NHD Watershed: Tools and

ApplicationsBy Pete Steeves,

USGS Water Resources DisciplineNorthboro, Massachusetts

508-490-5054psteeves@usgs.gov

Acknowledgements

• Jennifer Hill, Horizons Systems Corporation

• Aleda Freeman, MassGIS

• Craig Johnston, USGS

This Talk Focuses on:

• 2 NHD ArcView Toolkit extensions– NHD Watershed– NHD Watershed Characteristics

• 3 Applications of these extensions– VT Flood Frequency project– New Hampshire Low Flow project– Massachusetts Perennial / Intermittent

streams project

Background

• Massachusetts Watershed Analyst (MassGIS and USGS collaboration)

• Tools and datasets not immediately transferable nationally

• An application, Massachusetts ‘Streamstats’ showcases the applicability of these tools– http://ma.water.usgs.gov/streamstats

NHD Watershed: Objectives• To develop a tool in the NHD ArcView Toolkit which

delineates a watershed from any point location on NHD reaches quickly, reliably, and accurately

• To relate the resulting watershed to the reach and measure of the selected point (in essence, create a “polygon event”)

• To horizontally integrate 3 earth-surface-based physiographic datasets (hydrography, basin boundaries, and elevation data) through a series of pre-processing steps

• To document the pre-processing steps for others

National Datalayers

• Hi-resolution NHD (1:24,000 scale)

• 12-digit hydrologic unit (HUC)

boundaries (future WBD) (1:24,000

source scale)

• National Elevation Dataset (NED)

Pilot HUC:

White River Basin, VT (01080105)

Pre-processing steps - NHD• Convert the NHD route.rch table to an

arc coverage and direct all flow downstream

• Remove all routes that are not connected to major networks

• Optionally remove sections of braids (resulting in a dendrite network)

• Extend the exit centerline ~ 50 meters beyond the HUC boundary

Example: Removing a Braid

Pre-processing steps - WBD• Optionally add sub-basin boundaries to

the 12-digit HUC datalayer.

• Buffer the 8-digit HUC boundary 4000 meters for the subsequent TOPOGRID command analysis area

• Buffer the 8-digit HUC boundary 50 meters to ensure the vector boundary will be used in all raster analysis steps

Example: Adding Sub-basins

Pre-processing steps - NED• Run TOPOGRID to drainage enforce the

NED to NHD. Input includes:– The edited dendrite network from NHD– A NED-derived point coverage of elevation values

• Use a series of GRID steps to exaggerate the watershed boundary ridges where TOPOGRID output coincides with the WBD

• Run ‘agree.aml’ to ‘canyonize’ the dendrite using output from the TOPOGRID/ridge steps, further enforcing the NED to NHD

Example: Enforcing NED to NHD

Final Pre-processing Steps• Use the drainage enforced elevation grid

to produce the flow direction and flow accumulation grids (then discard the drainage enforced elevation grid)

• Use the ‘WATERSHED’ command to delineate a catchment for every NHD reach in the dendrite coverage

• Load the appropriate datasets into a standardized ‘NHD Watershed’ directory

Reaches Catchments

NHD Watershed Directory Structure

d ir_ g rd a ccu m _ g rd ca tch m e n t_cov

d e nd rite .shpd e nd rite .shxd e nd rite .d b f

d e nd rite

0 1 08 0 10 5_ w s

How NHD Watershed Works• The user selects a point on a reach• NHD Navigate determines all upstream reaches from that

point (including the partial reach segment of the selected reach)

• A relate is performed between reaches and catchments to select all upstream catchments

• A partial catchment is determined within the selected reach catchment

• The partial catchment is combined with selected upstream catchments and internal boundaries are dissolved

• Attribution of the newly delineated watershed includes the reach code and measure of the user selected point

NHD Watershed Fun Facts

• Is an ArcView 3x extension• Is designed to work with NHD and the NHD

ArcView Toolkit• For full functionality the user needs Spatial

Analyst (a ‘watershed for confluences only’ option can be used without Spatial Analyst)

• The extension, pre-processing instructions, list of available HUCs, and other related info is available on the NHD website: http://nhd.usgs.gov, under ‘Applications’

NHD Watershed Characteristics: Objectives

• A generic extension which helps guide users to summarize basin characteristics of choice for newly delineated watersheds

• Built on top of NHD Watershed• An open, well documented script

environment for users to modify as needed

NHD Watershed Characteristics (cont.)

• Designed as a transition tool from the general NHD Watershed environment to the specific user application environment

• Not yet available on the NHD website

Applications

• Vermont Flood Frequency project

• New Hampshire Low Flow project

• Massachusetts Perennial / Intermittent Streams project

Vermont Flood Frequency

• USGS NH District cooperative effort with VT Department of Transportation

• Regression equation estimates of peak flow for any point on any stream in Vermont

• The entire state has been processed for use in the NHD ArcView Toolkit

New Hampshire Low Flow

• USGS NH District cooperative effort with the State’s Geological Survey

• Seasonal and annual statistics for:– Ground water recharge– Low flow

• Hydro-climatic data (PRISM) used extensively as a source for significant seasonal predictors including: temperature, snow fall, and precipitation

Massachusetts Perennial / Intermittent Project

• Needed by Mass. DEP for regulatory purposes in enforcing the State’s River Protection Act of 1996

• A logistic regression equation has been developed to determine these points

• The NHD Watershed and NHD Watershed Characteristics tools are being used in batch mode to find these points and map them

Watershed Characteristics

• Basin area• Percent area of stratified-drift (sand

and gravel) deposits• Drainage density (length of streams

/ drainage area) • Mean basin elevation• Percent area of forested land

In the works….

• Considering the transition of the NHD Watershed and NHD Watershed Characteristics extensions to the NHDinGeo environment along with other NHD Toolkit functions

• Working with NHD Watershed preprocessed datasets in the ArcHydro global tools environment