U.S. Department of the Interior U.S. Geological Survey NED, NHD and WBD Preparation Using the New England Method Streamstats Data Preparation Workshop

U.S. Department of the InteriorU.S. Geological Survey

NED, NHD and WBD Preparation Using the New

England Method

Streamstats Data Preparation Workshop

Pete Steeves and Alan Rea

MA-RI and ID Districts

USGS

StreamStats Data Prep Workshop May 3-7, 2010 Page 1-2

NHD Watershed• DEM preparation using the New England method was

also used to create a watershed tool for NHD. For areas that were prepared for NHD Watershed, an intermediate elevation grid (topogr_gr) can be used as a source DEM in preprocessing data for StreamStats. Several overlapping objectives include:– Delineate a watershed from any point location on NHD

reaches quickly, reliably, and accurately– Relate the resulting watershed to the reach and measure of

the selected point (in essence, create a “polygon event”)– Horizontally integrate 3 earth-surface-based physiographic

datasets (hydrography, basin boundaries, and elevation data) through a series of pre-processing steps


The New England MethodApplied

• Massachusetts StreamStats

• New England SPARROW– Rich Moore and Craig Johnston

• NHD Watershed

• NHD Plus

• Many National StreamStats State Apps


Overview• Projections• Tiling scheme (database design)• Developing datasets in neighboring states• Preparing NHD and WBD• Preparing NED data

– NED Extract tools– Topogrid – Bathymetric Gradient processing– Walling and Burning (hydrodem.aml)


Projections

• The Streamstats team originally decided to go with a multi-projection environment.

• Every state will decide it’s own projection(s)• This requires some upfront GIS planning for a

given state:– Basemaps– DEM preparation– Basin characteristics

• If there is no obvious reason to go with a State-centric projection, the StreamStats team recommends a US Albers projection for your data


Tiling Scheme

• Streamstats has adopted the 8-digit Hydrologic Unit as it’s tiling scheme

• This tiling scheme is also being used for NHD, WBD, and EDNA

• The ‘single outlet’ standard for hydrologic unit tiles is ideal for the ArcHydro/Streamstats environment



Developing Datasets in Neighboring States

• Define your study area• Study areas are 2 tiered

– Tier 1 includes full or partial 8-digit Hydrologic Units (HUCs) where a complete set of ArcHydro datasets need to be produced

– Tier 2 includes full HUCs upstream of your state and not overlapping your state


Tier 1 Consideration for Massachusetts


Tier 2 Consideration for Massachusetts


Developing Datasets in Neighboring States

• Tier 1 data needs to be developed in your State projection

• Tier 2 data can be developed in any projection. The final vector Global datasets can be projected without complications








Preparation of NHD

• NHD acts as the backbone, upon which the other datasets are structured

• Keep in mind that the optimal goal is to have a dendrite network

• Only the centerline features (called Flowlines in NHD Geodatabase) are used when preparing the NHD for StreamStats ‘burning’ (waterbodies are used in the ‘bathymetric gradient’ process)


Preparation of NHD (cont)

• Acquire hi-resolution NHD for every HUC in your study area

• Best bet: Get NHD in Geodatabase format• Save a copy that you will modify just for

this process. The copied mdb can be projected at this time

• Load the flow lines into ArcMap & edit • When finished, export to a coverage



• Remove all isolated networks that are not part of the main network (optional)

• Flip arcs if working with NHDinArc. NHDGeo flowlines already point downstream (only needed for TOPOGRID).

• Extend the outlet arc • Trim inlets and headwaters 15 meters

inside the HUC (a huc buffer can be used to automate this process)





• A final step involves making a dendrite of the NHD

• A consequence of skipping this step may be incorrect watershed delineations for points on the braided section of a network

• Canals and other man made structures must be dealt with on a case by case basis




Preparation of WBD

• WBD boundaries act as retainer walls for DEM preparation.

• By including WBD in the preprocessing, watershed delineations are forced to recognize these boundaries as truth


Preparation of WBD (cont)

• Boundaries may need to be modified to make certain that they cross NHD in a single location for a given basin polygon.

• Boundaries can be added to WBD (i.e. basin boundaries delineated to gage station locations).








Preparation of WBD (cont)

• For dense basin boundary datasets weed out any boundaries that do not work well with NHD, particularly in areas with man-modified structures (i.e. canals)

• This work needs to be done in coordination with NHD preparation. At times it may be more appropriate to weed out NHD features (i.e. canals)

• WBD can be modified within a HUC, but any modifications along the HUC8 border need to be reconciled with neighboring HUCS







Preparation of NED

• NED Extract Tools (StreamStats tools developed by Al Rea)– Make NED Index– Extract Polygon Area From NED– Check NODATA – Fill NODATA Cells– Project and Scale NED


Preparation of NED (cont)

• Topogrid is a computation intensive step that enforces NED to recognize NHD as drainage truth.

• Subsequent walling and burning steps further enforce the Topogrid process by exaggerating elevation values along NHD and WBD features


Preparation of NED (cont)

• Several preliminary steps include:– Projecting – Clipping the NED to a 2000 meter buffer area

around the basin– Converting zunits to centimeters (zunits = 100)– If your HUC has partial areas with 10 meter

DEMs (and you want to use them), this data needs to be developed separately from the NED for these preliminary steps

– Converting DEM values to points


Topogrid

The Topogrid command is an interpolation method specifically designed for the creation of hydrologically correct digital elevation models (DEMs) from comparatively small, but well selected elevation and stream coverages. It is based upon the ANUDEM program developed by Michael Hutchinson (1988, 1989).


