environments

Current Workspace, Scratch Workspace, Default Output Z Value, M Resolution, M Tolerance, Output M Domain, Output XY Domain, Output Z Domain, Output Coordinate System, Extent, Output has M values, Output has Z values, XY Resolution, XY Tolerance, Z Resolution, Z Tolerance , Geographic Transformations.

Licensing information

This tool requires a valid Liquids HCA Tool user license or subscription. Please see the Request License and Register License tool help topics for details on obtaining and registering a Gas HCA Tool software license.

Credits

Use limitations

There are no access and use limitations for this item.