Utilizing LiDAR for Engineering Applications

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Utilizing LiDAR for Engineering Applications
Conservation Our Purpose, Our Passion
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Objectives

• Identify some engineering applications
• Present an Overview for Breach Routing
• Review a Breach Routing Case Study

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Utilizing LiDAR

• Applications include design and planning of
  physical land modifications or mitigations
• LiDAR is suitable for planning and in some cases
  even final design or aspects of final design.
• Applicability depends on degree of accuracy
  required.
• Hydraulic and Hydrology Modeling, Farm Field
  Terracing Systems, Irrigation Systems, Floodwater
  Retarding Structures, Grade Stabilization
  Structures, Water Supply Structures, etc.

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Surface Modeling

• Stage Storage
• Earthfill Excavation Quantities

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Hydrology Modeling

• Delineation of Watersheds and Water Flow Paths

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More Modeling

• Identify and map Flood Frequencies
• Identify and map hazard areas downstream of
  structures

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Inundation Boundary Mapping
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Structures, Ponds, Lakes
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Small Structure Case Study

• Breach Routing a Small Structure to Identify
  hazards downstream
• Three data sets
• Traditional Survey
• ESRI TIN from LiDAR
• ESRI TIN from USGS DEM
• Accuracy required, Budget, Time Constraints

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Traditional Process

• Using Total Station or Survey Grade GPS a survey
  crew would gather data at each cross section in
  the field
• Downloaded with CAD
• Copied Entered into Hec-RAS

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LiDAR Process

• Using a ESRI TIN developed from LiDAR
• Extract Valley Cross Sections with Hec-GeoRAS
  ArcGIS
• Immediate file import into Hec-Ras

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Hec-GeoRas Pre-Ras
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USGS DEM Process

• Same as LiDAR, except extracting data from the
  USGS DEM dataset

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Survey Data Analysis

• Kept all factors the same, except the differences
  in the two data sets
• Cut cross sections exactly at the same spot
• Utilized the same mannings N values
• Hec-Ras Steady State analysis run with TR-20
  flood routing

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Site H-39a Results

• Trimble GPS Survey overtopped Hwy YY by 1.6
• LiDAR Survey overtopped Hwy YY by 1.0

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Hec-GeoRasPost-RAS
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Reference Links

• Hec-Ras
• http//www.hec.usace.army.mil/software/hec-ras/
• Hec-GeoRas
• http//www.hec.usace.army.mil/software/hec-ras/hec
  -georas.html
• TR-60
• http//www.info.usda.gov/CED/ftp/CED/TR_210_60_Sec
  ond_Edition.pdf
• TR-20
• http//www.wcc.nrcs.usda.gov/hydro/hydro-tools-mod
  els-tr20.html
• Ag. Research Service
• http//www.ars.usda.gov/main/site_main.htm?modecod
  e62-17-10-00

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Helping People Help the Land

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