Topogrid Represents the ‘Intermediate Step’


Topogrid

• Resample cell size to 10 meters• Set your origin coordinates using the

subcommand ‘XYZlimits’• Buffer your HUC boundary 50 meters and

use for subcommand ‘Boundary’• Input layers include dendrite streams and

NED points• Save the resulting dataset after post

Topogrid processing


Topogrid• For most HUCs, breaking up your

watershed may be necessary prior to running TopoGrid– The key factor is GridAllocation– Be sure to buffer each subset 2000 meters

(hence, overlap) for input NED points– Be sure to buffer each subset 50 meters (hence

overlap) for the subcommand ‘Boundary’– Use the full dendrite layer for each subset



Walling and Burning

• Exaggerate the depth of the dendrite and height of the WBD boundaries

• Simply run the hydrodem.aml (which runs the agree.aml as well)

• Agree.aml is used for burning: http://www.crwr.utexas.edu/gis/gishyd98/quality/agree/agree.htm#Part1

U.S. Department of the InteriorU.S. Geological Survey



Getting NHD Data• http://nhd.usgs.gov/data.html• For SubBasins (8-digit HUCs):

– “Go to NHD Viewer NHD Geodatabase” – Activate the Subbasins layer under Hydrologic Units (in

the legend)– Use the Polygon Extract tool to draw a box through the

NHD datasets to download (maximum 10 at a time)– The popup window allows you to select resolution

(choose ‘High’) and format (choose ‘File Geodatabase’). Skip step 3 (Flow Table). Enter email address (step 4)

– Data should be made available within a day• For Pre-staged Subregions (4-digit HUCs):

– “Go to Pre-staged Subregions”– Select ‘High’ (resolution) and then ‘FileGDB’– Download datasets of interest


Getting WBD Data• http://www.ncgc.nrcs.usda.gov/products/d

atasets/watershed/• To obtain data by State or bounding box

– Select “Obtain Data by State, County, or Other Area” to go to the Data Gateway

– In the Data Gateway, select ‘Get Data’ to follow a simple 4 step procedure

• To obtain National Seamless Data– Select “Obtain Seamless National Data– Download the zip file

• WBD Guidelines can be accessed at: http://pubs.usgs.gov/tm/tm11a3/


Getting NED Data• 1/3 arc second NED data, as well as several

other national datasets are now available from EROS Data Center for free, at least for USGS customers

• Send them an external hard drive. You will have to get the whole country (they won’t pull out just the piece you want)

• Not the lead time required: 4-6 weeks• More info on the StreamStats wiki link:

http://privusgs2.er.usgs.gov/display/StreamStats/Getting_NED_Data



HydroDEM.aml


HydroDEM

• Required Input: DEM data, the 8-digit HUC boundary, and NHD flowlines for a given HUC.

• Optional Input: NHD waterbodies and waterbody centerlines (for bathymetric gradient processing), interior basin boundaries, and “drain plugs”

• Horizontally integrate the input datasets and set up a HUC tile for the ArcHydro global environment that perfectly fits neighboring tiles

• Ouput includes all grids necessary for watershed processing in ArcHydro: fil, fdr, fac, str, lnk, cat


Required Input # 1: DEM Data

• Must already be projected• Must buffer the HUC boundary by at least 5 cells • Units must be in meters or feet. • Cell size must equal 10 for meters or 30 for feet• Must have origin coordinates that are divisible by

10 (units = meters) or 30 (units = feet)• Must have zunits defined in the projection

parameters (zunits = 100)• Source can be 10 meter DEM, resampled 30 meter

NED, or New England Method Topogrid output



Required Input # 2: NHD Flowlines

• Must be clipped and trimmed back at least 1 full cell length inside the basin boundary, except where flow exits the basin. This includes true inlets (a good way to track these is to interesect the flowlines with a 10-meter buffer of the HUC boundary)

• The exit arc must extend beyond the 5-cell buffer boundary (50 meters)



Required Input # 3: 8-digit HUC Boundary

• Must be a polygon

• Used for 2 purposes– To create a 5-cell-buffer mask grid,

which is used as a raster analysis window and mapextent

– To define a hard wall around the HUC



Optional Input

• NHD Water Body and Water Body Flowline Grids >> used for bathymetric gradient conditioning in lakes, ponds, reservoirs, and wide rivers

• Inner Walls (any additional basin boundaries located inside the HUC that you want to use for inner wall ridging)– Boundaries must not overlap the outer wall

• Drain Plugs. Used in areas with playas or other true depressions (i.e. non-contributing areas)


Inner Walls


Setting up bathymetric gradient processing

• HydroDEM.aml requires 2 grids for baythymetric gradient processing– Grid of water bodies– Grid of flowlines for the water bodies

• These should only include waterbodies that connect to the network



Bathymetric Gradient in Waterbodies


Standard DEM Flow lines


Flow lines with Bathymetric Gradient





Flow Accumulation Adjustments for Downstream

HUCs


Flow Accumulation Adjust

• Flow accumulation grid values need to be adjusted for all downstream HUCs (any HUC that receives flow from another)

• The values need to be adjusted at the point where the outlet of an upstream HUC meets the inlet of the downstream HUC

• There could potentially be multiple inlets to a single HUC. In these cases flow needs to be adjusted at each inlet

• Flow accumulation adjustments must be done starting with headwater HUCs and proceeding downstream

• All grids that are created by HydroDEM.aml after the fac grid need to be re-computed (str, lnk, cat)


Before / After


Cleanup

• Temporary grids and coverages should be removed from the local workspaces (they are initially kept for QA/QC)

• Final terrain-processing grids (fdr, fac, cat, etc.) should all be integer grids

• Final geodatabases should be compacted


Exercise 1

Run HydroDem and Flow Accumulation Adjustment

AMLs in ArcMap


Documents

U.S. Department of the Interior U.S. Geological Survey NED, NHD and WBD Preparation Using the New England Method Streamstats Data Preparation Workshop