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North Carolina Stream Mapping Project

North Carolina Stream Mapping Project. Joe Sewash North Carolina Center for Geographic Information and Analysis Scott Edelman Watershed Concepts. Outline. Project Initiation Technical Approach Future Directions. Project Initiation. Stream Mapping Working Group Implementation Plan

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North Carolina Stream Mapping Project

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  1. North Carolina Stream Mapping Project Joe SewashNorth Carolina Center for Geographic Information and Analysis Scott Edelman Watershed Concepts

  2. Outline • Project Initiation • Technical Approach • Future Directions

  3. Project Initiation • Stream Mapping Working Group • Implementation Plan • Hurricane Recovery Act • Stream Mapping Advisory Committee • CGIA Project Roles

  4. Stream Mapping Working Group • Four facilitated meetings • Federal, state, local, academic and private participants • Focused on business requirements of a revised hydrography dataset

  5. Implementation Plan • Identified five year production period • Considered multiple compilation approaches • Provided detailed estimates of cost avoidances and increased efficiencies

  6. Implementation Plan • NC Ecosystem Enhancement Program (NCEEP), NC Department of Transportation (NCDOT) Current mitigation estimates fall around 1.5 million feet for the next three years, a twenty percent underestimation would mean that an additional 300,000 linear feet of stream would need mitigation. That would be approximately 100,000 linear feet a year, or an additional $20 million worth of restoration each year. If the new maps were to produce just a two percent increase in NCEEP staff efficiency during the next three years, NCEEP could provide approximately an additional 30,000 additional feet of stream mitigation credits to meet NCDOT’s needs. The additional mitigation credits would be worth approximately $6,150,000.

  7. Implementation Plan • City of Durham Review and approval of site plans would take staff less time to complete. Assuming the midpoint salary of a senior technician ($47,000) multiplied by 1.7 for benefits, training, etc. results in a yearly cost to the City of $215,730 to perform this task. The new statewide digital surface waters file would save the City of Durham $215,730 per year.

  8. Hurricane Recovery Act • Hurricanes Ivan and Frances • Nineteen counties in Western North Carolina • Funding provision for beginning Stream Mapping production in declared counties

  9. Stream Mapping Advisory Committee • Extension of original Stream Mapping Working Group • Advises and supports technical and programmatic related issues • Develops issues papers and participates in the review of technical and programmatic documents

  10. Transportation Division of Water Quality USGS EPA Water Resources Buncombe County City of Charlotte Wildlife Resources Commission Local Government Committee Stream Mapping Advisory Committee

  11. Stream Mapping Advisory Committee • Issue Paper Topics • Drainage area methodology • Water body specifications • Reach code conflation • GUID generation • Connector usage • Ground cover characteristics

  12. CGIA Project Roles • Project management • Completed two 24K NHD CUs • QA/QC • Web Mapping Application

  13. Technical Approach • Source Datasets • Database Design • Software Tool Development • Consistency of Horizontal Placement • Attribute Conflation • NC Enhancements and Technical Issues

  14. Source Datasets • LIDAR • 24K NHD • Orthoimagery • Ancillary Datasets

  15. Database Design • Based on NHD Geodatabase • State custom tables • Change Table • Submetadata • Workgroup • GUID-based

  16. Submetadata Table

  17. Software Tool Development • Suite of Software Tools • Tools assist with horizontal alignment, attribution and conflation of the 1:24K NHD attributes to the dataset • Optimize production and quality of the Streambed Mapping Dataset • Tools incorporated into “Streambed Mapping Analyst Toolset” as ArcGIS extension, and will be available to the public • Design • User requirements collection • Prototype Screenshots • Coding • Testing • Software Requirements Document • User Guide and Online Help

