The municipal area of Gilbués, in the extreme south of Piauí, is locked in a silent struggle against time. Over the last few years erosion has changed the scenery on the outskirts of the town and is now heading towards the urban centre itself, threatening the hospital, the cemetery as well as several houses. The feeling that the earth is disappearing is a forewarning of the greatest fear in the town today: that of being swallowed up by one of the giant craters, which are spreading across the region. "Gilbués is a doomed city. If nothing is done about it, this will just become one big hole" laments the municipal mayor, Felipe Ribeiro (PMDB)

In fact the desertification of the town is all the more impressive because of the damage caused over the years. Previously fertile land, which was once used for cultivating crops or for raising animals, has been devastated by wind and rain erosion. When the topsoil is not washed away by rainfall in the winter, the layers are blown away by winds reaching 80-100 km/h in the dry season, giving rise to huge dunes of soft soil and dust, without any vegetation cover whatsoever.

"Gilbués has the largest continuous area of desert in the country. The degradation has reached such a serious level that it ranks among the worst affected areas in the world, explains Waldemar Rodrigues, professor at the Federal University of Piauí (UFPI) and one of the foremost specialists in this field. The reason for such an advanced stage of erosion stares one in the face when one arrives at the communities of Boqueiro and Comprafiado, where in the 1950s and 60s thousands of people dug enormous holes in the search for diamonds. Such mining was the single most important factor responsible for the situation the town finds itself in today. The prospectors ravaged the land for years without anything being done to compensate for the damage caused.

In the mining heyday, the town had 18,000 inhabitants, almost double its present population. "It was a time of great wealth. Planes from all over Brazil would arrive everyday bringing people who wanted to buy diamonds", remembers former prospector Cícero de Oliveira Paiva, 75. Today just over 200 people still try to make a living prospecting, but the slagheaps of the mining region have left their indelible mark. In these places the soil is reminiscent of a lunar landscape, with huge craters. " Even today the techniques used by prospectors are very basic. They dug too many holes and now nature is paying them back" Cícero says.

The desertification in Gilbués is threatening the residents there in another way. The soil erosion has led to sedimentation in the rivers to such a degree that it compromises the main riverbeds and dams in the municipal area. The River Brejão, considered to be the "lungs" of the community, is being buried under displaced soil and has lost one third of its volume over the last ten years. As a result, many kinds of bird-life have also disappeared, such as the canary and the white wing. It is estimated that if the flow stops altogether, the temperature of the region will increase by around 3 degrees.

Farmer Amilton Lustosa is a typical of those affected by the devastation erosion has brought to the municipality. Three years ago he constructed a 6 metre deep reservoir on his land. Today the reservoir has practically disappeared buried underneath displaced soil from other regions and has been transformed into a plantation. "Gilbués must be the only place on earth where you cultivate pumpkin and rice in a reservoir," says the farmer resignedly.

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