influence of orography on r ainfall distribution and water resources in guadeloupe
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Influence of Orography onRainfall Distribution and Water
Resourcesin Guadeloupe
Marc Morell - Institut de Recherche pour le DéveloppementPhilippe Palany – Météo-France
Dominique Rossignol, ORSTOM ✚
CARIBSAT Project
Berlin, EMS 2011
Canal des Saintes – Ouragan David - 28/08/1979 - M. Morell
WWW.CARIBSAT.COM
Summary
IntroductionThermic and Orographic PhenomenaMonthly and Yearly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water ResourcesClimate Changes EffectsComments
Berlin, EMS 2011
Introduction – Location
Berlin, EMS 2011
Caribbean sea
Guadeloupe
Landsat Satellite Image of Guadeloupe islands
Introduction - Geography
La Soufrière
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Introduction – Climate
Berlin, EMS 2011
Monthly averages of temperatures and rainfalls
in Le Raizet (source Meteo-France)
Rainfalls Mini. Temperatures
Maxi. Temperatures
Cliamte changes effects
Berlin, EMS 2011 Hurricane Ivan – 7 September 2004
Guadeloupe
Introduction – Main studies
1978 – ORSTOM - Monographie des ressources en eau de surface de la Guadeloupe, Chaperon P. & al.
1990 – ORSTOM – Travaux de Dominique Rossignol, Physicien de l’Atmosphère & al.
1994 – ORSTOM – La Guadeloupe au fil de l’eau, Marc Morell & al.
1996 – METEO-France – Le régime pluviométrique de la Guadeloupe, N. Bleuse & C. Mandar
2010 – METEO-France – Analyse des sécheresses en Martinique, Philippe Palany, Projet CARIBSAT
Berlin, EMS 2011
Introduction – Networks and Data ORSTOM, started to implement a
rainfall recording network in Basse-Terre mountains in 1960’
ORSTOM has completed its network with electronic stations equiped with ARGOS transmitters in 1984
In 1990, 35 stations were managed by ORSTOM, 2/3 of them at an elevation higher than 300 m
In 1990, around 4500 years/stations of rainfall daily data were available on Guadeloupe archipelago La Soufrière, Dent de l’Est – R. Calvez
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaMonthly and Yearly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water Resources AssessmentClimate Changes EffectsComments
Berlin, EMS 2011
Landsat Satellite Image of Guadeloupe islands
Berlin, EMS 2011
Thermic and Orographic Phenomena
Thermic
Orographic
Thermic and Orographic Phenomena
Transect from Capesterre to Vieux-Habitants
Rainfall Gradient for 1 km :from 150 mm Upwind to 600 mm
Downwind
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11 m
EastWest
1 m 2.5 m
Short time steps Intensities
Nb Hours per year = 1,58 Altitude + 152 R2 .95 Yearly rainfall = 6,45 Altitude + 1234 R2 .92
100 200 300 400 500 600 700 800 900 1000
1100
1200
1300
1400
1500
0
2000
4000
6000
8000
10000
12000
Nb hoursYearly average
Altitude
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaYearly and Monthly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water Resources AssessmentClimate Changes EffectsComments
Berlin, EMS 2011
Yearly and Monthly Variability
Annual precipitation distribution Berlin, EMS 2011
20 km
Soufrière
Yearly and Monthly Variability
7 homogeneous climatic areas were defined by ORSTOM in 1984
Regulation of Rainfall regimes by orographic effect on interannual variability on seasonal distribution
Homogeneous areas
Berlin, EMS 2011
Yearly and Monthly VariabilityRatio Humid /Dry Year - Frequency
1/10
7 homogeneous climatic areas were defined by ORSTOM in 1984
Regulation of Rainfall regimes by orographic effect on interannual variability on seasonal distribution
Interannual Variability
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1.3
1.6-1.7
1.81.6-1.7
1.4-1.5
1.6-1.7
Yearly and Monthly Variability
7 homogeneous climatic areas were defined by ORSTOM in 1984
Regulation of Rainfall regimes by orographic effect on interannual variability on seasonal distribution
Seasonal distribution
Berlin, EMS 2011
Yearly and Monthly VariabilityRatio Maximum/Minimum Monthly
Rainfall 7 homogeneous climatic
areas were defined by ORSTOM in 1984
Regulation of Rainfall regimes by orographic effect on interannual variability on seasonal distribution
Seasonal distribution
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaMonthly and Yearly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water Resources AssessmentClimate Changes EffectsComments
Berlin, EMS 2011
Daily and Hourly Analysis
Maximum thermic effect on the North of Basse-Terre with pick in the early afternoon
Berlin, EMS 2011
Daily and Hourly Analysis
