ENVIRONMENT-BRAZIL: Capital’s Water Supply Threatened

By Mario Osava Reprint | | Print |

Mario Osava(Tierramérica*)

RIO DE JANEIRO, Jun 11 2001 (IPS) - The abundance of water in Brazil’s geographical centre was one of the reasons the new national capital was established there 41 years ago. But no one predicted the rapid increase in the local population, which already surpasses two million, or four times the number forecast for 2000, says José Eloi Campos, geologist from the University of Brasilia.

One of the major environmental concerns in Brasilia today is underground water, which is being over-extracted through artesian wells. The Federal District’s Secretary of Environment and Hydraulic Resources, Antonio Barbosa, calculates that there are 6,000 such wells in the area, 90 percent of which are illegal.

Unregulated perforations – if they occur near septic tanks or garbage dumps, for example – could contaminate the aquifers, which are the principal water source for the region’s residents, he cautioned.

The exhaustion of underground water reserves is evident in the reduced flow in the artesian wells, which are concentrated in the residential areas proliferating around Brasilia, according to geologist Campos.

The Environmental Secretariat is attempting to regulate the use of underground water, requiring residents to certify previously illegal wells or face fines and closure of the wells. The state- run sanitation company has already identified 2,300 such wells, Barbosa told IPS.

Some wells were shut down in the Pilot Plan area, the original planned district of Brasilia, where perforations are banned and all water is to be supplied through pipelines.

Those who violated the law were probably trying to cut costs. One supermarket saw its water expenses triple after its water well was closed, Barbosa pointed out.

It is widely held that the illegal artesian wells contributed to the effects of an earthquake last November that registered 3.7 on the Richter scale. The temblor, an unusual occurrence for the Federal District, involved “strong surface waves” and was felt 1,800 km away, according to Vasile Marza, a seismologist at the University of Brasilia.

Marza recognises five theories for explaining the earthquake. One of them implicates the wells as the direct cause. Local aquifers occupy the fissures in the subterranean rock that, without the water to fill them, could have shifted, thus causing the quake.

The Rumanian-born seismologist says the most likely cause was the collapse of an underground cave measuring at least 40 meters in diameter and 20 meters deep. The withdrawal of water from that space by residents of Brasilia could have caused the changes in pressure and structure that unleashed the phenomenon. “But it is very difficult to prove it,” he acknowledged.

Another hypothesis for explaining the quake involves Lake Paranoá, a large artificial reservoir in Brasilia. But this theory has a weak point: reservoirs tend to cause seismic shifts within a few years after they are created, not 40 years later, as is the case of Paranoá, Marza said.

As far as the surface water available in the area, it will not be enough to sustain further urban or industrial growth in the Federal District, according to Campos, who predicts that the city’s water supply system will collapse within 20 years if current trends continue.

Secretary Barbosa acknowledges that the current panorama is critical, characterised by drought and a water supply of 11 cubic meters per second – just 10 percent above consumption levels, a margin that leaves the city very vulnerable.

But he says the construction of the Corumbá IV dam will be complete within three years and will provide a 10-fold increase in water supplies, ensuring that water will be available for Brasilia for “the next 100 years.”

Campos, however, doubts that the Corumbá River will be able to produce electricity and supply water at reasonable costs.

Brasilia also suffers from low humidity in the winter months. With the current drought, humidity levels are the same as in a desert and spontaneous fires have occurred in and around the capital. In addition, with increased air-borne particulate matter as a result of the aridness, respiratory problems are on the rise, especially among children and the elderly.

During the Southern Hemisphere winter this year, Brasilia expects average humidity levels to be less than 14 percent.

* This article was published by Tierramérica (www.tierramerica.net) under the title “Clandestine Wells Threaten Brasilia”. Tierramérica is a specialised news service produced by IPS with support from the United Nations Development Programme and the United Nations Environment Programme.