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close this book A world safe from natural disasters
close this folder Chapter 3: What puts Latin America and the Caribbean at risk?
View the document Natural hazards in Latin America and the Caribbean
View the document Geological hazards
View the document Hydrometeorolocical hazards
View the document Vulnerability
View the document The relationship between disaster and development
View the document Risk in Latin America and the Caribbean

Hydrometeorolocical hazards

Hurricanes

Annually some 80 cyclones - or hurricanes as they have come to be known in the Western Hemisphere from the indigenous term "Hura Kan," or "winds of the Gods" - form over warm tropical waters during the summer months. Each year it is estimated that some 20,000 people lose their lives to tropical storms worldwide; the material losses can surpass billions of dollars. The Simpson/Saffir Scale is used to categorize hurricanes (see Figure 3.2).


Figure 3.2

Between 1990 and 1992, approximately two million people in Bolivia were seriously affected by both heavy flooding and drought.

According to the OAS, between 1960 and 1989 hurricanes claimed 28,000 victims, altered the lives of another 6 million, and destroyed property valued at close to US$16 billion in the Caribbean Basin alone, without counting losses caused by those storms in Latin America, the United States, and its possessions.

More than 4,000 tropical storms have occurred in the last 500 years in the Caribbean, half of which have been become hurricanes. The most devastating of all happened in October 1780, striking practically every island in the Caribbean, beginning with Tobago, continuing through the Leeward Islands, and across Hispaniola. Almost 20,000 people perished.

An average of 10 hurricanes threaten the West Indies and the east coast of Central America and Mexico between June and November every year. In 1988 Hurricane Gilbert dealt a devastating blow to the Caribbean, leaving hundreds of thousands of people without shelter in Jamaica before cutting across the Yucatan peninsula and ravaging the Mexican city of Monterrey (see Box 3.3). Barely two months later, after striking the Caribbean coasts of Venezuela and Colombia, Hurricane Joan left a trail of destruction from coast to coast in Nicaragua and other Central American countries. The next year, Hurricane Hugo ravaged the Leeward Islands, causing serious damages in Antigua, Guadeloupe, Montserrat, Saint Kitts and Nevis, Puerto Rico and the U.S. Virgin Islands. The storm ended by slamming into the eastern coast of the United States, heavily damaging the city of Charleston, South Carolina.

In August 1992 Hurricane Andrew tore across Eleuthera and other islands in Bahamas before delivering its most forceful blow on the Atlantic and Gulf of Mexico coasts of the U.S., devastating southern Florida and, to a lesser degree, Louisiana. Property damages in the United States were estimated at US$30 billion.

Floods

Floods are, perhaps, the most frequent and among the most ruinous type of natural disaster; however, they almost never receive the same immediate attention, for example, that an earthquake or a hurricane does. Almost every country in Latin America and the Caribbean is affected by the problem of floods.

During sudden-onset natural disasters, the different stages - impact, emergency response, and rehabilitation/reconstruction - are clearly delineated. However, with slow-onset floods, the boundaries are less clear. Months can pass before the authorities realize that an emergency exists. The isolation period may be prolonged and rehabilitation or reconstruction may overlap with the next flood.

The phenomenon known as El Niño has caused cycles of heavy rains and drought in many parts of the world. The effects of El Niño in 1982-83 in South America were among the most devastating (see Box 3.4).

The principal river cities of Paraguay were affected during the winter periods of 1982, 1983, and 1987, and more than 3,000 families had to be relocated. Because of its topography, large areas of Argentina and Uruguay also experience periodic flooding.

Between 1990 and 1992, approximately two million people in Bolivia were seriously affected by both heavy flooding and drought. The floods at the beginning of 1992 in the northeast part of the country affected more than 40,000 people in 160 communities. Agricultural and livestock losses were estimated at more than US$16.6 million. The deterioration in the standard of living and the interruption of basic public health services placed the affected population at risk for outbreaks of communicable diseases.

Cuba, the Dominican Republic, Jamaica and Trinidad and Tobago are also subject to frequent flooding which impacts on the transportation sector, for example, destroying large numbers of bridges and roads. But the Caribbean is also prone to flash floods which cannot be predicted by the national meteorological offices. A number of these flash floods are the result of other hazards such as hurricanes or landslides.

The serious flooding in the Atlantic region of northern Nicaragua in May and June 1990 affected more than 100,000 people. The indigenous communities of Miskitos and Sumos, located along the Prinzapolka, Bambana, and Coco Rivers were the most affected, together with settlements in the coastal areas. The condition of the land made cultivation impossible, resulting in food shortages, which in turn, made the population more susceptible to endemic diseases in the region.

A flood's major effects on health are in four main areas: communicable diseases, environmental sanitation, food and nutrition, and vectors. As a rule, dramatic, well-defined outbreaks of diseases generally do not occur in the immediate aftermath of a flood. Instead' a slower, widespread deterioration of general health conditions takes place, which all too often becomes part of the chronic lowering of the affected community's heath status.

