Flood From Stream WSE

Description

Determine floodplain depth and extent using "flood out" technique based on stream raster containing WSE. This is Python version of the Arc Hydro "Flood From Stream WSE" tool that simplifies user inputs. Tool uses Spatial Analyst Nibble function to assign water surface to each cell in the DEM based on the closest cell in the WSE raster. Cells where DEM is greater than flooded out WSE are removed. Unrestricted (by DEM or optional floodplain limit polygon) is kept for potential later use in BFE calculations. The provided result folder is used as a parent directory within which to create the process result folder and store the results of the tool. The short process name is used to name processing results:

• A folder within results directory to contain the process results.
• A geodatabase within the process result folder.
• A floodplain feature class prefixed by "FPPoly".
• Flood depth raster prefixed by "FD".
• Unrestricted (by DEM) WSE raster prefixed by "WSE".

For example, for results folder set to "C:\results" and short process name set to "B100", the tool will generate the following output structure:

• C:\results\B100\Layers\FDB100 - flood depth raster.
• C:\results\B100\Layers\WSEB100 - unrestricted WSE raster.
• C:\results\B100\B100.gdb\Layers\FPPolyB100 - floodplain extent polygon feature class.

Explicit naming of the output layers is not enabled.

If optional hydraulics river feature class is provided, only floodplain elements contiguous to the river will be maintained.

If optional floodplain limit polygon is provided, the floodplain extent will be limited to that polygon extent.

Usage

Parameters

Parameter Name	Type	Direction	Data Type	Dialog Reference
Input WSE River Raster	Required	Input	Raster Layer	Raster with WSE values along the stream that will be "flooded out".
Input DEM Raster	Required	Input	Raster Layer	DEM raster that will be "flooded".
Input Result Folder	Required	Input	Folder	Parent folder in which to store results.
Input Short Process Name (up to 10 characters)	Required	Input	String	Short name (up to 10 characters long) that will be used to name the process result folder and resulting layers.
Input Hydraulics River FC	Optional	Input	Feature Layer	Polyline feature class that if provided will be used to limit the extent of flooding to the area that is directly connected to the lines in this feature class (will remove "disconnected" flood polygons). If not provided, disconnected flood polygons will not be removed.
Input Floodplain Limit Polygon FC	Optional	Input	Feature Layer	Polygon feature class that if provided will be used to limit the extent of flooding to the area that is within the polygons in this feature class. This can be used to limit the extent of flooding to individual stream reaches or watersheds. If not provided, there will be no explicit limit to the extent of the derived floodplain (extent of the DEM will define the potential flooding extent).