Opinion – Claudio Bernardes: Do landslides occur due to technical, environmental or housing problems?

During the rainy season, the news of landslides, homeless people and deaths become more frequent in urban areas, and this is a real problem, not only for the population that inhabits these places, but also for the administrators of the cities.

It is a fact that the occupation of slopes is technically inadvisable and inappropriate from an environmental point of view. However, it is a reality, which occurs due to the housing shortage.

Research by the IBGE (Brazilian Institute of Geography and Statistics), based on the last Census, shows that 8.27 million Brazilians live in risk areas in 872 municipalities in the country. These people live in 2.47 million households, and the situation is getting worse. Recent mapping carried out by the Civil Defense of the city of São Paulo shows that the number of homes in risk areas in the capital of São Paulo has increased by 20% in the last 11 years.

According to a report by the João Pinheiro Foundation on the total housing deficit of existing housing in Brazil in 2019, approximately 1.4 million are classified as precarious housing.

Consequently, if there are 2.47 million households in risk areas, and only 1.4 million precarious housing, it is possible that at least 1 million more families need new housing and should therefore be included in the housing deficit. . Thus, the existence of housing in risk areas is a housing problem.

New units must be produced to house the families that occupy these areas. However, while they are not relocated to adequate housing, in safe places, it is necessary to mitigate the serious damage that has been repeatedly occurring to these families, with significant damage to the environment.

The geotechnical maps identifying risk areas are known and should serve as a basis for prevention plans, mainly preventing the occupation of these areas. Once occupied, however, the way to mitigate problems in these places is to take the necessary technical measures to prevent landslides.

Trees, grasses, and other vegetation can minimize the amount of water that seeps into the soil, and slow down erosion caused by surface water flow. While vegetation alone cannot prevent a landslide, removing vegetation from a landslide-prone slope can be the cause of the process starting.

Slopes without vegetation or cover are especially vulnerable to erosion problems. The most effective and natural way to control soil erosion on slopes is to plant vegetation, which will not only help slow down raindrops as they fall, but plant roots will help keep the soil more compact, making it harder for the water to break it down.

Water is one of the main factors in landslides. Therefore, improving surface and subsurface drainage at the site can increase the stability of a sloped area prone to landslides. Surface water must be diverted away from the hazardous region and conducted for safe disposal.

Ground anchor rods, although expensive, are a technically efficient way to prevent landslides. These mechanical anchors can be inserted in terrains with the potential to slip, preventing the soil from moving in the process of slipping, thus preventing accidents that could occur in those places.

Technical measures to prevent landslides can be costly, but life is priceless and it does not seem conceivable to watch, year after year, disasters occur in places where it is known that they could occur, without doing anything, or very little. to prevent these catastrophes.