In areas that are continually exposed to floods, a "disaster culture" has developed over time. The people of these regions have adapted to both the frequency and difference in intensity by constructing their houses on stilts and elevating the floors with wooden boards as the flood waters rise. It is not uncommon, when water levels have reached a high point, to observe a boat tied to a window, which has become the door!

 

Box 3.3

A HIGH-RISK SEASON: HURRICANE GILBERT

At 5:00 a.m. on 9 September 1988, Jamaica's National Meteorological Service issued its first hurricane alert. Two days later, the alert had become a warning. But a majority of Jamaica's population had never experienced the direct consequences of a hurricane, and were exceedingly conservative in heeding the warning. There would he time enough in the morning to make preparations, they thought.

That was not to he the case. Only three hours of daylight remained on the afternoon the warning was issued, and during the night wind speeds accelerated. Hurricane Gilbert, a storm of colossal proportions, made landfall on the eastern end of Jamaica on September 12 at 10:00 a.m. During its trek across the island from east to west, it gathered speed and turned into a Category 5 hurricane - the most severe.

Jamaica's last experience with a hurricane was Hurricane Charlie in 1951. Hurricane Gilbert differed from Charlie in several respects. Unlike Charlie, Gilbert's eight-hour rampage crossed the entire length of the island. Gilbert was also the largest cyclonic system ever observed in the western hemisphere, and one of the wettest, although fortunately for Jamaica, most of the precipitation fell on the sea.

The impact of Hurricane Gilbert was devastating for all sectors of the society and the economy. Damage was estimated at US$4 trillion, with the damage to agriculture accounting for over 40% of this total. Ninety-five percent of all health facilities suffered damage. Of the 25 public hospitals only two escaped with minimal damages. Two were destroyed and eleven suffered severe damage. There are 377 Health Centers in the island and 55% of these were severely damaged. The cost of emergency repairs was estimated at US$13 million with roughly 55% of this representing the cost of repairs to secondary care facilities.

The National Water Commission managed the storage and distribution of domestic water. The hurricane damaged over 50% of these facilities to a degree which varied from minor to complete destruction. Pipelines, storage tanks, pump and chlorinator houses were all affected. There were instances in which rivers changed their courses, threatening supplies and facilities.

The response from the international community was immediate and large quantities of supplies flooded the country. Daily meetings were held to coordinate donor response and the needs of the country. This achieved some measure of success. However, it was felt that prearranged needs lists would have speeded up the process of acquiring necessary supplies. Moreover, the major part of the relief effort centered around the transportation of goods. The cost of mobilizing distribution was, at times, greater than the value of the goods. A great deal of time was also spent in clearing, documenting and sorting the donations.

Source: PAHO/WHO

Box 3.4

El Niño

In June 1982, scientists again began to observe a series of atmospheric and oceanic changes in the region of the equatorial Pacific, which were related to the phenomenon known as El Niño. This phenomenon causes floods and droughts at irregular intervals of between 3 and 16 years along the western coast of South America, as well as in many other areas of the world. This 1982 occurrence of El Niño caused widespread drought in western Bolivia, southern Peru, northeastern Brazil, Costa Rica, southern Mexico, Indonesia, the Philippines, Australia, New Guinea, parts of Africa, southern India, and southern China. It also caused floods in Ecuador, Peru, eastern Bolivia, southern Brazil, northern Argentina, eastern Paraguay, and the Polynesian islands.

In the housing sector in Peru, the urban slums in Lima were the most affected by this phenomenon. In total, 62,771 dwellings were partially damaged or destroyed by flooding. The transportation and drinking water and sewerage infrastructure were practically destroyed. The floods ruptured water and sewerage networks, causing severe shortages of services to most of Peru's coastal population, including the city of Piura, where 16,750 meters of pipe were destroyed.

The consequences of El Niño along the coast of Ecuador caused the country's marine reserves to virtually disappear, severely damaging the fishing industry. In addition, heavy rainfall in these coastal areas reached into the mountains in some parts. causing rivers to overflow.

Source: PAHO/WHO.

 

Drought

Drought is a phenomenon that has affected large areas of the Western Hemisphere, but perhaps the case whose causes and effects have been most studied is that of Brazil. Since the 1940s, an increase in the population, the large scale destruction of natural resources, and growing desertification have caused this country to suffer increasingly severe droughts. These periodic droughts destabilize the primitive economy of the region, deplete the natural resources, burn the grasses, decimate livestock, and demolish crops, converting the sertão into a desert landscape whose inhabitants, deprived of reserves, die from lack of food and water. Many migrate to the large cities, where they add to the growing number who inhabit the favelas, or slums circling the cities.

The effects of drought, always disastrous, grow in proportion to the extent of the territory affected. If the affected area is not very large, neighboring regions that are not affected can offer aid. According to the Brazilian author Luis Augusto da Silva Vieira, in his account of drought in northeast Brazil in the first half of this century, the crises occur in irregular patterns: partial drought usually occurs every 4 to 5 years, normal drought, every 10 to 11 years, and exceptionally severe cases are seen every 50 years. The great drought of the 1980s verified this, since the two previous large-scale droughts had occurred in 1X77 and 1932.

