A brief survey on the legislation applied to floods and inundations in medium- sized municipalities in the state of Rio de Janeiro-Brazil

This work aims to carry out a survey on municipal legislation and other legal management instruments, related to the control and mitigation of urban floods and inundations in medium-sized municipalities in the state of Rio de Janeiro. In this context, 22 municipalities in the range between 100 and 500 thousand inhabitants were surveyed. Among the results obtained, it was found that only 13 municipalities had specific municipal legislation to mitigate the effects of inundations and urban floods. Approximately 59% of the analyzed municipalities had municipal legislation oriented to the local reality. There is a need to increase public policies and government incentives for the expansion of legal provisions in the municipalities analyzed.


Introduction
The occupation and waterproofing of soils as a result of urbanization collaborate with the aggravation of urban flood events and the urban environment degradation (TUCCI, 2007a;MIGUEZ;REZENDE;VERÓL, 2015). In Brazil, traditionally, plumbing works are employed to solve the problem of decreasing the natural storage of rainwater. These represent the classic drainage systems (CANHOLI, 2015). However, since the 1970s, new methods have emerged. Known as compensatory techniques, these basically aim to neutralize the urbanization effects on the hydrological cycle, based mainly on rainwater storage and infiltration (BAPTISTA; DE OLIVEIRA NASCIMENTO; BARRAUD, 2011).
The responsibility to manage public policies and adopt necessary measures for disaster reduction, as well as facing floods, relies on all levels of the federation, that is, at the federal, state and municipal levels (BRAZIL, 2010(BRAZIL, , 2012. These management instruments must contain general aspects and local characteristics of each municipality or region for the best applicability of each legislation. A challenging question that arises in this area is to verify what the existing local public policies are related to flood problem management. A study shows that more than half (59.4%) of Brazilian municipalities lacked tools to plan and manage risks in 2017. Only 25% of municipalities have a master plan that includes flood prevention measures and only 26% of the municipalities declared to have a Land Use and Occupation Law foreseeing these occurrences (IBGE, 2018). Given this scenario, it is extremely important to know the legal management instruments in Brazilian states and municipalities. There are limited studies on the panorama of municipal management in relation to flood mitigation and, normally, their main focus are metropolises and large municipalities, having as examples the works of Fonseca et al (2006) and Fontes da Luz et al (2020).
Generally, these works deal only with structural flood mitigation techniques, such as rainwater reservoirs. It is necessary to address the issue in medium-sized municipalities that present increasing urbanization and, at the same time, low growth in its infrastructure, such as basic sanitation and macro drainage works.
In this study, medium-sized Fluminense municipalities that already face the same problems as large cities were considered. Rio de Janeiro is the state with the second highest number of floods in the southeast region, according to the Atlas of Natural Disasters (CEPED-UFSC, 2013). Disasters caused by floods, runoff and mass movement correspond, respectively, to 35%, 26% and 21% of the total disasters in the entire state of Rio de Janeiro, totaling 82% of the events (CEPED-UFSC, 2013). The characteristics of the physical environment, such as the rain regime and the relief with great unevenness in some regions of the state of Rio de Janeiro, results in more susceptible conditions to these natural events, which become disasters when harm the population.
The objective of this work is to conduct a documentary research on legal management instruments related to the control and mitigation of urban floods, in addition to perform an investigation on the use of structural compensatory techniques in medium-sized municipalities in the state of Rio de Janeiro. Firstly, this article will address urban drainage and hydrological event mitigation measures as well as their legal structure. Secondly, information resulting from research on municipal legislation will be discussed.

