NHDPlus: A Big PLUS for User Applications ESRI User Conference - July 24, 2005 The NHDPlus Team HorizonSystemsCorporation Sponsored by US EPA

The NHDPlus Team EPA Project Lead Tommy Dewald Horizon Systems Cindy McKay Jen Hill Bob Deffenbaugh USGS WRD Rich Moore Craig Johnston Al Rea RTI International. Tim Bondelid

Our Agenda  What is NHDPlus? Data to Support Analysis & Modeling Data to Support Analysis & Modeling Data Availability Data Availability  Applications – Just a Start  Wrapup  Questions

NHD Plus – What is it?  Greatly Improved 1:100K NHD  A Set of Value Added Attributes  Elevation-based Catchment for Each Segment in the Stream Network  Catchment Characteristics  Flow Direction and Flow Accumulation Grids  NHD Network Node Elevations  Stream Gages Linked to Stream Network  Flow Volume & Velocity Estimates for Each Segment in the Stream Network

1:100K NHD Improvements  Stream and waterbody name corrections and additions  Correction to stream network coordinate order (pointing downstream)  Correction of gaps, overlaps, overshoots, etc. in network geometry  Independent QAQC of flow table.  Flow table and geometry agree.

The Value-Added Attributes:  A set of two dozen network characteristics  Based solely on native NHD content  Created with software  Built using the national NHD  Provides alternatives to navigating with the geometry

Display Generalization Attribute Stream Order Waterbody Identifier Waterbody Type Upstream Miles Distance to Sink Navigation Analysis Value Added Attributes Stream Order Waterbody Identifier Waterbody Type Upstream Miles Distance to Sink Drain Stream Level Link-Node Traversal Hydrologic Sequence Terminal Identifiers Level Path Identifiers Independent Flow Table

Simple Query Network Navigation  A Series of Attributes Computed From the Flow Table and the Geometry  Once Computed, Independent of Geometry and GIS  Navigate with SQL Query

VAAs Help with NHD Displays

e.g. Strahler Stream Order The smallest permanent streams are called "first order". Two first order streams join to form a larger, second order stream; two second order streams join to form a third order, and so on. Smaller streams entering a higher-ordered stream do not change its order number. Strahler VAAs for Analysis

Catchments  The portion of the land surface that drains to a network segment  Catchments built using 30m National Elevation Dataset (NED)  Generated using the “New England Method” (with AGREE.AML)  Outputs include catchments in grid format and as polygons

NHDPlus Catchments

Production status 7/8/05 – 2,161,911 catchments and counting

International Catchment Areas

Bathymetric Gradient in Waterbodies

Standard DEM Flow lines

Flow lines with Bathymetric Gradient

Elevation Smoothing Perform and display analyses along a stream profile

Flow Estimates Unit Runoff Method  Estimate average annual unit runoff by 8- digit HUC (sub-basin)  Estimate Drainage Area (DA) for Each NHD segment  Route and accumulate incremental flows to estimate mean annual flow by segment

 Flow estimates developed using mean annual flows at HCDN gages  Multiple regression technique with coefficients by hydrologic region  NHD Plus implementation uses catchment- based DA’s, PRISM data overlaid on catchments Flow Estimates Vogel, et al Method

Cumulative Drainage Area Snake River

Velocity Estimates  Inputs: Drainage area, stream segment slope, mean annual discharge  Future QAQC Possibilities: USGS Time of Travel Database  Reference: Jobson, H. E Prediction of Travel Time and Longitudinal Dispersion in Rivers and Streams. USGS Water Resources Investigations Report

NHDPlus Applications - Some Examples  Some of these are “Right out of the box”  Some are simple ArcView Operations  Some require programming  Within a database environment  The programming is not complex or lengthy  Analyses can go back and forth between catchments and the flow network  For many applications, building the front end user interface is probably more work than the actual application building

“Flexible Watersheds” Based on User Requirements

Quad Density Artifacts in NHD

NHD with Flow > 2 cfs: Hydrologic Equity

Cincinnati Watershed

Cincinnati “Area of Influence”: The Watershed that is 3 Days Time of Travel Upstream

Land Cover – Commercial/Industrial

Urban Catchment

Simple Dilution and Decay Model

SPARROW Model Results: Predicted Total Nitrogen Catchment Yield Contributions to Total Nitrogen from each source AtmosphericDeveloped AgriculturePoint Source = + ++

Correcting the GeoCoding, use Update NHD Location tool. 1)Zoom-in to site and NHD reach, DRG highly recommend. 2)Click Update NHD Location tool, (cursor changes to flag) 3)Click on NHD stream that best represents where streamflow is being gaged (before)(after) Update NHD Location -

23,945 gages were reviewed and examined 17,482 gages batch indexed correct & NHD location not moved - 73%. 962 gages were flagged as "Do Not Use“ - 4% 1230 gages were flagged as "No 100k NHD Reach" - 5% 4271 NHD locations moved an average of 795 meters - 18% 4111 site locations moved an average of 1123 meters - 17% 117 meters is the mean distance between the site location and NHD location Streamgage Review Summary

Wrapup - Importance of the VAAs  Easier answers to network questions  Fast, simple, reliable network navigation Fast, sequential routing Fast, sequential routing Simple SQL queries Simple SQL queries Link Node routing Link Node routing  Provide some commonly used attributes Stream Order Stream Order Hydrologic Sequence Hydrologic Sequence Stream Path Identifier Stream Path Identifier  Establish the integrity of the network

For More Information:  NHD Sessions I and II Tuesday AM Room 25-C (SDCC)  NHD User Group Meeting Wed 12:15— 1:15 Room 30-B (SDCC)

Contacts:  Tommy Dewald  Tommy Dewald   Cindy McKay Systems.com   Tim Bondelid   Rich Moore   Craig Johnston   Al Rea

20 NHDPlus Production Units (Targeted Completion Dec, 2005)