The%201999%20Venezuelan%20Flood

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The 1999 Venezuelan Flood

• Presented
• by
• Tibi Marin
• KDHE/KSU

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DEDICATED TO THE PEOPLE OF VENEZUELA WHO LOST
THEIR LIVES IN THE 1999 VENEZUELAN FLOOD
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MAP OF VENEZUELA
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Information about Venezuela

• Officially Republic of Venezuela
• Estimated Population 21,005,000
• Surface Area 352,143 sq mi (912,050 sq km)
• Venezuela has a coastline 1,750 mi (2,816 km)
  long on the Caribbean Sea in the north.
• It is bordered on the south by Brazil, on the
  west and southwest by Colombia, and on the east
  by Guyana.
• Dependencies include Margarita Island, Tortuga
  Island, and many smaller island groups in the
  Caribbean.
• The capital and largest city is Caracas.

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INTRODUCTION

• Landslides have caused major socioeconomic
  impacts on people, their homes and possessions,
  industrial establishments, and lifelines, such as
  highways, railways, and communications systems.

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• Socioeconomic losses due to slope failures are
  great and apparently are growing as the built
  environment expands into unstable hillside areas
  under the pressures of expanding populations and
  urban development.

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• Human activities disturb large volumes of earth
  materials in construction of buildings,
  transportation routes, canals, and communications
  systems, and thus have been a major factor in
  increases in damages due to slope failures, and
  increasing the extent of natural disasters such
  as the 1999 Venezuelan Flood.

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Topography of the Area in Study

• Venezuela is extremely steep and rugged. The
  crest of the Sierra de Avila reaches 2,700 m
  within about 6-10 km of the coast. The rivers and
  streams of this mountainous region drain to the
  north and emerge from steep canyons onto alluvial
  fans before emptying into the Caribbean Sea. In
  Vargas little relatively flat area is available
  for development with the exception of the
  alluvial fans.

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Nature of geologic event

• An unusually wet period in 1999 resulted in
  rainfall accumulation at sea level on the
  Caribbean coast of 293 mm for the first 2 weeks
  of December, followed by an additional 911 mm of
  rainfall from December 14 to 16 (MARN, 2000).

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• Fifteen days of constant and intense rainfall in
  Venezuela culminated on 16 December 1999 in
  extensive flooding and massive landslides in
  seven northern states of the country.
• Rivers overflowed their banks and swept through
  poor districts in the capital city of Caracas.

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THE FLOOD

• The disaster started when torrential rains
  triggered landslides that crashed down from Mount
  Avila, a mountain separating Caracas from the
  Caribbean coast.
• The floods affected the South American country's
  entire northern coast, stretching from the
  tourist resort Margarita Island to the western
  Zulia state bordering Colombia.

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Nature of geologic event

• The mountain soil had been weakened by the
  removal of vegetation through deforestation
  caused by urban development and migration from
  other nearby countries. (shantytowns )

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• The heavy rainfall caused massive flooding and
  debris flows in the channels of major drainages
  that severely damaged coastal communities along
  the Caribbean Sea.

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• In coastal valleys, mud slides buried most of the
  towns of Macuto and Caraballeda while the towns
  of Los Corales, Camuri Chico and Carmen de Uria
  totally disappeared under avalanches of mud.

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GEOLOGIC MAP OF VENEZUELA
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• On December 15 and 16, 1999, landslides (mostly
  debris flows) and flash floods along the northern
  coastal zone of the state of Vargas and
  neighboring states in northern Venezuela killed
  an estimated 30,000 people (USAID, 2000), caused
  extensive property damage, and changed hillslope,
  stream channel and alluvial fan morphology.

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• These shantytowns and resorts had been developing
  in the dry riverbeds and on steep unstable
  hillsides outside the larger city as part of a
  wide-scale population shift from farming regions
  to urban areas, especially those migrating from
  countries such as Colombia, Ecuador, Peru and
  others in search for better jobs.

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DEBRIS FLOW IN THE AFFECTED AREA
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• According to the national government, the
  partial figures on the disaster in the country
  are projected as follows
• Persons affected 331,164
• Persons left homeless 250,000
• Disappeared persons 7,200
• Deaths 50,000
• Housing units affected 63,935
• Housing units destroyed 23,234

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• Within this region the Venezuelan Geological
  Survey and the Ministry of Ambient and Natural
  Resources characterized geologic conditions where
  landslides initiated on hillsides and examined
  the texture of debris-flow deposits in the
  channels of nine drainages.

