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Hurricane Hazard Information forCaribbean Coastal Construction 1
Hurricane Hazard Datafor
Caribbean Coastal Construction
Project Overview
Funded by the Caribbean Regional Program of the US Agency for International Development.Executed by the Organization of American States, in conjunction with the
Engineering Institute of the University of the West Indies.
System Design and Analysis by Watson Technical Consulting.
Hurricane Hazard Information forCaribbean Coastal Construction 2
Introduction
Project Goals
Storm Hazard Assessment Methodology
Statistical Methodology
Data Bases
On-line Data Access System
Hurricane Hazard Information forCaribbean Coastal Construction 3
Project Goals
To create an easy to use on-line resource to allow planners and coastal engineers to access basic hurricane hazard data in a formatconducive for use in the design process.
Hazards reported are wind, wave, and storm surge, for 10, 25, 50, and 100 year return periods. Return period data is characterized at maximum likelihood (MLE), 75%, 90%, and 95%projection limits.
Two Web Sites to be established:Primary: University of the West IndiesBackup: Old Dominion University
Hurricane Hazard Information forCaribbean Coastal Construction 4
Storm Impacts at the Coast
MeanLow Water
Pressure Setup
Wind Setup
Astronomical Tide
Wave Setup
Wave Run up
Still Water Level at Shoreline
Wave Crest/TWL
Three phenomena output: Wind, Waves, and Storm Surge.Storm surge outputs include of wave setup, wind setup, pressure setup, and astronomical tide.
Wind
Hurricane Hazard Information forCaribbean Coastal Construction 5
Methodology Overview
Simulate every Atlantic storm since 1886 (1851) with the TAOShazard modeling system to generate the wind, wave, and storm surge at every grid cell in the study area.
At each point, compute weibull distribution for each phenomena.
Simulate return period events to test interactions.
Compute desired return period and projection limit results.
Hurricane Hazard Information forCaribbean Coastal Construction 6
The Arbiter Of Storms (TAOS) hazard model
Modular, 4D composite model platform with user selectable modules:12 Wind Models3 Boundary Layer Models3 Storm Surge Models5 Wave Models2 Rainfall/Runoff Models
- 1,620 basic combinations- with damage functions, over 10,000 possible outcomes for a single event!
Scalable, from single processor through supercomputer MPI orPVM systems such as the WTCI earthdome system.
TSAP Statistics System with plug in modules for various distributions, either desktop of batch run capability.
Hurricane Hazard Information forCaribbean Coastal Construction 7
Storm Hazard Model Modules
Key TAOS/mpi Modules:
•Wind Field
•Water Flow (Storm Surge)
•Waves
•Tides (UTex CSR Model)
•Rainfall and runoff
•DamageStructure DamageCoastal ErosionVegetation Damage
•GIS/Mapping InterfaceGrADS Meteorology packageArcInfo and ArcViewMapinfoGRASS
Storm components are interactive and can have feedbacks: for example, changes to land cover cause changes to wind speeds, etc.
Hurricane Hazard Information forCaribbean Coastal Construction 8
Input Data Bases for Simulations
•Digital Elevation Model (topography and bathymetry)Allows proper flow of water to be computedfor storm surge, waves, and inland flooding
•Land Cover/Land Use (land and underwater)Friction effects on both air and water to computecorrect wind speeds and flow ratesDebris generation
•Historical Storm Characteristics for Statistical Analysis and validation
Hurricane Hazard Information forCaribbean Coastal Construction 9
Model Physics: Wind
Module Used: Standard Project Hurricane (SPH)Source: NOAA Technical Report NWS 23
Basic wind field characteristics:Asymmetric wind fieldRadius of Maximum WindsStorm motionCentral and Far Field Pressure
Terrain effects: The wind at a point depends onwhat is upwind of the point, as much as 10 miles.
Note storm centered grid system.
