Utilizing LiDAR for Engineering Applications

Conservation

Our Purpose, Our Passion

Objectives

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

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.

Surface Modeling

Stage – Storage Earthfill & Excavation

Quantities

Hydrology Modeling

Delineation of Watersheds and Water Flow Paths

More Modeling

Identify and map Flood Frequencies

Identify and map hazard areas downstream of structures

Inundation Boundary Mapping

Structures, Ponds, Lakes

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

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

LiDAR Process

Using a ESRI TIN developed from LiDAR

Extract Valley Cross Sections with Hec-GeoRAS & ArcGIS

Immediate file import into Hec-Ras

Hec-GeoRas “Pre-Ras”

USGS DEM Process

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

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 manning’s N values Hec-Ras Steady State analysis run with TR-

20 flood routing

H-39a Centerline Dam R.S. 200

705

710

715

720

725

730

735

740

745

0 100 200 300 400 500 600 700 800 900 1000

Station (ft)

Ele

v. (

Ft)

Trimble GPS Survey LiDAR Data USGS Data

711.0711.3

H-39a Centerline Dam R.S. 190

700

705

710

715

720

725

730

735

0 100 200 300 400 500 600 700 800 900 1000

Station (ft)

Ele

v. (

Ft)

Trimble GPS Survey LiDAR Data USGS Data

704.9 ft

706.8 ft

H-39a Centerline Dam R.S. 160

700

705

710

715

720

725

730

0 100 200 300 400 500 600 700 800 900 1000

Station (ft)

Ele

v. (

Ft)

Trimble GPS Survey LiDAR Data USGS Data

701.6 ft702.7 ft.

0

1000

2000

3000

4000

5000

6000

7000

704 705 706 707 708 709 710 711 712 713

WSP (ft)

Q (

cfs)

0

500

1000

1500

2000

2500

3000

3500

Are

a (s

qu

are

ft)

Lidar_Flow Trimble_Flow LiDAR_Area Trimble_Area

River Station 160

Profile Rating

LiDAR data compared to Survey

Grade GPS Trimble Data

Site H-39a Results

Trimble GPS Survey; overtopped Hwy YY by 1.6’ LiDAR Survey; overtopped Hwy YY by 1.0’

0 500 1000 1500 2000 2500 3000 3500690

695

700

705

710

715

720

BCHC H-39a breachroute.prj Plan: TR-20_final Run_w interpolated xsecs 10/3/2007

Main Channel Distance (ft)

Ele

vation (

ft)

Legend

WS TR-20 Breach

Ground

cross s

ection s

urvey 2

-552 d

ow

nst...

Box c

ulv

ert on h

wy Y

Y r

oad c

ente

rline u

...

surveyed c

ross s

ection 5

-2510

surveyed c

ross-section 6

-3300 c

l dam

H-39a 1

Hec-GeoRas“Post-RAS”

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_Second_Edition.pdf

TR-20:http://www.wcc.nrcs.usda.gov/hydro/hydro-tools-models-tr20.html

Ag. Research Servicehttp://www.ars.usda.gov/main/site_main.htm?modecode=62-17-10-00

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