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Introduction - Training

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Introduction - Training Powered By Docstoc
					Coastal Flooding
 Short Course
Pacific Disaster Center
     Maui, Hawaii
 June 29-1July 2, 2009

                Jim O'Brien, Ph.D., P.E.
                 Reinaldo Garcia, Ph.D.
                 FLO-2D Software, Inc.
         Workshop:
Coastal flooding, river and floodplain flow
    exchange, mud and debris flows
Note…some slides may have buttons to
show flood simulations that will not work
on your computers because you don’t have
the data or output files.
    New Features for Version 2009.06
MODFLOW surface/groundwater interface
RiverFLO-2D in-channel 2-D model
Optimized for 64-bit multiple processors
Levee fragility curves - dam/levee breach erosion
Two new sediment transport equations
Enhanced HEC-RAS project data integration
Watershed delineation
Many new GDS & Mapper Features
         New Features (cont.)
SCS Curve Numbers
FreqPlot
NEXRAD rainfall modeling
Time depth plots for dam breach
Project output analysis reporting
Improved error messaging
New Features – Summary Box
   FLO-2D Model Features
Physical process model
Conserves volume and reports on it
Combined hydrologic and hydraulic model
Unconfined flooding with no boundary
 conditions or hot starts
Routes entire hydrograph
Variable timesteps enable fast simulations
    FLO-2D Products
Shaded color contours with background images
      River
      Flooding
Rio Grande Model
Albuquerque District
Corps of Engineers


173 miles –
167,000 grid elements (250 ft)
Urban Flooding
Hazard Maps
Urban Flood Hazard Delineation
                    Primary Attributes

2-D overland unconfined flow in 8-directions
Channel routing: rectangular, trapezoidal or cross sections
Computes channel-floodplain exchange flow
Floodplain/channel rainfall, infiltration and evaporation
Evaluates development on storage and flow path
Models street flow and levees
Simulates sediment transport and mud/debris flows
Hydraulic structures (bridges, culvert, weirs – rating tables)
Channel - Floodplain Interface
Monroe Creek, Richfield, Utah
Monroe Creek, Richfield, Utah
  Monroe Creek, Utah


• Channel flooding on an alluvial fan
• 3026 grid elements
• Channel - floodplain flow exchange



                                        Flood
                                Rio Grande - Isleta Reach
                              • Overbank flooding
                              • Effects of floodwave attenuation
                                                                                                           250-yr no levee
                                       100-yr Peak Discharge (cfs) vs River Mile                             250-yr levee
                                                                                                             100-yr levee
                  25000
                                                                                                             Annual flood
                  20000
Discharge (cfs)




                  15000
                  10000
                                                     100-yr Flood 1996 HEC-2 Q (cfs)
                  5000
                                                     FLO-2D Results - Revised Hydrology
                      0
                          0       20        40                   60                       80   100   120
                 4500
                                                           1998 Predicted San Felipe Hydrograph


                 4000



                 3500                                                                                  USGS Discharge at San Felipe
                                                                                                       URGWOM Predicted Discharge at San Felipe
                                                                                                       FLO-2D Predicted Discharge at San Felipe
                 3000
Discharge, cfs




                 2500



                 2000



                 1500



                 1000



                  500



                    0
                   04/05/98   04/15/98   04/25/98   05/05/98   05/15/98   05/25/98   06/04/98   06/14/98   06/24/98     07/04/98      07/14/98    07/24/98
                                                                           Date, MM/DD/YY
                                          Discharge (cfs)




                                                                1000
                                                                              1200
                                                                                     1400
                                                                                            1600




                          0
                              200
                                    400
                                           600
                                                 800
                4/22/03


                4/23/03


                4/24/03


                4/25/03


                4/26/03


                4/27/03


                4/28/03


                4/29/03


                4/30/03


                 5/1/03




Date and Time
                 5/2/03


                 5/3/03


                 5/4/03
                                                                                                                                                     Reach 8/9 Hydrograph




                 5/5/03


                 5/6/03


                 5/7/03
                                                                                                   Embudo Gauge + Chamita Gauge vs FLO-2D (Grid 3)




                 5/8/03


                 5/9/03
                                                       grid 3
                                                                 chama conf
Mudflow Simulation:
Barnard Creek, Centerville, Utah
Simple Simulation:
Barnard Creek, Centerville, Utah
Example: Barnard Creek, Utah

Urbanized alluvial fan
• Very steep slopes (streets ~ 10%)
• Small debris basin at fan apex
• Street flow conveyances
                                            Mud
• Numerous buildings                       Water

• Mudflow, water flood and rain        No Streets
                                      No Buildings

                                      Rain + Mud
 Required Data Base

• Digitized topo map or DTM of the flow surface
• Hydrology - rainfall and inflow flood hydrographs
• For Channel Option - cross section surveys
When Do I Need a 2-D Model?
Answer: Whenever the flood volume
determines the area of inundation...
 Unconfined flow or distributary flow
 Very flat topography
 Split flow (channel or floodplain)
 Combine hydrologic and hydraulic modeling
 Routing flood hydrograph
 Floodwave attenuation
Variable Water Surface Elevations
Urban Flooding with Streets and Buildings