Hurricane Hazard Information forCaribbean Coastal Construction 10
Wind Model Validation Example
15
20
25
30
35
40
45
50
55
60
15 20 25 30 35 40 45 50 55 60
Reported
Comparison of observed and computed peakwinds for Hurricane Floyd (1999)
Correlation: 0.9222
Hurricane Hazard Information forCaribbean Coastal Construction 11
Model Physics: Storm Surge
Modules, vertical coordinates (3D vs. 4D), horizontal resolutionsdepends on underlying data bases
Low Res (> 600 meter grids): vertically integrated equationsSource Equations: Harris
High Res (< 600 meter grids): 5 vertical layersSource Equations: Watson, based on Mellor
Tides: University of Texas CSR Tide Model
Hurricane Hazard Information forCaribbean Coastal Construction 12
Comparisons with Tide Gauges
-0.4
-0.2
-0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 10 20 30 40 50 60 70 80 90 100 110 120
time
-0.4
-0.2
-0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0 10 20 30 40 50 60 70 80 90 100 110 120
time
St. Augustine
Trident Pier
Solid Line: ModeledDots: Observed
Hurricane Hazard Information forCaribbean Coastal Construction 13
Peak Surge Observations (Marilyn, 1995)Storm Source Location Type Observed Modeled %error Error (m)Marilyn 95 USGS SC 1 OB 0.98 1.00 2.50% 0.02
SC 2 OB 2.65 2.50 5.75% 0.15SC 3 OB 2.90 2.50 13.68% 0.40SC 4 OB 1.77 1.50 15.17% 0.27SC 5 OB 1.52 1.50 1.60% 0.02SC 6 OB 1.52 1.50 1.60% 0.02SC 7 OB 1.89 1.75 7.42% 0.14SC 8 OB 1.43 1.75 22.13% 0.32SC 9 OB 2.04 2.00 2.09% 0.04SC 10 OB 1.98 2.00 0.92% 0.02SC 11 OB 1.59 1.80 13.54% 0.21SC 12 OB 1.83 1.80 1.60% 0.03SC 13 OB 2.59 2.20 15.11% 0.39SC 14 OB 3.57 2.80 21.50% 0.77SC 15 OB 2.90 2.50 13.68% 0.40ST 1 OB 2.01 2.00 0.61% 0.01ST 2 OB 2.16 2.00 7.61% 0.16ST 3 OB 2.16 2.20 1.63% 0.04ST 4 OB 2.32 2.20 5.05% 0.12ST 5 OB 2.26 2.20 2.49% 0.06
Average: 0.18
Marilyn Storm Surge y = 0.6741x + 0.567
R2 = 0.9003
0.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00
Observed
Co
mp
ute
d
Observed peak water levels frompost storm surveys on St. Croix and St. Thomas by the USACE
Hurricane Hazard Information forCaribbean Coastal Construction 14
Model Physics: Waves
NOAA Wavewatch III Model (deep and transitional water)Source: Tolman, modularized and modified for
moving grid
WTC inshore model (shallow water)Sources: Lyons, Watson
Again, physics used depends on resolution.
Hurricane Hazard Information forCaribbean Coastal Construction 15
Wave Validation
Comparison of operational (real time) wave forecastand NOAA buoy reports
Hurricane Hazard Information forCaribbean Coastal Construction 16
Validation Summary
Tests against detailed data from over 30 storms worldwide.
Performance summary (90% limits)Peak Wind (350 observations): +/- 5 knotsPeak Wave (185 observations): +/- 0.8 meters (deep water Hs)Peak Storm Surge (1500 observations): +/- 0.3 meters
Model uncertainty is included in the projection limit calculations.
Hurricane Hazard Information forCaribbean Coastal Construction 17
Statistical Terminology
MLE: Maximum Likelihood Estimate. The ‘best guess’ at a value. Thisis NOT the same as the 50% estimate.
Projection Limit: For a given projection limit, the value which shouldnot be exceeded more than 1-(limit) of observations.
Example: 100 year, 75% projection limit.For a large number of 100 year periods, 75% of them will fallat or below this value. Only 25% should be greater.OR, for a large number of sites over a 100 year period, 75%of the sites will see less than this value; 25% would be expectedto exceed it.
Hurricane Hazard Information forCaribbean Coastal Construction 18
Statistical Analysis
Once storm runs are completed, outputs are analyzed to producereturn period data sets.
