North Carolina Stream Mapping Project Joe Sewash North

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 Hurricane Recovery Act Stream Mapping Advisory Committee CGIA Project Roles

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

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

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.

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.

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

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

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

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

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

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

Source Datasets • • LIDAR 24 K NHD Orthoimagery Ancillary Datasets

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

Submetadata Table

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

Software Tool Development Software Development Life Cycle

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

Software Tool Development Flowchecker Tool

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

Software Tool Development Manual Attribute Transfer Toolset

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)

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 Arc. Hydro, LIDAR Tool, 1: 24 K 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

Consistency of Horizontal Placement – Horizontal Accuracy Study

Consistency of Horizontal Placement – Horizontal Accuracy Study Average Distance from Stream Bank for 100% of the Data Average of Distance from Point (feet) User Distance 6 -Acre Streams 11. 10 Analyst 1 3. 74 Analyst 2 5. 06 Arc Hydro 13. 07 Custom Software Tool 6. 64 NC FMP Phase II Breaklines 6. 16 Independently-Derived Streamlines 4. 55 1: 24 K NHD 10. 74

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: 24 K 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

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

Consistency of Horizontal Placement – Comparisons of 24 K NHD and Streambed Mapping Dataset 1: 24 K NHD Streambed Mapping Dataset Δ Stream Miles 20, 792 65, 331 214% Double Line Stream Miles 2, 733 3, 870 42% # of Waterbodies 4, 828 5, 389 12% Total # of Features 53, 436 528, 834 890%

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

Attribute Conflation • • • All attributes found in the 1: 24 K 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: 24 K NHD data, and generated for new streams that do not exist in the NHD All changes from existing 1: 24 K 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

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 / Stream. Stats pilot for local resolution

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 / Stream. Stats pilot for local resolution

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

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

North Carolina Stream Mapping Project: Phase II Priority Areas

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

Stream Relocation to be shared with Streambed Mapping Program

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 24 K NHD?

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

Roadway Maintenance and Stream Mapping

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

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

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

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/

General Discussion