Unusual rainfall intensity and total amount causing more than 200 deaths in Petrópolis City,
Rio de Janeiro State, Brazil, in February 2022.
By Prof. Masato Kobiyama(Hydraulic Research Institute, Federal University of Rio Grande do Sul, Brazil)

On the afternoon of February 15th, 2022, heavy rainfall triggered shallow landslides, debris flows
and flash floods in Petrópolis City (22° 30' 17'' S and 43° 10' 56'' W) which is located in mountainregion of Rio de Janeiro State, Brazil. The incident resulted in 234 deaths, 3 missing persons, 994
homeless people and an economic loss of about US$ 133 million (considering only the direct
damage to companies). The population, area and mean elevation of this city are 306,678 in 2020,795.798 km2, and 838 m, respectively. According to METSUL (2022), the Civil Defense ofPetrópolis City Hall reported that there were 325 incidents in 24 hours, including 269 landslides.
Figure 1 shows one of shallow landslides occurrences in the city.

Figure 1 – Shallow landslide in Petrópolis City in February 2022 (Source: METSUL, 2022).

The intensity of the rain that fell in a very small region of the city was 230 mm in just three hours
and the maximum intensity was recorded of 199.2 mm/h at the Alto da Serra rain gauge in the city.
These values are extremely rare in the region. The total amount of rainfall in 24 hours was 259 mm
which is the highest record in Petrópolis since the beginning of measurements in 1932. In fact, thisamount occurred in 6 hours. This extremely-heavy rainfall was caused by the combination of heatand humidity, which favored the development of nuclei in atmospheric instability areas inPetrópolis. In this city, the previous rainfall record in 24 hours was 168.2 mm that occurred in 1952,
and the average monthly rainfall in February is 240 mm.
In order to collect information for supporting decision making, the Geological Survey of Brazil(Serviço Geológico do Brasil – CPRM) sent a specialized technical team during the period February
17th to March 2nd. By carrying out the field survey and also using other available data such as
airplane and DRONE photos and old hazard maps of mass movements and floods, the teamanalyzed and identified hazard areas in the city. Finally, the team presented a synthesis report with
11 technical reports as supplement materials (Modesto et al., 2022). Each of these 11 technicalreports corresponds to a severely-affected neighborhood or street. Some photos presented in thesereports are shown in Figure 2.

Figure 2 – Several localities of hydrological disasters in Petrópolis, Rio de Janeiro, Brazil (Sources:Modesto et al., 2022)

The social element associated to residents' vulnerability and exposure further intensified thistragedy. At the moment of a certain survey performed in 2012, Petrópolis City had 500 hazard
areas. The evolution of the number of hazard areas and exposed people has been greatly intensified
due to the large population growth as well as the lack of territorial control in the city. Therefore, in
2022, the numbers of hazard areas and highly-vulnerable population could be much higher. Suchpopulation growth results from the fact that Petrópolis belongs to the Metropolitan region of Rio deJaneiro and has many tourist spots.
Most of all places where disasters occurred are located at the foot of the steep hillslopes (Figure 1)
and characterized with precarious land-occupations. There is no good infrastructure in these places,
where, without projects approved by the city hall, residents have been carrying out selfconstructions. This actual situation makes the areas even more fragile. Such a land-occupation's
style can be considered typical both in Brazil and in Petropolis and is becoming common more andmore. In other words, these areas have turned into shantytowns (or slums), i.e., ‘favelaizations’(Müller, 2017). Thus, hazard areas have been occupied by a poor population with no other choice.

