Intense rainfall causes
floods in Rio de Janeiro

Two months’ worth of rainfall fell within nine hours to cause flooding across the city of Rio de Janeiro on 8 April 2019. During the downpour, the 24-hour rainfall total at Rio de Janeiro exceeded 340mm (Fonseca and Gaier, 2019). To put this into context, the average rainfall for the city in April is ~95mm (Watchers News, 2019). Copacabana Fort received 246mm of rain within nine hours, which represented two-and-a-half times April’s average rainfall total (Watchers News, 2019).

Figure 1: An extract of the JBA 1-in-20-year 30m Brazil River and Surface Water Flood Maps. The area illustrated is south of Rio de Janeiro city. Barra da Tijuca, Niemeyer Avenue, Jardim Botanico, Copacabana Beach, Humaita and Botafogo neighbourhoods were some of the areas affected in Rio de Janeiro based on reports by Reuters. (JBA Risk Management Limited™).

Southern and western areas of the city appear to be worst affected (Figure 2), such as the Guaratiba and Santa Cruz neighbourhoods (FloodList, 2019). Many apartment blocks in these bairros (or neighbourhoods) are built on steep slopes and at the foot of mountainous regions, which can exacerbate the risk of both flooding and landslides due to rapid runoff of water down the steep slopes (The Japan Times, 2019). So far, there have been at least 10 fatalities due to the recent storms and secondary impacts (FloodList, 2019).

Figure 2: 24-hour rainfall totals for the Rio de Janeiro and São Paulo area using NASA Precipitation Measurement Mission data at a 10km resolution. The highest rainfall was recorded to the south of Rio de Janeiro (NASA PPM, 2019).

An overview of flood hazard in Brazil

River (fluvial) flood, surface water (pluvial) flood and landslides are a major hazard in Brazil. In February 2019, 35 incidences of similar flooding occurred in Rio de Janeiro city in the neighbourhoods of Barra da Tijuca, Barra de Guaratiba, São Conrado, Itanhangá, Vidigal and Rocinha (Davies, 2019).

Floods in Brazil are estimated to have caused 1,300 deaths and USD $2.8 billion in economic losses between 2000 and 2010 (Swiss Re, 2011). The country’s south-eastern states are often the most vulnerable to surface water floods due to their mountainous topography. In this region, the Serra do Mar mountains run through two major metropolitan areas – Rio de Janeiro and São Paulo.

Swiss Re has estimated the proportion of population exposed to flood risk in the different regions of Brazil, with states in the Amazonas, including Maranhão, Para, Pernambuco and São Paulo, being amongst the most exposed to river flood. São Paulo is also susceptible to surface water floods, along with the states of Bahia, Minas Gerais, Rio de Janeiro and Santa Catarina. The proportion of the populations estimated to be at risk of flooding in several states and the municipalities of São Paulo and Rio de Janeiro can be seen in Table 1.

Table 1: Estimated population and proportion of people at risk of river and flash flood in various states of Brazil. The data were generated using a study conducted by Swiss Re (Swiss Re, 2011).

The estimated total annual expected loss for floods in Brazil in 2010 was USD $1.4 billion (Swiss Re, 2011). More than half of the expected losses were from south-east Brazil, which includes both São Paulo and Rio de Janeiro.

Historical floods in Brazil

In 2014, the World Bank partnered with local Brazil state governments to conduct studies into flood risk, which found that the four main flood events that occurred between 2008 and 2011 cost R$ 15.3 billion (USD $6.6 billion), of which 61.4% were from direct damages while the remaining 38.6% were indirect losses (World Bank, 2014). Most of the damages and losses were incurred by the housing sector, followed by the transportation sector (World Bank, 2014).

One of Brazil’s worst flood events in recent history occurred in January 2011 in Rio de Janeiro state (Table 2). During the 2011 floods, the city of Petrópolis, along with various municipalities of Rio de Janeiro (including Teresópolis, Nova Friburgo and Sumidouro) were inundated (Swiss Re, 2011). Prolonged rainfall resulted in flash floods, landslides, and 1,000 lives lost in seven municipalities of Rio de Janeiro state (Reuters, 2011; World Bank, 2014). At the peak of the event, an estimated 254mm of rain fell within 24 hours (Phillips, 2011).

Table 2: Historical events and economic losses in Brazil (World Bank, 2014). The conversion between Brazilian Real to US Dollar is based on a historical record rate of 1 BRL to 0.573 USD on 1 January 2010 (X-Rates, 2019).

Future Outlook

Urbanisation is a major factor that exacerbates surface water flooding in Brazil. The movement of people into urban areas leads to the increase in surface runoff due to impermeable road infrastructure, housing and a general reduction in natural floodplains.