Urban drainage and the problems of floods, inundations and overflows
The growth of cities in an accelerated and disordered way aggravated the problems of urban floods, since urbanization processes tend to waterproof the soil, occupying infiltration areas and altering the natural hydrological cycle. Urbanization is one of the anthropic actions that most generate environmental impacts, as they change the water, air and especially soil properties (TUCCI; CLARKE, 1997;TUCCI, 1997a;MIGUEZ;REZENDE;VERÓL, 2015).
According to Licco and Mac Dowell (2015), urban floods or inundations can be understood as natural processes, as these occur when the maximum level of a drainage channel is reached due to increased flow, however, the waters do not overflow. The term inundation is used to characterize the overflow of water from a stream, this occurs when river drainage is not able to contain the rain flow. The process is aggravated due to the river rectification and waterproofing of their banks. Overflow is a momentary situation generated in areas where the drainage system does not support the precipitation volume (LICCO; MAC DOWELL, 2015). In turn, flash flood can be characterized as a large volume of water that superficially seeps, usually very strongly (LICCO; MAC DOWELL, 2015).
According to Tucci (1997a;2003;2008), floods in urban areas are the result of two processes that occur in an integrated or isolated way: Floods due to urbanization: represents the increase in floods frequency and magnitude due to the soil occupation with impermeable surfaces and flow ducts. In addition, urban development can produce flow obstructions, such as landfills and bridges, inadequate drainage and silting up. (our translation) Floods in riverside areas: natural floods that affects the population that occupies the largest riverbed. These floods occur mainly due to the natural process in which the river occupies its largest bed, according to extreme events, on average with a recurrence interval of 2 years. (our translation) The main conception of urban drainage in Brazil is still based on the "classic system", that is, the principle of conducting rainwater through underground ducts, pushing water away from man, historically linked as a means of proliferating diseases and vectors (NUCASE, 2007). To mitigate the effects of floods, engineers around the world have researched numerous techniques and measures. These techniques were mapped and brought together in two large groups: structural and non-structural measures (CHRISTOFIDIS; ASSUMPÇÃO; KLIGERMAN, 2019). In general, structural measures are engineering work that can be extensive or intensive. Non-structural measures, in turn, are those in which losses are reduced to guarantee a better coexistence of the population with the floods, such as the land use regulation or flood zoning (TUCCI, 2007b). Baptista, de Oliveira Nascimento and Barraud (2011), divided the use of measures to try to control and mitigate the urban drainage problem into two large groups. First group, non-structural compensatory techniques: legislation, environmental education and better urban land use. Second group, structural compensatory techniques: One-off works (infiltration wells and roofs), linear works (paving and infiltration trenches) and basin works (detention, retention and infiltration).
Around the world, several researchers have been working in this urban drainage context, trying to mitigate cities flood and inundation problems, using manifold techniques, whether structural or nonstructural compensatory.
A recent study reveals the use of large containment tanks and individual rainwater reservoirs to control flooding in highly developed urban watersheds (FRENI; LIUZZO, 2019), to mitigate risks of urban floods. In recent years, control measures such as green roofs, permeable pavements, rain gardens and vegetation ditches, have been implemented to deal with flooding in urban environments and have proven to be economical and sustainable. (MEI et al., 2018).
In addition, advanced real-time automation techniques for these centralized and decentralized reservoirs have shown satisfactory and significant effects, increasing the system's resilience, with small In parallel with the detention reservoir techniques, current researches execute work on rivers and channels using advanced hydrological, computational and mathematical models in software such as MOHID LAND, aimed at flood mitigation and control (TAVARES et al., 2017(TAVARES et al., , 2018JUSTINA et al., 2019;. Remote sensing techniques help to understand the geomorphological behavior of rivers and channels and to acknowledge the functioning of the hydrographic basin in its entirety (SALES; OLIVEIRA; LUGON JUNIOR, 2020).
Seeking to improve the hydrological cycle balance in urbanized areas, sustainable hydrology uses low-impact development technologies, flow control systems installed in roofs, for example, can contribute to runoff reduction and, consequently, mitigate frequent flooding. (SCHELLIN; LEINIG, 2018).
As we can see in the previous paragraphs, several studies in different areas are carried out to try to mitigate floods in urban areas. Including research on flood forecasting techniques, considering the intensity and duration of rainfall (CHOO et al., 2019).
Medium-sized cities have assumed a prominent role due to the continuous urbanization process.
Characteristics such as a greater concentration of equipment, goods and services in its intra-urban space and a greater offer of jobs contributed to the rapid population growth, governments began to encourage a migration movement towards medium-sized cities, so that they work as retention places of flow, this one previously directed to large cities, at the same time contributing to regional development (COSTA; LOBO; SOARES, 2020).
There is a need to think about the environmental management of cities, and legislation is the main instrument to assist and guide in this task, provided it is adapted to the local reality of each municipality.
Since medium-sized municipalities have characteristics, problems and challenges similar to those of large cities, they acquire singular relevance for this public policy.