Landslides

The impact of landslides depends on the specific nature of the event and its origins. For example, landslide failures of hillsides or mountain slopes obviously constitute a hazard to human beings and property; but in general cause damage in only a limited geographic area. By contrast, volcanic-triggered slides, avalanches, mudflows and lateral blasts can affect larger areas and can cause greater life and property loss. The large majority of landslides are caused or intensified by geologic and hydrometeorologic factors. The case of Armero, Colombia, in 1985, demonstrated one of the most destructive consequences of a volcanic eruption: volcanic mudflows descended from the summit of Nevado del Ruiz at great speeds following the paths of several rivers in the area.

However, the most severe landslides are those caused by the gradual displacement of large areas of the earth's surface, since their effect on buildings and other infrastructure is slow but dangerous. This type of landslide is triggered by extreme hydrometeorological conditions or by earthquake shaking.

Road and highway construction can cause slope failures: limited budgets often dictate where and at what angle a slope is cut rather than what is most stable. When severe rains occur, the roads collapse, not only claiming lives and interrupting important lines of communication but also placing severe demands on the limited institutional resources available to rebuild them.

Human activity, particularly deforestation of watersheds, pollution, and other impacts can result in landslides with extreme economic and social impacts. A landslide dam on the Paute River in Ecuador flooded most of the fertile land upriver of the slide. Population centers downriver were threatened by the catastrophic failure of the landslide dam (see Box 3.5).

Landslides caused by strong rains and flooding have had devastating effects in the Region, particularly in deforested areas and in areas where housing has been constructed on unstable soils. One tragic failure occurred in the Bolivian goldmining camp of Llipi, north of the capital city, La Paz. Torrential rains on 8 December 1992 caused a landslide that buried the entire village; 49 people were killed. Deforestation contributed significantly to the disaster; tunnels used for mining collapsed. A similar landslide occurred in Ecuador in May 1993, in the goldmining region of Nambija, claiming 140 lives.

In early August 1993, Tropical Storm Bret raced through the eastern Caribbean, causing severe structural damage in Trinidad and Tobago before striking Caracas, Venezuela, with full intensity. The storm's rains and winds triggered landslides in poor neighborhoods located in the outskirts of the capital and in the States of Miranda and Aragua. At least 100 people died, 400 were injured, and approximately 5,000 were left homeless.

 

Box 3.5

LANDSLIDES

Medellín, Colombia. September 1987 a major landslide estimated to contain 20,000 cubic meters of earth descended on the neighborhood of Villatina in the city of Medellín, Colombia. An uncovered open channel, located in the upper part of the neighborhood, which had deteriorated because of a lack of maintenance, overflowed and added to the mass, destroying 100 dwellings, killing 207, leaving 300 missing, and nearly 2,000 affected. The Villatina neighborhood was located in an appropriate area for urbanization, given the topographical conditions and was not thought to be susceptible to such hazards.

Source: Bustamante, 1987.

Rio de Janeiro, Brazil. In February 1988 a strong cold Arctic air mass passed over southern Brazil, triggering torrential rains in the state of Rio de Janeiro and depositing 279 cubic millimeters of rain on the city of Rio de Janeiro and neighboring areas. The rains caused rivers to overflow and flooded the poorer neighborhoods that surround the city, destroying hospital and dwellings and leaving 289 dead, 734 injured, and 18,560 affected. The drinking water services, sewerage, electric energy and telephones were interrupted for several days. The direct cause of the landslides was the rainwater that saturated the steep slopes of unstable soil and insufficient drainage for the large volume of water.

Source: UNDP; PAHO/WHO.

La Josefina, Cuenca-Ecuador. In March 1993 a landslide containing 20 million cubic meters of earth blocked the Paute River with a dam of rubble and dirt 100 meters high and one kilometer long, causing a reservoir of 200 million cubic meters of water to form upstream from the blockage. Warning had been given about this hazard, but measures needed to avoid the disaster had not been taken. It occurred because of heavy rainfall at the site of a previous landslide, and was brought on as well by inadequate road construction.

Following the landslide, a channel was constructed to drain water from behind the blockage, thereby reducing the flooded area upstream. But 26 days after the original landslide, the drainage channel itself collapsed, and due to the erosion brought on by continua rains, the dam fared one week later. This failure resulted in flash floods damaging an area that extended 100 km below the dam. Although inhabitants in the floodplain had been evacuated, a tote of 35 people lost their lives, and economic losses were estimated at US$ 140 million.

The flooding and impending dam collapse threatened the Paute Hydraulic Project, located 50 km downstream! which provides 65% of Ecuador's power. The dam failure was simulated so that contingency plans could be prepared for that occurrence.

Source: Zevallos, 1994