Occupation of disaster-prone areas nearly tripled in Brazil since 1985

The occupation for housing purposes of areas known as susceptible to floods, landslides, droughts, and other climatic disasters surged by 2.8 times between 1985 and 2022—a period in which 123 thousand hectares of Brazil’s risk regions became occupied.

The data were released Tuesday (Oct. 31) by MapBiomas, a collaborative association of NGOs, universities, and technology companies.

The growth in the occupation of territories at risk was proportionally greater in favelas, where the expansion stood at 3.4 times during the time span monitored. In 2022, three percent of the total urban area was reported to be located in risk regions. In the favelas, this percentage reached 18 percent.

Among the risk situations assessed are valley bottoms, i.e. areas that no more than three meters away from the nearest river vertically. The study identified 425 thousand hectares of such areas, not yet officially recognized as risky. Two thirds (68%) of this occupation has occurred in the last 38 years.

“The data show an alarming situation, where precarious settlements with higher vulnerability to extreme events have grown rapidly. While urban areas in Brazil have tripled since 1985, occupation very close to riverbeds has quadrupled and occupation in high slope areas has quintupled in the same period,” said Julio Pedrassoli, one of MapBiomas’s Urbanized Areas mapping coordinators.

Steep areas

The survey also assessed compliance with Law 6766 of 1979, which prohibits occupation and plotting on land with a declivity degree above 30 percent, as it is susceptible to landslides.

According to the document, 98.8 percent of the occupied area complies with the law. However, occupation of prohibited areas has rose by 5.2 times since 1985.