Hydraulic Modeling with HEC RAS. Susan Cundiff, PE December 4, 2017

Transcription

1 Hydraulic Modeling with HEC RAS Susan Cundiff, PE December 4, 2017

2 Overview Introduction to HEC RAS Computational Procedures Building a Model Example Projects

3 Introduction to HEC RAS U.S. Army Corps of Engineers Hydrologic Engineering Center-River Analysis System HEC located in Davis, CA Download from: What does it do?

4 Why HEC-RAS? It is free! Easy to use 1D steady state model 1D and 2D unsteady modeling 1D Sediment Transport and Mobile Boundary Modeling Widely accepted software

5 1D or 2D? Steady or Unsteady? What questions are you trying to answer? Floodplain inundation boundaries? Structures Other considerations Available resources $$ Time Scour/Erosion Dam Breach analysis Available data Timing of flood Flood inundation Habitat Design Depths Velocities Sediment Transport

6 Computational Procedures Steady Flow

7 Computation Procedures Energy Losses, h e

8 Computational Procedure Conveyance Calculation Manning s Equation Q = KS f 1 2 K = n AR2 3 Where: K=conveyance for subdivision n= Manning s roughness coefficient A=flow area for subdivision R=hydraulic radius for subdivision Sf = slope of the energy gradeline

9 Building a Model Assemble Necessary Data Geometry Hydrology Sediment Data

10 Building a Model Assemble Necessary Data Topography Surveyed Cross Sections DEM Hydrology Gage Data HEC-HMS or other hydrology software Bankfull, Range of flows, etc Sediment Data Representative Material Appropriate transport equations

11 Building a Model Geometry File Topography Cross sections Alignment Hydraulic Controls Evenly spaced Energy Losses Perpendicular to Flow Channel Roughness Horizontal Variability Vertical Variability Expansion and Contraction Bridges/Structures I m not bad, I was just drawn that way.

12 Building a Model Developing the geometry data

13 Building a Model Developing the geometry data Build Quick 2D model

14 Building a Model Start a New Project

15 Building a Model Start New Project continued..

16 Building a Model Create New Geometry Import geometry data CAD/GIS program RAS Mapper

17 Building a Model Editing Geometry Bank Stations Levees Ineffective Flows Blocked Obstructions Mannings n-values Reach Lengths Coefficients

18 Building a Model Defining Hydrology Boundary Conditions Normal Depth Known WSEL Critical Depth Rating Curve

19 Building a Model Defining Hydrology Continued

20 Building a Model Defining Hydrology Continued

21 Building a Model Defining Hydrology Continued

22 Building a Model Sediment Data Define Bed Gradations Set gradation for each XS

23 Executing a Model Build your Plan Geometry *.g0x Hydrology Steady*.f0x Unsteady*.u0x Quasiunsteady*.q0x Sediment Data *.s0x

24 Executing a Model Options Define Methods Conveyance Calculations Frictions Slope Methods Critical Depth Calc Tolerances Number of iterations WS Calcs Sediment Transport

25 Model Results

26 Model Results

27 San Joaquin River Restoration

28 Total Subsidence over 13 years (feet, ) Subsidence Reach 4A Subsidence Upper Eastside Bypass Middle Eastside Bypass Chowchilla Bypass , , , , , ,000 River Station (feet, relative to the Main SJR stationline)

29 Subsidence

30 SJR Sediment Transport Geometry

31 Sediment Transport Modeling Results

32 Sediment Transport Modeling Results

33 Sediment Transport Modeling Results 5,500 cfs

34 Sediment Transport Modeling Results

35 References Bender, Theodore, HEC-RAS 5.0 Presentation. Interoffice Training for Tetra Tech. HEC-RAS Users Manual Gary Brunner, Army Corps of Engineers Version February 2016 Horner and Julien, CIVE 401 HEC RAS Presentation. Available at: 0Lectures%202016/Introduction%20to%20HEC-RAS.pdf Lai, Goy, and Julien CIVE 401 HEC-RAS Presentation. Available at: RAS%20Lecture/F15CIVE401%20HECRAS%20Presentation%20%28final%29-1.pdf

36 Contact Information Susan Cundiff, PE Hydraulic Engineer Direct: Main: Ext Tetra Tech Science, Engineering, and Technology 3801 Automation Way, Suite 100 Fort Collins, CO 80525

37 Questions?