Legislation applied to urban floods and inundations
The National Water Resources Policy (Law No. 9433/1997) is the Brazilian federal legislation that indirectly addresses the urban floods and inundations issue. Among its objectives, it is interesting to highlight: ensure current and future generations necessary water availability, in quality standards appropriate to their respective uses; prevention and defense against hydrological events due to the inappropriate use of natural resources; and encourage rainwater capture, preservation and use (BRAZIL, 1997). In agreement with Brazilian Federal Constitution (BRAZIL, 1988), we can quote Law No. 10257/2001, which sets general urban policy guidelines, whose objective is to order the development of the social functions of cities and urban properties (BRAZIL, 2001).
The National Basic Sanitation Policy was instituted by Law No. 11445/2007, which considers that rainwater management and the drainage, cleaning and preventive inspection of urban networks are part of basic sanitation. Among its fundamental principles, it can be highlighted the adoption of methods, techniques and processes that consider local and regional peculiarities (BRAZIL, 2007), where municipal legislation plays an extremely important role in meeting these objectives.
In 2012, the National Policy for Civil Protection and Defense was created by Law No. 12608. Its main objectives are: stimulate urban and rural land use planning, considering its conservation and the protection of native vegetation, water resources and human life; monitor meteorological, hydrological, geological, biological, nuclear, chemical and other potentially disruptive events; stimulate the development of resilient cities and sustainable urbanization processes (BRAZIL, 2012).
In the Rio de Janeiro state, the main legislation on the subject is Law No. 7463/2016, which mainly addresses procedures regulation for rainwater and greywater storage, aiming at its use or discharge delay in the public network. From the date of its publication, all private or public buildings that presents over five hundred square meters of waterproofed area, must dispose a greywater and rainwater reservoir, as well as recycling the greywaters of buildings, thus creating a regulatory framework across the state of Rio de Janeiro (RIO DE JANEIRO, 2016). However, each municipality presents distinct characteristics among themselves in different economic, social, demographic and pluviometry aspects. Thus, regardless of the aforementioned State Law, these characteristics constitute the need for more specific legislation for each municipality, that is, appropriate to their local reality.
Municipal legislation manifests itself as a structure/base that must be proportional to the locally observed problems scale, always respecting regional and local peculiarities (BRAZIL, 2007). Management and regulatory instruments such as the Master Plan can guarantee less costly preventive measures and provide subsidies to improve human life conditions (TUCCI, 1997b). Combined with other normative instruments such as the Land Use and Occupation Law and the Organic Municipality Law, they are moving towards more satisfactory public and urban policies (MINAKI; AMORIM, 2012). The public manager must have the ability to promote urban and environmental planning organized in a multisectoral way. That is, elaborate and develop the planning considering the city, in an integrated and systemic way (TAMPOROSKI; ALVES, 2012).

Materials and Methods
For the present study, a bibliographic review was carried out on the legislation and structural and non-structural measures used to mitigate urban floods and inundations in the literature. The research was performed by consulting renowned databases, such as: Scopus, Elsevier, Web of Science, Capes Journal Portal and Google Scholar. Subsequently, a survey was carried out on the legislation and legal instruments of management related to the control and mitigation of urban floods and inundations, and the use of structural compensatory techniques in medium-sized municipalities in the state of Rio de Janeiro. Searches were carried out, preferably, in the last ten years in the bases. Because the literature is a little scarce, we tried to expand the research to previous years. Medium-sized Fluminense municipalities with a population between 100 and 500 thousand inhabitants in the state of Rio de Janeiro were selected. Thus, socioeconomic information from the last demographic census (IBGE, 2010a) was analyzed and scientific information from government documents made available, through of each municipalities Transparency Portal was selected.
The Zotero version 5.0 software was used for the organization and classification of scientific articles and the QGIS version 3.12 software for mapping information. Both software used in free versions.

