NHD Stream Order Possibilities Timothy R. Bondelid Research Triangle Institute Research Triangle Park, North Carolina (919) ; fax (919)

Stream Order

Topics The Three Main Characteristics of NHD (and all Reach Files) Hydrologic Sequencing and Routing Example of NHD Routing, Stream Orders, and Changing Network Density “Hydrologic Equity” Example

The Three Main Characteristics A Common Numbering Scheme for All Surface Waters in the System –The Reach Number A Map Representation of the Surface Water Features A Tabular/Database Routing Network

Tabular Routing “Engine” for Modeling Invented by Bob Horn, USEPA Retired

Stream Level

Hydrologic Sequence

Stream Order

Stream Number

NHD Example of the Tabular Routing for Stream Orders and Density ArcView Presentation

“Hydrologic Equity” Define the Network in Terms of Hydrologic Characteristics Example in ArcView (RF3) Using Mean Annual Flow Estimates

Summary Stream Orders Can be Made With NHD Stream Orders are “Sensitive” to the Density Issue The NHD is a Very Flexible Network –The Full Richness of the Network Can Be Used for Varying Levels of Analysis, Display, and Modeling

Thank You!

Water Quality Management and Policy Modeling Tools using the National-Scale Reach File 3 (RF3) Hydrography Network Timothy R. Bondelid, Suzanne J. Unger, Randall C. Dodd, and Dario J. Dal Santo, Research Triangle Institute Research Triangle Park, North Carolina (919) ; fax (919)

The National Water Pollution Control Assessment Model (NWPCAM) This Work Has Been Funded by The U.S. Environmental Protection Agency Acknowledgements: –Dr. Mahesh Podar, Dr. John Powers, and Ms. Virginia Kibler in the U.S. EPA Office of Water –Dr. Charles Griffiths in the U.S. EPA National Center for Environmental Economics Significant Others: –C. Robert Horn, Mary Jo Kealy, George Van Houtven, and Tayler Bingham

Agenda Overview of Approach Major Challenges Assessment Framework Hydrologic Components Example of Results Conclusions

Overview of Approach

Major Challenges Need to be Able to Evaluate Large-Scale Changes Due to Pollution Control Policies But: Water Quality is Generally a “Local” Issue Need to Link to Economic Benefits Addressing These Two Challenges Makes the System Unique

The 18 Hydrologic Basins

The 2100 HUC’s

Subset of Reach File Version 1

Hydrologic Region 7 with RF1

Assessment Framework

Reach Files and Modeling Any Reach File Contains Three Elements: –A Standard, Unique Identifier for Each Surface Water Feature in the System –A Digital Map Representation of the Features –A Tabular Routing/Navigation “Engine” that is Powerful and Fast The Reach Files Have Been Used for Modeling Since 1982

RF1 In Upper Potomac

RF3 in Upper Potomac

RF3Lite in Upper Potomac

Hydrology: How Much Water? Estimate Average Unit Runoff by HUC Estimate Drainage Area for Each RF3 Reach Route and Accumulate Drainage Areas and Flows Down RF3

Average Annual Runoff Use “Hydrologic Centroids” of HUC’s Apply Distance-weighted Average of Annual Unit Runoff for USGS NCD Gages Testing: –HUC-level Unit Runoff –Drainage Areas –Flows

USGS Isopleths of Unit Runoff

Calculated Unit Runoff By HUC

Drainage Areas: Connecting Land Cover Database to RF3 Reaches

USGS Drainage Areas Vs. RF3 Drainage Areas

USGS Flows Vs. RF3 Flows

How Deep, Wide, Fast?

Basic Hydraulics Assume Rectangular Channel Manning’s “n” is a Function of “Sinuosity” of the Reach: –Sinuosity is the Reach Length/CFD –CFD = “Crow Fly Distance” –Reach “n” Increases as Sinousity Increases Slopes Derived From RF1/DEM-based Data Channel Widths From RF3 Geometry or Keup-derived Function for single-line streams

RF3Lite: Open Water Widths and Sinuosities

Channel Widths and Depths Single-Line Stream Widths (Keup): –W = 5.27 * Q Double-Wide Channel Widths from RF3 Geometry Depth: Manning’s Formula Assuming a Rectangular Channel –Y 0 = 0.79 * (Q * n /(W * (S 0 ) 0.5 ) 0.6

The Whole Process

Example: Two Scenarios on a Stretch of River

Conclusion: NWPCAM is an Evolving System with Every Component Undergoing Enhancements

Thank You!