Single Site Example: Four Seasons Hotel, Nevis
Hurricane Hazard Information forCaribbean Coastal Construction 19
Single Site Analysis: Wind
BASIC TC WIND STATISTICS REPORT FOR Nevis
1220 EVENTS EXAMINED FROM 1850 TO 1999
NOTES: RAW DATA IS IN FILE YRMAX.DAT CAT 0 = TROPICAL STORM
EVENTS BY CATEGORYSAFFIR/SIMPSON CATEGORY 0: 48SAFFIR/SIMPSON CATEGORY 1: 9SAFFIR/SIMPSON CATEGORY 2: 4SAFFIR/SIMPSON CATEGORY 3: 1SAFFIR/SIMPSON CATEGORY 4: 1SAFFIR/SIMPSON CATEGORY 5: 0
------------------------------------------------ EMPIRICAL ESTIMATE OF RETURN PERIODSSAFFIR/SIMPSON CATEGORY 0: 2.5 YEARS 0.396SAFFIR/SIMPSON CATEGORY 1: 8.3 YEARS 0.121SAFFIR/SIMPSON CATEGORY 2: 24.8 YEARS 0.040SAFFIR/SIMPSON CATEGORY 3: 74.5 YEARS 0.013SAFFIR/SIMPSON CATEGORY 4: 149.0 YEARS 0.007SAFFIR/SIMPSON CATEGORY 5: Infinit YEARS 0.000
2 PARAMETER WEIBULL ESTIMATE OF RETURN TIMES
ALPHA 1.333316, BETA 35.105717SDA 0.21 SDB 4.40, CORREL: 0.871427
CHI**2 13.486692K-S 0.046980, K-S PROB 0.995793
5 YEAR WIND 50KTS (EMP: 52KTS) 10 YEAR WIND 65KTS (EMP: 70KTS) 25 YEAR WIND 84KTS (EMP: 79KTS) 50 YEAR WIND 97KTS (EMP: 89KTS)100 YEAR WIND 110KTS (EMP: 91KTS)
MLE BASED WIND RETURN TIMESWIND SPD PROB RETURN PD 50KTS 0.2014 5.0 YRS 64KTS 0.1078 9.3 YRS 100KTS 0.0176 56.7 YRS ------------------------------------------------ PROJECTION LIMIT CONFIDENCE LEVELS
YEAR 50% 75% 90% 95% 99% 10YR: 66.4 69.0 71.4 73.2 76.8 25YR: 85.3 89.3 93.5 96.9 108.8 50YR: 98.5 104.1 110.8 116.7 132.7100YR: 110.7 118.9 128.7 136.8 157.3
Raw text output of TSAP program:
Hurricane Hazard Information forCaribbean Coastal Construction 20
Single Site Statistics: Nevis Wind
Graphic output ofweibull fit for windsat Four Seasons, Nevis
Hurricane Hazard Information forCaribbean Coastal Construction 21
Statistical Methodology Validation
Used data from 1886-1987 to make a 10 year forecast.
Validated wind forecast against 10,600 land sites in the Atlantic Hurricanebasin using the 10 year period 1988 - 1997.
Percentage of sites below prediction limit:
Predicted Observed50% 53%75% 75%90% 90%95% 94%99% 97%
Hurricane Hazard Information forCaribbean Coastal Construction 22
The Caribbean Hazard Data Web Server
Temporary URL:http://weather.methaz.com/cdcm/
Permanent URL:UWI: ??ODU: http://cdcm.cee.odu.edu/
Primary site will provide formailing lists to discuss coastalengineering and design problems,techniques, etc.
Interactive, web based system using open source/public domain software.
Hurricane Hazard Information forCaribbean Coastal Construction 23
On-line Documentation
• Notes on wind, wave, and storm surge model outputs• Validation and uncertainty• Terminology• Building Code Notes
Hurricane Hazard Information forCaribbean Coastal Construction 24
Available Data Bases
Regional 30 arc second (nominal 926 meters)As part of the Caribbean Disaster Mitigation Project (CDMP), a regional storm risk atlas was developed. The return period was based on an analysis of hurricanes from 1886 to 1998, with storm hazard model runs conducted using a regional 30 arc second (nominal 926 meter) grid. It covers the Eastern Caribbean from Puerto Rico through Trinidad and Tobago.
6 arc second (182 meter) Kitts/Nevis/Antigua/BarbudaThis data set was developed for the Post Georges Disaster Mitigation Project. It covers the islands of St. Kitts, Nevis, Barbuda, and Antigua. The return period analysis was based on data from 1851 through 1999. The storm hazard model runs were made at a resolution of 6 arc seconds (182 meter grid).Only MLE data available for this area.
Hurricane Track Data BaseThis is a version of the 1851-2000 storm track data set created by from the US National Hurricane Center.
Hurricane Hazard Information forCaribbean Coastal Construction 25
Data Set Access
• User may select return period and projection limit• Choice of background maps• Point and click report generation
Hurricane Hazard Information forCaribbean Coastal Construction 26
Report Format
Site Map and Data Location
Site information
Hazard Data
Hurricane Hazard Information forCaribbean Coastal Construction 27
Summary
• On-line hurricane hazard data for the Eastern Caribbean• 10, 25, 50, 100 year return period data bases• MLE, 75%, 90%, and 95% projection limits for regional data set• R&D site available at http://weather.methaz.com/cdcm/• Final data sets and user interface by end of September 2001• Final web sites at UWI and ODU by end of 2001