advantages of 2-d versus 1-d hydraulic modeling...advantages of 2-d versus 1-d hydraulic modeling...
TRANSCRIPT
Advantages of 2-D Versus 1-D Hydraulic Modeling
52nd ASCE Environmental and Water Resource Conference
April 3, 2014
Iowa DOT Projects Using 2D Modeling
Statewide Lidar – Completed in 2010
U.S. 69 over Iowa River near Belmond
IA 330 over Iowa River near Albion
I-35 over South Skunk River south of Ames
U.S. 65 over Des Moines River near Pleasant Hill
U.S. 34 over White Breast Creek near Lucas
I-80 over N. Raccoon River – Bendway Weirs
What is LiDAR?
Courtesy of Dodson & Associates
Contours/DEM
LiDAR Tools
• UNI GeoTREE
– http://www.geotree.uni.edu/lidarProject.aspx
• Quick Terrain Modeler
– http://appliedimagery.com/index.html
• ESRI ArcGIS
– Spatial Analyst Extension
– 3d Analyst Extension
1D Hydraulic Model (HEC-RAS)
• 1D – HEC-RAS –widely accepted –predicts average velocity in cross section and water surface elevation
• Very challenging to model in 1D, Ineffective Flow Areas, Losses from channel bends, Overtopping levee systemsSections from
USACE – Des
Moines River
Model0 1000 2000 3000 4000 5000 6000 7000 8000
530
540
550
560
570
580
590
600
610
Iowa DOT _transmtl Dec 2007 Mitigation Plan: Oc07_PFB_Alt-1 max dike removl+newsoundg 1/31/2008
Station (ft)
Ele
vation
(ft)
Legend
EG PF 4
WS PF 4
Ground
Bank Sta
.07 .028 .07
2D Hydraulic Models
• 2D Models– predicts depth-averaged two-dimensional velocity and water surface elevation
• Combines channel bathymetry + LiDAR (floodplains) + Surface Roughness into a velocity field
Bathymetry Roughness
Mesh Computed velocity field
U.S. 69 over Iowa River – Belmond, IA
IA 330 over Iowa River Near Albion
I-35 over South Skunk River
I-35 Skunk River Crossing - 2010 Event
US 30 Skunk River Crossing - 2010 Event
US 30 Skunk River Crossing - 2010 Event
South Dayton Ave. U/S Closure - 2010 Event
Location Subject To One Foot
Water Surface Increase Due To
Dayton Closure
South Duff Ave. - 2010 Event
S. 4th St. Squaw Creek Crossing - 2010 Event
Looking East
2.4 Ft Drop U/S To D/S
Squaw Creek University Blvd. - 2010 Event
Flowage Easement Mapping I-35 Skunk River
2D Models Provide Quick And
Accurate Inundation/Easement
Mapping
U.S. 65 over Des Moines River
US 65 Des Moines River Crossing - 2008 Event
Looking West at 466’ Overflow Bridge
466’ Overflow Bridge
Looking South
Looking West at SB Lanes
U.S. 65 over White Breast Creek near Lucas
I-80 over North Raccoon River
1950’s
Early 1960’s
1970’s
Current Aerial
Verification of Bendway Weir Design
When Should 2-D Hydraulic Modeling Be Used?
Overflow Bridges
Flood Plains with Flank/Lateral Levees
Roadways Significantly Skewed to the Flood Plain/River
Locations that are Hydraulically Complex
