North Carolina Stream Mapping ProjectJoe SewashNorth Carolina Center for Geographic Information and Analysis

Scott EdelmanWatershed 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 24K 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

• 24K NHD

• Orthoimagery

• Ancillary Datasets

Database Design

• Based on NHD Geodatabase

• State custom tables– Change Table– Submetadata– Workgroup

• GUID-based

Attribute table to provide supplemental data regarding horizontal accuracy and placement of stream.

State Mapping Project Globally Unique ID.

NHD Reach Code of feature.Source of orthophotography used to supplement stream delineation.LIDAR nominal post spacing.

Reference to the horizontal accuracy study report for a specific phase of the project.

Agency responsible for delineating stream.

Date streamline was edited.

Additional comments field.

Orthophotography source date.

Terrain source date.

TableSubmetadata

Data typeField namePrec-ision Scale LengthDomainDefault value

Allow nulls

OBJECTID Object ID StateGUID Yes 36ReachCode String Yes 14AlnOrthSrc Short integer Yes AlnOrthSrc 7LIDARnps String Yes 50TerrSrcDat Date Yes 8OrthSrcDat Date Yes 8HrzntlAcc String Yes Accuracy Source 100

RslvgAgncy Short integer Yes Resolving Agency 50EditDate Date Yes 8Comment String Yes 100

GUID

Submetadata Table

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

Software Tool Development

Existing Systems Analysis/User Requirements Analysis

Develop Prototype 1

Physical and Logical Database Design/Technical Design

Test PlanAcceptance Testingby Client (beta release)

Training (beta release)

Component, Integration and System Testing

(pre-alpha/alpha release)

Develop Final Application Implementationand Unit Testing

Technology Transfer –Software release/Source

Code and Metadata

Technical Support

Maintenance (optional)

Design and Implementation

QA/QC

Documentation and Support

Database Implementationand Testing

Documentation/Online Help and

Tutorials

Review Meeting Prototype 1

Review Meeting Prototype 2

Start

Requirements AnalysisDocument

System DesignDocument

Develop Prototype 2

Software Development Life Cycle

• 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

Software Tool DevelopmentFlowchecker Tool

• 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

Software Tool DevelopmentManual 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

• 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

Consistency of Horizontal Placement – Horizontal Accuracy Study

Average Distance from Stream Bank for 100% of the Data

Consistency of Horizontal Placement – Horizontal Accuracy Study

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

1:24K NHD 10.74

Consistency of Horizontal Placement – Horizontal Accuracy StudyFindings:• 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

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

1:24K

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 24K NHD and Streambed Mapping Dataset

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

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

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

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

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 24K 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 SewashNC Center for Geographic Information

and Analysis

e: joe.sewash@ncmail.netp: 919.733.2090w: http://www.ncstreams.net/

General Discussion