Furthermore, as a part of the metropolitan region, Petrópolis has been exercising typical (orconventional) urbanization without adequate land-planning. In this city, there is a strong tendency
to reduce river channel width for construction of roads and buildings, which certainly reduce river’stransport capacity. Vegetation areas have been also decreasing. Urbanized areas without planningshould seek for ecosystem services and/or ruralization proposed by Kobiyama et al. (2021).
According to Xavier (2022), the administrative movement for regularization of residences
demonstrated the seriousness’ lack in the housing policies of the city hall. In 2017, the Municipal
Risk Reduction Plan had already indicated that more than 28,000 houses were in high or very highhazard areas which represented one third of the total area of the city at that time.
Thus, inappropriate (and sometimes illegal) land-occupation of vulnerable population andinefficient land-management of public institutions have been increasing social vulnerability andpopulation exposure, consequently increasing risk of residents. In this sense, Daré (2022) presented
common opinions of several experts of Geosciences Institute of State University of Campinas(Universidade Estadual de Campinas – UNICAMP). Their opinions are that excessive rainfall
should not be considered the sole cause of the tragedy in Petrópolis and that the tragedy in
Petrópolis was not a natural disaster. Social factor should be always considered a key in disasterrisk management.
The society itself which may be the principal social factor consists of local habitants and public
institution such as city hall as well as scientists and so on. Hence, it is worth discussing actions ofscientists especially meteorologists. The Brazilian Center for Monitoring and Early Warnings of
Natural Disasters (Centro Nacional de Monitoramento e Alertas de Desastres Naturais –CEMADEN) warned about rain in Petrópolis by sending a “very intense weather event” alert toPetrópolis City two days before the tragedy, but without informing the probable rainfall intensity.
Responding to an interview, the director of CEMADEN said that people need to fully understandthat the CEMADEN informed the weather scenario and that it was impossible to predict how muchit would rain. He emphasized that the natural disaster alert had been issued two days in advance by
CEMADEN. According to him, Brazil has improved weather monitoring system very well;
however, there has been no progress in prevention work (forecasting system).
One meteorologist of the CEMADEN explained that there had been practically no displacement of
the clouds. In this case, the rain appeared on top of Petrópolis and remained there practically until itdissipated. In case of this phenomenon, the monitoring equipment and system were very inefficient.
Besides, in the world there is no meteorological model capable to predict this type of naturalphenomenon even now. In summary, he commented that there were no models, methodologies andtools that could predict this very large amount of rain in a very small space in a very short time, andconcluded that it was not a failure of Brazilian meteorology.
Even though his comment “it was not a failure of Brazilian meteorology” can be true, I surely thinkthat Brazilian science and technology related to hydrometeorology could have reduced themagnitude of this tragedy. In my opinion, weather monitoring system is not satisfactory in Brazil
even now, especially in mountain regions. Based on the fact that water-related and sediment-related
disasters have been intensified in mountain regions in Brazil (Kobiyama et al., 2019), it is exactly
the moment to improve more the weather monitoring system in this country. In case that immensedifficulty in predicting rainfall in mountain regions results from the poor investment for monitoring
system, rainfall-induced disasters in Brazil might become social disasters indeed.
As Daré (2022) criticized the public policies in the city by mentioning frequent occurrences oftragedy, Petrópolis is well-known as a city frequently suffering from hydrological disasters. In themountain region of Rio de Janeiro State, on January 11th, 2011, intense rainfall (281.6 mm in eight
hours in Nova Friburgo) caused a historic tragedy, where 947 deaths, nearly 300 disappearances,more than 50 thousand homeless, affecting nearly 1 million people were reported (Dourado et al.,2012). Petrópolis was one of three most damaged cities in this tragedy. Table 1 shows the history ofhydrological disasters with the number of victims recorded by the Civil Defense of Petrópolis
during the period 1966 to February 2022.

Table 1 – Number of human deaths of hydrological disasters in Petrópolis during the period from1966 to 2022 February.
Year
1966
1977
1979
1988
1997
2001

Death
80
1187
171
651

Year
2003
2007
2008
2009
2010
2011

Death
17
3
9
6
1
73

Year
2013
2016
2017
2018
2021
2022

Death
34
2
1
4
1
234

Pinto and Iory (2022) demonstrated that Petrópolis City Hall invested US$ 26,000 in Civil Defense
in 2020. This amount is just 0.009% of the municipal revenue of US$ 298 million in 2020. In 2021,the City Hall cut spending on Civil Defense, investing only US$ 18,000, which is only 0.007% of
the revenue of US$ 250 million in 2021. Though this investment reduction may be serious concernfor Petrópolis City residents, various actions in disaster risk reduction (DRR) can be performed withlow cost. In risk and disaster management, there is the principle where education is the key to DRR.
In the case of a city with economic problems such as Petrópolis, it is necessary to return to thisprinciple and enhance education for DRR.
According to Silva et al. (2021) which reported the “Civil Defense Program in School” executed by
Santa Catarina State government, Brazil, it is not easy to carry out a insertion of civil defense
activities to primary and secondary schools. However, since education is the principle and does notdemand high-cost investment, Petrópolis city residents together with their city hall must implement
several educational activities for DRR.

References
Daré, E.F. (2022) Petrópolis: não foi um desastre natural! In: Jornal da Unicamp. Campinas, 22Feb. 2022. Available in https://www.unicamp.br/unicamp/ju/noticias/2022/02/22/petropolis-naofoi-um-desastre-natural Access on July 10, 2022.
Dourando, F.; Arraes, T.C.; Fernandes e Silva, M. (2012) O megadesastre da Região Serrana do Rio
de Janeiro – as causas do evento, os mecanismos dos movimentos de massa e a distribuição espacial
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v.35, n.2, p.43-54.
Kobiyama, M.; Michel, G.P.; Goerl, R.F. (2019) Proposal of debris flow disasters management inBrazil based on historical and legal aspects. International Journal of Erosion Control
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Kobiyama, M.; Campagnolo, K.; Fagundes, M.R. (2021) Ruralization for water resourcesmanagement in urban area revisited. Revista Geográfica Acadêmica, v.15, n.2, p.68-88.
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