Hurricane Hazard Data for 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
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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.
Storm Hazard Assessment Methodology
On-line Data Access System
To create an easy to use on-line resource to allow planners and
coastal engineers to access basic hurricane hazard data in a format
conducive 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%
Two Web Sites to be established:
Primary: University of the West Indies
Backup: Old Dominion University
Three phenomena output: Wind, Waves, and Storm Surge.
Storm surge outputs include of wave setup, wind setup, pressure setup,
and astronomical tide.
Wave Run up
Still Water Level at Shoreline
Simulate every Atlantic storm since 1886 (1851) with the TAOS
hazard 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.
Modular, 4D composite model platform with user selectable modules:
12 Wind Models
3 Boundary Layer Models
3 Storm Surge Models
5 Wave Models
2 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 or
PVM systems such as the WTCI earthdome system.
TSAP Statistics System with plug in modules for various distributions,
either desktop of batch run capability.
Storm components are interactive and can have feedbacks: for example, changes to land cover cause changes to wind speeds, etc.
Module Used: Standard Project Hurricane (SPH)
Source: NOAA Technical Report NWS 23
Basic wind field characteristics:
Asymmetric wind field
Radius of Maximum Winds
Central and Far Field Pressure
The wind at a point depends on
what is upwind of the point, as
much as 10 miles.
Note storm centered grid system.
Comparison of observed and computed peak
winds for Hurricane Floyd (1999)
Modules, vertical coordinates (3D vs. 4D), horizontal resolutions
depends on underlying data bases
Low Res (> 600 meter grids): vertically integrated equations
Source Equations: Harris
High Res (< 600 meter grids): 5 vertical layers
Source Equations: Watson, based on Mellor
Tides: University of Texas CSR Tide Model
Solid Line: Modeled
Observed peak water levels from
post storm surveys on St. Croix
and St. Thomas by the USACE
NOAA Wavewatch III Model (deep and transitional water)
Source: Tolman, modularized and modified for
WTC inshore model (shallow water)
Sources: Lyons, Watson
Again, physics used depends on resolution.
Comparison of operational (real time) wave forecast
and NOAA buoy reports
Tests against detailed data from over 30 storms worldwide.
Performance summary (90% limits)
Peak Wind (350 observations): +/- 5 knots
Peak 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.
MLE: Maximum Likelihood Estimate. The ‘best guess’ at a value. This
is NOT the same as the 50% estimate.
Projection Limit: For a given projection limit, the value which should
not 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 fall
at 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 expected
to exceed it.
Once storm runs are completed, outputs are analyzed to produce
return period data sets.
Single Site Example:
Four Seasons Hotel, Nevis
Raw text output of TSAP program:
BASIC TC WIND STATISTICS REPORT FOR Nevis
1220 EVENTS EXAMINED
FROM 1850 TO 1999
RAW DATA IS IN FILE YRMAX.DAT
CAT 0 = TROPICAL STORM
EVENTS BY CATEGORY
SAFFIR/SIMPSON CATEGORY 0: 48
SAFFIR/SIMPSON CATEGORY 1: 9
SAFFIR/SIMPSON CATEGORY 2: 4
SAFFIR/SIMPSON CATEGORY 3: 1
SAFFIR/SIMPSON CATEGORY 4: 1
SAFFIR/SIMPSON CATEGORY 5: 0
EMPIRICAL ESTIMATE OF RETURN PERIODS
SAFFIR/SIMPSON CATEGORY 0: 2.5 YEARS 0.396
SAFFIR/SIMPSON CATEGORY 1: 8.3 YEARS 0.121
SAFFIR/SIMPSON CATEGORY 2: 24.8 YEARS 0.040
SAFFIR/SIMPSON CATEGORY 3: 74.5 YEARS 0.013
SAFFIR/SIMPSON CATEGORY 4: 149.0 YEARS 0.007
SAFFIR/SIMPSON CATEGORY 5: Infinit YEARS 0.000
2 PARAMETER WEIBULL ESTIMATE OF RETURN TIMES
ALPHA 1.333316, BETA 35.105717
SDA 0.21 SDB 4.40, CORREL: 0.871427
K-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 TIMES
WIND 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: 98.5 104.1 110.8 116.7 132.7
100YR: 110.7 118.9 128.7 136.8 157.3
Graphic output of
weibull fit for winds
at Four Seasons, Nevis
Used data from 1886-1987 to make a 10 year forecast.
Validated wind forecast against 10,600 land sites in the Atlantic Hurricane
basin using the 10 year period 1988 - 1997.
Percentage of sites below prediction limit:
Interactive, web based system using open source/public domain software.
Primary site will provide for
mailing lists to discuss coastal
engineering and design problems,
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/Barbuda
This 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 Base
This is a version of the 1851-2000 storm track data set created by from the US National Hurricane
Site Map and Data Location