elevation surface generation for hec-ras modeling · –swmp – gekeler slough •city of la...
TRANSCRIPT
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Elevation Surface
Generation for
HEC-RAS Modeling
Jason Gibbons
Anderson Perry Natural Resource Tech/GIS Tech
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GEKELER SLOUGH
• Surface Water Management Plan (SWMP)
Project Overview
– Located in Grande Ronde Valley, Union County,
Oregon
– SWMP – Gekeler Slough
• City of La Grande
• Union County
– Focus of SWMP
• Evaluate possible improvements to address:
– Water quality issues
– Water quantity issues
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PROJECT LOCATION
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PROJECT LOCATION
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PROJECT STATISTICS
• Study Area:
– Approximately 18,000 Acres
• Gekeler Slough and Associated Tributaries:
– ±11.8 miles
– 68 Channel Structures (e.g., culverts, bridges)
• Most efficient and cost-effective way to
perform analysis?
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ANALYSIS SOLUTION
• USACE HEC-RAS Software and ArcGIS
Software
– LiDAR data to produce surface in ArcGIS
– Import surface elevation data into HEC-RAS
– Perform HEC-RAS analysis
– Export results to ArcGIS
• Perform analysis to produce visual reference
guides
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PROCESS
Source: USACE HEC-GeoRAS GIS Tools for Support of HEC-RAS using ArcGIS User’s Manual. Version 4.3.93. Feb., 2011
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SURFACE GENERATION
• Mosaicked LiDAR
DEMs, procured from
DOGAMI, to produce
new surface in ArcGIS
– Entailed geoprocessing
operations for projection
transformations and vertical
elevation conversion to
correspond to NGVD 29
elevations
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DEM INPUTS
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TRANSFORMATIONS
• DOGAMI LIDAR data for the study area were delivered in the following
geographic coordinate systems and units: – Oregon Geographic Information Council High Accuracy Reference Network (HARN) Projection:
Oregon Statewide Lambert Conformal Conic
– Horizontal Datum: North American Datum 1983 (NAD 83) HARN
– Vertical Datum: North American Vertical Datum of 1988 (NAVD 88)
– Units: International Feet
• One LiDAR dataset is the exception to this, which was delivered in the following
coordinate system and units: – Projection: UTM Zone 11
– Horizontal Datum: NAD 83 HARN
– Vertical Datum: NAVD 88
– Units: Meters
• The Project Raster Tool was used to project the LiDAR DEMs into: – Projection: Oregon State Plane North Lambert Conformal Conic
– Horizontal Datum: NAD 83
– Vertical Datum: NAVD 88
– Units: International Feet
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SURFACE GENERATION: MODEL BUILDER
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FINAL SURFACE - DEM
File size: 1.09 GB
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FINAL SURFACE - TIN
File size: 393 MB
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CONCLUSION • Integration of HEC-RAS and ArcGIS software packages provided the following
benefits for this project: – Efficient DEM production for large project area.
– Ability to analyze data in one program and convert that data to a usable format in another.
– Ability to convey specific information related to floodwater elevations and evaluating alternative improvements for the Gekeler
Slough.
– MAPS – Tools that enhanced communication and collaboration among project partners.