State of Topography North Carolina LiDAR-Derived Elevation Acquisition. NSGIC Hope Morgan- GIS Manager NC Floodplain Mapping Program- NCEM

Transcription

1 State of Topography North Carolina LiDAR-Derived Elevation Acquisition NSGIC Hope Morgan- GIS Manager NC Floodplain Mapping Program- NCEM

2 1 st Generation 1 st Phase I Topographic-Bathymetric Flood - Lidar-Derived Hazard Mapping Topography Model (circa ) ) ) Following Hurricane Floyd in 1999, North Carolina committed to update and maintain accurate Flood Hazard data, models and maps. Statewide acquisition and incorporation of high-resolution elevation data. North Carolina utilized Lidar technology for the data acquisition. NC Floodplain Mapping Program received financial partnering through USGS and NC DOT.

3 1 st Generation Phase I Flood - Lidar-Derived Hazard Mapping Topography 1 st Generation Flood Inundation Mapping / Warning (circa (circa ) - present) (circa )

4 Phase 2 Structural Flood Risk Assessment (circa 2008-present) 1 st GENERATION ELEVATION DATA - MAJOR RESULTS Statewide Update of Flood Hazard Studies (~31,000 stream miles) 321,000 Base Flood Elevations Issued Statewide / No Unnumbered A Zones Statewide Issuance of ~10,000 Digital Flood Insurance Rate Map Panels Updated High-Resolution Coastal Storm Surge Models Flood Inundation Mapping and Alert Network Structure-Specific Flood Impact / Risk Assessment (Financial) 100% Adoption of DFIRMs by Communities. Estimated Statewide Annual Flood Loss Avoidance of $102.0 million (homes and infrastructure: 20% Build-Out) Reduction of Approximately 1 Year on Roadway and Bridge Construction Projects - Elevation Data Supporting Preliminary Design Lidar-DERIVED TOPOGRAPHIC DATA WAS SILVER BULLET

5 Next Generation 3DEP Lidar-Derived Topography ACQUIRED

6 1 st Generation 3DEP Lidar NC Topography Lidar Topography (2014) ( ) 3 Meter Point Spacing 0.3 Meter Point Spacing *3DEP is a 1,000% increase in analysis points LiDAR Quality Ground Points in 5 Acre Parcel 30m NED 32 10m NED 300 3m (circa 2003) 7,696 3DEP 76,957

7 Ground Low Vegetation Roads Medium Vegetation Buildings High Vegetation

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9 Actual Survey Elevations 30 Meter Elevation Model

10 Actual Survey Elevations 10 Meter Elevation Model

11 3 Meter Lidar Topography ( ) Actual Survey Elevations 5 ½ Foot Vertical Error in Stream Bed Elevation

12 3DEP Next Generation Flood Hazard Accuracy (2014) 3DEP Profile Actual Survey Elevations Nearly mirrors existing high precision survey data.

13 3DEP Next Generation Business Value Through the acquisition of new 3DEP topographic data, North Carolina will also be able to update and/or support the following areas: Storm Surge Structure Impact Utility Management Line Detection Transportation Design / Asset Management Vegetation / Forestry Management Hydrologic / Streambed Detection Wetland Identification Aviation Obstruction Assessment Precision / Efficient Farming Structure Delineation High Large Trees

14 3DEP - Next Generation Hydrographic / Stream Delineation Traditional / Manual Approach No automation Highly labor intensive, very expensive Statewide effort 200,000 labor hours 3DEP Supported Approach Initial calculations yield quality results for an automated routine 3DEP Supported effort 800 labor hours Labor Hour Effort % Savings

15 3DEP - Next Generation Wetland Identification Traditional/Manual Approach Heads up digitizing from Orthophotography Highly labor intensive / Inaccurate (best guess of operator) Sampson County 947 square miles Labor Effort 474 hours 3DEP Supported Approach Uses supervised scientific classifications from known wetlands Automated algorithm routines Potential identification for a 10 square mile area takes minutes versus hours 3DEP Supported Effort 107 hours Labor Hour Effort - 78% Savings

16 3DEP - Next Generation Building Footprint Extraction Classification Elevation Intensity Imagery Profile

17 3DEP Structure Impact Analysis from Hazards Analyses Example

18 3DEP Next Generation Letter of Map Amendments Elevation Certificate Costly to Property Owners ($500-$1,500) High Precision Survey Grade 3DEP Support LOMA 3DEP Derived Highest Adjacent Grade and Lowest Adjacent Grade Batch routine entire Counties Accuracy could be +/- 0.3 foot Petition FEMA to use 3DEP as alternative LOMA to remove properties when above the Base Flood Elevation (BFE) No Cost to Homeowner Quality Level HAG Elev. (ft.) HAG Delta (ft.) BFE = ft. In/Out of SFHA Survey n/a OUT 30 Meter In 10 Meter In 3 Meter In 3DEP OUT

19 3DEP State Perspective on Next Generation Topography North Carolina believes that: 3DEP / LiDAR-Derived Elevation Data is an enabler for efficiency, improved accuracy, and robust analytics; LiDAR is an Efficient / well-matured Technology; High-Resolution Topography is the Silver Bullet, prerequisite for the efficient and accurate generation of Flood Insurance Rate Maps and Flood Risk Assessment; High-Resolution Topography Supports a Multitude of Disciplines / Processes; The Cost of High-Resolution Topography is Far Outweighed by the Efficiencies Gained / Added Value Products Generated; Acquiring High-Resolution Topography is Typically Cost Prohibitive without Multiple Financial Partners; USGS 3DEP has Partnering Framework that compliment and supports NC s needs.

20 Questions