Maximum thermic effect on the North of Basse-Terre with pick in the early afternoon
Maximum orographic effect on the top of the mountains in Basse-Terre with occurrence of rainfall during the night explained by the decrease of the temperature of the top of the clouds
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaYearly and Monthly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water Resources AssessmentClimate Changes EffectsComments
Berlin, EMS 2011
Short time steps Intensities
Statistical Analysis of Intensities in one minuteImportant contribution of low intensities (< 10
mm/h) in the total amount of rainfall in mountainsIncreasing contribution of higher intensities on
the slopesNo orographic effect on the heaviest intensities
clearly linked with convective thermic phenomenaThe strongest rainfall intensities for duration from
5 mn to 3 hours are not related to hurricanes
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Short time steps IntensitiesInfluence of the wind on
the measurement of rainfall
Hurricane David – 28/08/1979 – M. Morell
Incidographe – Marc Morell 1985
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A
Short time steps Intensities
Duration 2 years 10 years 100 years6 mn 12 17 2315 mn 22 31 4230 mn 33 49 691 hour 45 63 856 hours 78 123 17912 hours 92 157 2391 day 105 189 294
Rainfall in mm in Le Raizetfor various time periods
Statistical analysis - METEO-France
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaMonthly and Yearly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water ResourcesClimate Changes EffectsComments
Berlin, EMS 2011
Water Resources
ORSTOM Hydrometric network in Basse-Terre
Chutes du Carbet - M. Morell
Berlin, EMS 2011
Basse-Terre = 95% of the WR ofthe Guadeloupe island
Water Cycle Balance
Water Cycle Variables
%
Rainfall 100 . Evapotranspiration
16
. Runoff 84Runoff 100
. Flash Floods 70
. Delayed flows 10 . Ground water 20
Yearly rainfall basis : 5000 mm
Berlin, EMS 2011
Summary
IntroductionThermic and Orographic PhenomenaYearly and Monthly VariabilityDaily and hourly analysisShort time steps intensitiesWater Cycle and Water Resources AssessmentClimate Changes EffectsComments
Berlin, EMS 2011
Climate Changes effects
Climate changes will increase the vulnerability of the ecosystems and human population of the tropical islands : Anthropogenic activities (pollution, sedimentation),
increasing temperatures and acidification of ocean are impacting the marin ecosystems (mangrove destruction, coral bleaching, etc.)
Rising sea levels and disappearance of the coral reefs will lead coastal erosion processes, salt water intrusion, etc.
More frequent and longer dry periods and more frequent and intense meteo-marin events are expected during the next decades
Decreased water resources and higher atmosphere temperatures (2 to 3° in 2050) will induce serious consequences on agriculture, biodiversity and sanitary issues (vector diseases), etc.
Berlin, EMS 2011
Climate Changes effects
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Increasing Number of Tropical Storms on North Atlantic Ocean 1966-2007
Source NHC Miami, Wind speed > 63 km/h
Average : 10,4/year mini 1983 : 4 max 2005 : 27
Climate Changes effects
In 1989, Dominique Rossignol studied the relationships between El nino and QBO occurrences and the yearly rainfall variability and its seasonal distribution.
Among the main results : 90% of El Nino events are followed by severe
droughts during the “Carême”, like in 1983 and 1987, and a predictive method must be implemented
Orography and elevation are significant local modifiers of sub-regional climate change
Berlin, EMS 2011
Comments Guadeloupe appears as an ideal laboratory for studying
the rainfall distribution in tropical islands Specific thermic and orographic effects can be
analysed Long data series are available
In this presentation, we have reported on the main achievements obtained 20 years ago when the concept of climate changes was very new
In the present context of climate changes, water resources scarcity and biodiversity conservation, it is urgent to implement some monitoring networks at Caribbean scale which will provide the scientists with all necessary data to improve the knowledge on the dynamic of the
phenomena generating rainfall and water resources, and
to give a better accuracy to the downscaling of the regional climatic change models Berlin, EMS 2011
www.CARIBSAT.com
Grand-cul-de-sac-marin – 1979 - M. Morell
Berlin, EMS 2011
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