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Streambed Mapping Project For Western North Carolina Counties. Presentation Topics. Background Task Descriptions Progress To Date Path Forward. Background. Background. PROJECT TEAM Sponsor: North Carolina Center for Geographic Information and Analysis

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presentation topics
Presentation Topics
  • Background
  • Task Descriptions
  • Progress To Date
  • Path Forward


    • Sponsor: North Carolina Center for Geographic Information and Analysis
    • Advisory Committee: USGS, EPA, NC DWQ, NC DOT, NC EEP, City of Charlotte, Buncombe County
    • Contractors: Watershed Concepts, EarthData, ESP Associates, Data Enhancement Services


  • North Carolina Senate Bill 1152
    • Mandated that a plan be created to improve the mapping of streams in the State of North Carolina
    • Creation of new dataset to map surface waters in North Carolina including streams, lakes, ponds, and other water bodies


  • Stream Mapping Working Group
    • Four meetings in late 2004
    • Requirements Survey / User Requirements Summary
  • Stream Mapping Implementation Plan
    • Submitted to the NC Legislature in January 2005
    • Endorsed by the GICC and presented to the General Assembly’s Environmental Review Commission in January of 2005
    • Statewide implementation in a 5 year period

Website for Document Download:



  • A benefit / cost analysis was performed to show the value of the Streambed Mapping Project to agencies as well as the general public.

Note: This estimate yields an initial B/C ratio of 16:1, a value that does not reflect long term benefits.



  • Senate Bill 7 Hurricane Recovery Act
    • Allocated mapping funds for the 19 counties in Western North Carolina that were declared disaster areas after Hurricanes Frances and Ivan.
task descriptions12
Task Descriptions
  • The Streambed Mapping Project is comprised of many tasks including:
    • Project Management
    • Horizontal Accuracy Study
    • Schema and Geodatabase Design
    • Software Tool Creation
    • Drawing of Streamlines and Water Bodies to 6-Acre Upstream Drainage Limit
    • NHD Conflation and Attribution of Streamlines and Water Bodies
project management
Project Management
  • Project Management Plan
    • Project Organization, Communications, QA/ QC, Change Management, Risk Management, File Management, Project Schedule and Deliverables
  • Coordination Activities
    • Advisory Committee formed to assist with project decisions
horizontal accuracy study
Horizontal Accuracy Study
  • Purpose was to perform a pilot study to determine the horizontal accuracy of the streamlines in various situations.
  • Study was based on:
    • 250 Survey Points, 100 miles of stream
    • Varying degrees of terrain density, differing imagery resolutions, and varying drainage areas
    • Varying land characteristics (open, brush, forest, and urban)
horizontal accuracy study15
Horizontal Accuracy Study
  • Two GIS specialists digitized the streamlines
    • Two types of imagery (DOQQs and Local)
    • TIN surfaces generated from bare earth LIDAR returns, hillshades, DEMs, and contours
    • Each analysts work performed independently of one another
  • Simultaneously, surveyors collected 250 GPS points and stream widths using survey grade GPS and OPUS post-processing methods
  • ArcHydro, LIDAR Tool, 1:24K NHD streams, NCFMP Breaklines, Independently-Derived Streamlines, and Streamlines Derived to the 6-Acre Drainage Area Limit were also analyzed against the survey points and the analysts linework

Horizontal Accuracy Study

Average Distance from Stream Bank for 100% of the Data

Note: Analyst 1, Analyst 2, and Independently-Derived Streamlines are over twice the accuracy of the existing NHD streamlines

horizontal accuracy study18
Horizontal Accuracy Study
  • Cumulative Probability Distribution for Selected Manual Methods (Including Analysts 1 and 2, NC Independently Derived Streamlines and 1:24K NHD) for All Streams