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• Boulders up to 5 m long were carried along by
  the flows, impacted structures causing serious
  damage, and were deposited on the fan.

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• The volume of debris-flow and flood deposition on
  the fan was measured to be about 2 million cubic
  meters.
• The total volume of material transported and
  deposited by landslides throughout the Vargas
  region ranks this as one of the most severe
  historical erosional events worldwide.

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• Large populations live on or near alluvial fans
  in locations such as Los Angeles, California,
  Salt Lake City, Utah, Denver, Colorado, and
  lesser known areas such as and Vargas, Venezuela.

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• A combination of debris flows that transported
  massive boulders, and flash floods carrying
  extremely high sediment loads were the principal
  agents of destruction
• On virtually every alluvial fan along the Vargas
  coastline, rivers incised new channels into fan
  surfaces to depths of several meters, and massive
  amounts of new sediment were disgorged upon fan
  surfaces in quantities of up to 15 metric tons
  per square meter.

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• Sediment size ranged from clay and sand to
  boulders as large as 10 m in diameter. Sediment
  and debris including massive boulders were
  deposited up to several meters thick across large
  sections of alluvial fans in Camuri Grande and
  Caraballeda

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• The states of Zulia, Falcón, Yaracuy, Sucre,
  Anzoátegui and Nueva Esparta were also affected,
  but in less degree.
• The fact remains, however, that the environmental
  hazards of disease transmission are heightened,
  and epidemic outbreaks are possible, which makes
  it necessary to assign priority to
  epidemiological and environmental surveillance so
  that proper sanitary measures may be taken.

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EPIDEMIOLOGICAL REPORT

• The epidemiological and environmental information
  was analyzed to determine the effects on health
  and the needs for allocation of resources.
• The states hardest hit by the disaster were
  Vargas and Miranda. The effects on the Federal
  District (D.F.) was also considered owing to its
  geographic contiguity to them and to the fact
  that it shares their population dynamics and
  similar geololgical makeup

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• The following factors operate in the
  transmission of diseases in the wake of a
  disaster
• The diseases already present in the population
  prior to the disaster and their endemic and
  epidemic levels.
• The environmental changes caused by the disaster.
  
• Population shifts.
• Damage to public facilities.
• Shortcomings in surveillance and in
  disease-control programs.
• Changes in the resistance of individuals to
  diseases.

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• Diseases already present in the population
• The danger of an epidemic in the wake of a
  disaster is a function of the preceding endemic
  and epidemic levels of diseases in the
  population.
• The recurrently most important diseases are the
  diarrheas, dysentery from different causes,
  measles, airway infections, meningococcal
  meningitis, intestinal parasitoses, scabies and
  other dermatoses, tuberculosis, and malaria.

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• Predisaster situation of the leading
  endemo-epidemic diseases in Venezuela Malaria
  the cumulative reported incidence in the country
  in 1999 was below that of 1998.
• In the six epidemiological weeks prior to the
  disaster incidence was on the rise. The entire
  country was affected, and the states at greatest
  risk for this disease were Zulia, Vargas, Sucre,
  Portuguesa, Miranda, Falcón, Barinas, and the
  Federal District. The situation was aggravated by
  the presence of hemorrhagic dengue.

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Environmental changes brought about by the
disaster

• These changes could alter the possibilities for
  the spread of diseases, the most important of
  which are the vector-borne (mainly mosquitoes)
  and the water-borne.
• Floods heighten the risk of leptospirosis.
  Inadequate collection of solid wastes leads to
  the multiplication of flies as a physical vector
  for diarrheas and conjunctivitis.

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• The water supply is reportedly greatly
  compromised in the states of Vargas and Miranda,
  and water disinfection is a high priority for the
  prevention of water-borne outbreaks (diarrheas,
  including cholera).
• In building a scenario for the effects on the
  health of the population in the short and middle
  run, it is also necessary to take account of the
  outbreaks of diseases in the wake of natural
  disasters among them leptospirosis, typhoid,
  food poisoning, minor infections of the airways,
  diarrheas, cholera, and malaria.

