International Hydrological Programme
Latin America and the Caribbean
South America has an area of 17.9 million km2 and a population of less than 400 million, about 6 % of the world total, but produces about 26 % of the world’s water resources.
It has a modern hydrological network with 6,000 or so stations, some with records longer than fifty years.
Precipitation averages over South America are about 1,600 mm a year, with a mean of about 2,400 mm across the Amazon basin.
Totals can be as low as 20 mm a year in the Atacama Desert and over 4,000 mm in the Andes in southern Chile. Evaporation rates are high across much of the continent, and with the variability of the precipitation in certain areas, such as north-east Brazil, drought can be a frequent problem.
The Amazon is the world’s largest river, but the Rio de la Plata, Orinoco, San Francisco and Paranaiba rivers are also very important. The average runoff from South America for the 1921–1985 period was calculated to be about 12,000 km3 per year.
There are large and productive aquifers, lakes and reservoirs, but the high density of population in certain areas and the untreated sewage resulting causes water pollution problems and there are similar problems due to agricultural effluents and mine wastes in some parts.
Central America has a surface area of 807,000 km2 and a population of 35 million.
Various factors have put substantial pressure on the water resources, in spite of their abundance. The annual per capita water availability exceeds 3,000 m3/year, but only 42 % of the rural population and 87 % of the urban population have access to drinking water. Two thirds of the population live in areas with drainage to the Pacific ocean, while 30 % of its water discharges into this water body. The other third of the population is located in the Caribbean basin, which generates 70 % of the ‘isthmus’ water. This uneven distribution puts stress on the region’s water resources.
The Caribbean has a surface area of 269,000 km2. Countries differ in size, population and economic conditions. The temperature varies between 24°C in February and 31°C in August, also presenting a wide rainfall variation throughout the region, from 500 mm/year in the Netherlands Antilles to 7,700 mm/year in the Dominican Republic.
The region has sufficient water but the availability of safe water is becoming a major socio-economic issue. Population growth has notably increased water demand. Water quality is a generalized issue in the region due to the degradation caused by agricultural toxic substances and the mismanagement of solid waste as well as mining and industrial activities.