Horizontal Accuracy Study

Observed Accuracy by Land Cover Setting

horizontal accuracy study20
Horizontal Accuracy Study


  • Six different methods tested
  • In general, manual processes more accurate than automated processes
  • Manual methods 2 and 3 times more accurate than existing 1:24K NHD
  • NHD for all points -- 70% were within 15 ft of stream banks, 85% are within 25 ft of stream banks, and 90% were within 35 ft of stream banks
  • Manual process for all points -- 70% within 3 ft of stream banks, 85% within 10 ft of stream banks, and 90% within 15 ft of stream banks
  • Of open, brush, forest, and urban, the urban environment posed the biggest challenge in terms of horizontal placement
geodatabase schema and design
Geodatabase Schema and Design
  • Schema
    • Various models reviewed
    • NHD data model appended with additional attributes previously identified in the Implementation Plan
  • Design
    • Conceptual – feature classes, object classes, entity relationships, cardinality, topologies, and domains defined
    • Logical – finalizes the conceptual design
    • Physical – utilizes SQL Server 2000 with SDE
geodatabase schema and design22
Geodatabase Schema and Design
  • Additional Features Include State Custom Tables
    • Change Table: Tracks history of edits
    • Submetadata Table: Provides information on source data used to create or edit stream data
  • Significant Coordination Effort
  • Data Dictionary Created
software tool development
Software Tool Development
  • Suite of Software Tools
    • Suite of software tools created to assist with horizontal alignment, attribution and conflation of the 1:24K NHD attributes to the dataset
    • Optimize both production and quality of the Streambed Mapping Dataset
    • Tools incorporated into the “Streambed Mapping Analyst Toolset” as an extension in ArcGIS, and will be made available to the public
  • Design
    • User requirements collection
    • Prototype Screenshots
    • Coding
    • Testing
    • Software Requirements Document
    • User Guide and Online Help
software tool development25
Software Tool Development
  • Project Configuration Options Tool
  • Multiple Dataframe Modeler
  • Create Feature Types Toolset
  • Source File Comparison Tool
  • Streambed Mapping Analyst Toolset – Horizontal Alignment Tools
  • Horizontal Placement QC Tool
  • Flow Checker Tool
  • Tree Builder Tool
  • NHD Breakpoint Extraction Tool
  • Move Breakpoint Tool
software tool development26
Software Tool Development
  • Assign Streambed Mapping Attributes Tool
  • Drainage Area Transfer and QC Tool
  • NHD Batch Attribute Transfer Tool
  • NHD Manual Attribute Transfer Toolset
  • QC Streambed Mapping Attributes Tool
  • Populate Submetadata Table Tool
  • NHD Cross Reference and Change Table Population Tool
  • Stream Leveling and Flow Table Population Tools
  • Streambed Mapping Analyst Toolset – Attribution / Conflation Tools
streamline and waterbody identification and attribution
Streamline and Waterbody Identification and Attribution
  • Horizontal Alignment
    • Streamlines terminate at the 6-acre drainage area upstream limit – creates a consistent dataset
    • Same base data used for alignment as the sources used for the Horizontal Accuracy Study
    • Increasing both the quality and quantity of streams in existing stream files
streamline and waterbody identification and attribution32
Streamline and Waterbody Identification and Attribution
  • Attribution
    • All attributes found in the 1:24K NHD are conflated to the Streambed Mapping Dataset (point, line, polygon)
    • Additional attributes placed in an appended table to the NHD model
    • Reach codes conflated from 1:24K NHD data, and generated for new streams that do not exist in the NHD
    • All changes from existing 1:24K NHD attributes are recorded in the Reach Cross Reference Table and the Change Table created for the project
    • Attribution performed with the assistance of automated tools

Progress To Date

  • Project Management Plan created
  • Multiple stakeholder briefings and updates
  • Accuracy Study completed – final report of findings submitted
  • Geodatabase finalized and physical Geodatabase installed
  • Prototypes created for all tools; tools finalized & implemented
  • User guide and online help completed for all tools
  • Software Requirements Specification Document finalized

Progress To Date

  • First Delivery Area Submitted as Final to State (Pigeon)
  • Two Additional Delivery Areas (Upper New and Upper Yadkin, Seneca) have been finalized as of beginning of year

Path Forward

  • Entire project is a 2 year effort with a completion date of Summer 2007 for all 19 counties
  • A long term maintenance plan for the Streambed Mapping Dataset will be developed that documents the business and technical requirements of project stakeholders
  • North Carolina will develop an NHD Stewardship Agreement with USGS for long term maintenance of NC Stream Mapping dataset