  18. Software Tool Development Software Development Life Cycle

  19. Software Tool Development • Streambed Mapping Analyst Toolset – Horizontal Alignment Tools • Horizontal Placement QC Tool • Flow Checker Tool • Tree Builder Tool • NHD Breakpoint Extraction Tool • Move Breakpoint Tool • Project Configuration Options Tool • Multiple Dataframe Modeler • Create Feature Types Toolset • Source File Comparison Tool

  20. Software Tool Development Flowchecker Tool

  21. Software Tool Development • Streambed Mapping Analyst Toolset – Attribution / Conflation Tools • 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

  22. Software Tool Development Manual Attribute Transfer Toolset

  23. Consistency of Horizontal Placement – Horizontal Accuracy Study • Purpose was to perform a pilot study to determine the horizontal accuracy of the streamlines in various situations • Study 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)

  24. Consistency of Horizontal Placement – 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 • 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

  25. Consistency of Horizontal Placement – Horizontal Accuracy Study

  26. Consistency of Horizontal Placement – Horizontal Accuracy Study Average Distance from Stream Bank for 100% of the Data

  27. Consistency of Horizontal Placement – Horizontal Accuracy Study Findings: • 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

  28. Consistency of Horizontal Placement – 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 was used for the Horizontal Accuracy Study • Increasing both the quality and quantity of streams in existing stream files

  29. Consistency of Horizontal Placement – Comparisons of 24K NHD and Streambed Mapping Dataset

  30. Consistency of Horizontal Placement – Comparisons of 24K NHD and Streambed Mapping Dataset *Seneca Basin covers portions of Jackson and Transylvania Counties in Western North Carolina

  31. Attribute Conflation • 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 • Areas of significant erosion included in point event table

  32. NC Enhancements and Technical Issues • Submetadata Table • GUID-ready • Perennial / Intermittent NC Requirements • Connector Features of Known Spatial Accuracy • Alignment of watershed boundary maintenance • NHDPlus / StreamStats pilot for local resolution

  33. NC Enhancements and Technical Issues • Submetadata Table • GUID-ready • Perennial / Intermittent NC Requirements • Connector Features of Known Spatial Accuracy • Alignment of watershed boundary maintenance • NHDPlus / StreamStats pilot for local resolution

  34. Future Directions • Phase II Production • Data Maintenance Planning • NHD Stewardship Participation • Performance Measurement • Lessons Learned

  35. Phase II Production • Thirteen (13) sub-basins • Coastal Pilot • Future Issues • Urban / rural mix • Existing datasets from local stakeholders • Stormwater management

  36. North Carolina Stream Mapping Project: Phase II Priority Areas

  37. Data Maintenance Planning • Business-case orientation • Cost modeling / certainty • Estimating on-going maintenance and significant events • De-coupling geometry maintenance from business data maintenance • Data integrity / source QC from all NHD sources • Aligning maintenance cycles and business requirements

  38. Stream Relocation to be shared with Streambed Mapping Program

  39. NHD Stewardship Participation • Scope of responsibility • Participation in NHD direction-setting • Role of stewards in NHD Maintenance Process • Data integrity issues driven by state and local business requirements • Business model change within USGS • BGN issues with local resolution NHD • What happens to the 24K NHD?

  40. Performance Measurement • Implementation Plan identified detailed cases for cost avoidance and efficiency increases • Identified business cases will be validated and new cases will be documented

  41. Roadway Maintenance and Stream Mapping

  42. Lessons Learned • Local resolution NHD will continue to identify issues • Software and workflow documentation are critical knowledge sharing vehicles • Data sharing and distribution necessitates a new paradigm

  43. www.ncstreams.net • Project status • Data access • Technical and programmatic documentation • Web mapping application

  44. Gladys Conway Chris Kannan David Nail Carl Nelson Jeff Simley Larry Stanislawksi Steve Strader Silvia Terziotti Chad Wagner Paul Wiese Special Thanks

  45. Additional Information Joe Sewash NC Center for Geographic Information and Analysis e: joe.sewash@ncmail.net p: 919.733.2090 w: http://www.ncstreams.net/

  46. General Discussion

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