Results and Discussion
Twenty-two medium-sized municipalities in the state of Rio de Janeiro were selected (IBGE, 2010b), as shown in Figure 1, and their respective urban flood mitigation laws have been identified. Thirteen municipalities (59%) have municipal legislation aimed specifically at flood control. Socioeconomic, geographic and rainfall data from the municipalities were also described, for better understanding and comparison between them. Table 1 shows the results obtained, in decreasing order of population.
In this research, only specific legislation was found, mostly focused on residential works and commercial or industrial enterprises. To better detail each local strategy, in mitigating the effects of inundations and urban floods, Table 2 was prepared with a brief description of each municipal legislation found in this research. As can be seen in Table 2, the municipal legislation of the vast majority of municipalities makes it mandatory to adopt structural compensatory techniques, such as the use of rainwater reservoirs, as a way of reducing the impacts caused by rains and favoring the urban drainage system.
In Volta Redonda, the current municipal legislation provides for rainwater harvesting only in public sectors, thus reducing these systems covered area in the municipality.  Addresses solar water heating systems installation and rainwater use in public and private constructions situated in the municipality of Niterói and creates the municipal commission for urban sustainability.

Law No. 2630/2009
Disciplines procedures related to rainwater storage for reuse and its discharge delay in the public network. Institutes the municipal program for water conservation and rational use in buildings and establishes, for collective building projects, the requirement for a water meter in each autonomous unit. Creates the rainwater harvesting program, whose objectives are the rainwater capture, storage and use by public and private buildings, in urban and rural areas, in residential, commercial and industrial buildings. Fields, when receiving buildings, should be prepared to drain rainwater and water infiltration with the adoption of control erosion measures. Prohibits rainwater or wastewater dumping, including that from equipment operation, on sidewalks, neighboring buildings and sewage collection networks. These must be connected by piping under the sidewalk to the gutter and/or its own collection network, in accordance with the rules issued by the sanitation competent institution. In sloping situations rainwater and sewage piping from upstream lots may pass through downstream neighboring properties, when it is not possible to route them to the streets on which they are located and if there is no other alternative by public domain area.

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Law No. 2093 No land parceling modality will be allowed in fields subject to flooding, before performing works and services that ensure adequate water drainage are carried out.

Law No. 3751/2018
Institutes Municipal Policy for Conservation, Rational Use and Water Reuse, which aims to promote necessary measures for conservation, reduction of waste and alternative sources use for water capture in buildings, as well as to make users aware of its importance for life.
(Continuation)  Friburgo Law No. 3046/1999 Establishes that every property built on or after January 1, 2000 must have planned a rainwater harvesting and storage project, with a third of the volume of stored treated water to be stored. Establishes for all constructions the mandatory reserve of free area, which will be used as a permeable and/or green planted area, defined by the government. If total or partial impossibility of reserving a permeable area and/or planting seedling in the construction lot is proven, a technical study must be prepared with the municipal environmental agency for environmental compensation defined in specific legislation. Creates the Rainwater Harvesting and Reuse Program, whose main objectives are the rainwater capture, storage and use by urban buildings, in addition to: A. Awaken ecological awareness in order to conserve this environmental resource; B. Foster water conservation and self-sufficiency for supply; C. Reduce drinking water consumption from public network; D. Avoid using drinking water where it is not needed; E. Promote savings in fees by reducing drinking water consumption from public network; F. Helping to contain possible floods, damping part of the rainwater that drains into water bodies.

Conclusion
Among the twenty-two medium-sized municipalities analyzed in the state of Rio de Janeiro, only thirteen have specific municipal legislation to mitigate the effects of urban floods. The requirement for buildings rainwater reservoirs was instituted in most of these municipalities. A worrying aspect was detected in approximately 41% of the municipalities, where no specific legislation directed to urban floods mitigating was found.
There is a need for a greater number of public policies aimed at the development of legal instruments in the municipalities analyzed. These devices expansion will favor the inclusion of several structural and non-structural compensatory techniques in municipal legislation. When applied together, these techniques obtain a more satisfactory result in urban floods mitigation and control, when compared to isolated measures.
Based on the results, it is concluded that this research objectives were achieved. Such findings enable a greater understanding of municipalities laws and local characteristics. However, it is suggested to carry out further studies considering other variables, for example: the impact of simultaneous structural compensatory techniques on rivers and watersheds, in order to measure its flood control efficiency, mitigate inundations and improve cities water management.