flooding in the caribbean: improved forecasting · 2014. 2. 8. · caribbean water initiative 2nd...
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Caribbean Water Initiative2nd Senior Administrators’ Workshop
Flooding in the Caribbean: Improved Forecasting
Presented by:
Shawn BoyceCaribbean Institute for Meteorology & Hydrology
Husbands, St. JamesBarbados
Examples of Recent Flooding in Jamaica
Examples of Recent Flooding in Jamaica
Examples of Recent Flooding in Jamaica
Examples of Recent Flooding in Haiti
Examples of Recent Flooding in Haiti
Examples of Recent Flooding in Haiti
Examples of Recent Flooding in TCI
Examples of Recent Flooding in TCI
Examples of Recent Flooding in TCI
Flash Flooding on Barbados
Flash Flooding on Barbados
2004 Flooding in Guyana
2004 Flooding in Guyana
2004 Flooding in Guyana
Flooding Mechanisms in the Region
Functions of:Rainfall intensityRainfall durationRiverine floodingTidal InfluenceCatchment characteristics
Rainfall IntensityLocalized convective eventsRecording rain gauge dataMaximum accumulations for 5, 10, 15, 30 mins and 1, 2, 6, 12 hour durationsShort duration rainfall frequency analysisShort duration data sparse in the regionEstimate short duration maxima from 24hr data
1hr Frequency Plot
2 5 10 50 100 200 T
0
10
20
30
40
50
60
70
80
90
-2 -1 0 1 2 3 4 5 6
Reduced variate
Ann
ual m
axim
um
rain
fall
(mm
)
Barbados: August, 2008
Rainfall DurationRainfall on consecutive daysIncreased saturation levels (i < K)Surface ponding (i > K)Frequency analysis on rainfall accumulations greater than 1 day
Guyana: January, 2005
Riverine FloodingFlooding when river overflows banksFlood risk high
Fertile landsHeavily populated
Rainfall generated surface runoff + river channel routingFactors that affect runoff need to be considered
Climatic factorsCatchment characteristics
Jamaica: August, 2008
Tidal InfluenceStorm surge
Significant flooding along low lying coastlinesHurricane related
Spring tidesHigh tides + rainfall
Increases the probability of floodingContributes to flooding in Guyana
Martinique: November 1999
Catchment CharacteristicsWatershed delineation
DEM resolutionCatchment size and shape
Land use and land coverSoil and rock types
Infiltration ratesHydraulic conductivities
Characteristics can be used to determine high risk zones
Narrow, steep sided valley in Dominica
Objective:Integrate precipitation forecasts into a hydrological model
Provides an early flood warning system before the precipitation eventLead times of at least two daysForecast updates (weather radar)Water depths simulated throughout catchmentFlood extents delineated
Improved Flood Forecasting
Weather Research Forecasting model Outputs: atmospheric variables at all levels of the troposphere; the state of the atmosphere at different times in the future Forecasting tool:
Provides simulations on different spatial scalesReal-time forecasting out a fortnightCan be altered to better represent the tropical atmosphereRegional climate scenarios
HydroGeoSphere (Hydrological Model)Outputs: Water depths; SW/GW flows; GW saturations; ConcentrationsWater resources management tool
Flood forecastingSimulate impact of contaminant transportSimulate climate change scenarios scenariosReal time monitoring
The Models
Calibration and ValidationLocalized convective event in Barbados 26/08/2008, 12:00-00:00 UTC
*TMPA-RT
60.94km x 4kmWRF V3.0
1.40.25° x 0.25°TRMM 3B42*
29Point estimateRain gauge
Rainfall(mm)
ResolutionInstrument
Calibration and ValidationObserved data
Weather radar (calibrated) dataHydrometric network installationsData logging and transmission
Uncalibrated Water Depths at Arch Cot, St. Michael
Complementing InitiativesCARIWIN
Capacity BuildingCCRIF
Flood risk insurance feasibilityCarib-HYCOS
Hydrometric networks, Database management software
Italian projectHydrometric networks