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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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Hurricane hazard data for caribbean coastal construction project overview
Hurricane Hazard DataforCaribbean Coastal ConstructionProject 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.


Introduction
Introduction

Project Goals

Storm Hazard Assessment Methodology

Statistical Methodology

Data Bases

On-line Data Access System


Project goals
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 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%

projection limits.

Two Web Sites to be established:

Primary: University of the West Indies

Backup: Old Dominion University


Storm impacts at the coast
Storm Impacts at the Coast

Three phenomena output: Wind, Waves, and Storm Surge.

Storm surge outputs include of wave setup, wind setup, pressure setup,

and astronomical tide.

Wind

Wave Run up

Still Water Level at Shoreline

Wave Crest/TWL

Wave Setup

Wind Setup

Pressure Setup

Astronomical Tide

Mean

Low

Water


Methodology overview
Methodology Overview

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.


The arbiter of storms taos hazard model
The Arbiter Of Storms (TAOS) hazard model

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 hazard model modules
Storm Hazard Model Modules

  • Key TAOS/mpi Modules:

    • Wind Field

    • Water Flow (Storm Surge)

    • Waves

    • Tides (UTex CSR Model)

    • Rainfall and runoff

  • Damage

    • Structure Damage

    • Coastal Erosion

    • Vegetation Damage

  • GIS/Mapping Interface

    • GrADS Meteorology package

    • ArcInfo and ArcView

    • Mapinfo

    • GRASS

Storm components are interactive and can have feedbacks: for example, changes to land cover cause changes to wind speeds, etc.


Input data bases for simulations
Input Data Bases for Simulations

  • Digital Elevation Model (topography and bathymetry) Allows proper flow of water to be computed for storm surge, waves, and inland flooding

  • Land Cover/Land Use (land and underwater) Friction effects on both air and water to compute correct wind speeds and flow rates Debris generation

  • Historical Storm Characteristics for Statistical Analysis and validation


Model physics wind
Model Physics: Wind

Module Used: Standard Project Hurricane (SPH)

Source: NOAA Technical Report NWS 23

Basic wind field characteristics:

Asymmetric wind field

Radius of Maximum Winds

Storm motion

Central and Far Field Pressure

Terrain effects:

The wind at a point depends on

what is upwind of the point, as

much as 10 miles.

Note storm centered grid system.


Wind model validation example
Wind Model Validation Example

Correlation: 0.9222

Comparison of observed and computed peak

winds for Hurricane Floyd (1999)


Model physics storm surge
Model Physics: Storm Surge

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


Comparisons with tide gauges
Comparisons with Tide Gauges

St. Augustine

Trident Pier

Solid Line: Modeled

Dots: Observed


Peak surge observations marilyn 1995
Peak Surge Observations (Marilyn, 1995)

Observed peak water levels from

post storm surveys on St. Croix

and St. Thomas by the USACE


Model physics waves
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.


Wave validation
Wave Validation

Comparison of operational (real time) wave forecast

and NOAA buoy reports


Validation summary
Validation Summary

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.


Statistical terminology
Statistical Terminology

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.


Statistical analysis
Statistical Analysis

Once storm runs are completed, outputs are analyzed to produce

return period data sets.

Single Site Example:

Four Seasons Hotel, Nevis


Single site analysis wind
Single Site Analysis: Wind

Raw text output of TSAP program:

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 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

CHI**2 13.486692

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


Single site statistics nevis wind
Single Site Statistics: Nevis Wind

Graphic output of

weibull fit for winds

at Four Seasons, Nevis


Statistical methodology validation
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 Hurricane

basin using the 10 year period 1988 - 1997.

Percentage of sites below prediction limit:

Predicted Observed

50% 53%

75% 75%

90% 90%

95% 94%

99% 97%


The caribbean hazard data web server
The Caribbean Hazard Data Web Server

Interactive, web based system using open source/public domain software.

Temporary URL:

http://weather.methaz.com/cdcm/

Permanent URL:

UWI: ??

ODU: http://cdcm.cee.odu.edu/

Primary site will provide for

mailing lists to discuss coastal

engineering and design problems,

techniques, etc.


On line documentation
On-line Documentation

  • Notes on wind, wave, and storm surge model outputs

  • Validation and uncertainty

  • Terminology

  • Building Code Notes


Available data bases
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/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

Center.


Data set access
Data Set Access

  • User may select return period and projection limit

  • Choice of background maps

  • Point and click report generation


Report format
Report Format

Site Map and Data Location

Site information

Hazard Data


Summary
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