Without proper planning, Brazilian urbanization was not accompanied by structural works compatible with natural characteristics and with the speed of socioeconomic transformations. In many locations, floods and landslides represent a constant challenge for our society, especially for low-income people.
Floods can be seen as a natural occurrence, when the volume of water in a river overflows towards the banks. Irregular occupation and removal of riparian vegetation that accompanies the course of the rivers promote an increase in surface runoff towards the river courses, increasing floods. The duplication of expressways towards the floodplains of the rivers, as well as the channeling and straightening of courses surface water changed the hydrological and soil dynamics, aggravating the risks of silting up of rivers and floods. The waters also face another obstacle: the garbage accumulated in manholes, streets and avenues, which joins the sediment and overflows the channels. The combination of convective rains, population concentration, irregular occupation and lack of planning can be considered the biggest factors leading to the scenario of catastrophes that we are forced to live with at the time of the seasons rainy.
Landslides, on the other hand, consist of a soil erosion process, where areas with slopes suffer the action of the force of rainwater. The construction of houses and the removal of vegetation make the soil unprotected and subject to landslides. These occurrences are more common on the outskirts of cities, where land with lower market value or simply occupied by immigrants are situated in rugged topographies, known as hillsides, or even on top of hills. The same reasoning presented in relation to riparian forests can be used to understand landslides, as the vegetation present on the slopes it is able to absorb rainwater and prevent the loading of large amounts of sediment to the most areas. low.
As concrete proposals to reduce impacts or even avoid such problems, there are options that have found success in some Brazilian cities. The construction of linear parks, for example, draws attention, as they are projects capable of integrating a series of benefits for society. These parks are arranged parallel to the water courses, with the advantage of recovering the areas of riparian forest and, at the same time, help to absorb rainwater and reduce runoff speed superficial. The parks also offer the possibility of integrating stretches of forest and water resources that are scattered and fragmented in urban areas.
The reuse of rainwater, well known in the northeastern hinterland as cisterns, takes on new contours in the urban environment. Residential condominiums and business centers can take advantage of this huge volume of water for cleaning and gardening, without needing specific treatment, which would generate more expenses. Ultimately, with a more simplified treatment, reuse water can be used in household discharge systems. This practice can contribute to reducing the volume of water that goes towards streams and manholes.
Another contributing factor to the formation of rain showers is urban climate change, such as heat islands. With regard to changes in the urban climate, the need to reduce the impacts of changes caused by the man demands stricter measures, such as the control of emission of pollutants and the application of the master plan municipal. Cities such as São Paulo and Mexico City have a rotation of vehicles, which consists of a ban on the circulation of cars in certain sectors of the city, which varies according to the license plate and peak hours of the Traffic.
Finally, landslides represent one of the reflections of social inequality in the country. It is not possible to simply remove people living in risk areas, but to plan the occupation of cities and the use of resources in the construction of affordable housing or lines of credit that are really affordable for those without a family income high. It is possible to create low-impact residential areas in the vicinity of hillside areas, provided they are respected certain construction patterns, such as the use of terracing techniques and the restoration of native vegetation.
Julio César Lázaro da Silva
Brazil School Collaborator
Graduated in Geography from Universidade Estadual Paulista - UNESP
Master in Human Geography from Universidade Estadual Paulista - UNESP
Source: Brazil School - https://brasilescola.uol.com.br/geografia/enchentes-deslizamentos-terra-no-brasil-principais-causas.htm