Non-life insurance penetration (as a percentage of GDP) increased for most countries in Latin American nations, including Brazil, between 2007 and 2017 (Figure 3).

Figure 3: Non-life insurance penetration for several countries in Latin America (Swiss Re Explorer, 2019).

Brazil has been one of the fastest emerging markets, with non-life insurance penetration growing from 1.5% of GDP in 2007 to 1.8% in 2017 (Swiss Re Explorer, 2019). Compared to more established markets, however, penetration remains low in Latin American countries. Hence, public and private funds are utilised and relied on to cover losses and costs for rebuilding and recovery (World Bank, 2014).

Property insurance makes up the largest proportion of non-life insurance in Brazil. Generally, insurance coverage for flood is applied when policies insure against natural perils, which is usually included under standard property insurance. Swiss Re has suggested that flood coverage for buildings and contents should also be covered by microinsurance aimed at low-income groups, which currently only covers fire, lightning and explosion in Brazil.

As the urban population continues to grow, by 2030, an estimated 42.5 million people are likely to live in flood risk areas in Brazil; around 30% higher than the estimated figure in 2010 (Swiss Re, 2011). Based on climate change projections, the centre, south and south-east areas of the country are likely to have more extreme rainfall events. This suggests that flood risk in the aforementioned regions may increase – a notion supported by a Swiss Re study which found that expected annual losses for Brazil are likely to increase from USD $1.4 billion to USD $4 billion between 2010 and 2030 (Swiss Re, 2011). Furthermore, the research concludes that the south-east region, which includes the large economic hubs of Sao Paulo and Rio de Janeiro, is likely to account for more than half of the losses incurred (Swiss Re, 2011).

JBA Risk Management has nationwide return period flood maps available for Brazil at 30m resolution. For more information about our maps and how they can help you to manage your exposure to flood in the country, please get in touch.

 

References

Davies, R. 2019. Brazil – Deadly Floods and Landslides in Rio De Janeiro After 90mm of Rain in 1 Hour. [online] Available at: http://floodlist.com/america/brazil-rio-de-janeiro-flood-storm-february-2019 [Accessed 24 Apr. 2019].

FloodList. 2019. Brazil – 10 Dead After Torrential Rain in Rio De Janeiro. [online] Available at: http://floodlist.com/america/brazil-rio-floods-april-2019 [Accessed 24 Apr. 2019].

Fonseca, P. and Gaier, R. 2019. Powerful, 'abnormal' rains lash Rio de Janeiro, at least six dead. [online] Reuters. Available at: https://www.reuters.com/article/us-brazil-weather/powerful-abnormal-rains-lash-rio-de-janeiro-at-least-six-dead-idUSKCN1RL20U [Accessed 24 Apr. 2019].

The Japan Times. 2019. Torrential rain in Rio de Janeiro leaves 10 dead, floods favela. [online] Available at: https://www.japantimes.co.jp/news/2019/04/10/world/torrential-rain-rio-de-janeiro-leaves-10-dead-floods-favela/#.XLf7RZMzZmA [Accessed 19 Apr. 2019].

NASA PPM. 2019. NASA Precipitation Measurement Missions. [online] Available at: https://pmm.nasa.gov/data-access/pps-ftp#jsimpson-NRTPUB/imerg/gis/early [Accessed 23 Apr. 2019].

Phillips, T. 2011. Brazil landslides leave hundreds of people dead. [online] The Guardian. Available at: https://www.theguardian.com/world/2011/jan/12/brazil-landslide-leaves-115-dead [Accessed 24 Apr. 2019].

Reuters. 2011. Eleven dead as Brazil's largest city flooded. [online] Reuters. Available at: https://www.reuters.com/article/us-brazil-weather/eleven-dead-as-brazils-largest-city-flooded-idUSKBN1QS2JU [Accessed 23 Apr. 2019].

Swiss Re. 2011. Flood Risk in Brazil. [online] Available at: https://www.researchgate.net/profile/David_Bresch/publication/253327670_Flood_risk_Brazil_full_study/links/00b4951f7f5db0793d000000/Flood-risk-Brazil-full-study.pdf [Accessed 23 Apr. 2019].

Watchers News. 2019. Extreme rainfall: More than 2 months' worth of rain in 9 hours, severe floods hit Rio de Janeiro, Brazil. [online] Available at: https://watchers.news/2019/04/09/rio-de-janeiro-flood-extreme-rain-brazil-april-2019/ [Accessed 19 Apr. 2019].

World Bank. 2014. Coping with losses: options for disaster risk financing in Brazil. [online] Available at: https://www.gfdrr.org/sites/gfdrr/files/publication/Options-for-Disaster-Risk-Financing-in-Brazil-English.pdf [Accessed 23 Apr. 2019].

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