Best Practices and Numerical Modeling Elements of a FEMA ... · Summary –Best Practices and...
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June 19, 2018 ASFPM Session C-1 Best Practices and Numerical Modeling Elements of a FEMA Coastal Flood Study Darryl Hatheway, CFM and Chris Mack, PE, MBA, PMP
Transcript of Best Practices and Numerical Modeling Elements of a FEMA ... · Summary –Best Practices and...
June 19, 2018 ASFPM Session C-1
Best Practices and Numerical Modeling
Elements of a FEMA Coastal Flood Study
Darryl Hatheway, CFM
and
Chris Mack, PE, MBA, PMP
Study Phases of a FEMA Coastal Study
Analysis - Storm Climatology
Analysis – Models & Water Levels
Analysis - Types of Models
Good Coastal Modeling & Best Practices
• Elements of Modeling Reality
(the natural system)
– Conceptual Model
– Computer Model
– Site-Specific Model
• Processes of Modeling
– Analysis
– Model Selection
– Model Set-up
– Simulation
Data Analysis Mapping Planning
Wind
• Field
• Track
Wave
• Height
• Period
Water Level
• Tide
• HW
Erosion
• Heel
• Toe
• TS
• NE
• Setup
• Runup
• Validation
• Surge
• Removal
• Retreat
• Power
• Zones
• V-Zone
• Grids
• SWEL
• T-SWEL
• PFD
• Delta
• B Codes
• Ins.
• B Codes
• Advisory
• DFIRM
• Evac.
• Baseline
• Setbacks
Numerical Elements of a Coastal Study
Comparison of Old & New Mesh
Good Coastal Modeling & Best Practices
• Evaluation Procedures of
Modeling
– Model Confirmation
– Model Verification
– Model Calibration
– Model Validation
Data Collection
Calibration
& Validation
Validation
Assumptions
Tide: Constituent
Amplitude and
Phase
Select Skill MetricsIdentify Historic
Data Sources
Compare
Modeled to
Measured
Results
Select Model Run:
Tide Surge or
Wave
Wave:
Sig. Height, Period,
and Direction
Surge:
Peak Water Levels
and/or Hydrograph
Project Kick-
Off
Model
Development
Display: Plots, Tables, and Graphs
Differences (actual, %,
mean), Standard
Deviation, Mean Error,
RSME, Bias,
Correlation Coefficient,
Scatter Index, Best Fit
Slope
Differences (actual, %,
mean), Standard
Deviation, Mean Error,
RSME, Bias,
Correlation Coefficient,
Scatter Index, Best Fit
Slope
Differences (actual, %,
mean), Standard
Deviation, Mean Error,
RSME, Bias,
Correlation Coefficient,
Scatter Index, Best Fit
Slope
HWMs,
Astronomic Tides
and/or
Tide Gage Event
Hydrographs
Differences (actual, %,
mean), Standard
Deviation, Mean Error,
RSME, Bias,
Correlation Coefficient,
Scatter Index, Best Fit
Slope
ADCIRC hydrodynamic
(tide & surge) and
SWAN
offshore/nearshore
waves & wave setup
Boundary conditions,
topographic data,
bathymetric data, and
land use features
ADCIRC hydrodynamic
model (tides & surge),
and SWAN
offshore/nearshore
waves & wave setup
Model Calibrated
(Mesh, variables, land
use, and wind drag
coefficients)
• Definition of the Modeling
Project
– Problem Description
– Define Objective
– Analyze the Context
– Specify Model Requirements
• Conceptual Model
– Data Analysis
– System Understanding
– Development of the Conceptual
Model
– Conceptual Model Confirmation
• Document Analysis Process
Good Coastal Modeling & Best Practices
• Numerical Model Setup
– Sensitivity Analysis
– Model Calibration
– Uncertainty Analysis
– Documentation
Good Coastal Modeling & Best Practices
• Model Simulations
– Validation of Model
– Application of Model
• Final Report
Good Coastal Modeling & Best Practices
Numerical Elements - Base Flood Elevation on FIRM
includes 4 components:
1. Storm surge stillwater elevation (SWEL)
2. Amount of wave setup – determined from the 2D wave and surge
models
3. Wave height above storm surge (stillwater + setup) elevation
4. Wave runup above storm surge elevation (where present)
Analysis – Wind and Pressure
Five primary parameters of interest
for coastal modeling reproduced
from hindcasted time series per
storm track:
o Central pressure deficit
o Radius to maximum wind
speeds & direction
o Storm track heading
o Forward velocity
o Shoreline crossing point
Historical & Hindcasted:
o Wind Speed
o Wind Direction
o Pressure
o (time series)
Analysis – Wave Modeling
Tools & Technologies:
SWAN, STWAVE
Historical & Hindcasted:
o Wave Height
o Wave Period
o Direction
o (time series)
Analysis – Overland Wave
Tools & Technologies:
o FEMA WHAFIS model
o Coastal WISE (CHAMP Integrated)
Analysis - Wave Runup
2007 FEMA Guidelines require computation of 2% runup,
prior to 2007 the mean runup was used
Runup 2.0 for moderate slopes
TAW method for structures
SPM method for vertical walls
Analysis - DEM Extents
Analysis - DEM Source Data Diversity
Analysis - Complex Bathymetric FeaturesDEM Issue Areas 40-47
Analysis - DEM Quality Control (QC) and Corrections
Analysis - ADCIRC Model Mesh
Analysis – Flooding and Model Mesh Resolution
Analysis – Results and SWEL Surface Creation
• Final SWEL points from
2D model are used to
create raster SWEL
surfaces.
• Provides input to
WHAFIS model.
• Provides flooding
extents/boundaries.
Analysis – Use of GIS Desktop Tools & Technologies
Summary – Best Practices and Coastal Modeling
• Evaluate, interpret model results and
documentation.
• Other steps that will follow the
description of the results are:
– Discuss results
– Describe the conclusions.
– Define if the objective has been achieved.
– Identify any limitations in the domain
knowledge that affect uncertainty.
– Documentation requirements are defined in
the Coastal Data Capture Guidance
Document (FEMA, 2014)
Summary - Numerical Modeling Integration?
• All study phases & elements (i.e., wind,
wave, water level, erosion).
• Data Analysis Mapping Planning
• Mapping Assessment Planning
(Risk MAP)
• Integrated with other geospatial tools &
technologies through common data
structures and formats.
