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© 2014 HDR, Inc., all rights reserved.
Utilizing Two Dimensional Hydraulic Modeling on West Cathedral Channel
Deborah de Chambeau, P.E., CFM Yunjing Zhang, P.E., CFM Mitchell Blum, P.E., CFM Mark Seits, P.E., CFM
Project Overview Project Location Project Purpose HEC-RAS 2D Capability HEC-RAS 2D Modeling o Geometry o Unsteady Flow o RAS Mapper o Model Results
Project Location
Study Area - Purpose
Study area Eagle Canyon Dam o Recently constructed upstream of the study area o CLOMR has been submitted in 2014
Cove Development West Cathedral Channel North Cathedral Channel, East
Cathedral Channel Levees
Project Purpose
Eagle Canyon Dam o Recently constructed upstream of the study area o Commercial Area to be remove from floodplain due
to North Cathedral Channel o Depth and duration of the flooding
Floodplain due to West Cathedral Channel o Zone AE within channel banks o Zone A outside of channel banks
Project Description
West Berm o Not Certified Levee
East Levee Concrete Channel Downstream of Bridge 111 Model with and without Berm conditions
West Berm
Concrete Channel
Levee West Cathedral Channel
Results – 1D
Why 2D modeling
HEC-RAS 1 Dimensional Model Limitations Overland Flow Complex Hydrodynamic Flow Flow Breakout Flow Depth Model with and without Berm conditions
HEC-RAS 2 D Model Capabilities HEC-RAS 5.0 Beta Version o 2D Capability
HEC-RAS 2D Modeling Capabilities o Can perform 1D, 2D and combined 1D and 2D
modeling o Solve Full Saint-Venant or Diffusion Wave
Equation o Unstructured or structured computational meshes o Detailed Hydraulic Table properties for 2D
computational cells and cell faces o Detailed flood mapping and flood animations
Current HEC-RAS 2 D Model Limitations Can’t perform sediment transport erosion Can’t perform water quality modeling Can’t connect pump stations to 2D flow area
cells Can’t use the HEC-RAS bridge modeling
capacity
Geometry Terrain 2D Flow Area
o 3 – 2D areas o Mesh – regular and Irregular size o Cell size 10x10 o Breaklines
Geometry (Cont’d)
Boundary Condition o 2D – Area BC line o 2D - Normal Depth o 2D - Flow Hydrograph o 1D – Flow Hydrograph (Upstream) o 1D - Stage Hydrograph (Downstream)
Geometry (Cont’d)
1D - Channel o Bridge
1D/2D Connection o Lateral Structures
Land Cover to Manning’s n
1D area – Manning’s n o Channel, overbanks
2D Flow Area o Land Cover Name and Base Manning’s
n numbers were assigned o Associated layer
Unsteady Flow Analysis
Geometry o With West Berm o Without West Berm
Unsteady Flow o 100 year 3 hour - controls o 100 year 6 hour o 100 year 24 hour o 10 year 3 hour o 50 year 3 hour
RAS Mapper
Results (without Berm) Results (with Berm)
100-year 3 hour
Results (Max Depth, Velocity)
Results (Water Surface El.)
Results – Animation