[SÃO PAULO] As many as 155,000 people are exposed to the risk of landslides or floods in highland region of Rio de Janeiro, southeast Brazil, a study published in the International Journal of Disaster Risk Reduction has estimated.

Using a new methodology, researchers from the Brazil’s natural disasters early warning centre Cemaden cross-reference information about areas susceptible to natural disaster with demographic and socioeconomic data provided by the Brazilian Institute of Geography and Statistics.

In this way, they were able to estimate the number of people living in at-risk areas in the region, as well as their living conditions, age and housing situation – aspects that other methodologies cannot identify.

The new approach was applied in the mountain towns of Petrópolis, Teresópolis and Nova Friburgo. All these cities were devastated by floods and landslides triggered by torrential rainstorms in January 2011, leaving thousands of people homeless.

“This sort of information is essential to improve monitoring and early warning capacity in operational disaster centres”

Silvia Midori Saito

From approximately 155,000 people living in 1,357 areas at risk of landslides or floods in region of Rio de Janeiro city identified by the new approach, 52 per cent are women, 48 per cent are men, and 20 per cent are children and the elderly, the most vulnerable age groups for disasters.

Researchers also determined that most of the houses are located in areas with no water or adequate sanitation, which indicates the precariousness of living conditions in these regions.

“Our results showed detailed conditions of at-risk populations in these cities, which could contribute to risk management actions and disaster response,” Mariane de Assis Dias, a geographer at Cemaden and the main author of the study, tells SciDev.Net.

She argues that as long as maps of disaster risk areas are made available, the new methodology could be used to estimate all exposed populations in Brazil. Similarly, it also could help prioritize the removal of vulnerable people in case of disaster, as well as identify areas with the highest concentration of exposed people.

“This sort of information is essential to improve monitoring and early warning capacity in operational disaster centres,” Silvia Midori Saito, a geographer at Cemaden and one of the authors of the study, tells SciDev.Net.

About 85 per cent of disasters in Brazil are caused by flash floods, landslides and prolonged droughts.Between 1991 and 2010 there were almost 39,000 disasters linked with these phenomena, affecting more than 125 million people, and causing 10,225 deaths, according to a study conducted by researchers from the Institute of Geosciences at the University of Campinas, released in the book Urbanização e Desastres Naturais - Abrangência América do Sul, published in mid-2015.

“The new method should make the implementation easier of contingency plans, alerts and monitoring of possible disasters areas, as well as the development of public policies to remediate or prevent natural catastrophes,” Nathan Debortoli, a Brazilian geographer currently at Canada’s McGill University Department of Geography, tells SciDev.Net.

“It is also innovative because it allows us to verify how people are intervening in the landscape in the municipalities based on the mapping of areas of irregular occupation,” highlights the researcher, who has not participated in the study.

“By doing so, the method is able to see not only the areas that are irregularly occupied, but also tells security services where people are located and the profile of the inhabitants of those areas, so the security services’ work becomes more efficient, agile and directed to a specific public.”

Debortoli is co-author of two studies based on climate simulations that indicate that the risk of occurrence of flash floods, landslides and prolonged drought will increase by the end of this century in most of the areas already affected by these phenomena.

He also predicts that severe droughts, a catastrophe today nearly always associated with places in the northeast, are expected to intensify in other parts of Brazil including Amazonia.

“It is important that new methods be developed to improve and calibrate the available tools, improving the disaster response capacity in municipalities when it is about to occur,” he adds.

The study published in International Journal of Disaster Risk Reduction was partially supported by FAPESP, a SciDev.Net donor.