  Typical HEC-RAS Cross Section
When flood volume controls the area of
inundation not the peak discharge, the
cross section water surface elevation is
highly variable.
     Dam Break or Levee Breach




Jim O’Brien
FLO-2D Software, Inc.
     Mapper Delineated North Breach




Area of Inundation
 Porting from Version 2007.06
      to Version 2009.06
 1. Add switch IMODFLOW = 0 end of line 3 CONT.DAT
 2. Delete IQDIR from CHAN.DAT (automated)
 3. New CHANBANK.DAT


Optional Items:
1. Levee Fragility Curve Data (LEVEE.DAT and
   BREACH.DAT).
2. MODFLOW parameters
Porting from Version 2007.06
     to Version 2009.06

Sequence:
1. Add switch IMODFLOW = 0 end of line 3 CONT.DAT
2. Open GDS or FLOENVIR (load channel) and save the
   data files. Deletes the IQDIR variable and creates
   the CHANBACK.DAT file.
3. Open the GDS or FLOENVIR and review the channel
   bank positions.
4. ERROR.CHK will list and over- or under- channel
   extensions.
   What are my resources?
Manuals and tutorials/lessons on the CD
Example projects on the CD
GUI, GDS and Mapper In-Help
Power Point presentations
Technical support (email or phone)
Website ‘forum’ chat web page
Consulting project technical oversight
      User’s Manual
Model theory & routing algorithms
Description of model components
Parameter sensitivity
Limitations and assumptions
Applications
Model verification
    Data Input Manual

Data files format and description
Data limitations and variable ranges
Output files
Debugging and troubleshooting guide
         Input Data Manual Format

FLO-2D reads the data exactly as specified in the
 manual Data Input Section:

 Data   format
 Data   variable description (alphabetical)
 List   of instructional comments
GDS, Mapper and Mapper.NET Manuals


  GDS and MAPPER Manuals
  Simple to use and well illustrated
    Graphical User Interface - GUI


 Self-explanatory   with help comments
 Data   entry in fields or tables
 Run    the model and processor programs


                                     GUI
           Pre-processor Programs

Frequently used…
   GDS – creates and edits the grid attributes
   FLOENVIR – edits the system attributes –
    becoming obsolete
   PROFILES - plots water surface and bed profiles,
    adjusts channel bed elevation and channel depths,
    interpolates slope and cross sections
        Post-processor Programs

   MAXPLOT – simple, fast graphical output
   MAPPER – mapping tool creates shaded color
    contour plots, animation and much more
   HYDROG - graphically displays a channel
    hydrograph for every channel element
   PROFILES - graphically displays the water surface
    and bed profile
       ASCII Editor

   Editors – WordPad, TextPad, UltraEdit
   Files: *.DAT *.BAC *.OUT *.CHK
Grid Size Selection
A common misconception is:
                       Smaller grid elements
                        increase model
                        flood resolution.


Most common problem is:
                       Too many grid
                         elements slow
                         down the model.

How do I choose the grid size?
 Balance three things:
1.Accuracy of the data base
2.Desired results
3.Model speed and data editing
         1. Data Base
i. Resulting flood maps can’t exceed
   the accuracy of the topo maps
   made with the DTM
ii. Accuracy of the map contours will
    not necessary improve because
    you select smaller grid elements
     2. Desired Results
i. Unconfined and shallow flooding
   maps - use smaller grid elements
Frequent return period flooding, smaller
     discharge, distributary flooding
ii. Large flood inundation – use larger
    grid elements
       100-year flood fills valley
Shallow distributary flooding
Use smaller grid elements to improve
flood boundary resolution.
Valley Flooding



Use larger grid elements
 3. Model speed and editing
i. 150,000 to 200,000 grid elements
   with a 10 day hydrograph = 6 to 12
   hours computer run time
ii. Graphical editing – adding
    channels, streets, buildings,
    spatially variabilty (infiltration, n-
    values) – takes time = 1-2 weeks
        Grid System Selection

Qpeak/Asurf < 1.0 cfs/ft2 (0.3 cms/m2)
Qpeak = peak discharge inflow to one grid element

Asurf = surface area of one grid element
   Grid System Selection

Number of grid elements:

1,000 – 15,000     very fast - minutes
15,000 - 60,000    moderate – hour(s)
60,000 - 150,000   slow – 2 to 8 hours
    >150,000       > 8 hrs - overnight
 Basic steps for starting a FLO-2D project


Understand the project: flood hazard delineation,
 mitigation design, flow hydraulics, rainfall-
 runoff
Determine basic project area (5 miles x 1 mile)
Select grid element size (try 50 ft, 200 ft, etc.)
Estimate peak discharge
Where to get more information:

Web Site: www.flo-2d.com
Email: jim@flo-2d.com
    What’s coming up?



Grid System Attributes – Graphical
 Editing with the GDS

				
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