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• MITIGATION
• Because most of the coastal zone in Vargas
  consists of steep mountain fronts that rise
  abruptly from the Caribbean Sea, the alluvial
  fans provide practically the only flat areas upon
  which to build.
• Rebuilding and reoccupation of these areas
  requires careful determination of hazard zones to
  avoid future loss of life and property.

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• ACTIVITIES TO BE CARRIED OUTFOR MITIGATION OF
  RISK FACTORS
• 1. Internal cleaning of buildings
• Mud removal
• Rubble removal
• Removal of unserviceable articles
• 2. Cleaning of surroundings and common areas.
• Removal of mud from streets and avenues.
• Removal of rubble from streets and avenues.

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• 3. Collection and final disposal of wastes.
• Sanitary landfills.
• Spillways.
• Incineration.
• 4. Health surveillance and education
• Framing and circulation of directives.
• 5. Provision to the community of reliable access
  to drinking water.

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• 6. Repair of the drinking water distribution
  system.
• 7. Health surveillance and education.
• 8. Ensuring that foods supplied to disaster
  victims are in wholesome condition.
• 9. Sanitary evaluation of establishments that
  process foods and dispense them to the community.

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Conclusions

• In Venezuela, the extremely steep, tectonically
  active Cordillera de la Costa forms the boundary
  with a tropical sea.
• Easterly trade-winds can force moist air masses
  upslope and precipitate large rainfall volumes,
  creating conditions for high-magnitude debris
  flows and flash floods such as the one in 1999.

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• This example from Venezuela shows the potential
  for extreme loss of life and property damage
  where a large population occupies an alluvial
  fan Without careful planning of human
  settlements, the impacts of these types of
  disasters are likely to increase in the future.

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• By building communities and other infrastructure
  on alluvial fans, dramatic natural hydrologic
  processes have been changed into major lethal
  events such as the ones in California,
  Venezuela, Peru, Colombia, Chile, Panama, Kansas.

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REFERENCES

• MARN, 2000. Informe Preliminar Sobre los
  Aspectos Ambientales Vinculadas al Desastre
  Natural Ocurrido en Venezuela Durante el Mes de
  Diciembre de 1999.
• Wieczorek, G. F., B. A. Morgan, and R. H.
  Campbell, 2000. Debris-Flow Hazards in the
  Blue Ridge of Central Virginia. Environmental
  Engineering Geoscience, 6(1) 3- 23.

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• Garner, H.F., 1959. Stratigraphic-Sedimentary
  Significance of Contemporary Climate and Relief
  in Four Regions of the Andes Mountains.
  Geological Society of America Bulletin 70(10)
  1327-1368.
• El Nacional. Venezuelan Newspaper El-Nacional.com
• El Universal. Venezuelan Newspaper.
  El-Universal.com.
• CNN.COM
• www.fema.gov

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Report of the Flood in Caraballeda, Venezuela.
(Debris-Flow Deposits and Contours of Maximum
Boulder Size on the Caraballeda Fan,
Venezuela) Wieczorek, G.F., Larsen, M.C., Eaton,
L.S., Morgan, B.A. and Blair, J. L. U.S.
Geological Survey MARN, 1999, Cronica
Cartografica de la Catastrofe de Venezuela
Ministerio del Ambiente y de los Recursos
Naturales (MARN), Servicio Autonomo de Geografia
y Cartografia Nacional, 15 p. MARN, 2000,
Comison ambiental para la evaluation y
tratamiento intergral de las cuencas torrenciales
del Estado Vargas, Informe de advance Marzo,
2000, 43 p.
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• Pierson, T.C., and Costa, J.E., 1987, A rheologic
  classification of subaerial and sediment-water
  flows, in Costa, J.E., and Wieczorek, G.F., eds.,
  Debris flows/avalanches  Process, recognition
  and mitigation  Geological Society of America,
  Reviews in Engineering Geology, v. 7, p. 1-12.
• Salcedo, D.A., 2000, Los flujos torrenciales
  catastróficos de Diciembre de 1999, en el estado
  Vargas y en Caracas Características y lecciones
  apprendidas. Memorias XVI Seminario Venezolano de
  Geotecnia, Caracas. p. 128-175.
• Schuster, R.L., Salcedo, D.A., and Valenzuela,
  L., in press, Catastrophic landslides of South
  America, S. Evans and J. DeGraff, eds., Reviews
  in Engineering Geology, v. 14, Geological Society
  of America, pp.