Heavy rain showers have become a cause for concern for many residents of Foz do Iguaçu. The fear is of flooding, which occurs constantly in various parts of the city. Part of this problem could be solved with a more efficient drainage system.
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The IBGE (Brazilian Institute of Geography and Statistics) shows that only 52,5% of Foz residents live on streets that have sewer and storm drain infrastructure. These devices perform important functions, as they drain rainwater by collecting rain from streets and sidewalks, preventing flooding and water accumulation.
IBGE released the data in the survey Urban Characteristics of the Surrounding Areas of Households, based on the 2022 Census. Foz do Iguaçu has the worst rate among the ten most populous cities in Paraná. Despite this, the state has the second best national average: 83,5% of streets have these devices. In Curitiba, coverage reaches almost 95%.
Alex Castagnaro, census area coordinator, explains how the survey was conducted: “The assessment unit is the block face. In simple terms, it is the route between one corner and another. Along this route, the supervisor recorded the conditions found, observing whether there were manholes or storm drains on both the worked face and the opposite side (the other side of the street).”
Manholes and storm drains: the importance of these devices
In the survey, the IBGE explains that these components are essential for urban infrastructure. They perform functions such as stormwater drainage, as they collect rainwater from streets and sidewalks. This prevents flooding and water accumulation, which can cause damage to infrastructure and properties.
They also help prevent flooding, as they facilitate the rapid flow of water to the underground drainage system, reducing the risk of flooding in urban areas. In addition, they help to ensure road safety for drivers and pedestrians by preventing water from accumulating on the streets, preventing accidents caused by landslides in puddles and hydroplaning.
Manholes and storm drains also help protect roads, sidewalks and building foundations from damage caused by water infiltration. In public health, by preventing the formation of stagnant water, they help prevent the proliferation of mosquitoes and other disease vectors. Finally, they are integrated into larger stormwater management systems, contributing to the sustainability and efficiency of water resource management in the city.
The solution is much broader
For Haralan Mucelini, a volunteer at the Foz do Iguaçu Social Observatory who has been studying the subject for several years, storm drains and manholes are just some of the urban drainage instruments. “The number of urban roads with these devices is not the best way to explain the constant flooding. A city may not have any storm drains and still not suffer from flooding,” he explains.
He emphasizes that this indicator needs to be analyzed in conjunction with others, such as the waterproofing index of urban soil, the average size of drainage galleries and the volume of urban solid waste generated daily. “In Foz, the biggest problem is the excess waterproofing and the lack of criteria for paving urban roads,” he says.
Mucelini also attributes the problem to the excess of approved subdivisions without the proper drainage infrastructure. “The legislation that requires subdivisions to have galleries and storm drains, if I’m not mistaken, is no more than 20 years old. Therefore, most old subdivisions do not have this infrastructure,” he concludes.
City Hall cites disorderly growth
Regarding the situation, the City of Foz do Iguaçu sent a note to H2FOZ and attributed the low percentage of manholes, drains and other devices for water drainage to the historical context.
The city administration emphasizes that the city grew rapidly and in a disorderly manner, especially from the 1970s onwards. According to data from the IBGE, the population jumped from 33 to 190 inhabitants in just over 20 years. Major construction projects, the development of tourism and the economic expansion of Ciudad del Este drove this growth.
Regarding urban drainage, the city hall outlines the following timeline:
- in 1975, the city government created the first municipal legislation on the subject, but did not require the presentation of projects from entrepreneurs;
- In 1991, the city government published Complementary Law 05/1991, on the subdivision of land for urban purposes, and Law 03/1991. The text deals with the city's building and construction code. Even so, the administration did not define parameters for drainage in subdivisions under construction;
- It was only in 2011, with Complementary Law No. 170, that the administration included the description of the elements required for the rainwater drainage system of subdivisions. These definitions provided legal support for municipal technical teams to require new subdivision developers to install drainage and water runoff networks.
And now… how to solve it?
The City of Foz do Iguaçu is working on two fronts to solve the problem. The current administration is forming a committee with technicians from the Planning, Urbanism and Public Works departments. The group will publish the Municipal Drainage Manual, which future ventures should follow.
This document will establish the minimum conditions for the drainage network, taking into account the increase in the occurrence of heavy rains in Foz do Iguaçu in recent years. The acquisition of video inspection equipment is also planned, which will make monitoring compliance with these conditions safer and more efficient.
On another front, the technical team is mapping drainage throughout the city — work that is already 80% complete — to help the municipal administration identify the points that require greater attention and priority intervention.
The Public Works and Planning and Urban Planning departments jointly prepare preliminary projects that will allow the municipality to request resources for these drainage works, which normally have a higher cost.
This is because we are at the meeting point of two large rivers that surround our city. Wouldn't it be less expensive to expel rainwater? Most cities don't have this privilege. What they really need is good management.