Unveiling water security in Brazil: current challenges and future perspectives

ABSTRACT

Water crises have risen over the past decade. In the Brazilian context, extreme events have intensified over the country, undermining water systems in regions that already face water shortages. Although previous studies have focussed on individual regions of Brazil, an overview of the entire country will contribute to developing a national action plan for mitigating water inequalities. Therefore, we reviewed and analysed water security in Brazil, presenting a diagnosis focussed on the peculiarities of each geographic region and hydrographic area. One of the biggest threats is the slow pace towards a robust policy for strengthening national water security. As shown here, water security depends on several variables such as availability, quality, and external factors such as climate forcing and anthropogenic pressure. Therefore, water governance needs to integrate human needs with ecosystem functioning, considering climate uncertainties to move towards better water resources planning.

KEYWORDS:

• freshwater resources
• extreme events
• consumptive water use
• water management

Editor A. Castellarin Associate Editor B. Dewals

1 Introduction

Water is an essential resource for all ecological and socioeconomic activities. Although there is sufficient freshwater to meet the world demand, spatiotemporal variations in its availability are wide, leading to water scarcity in many parts of the world. Moreover, approximately 80% of the world’s population live in areas subjected to water scarcity (Vörösmarty et al. 2010), and two-thirds of them suffer from water shortage for at least 1 month of the year (Mekonnen and Hoekstra 2016).

Water resources are constantly under pressure as demand for water, energy, and food is increasing due to global population growth and enrichment of nations (Wada et al. 2016). Furthermore, water availability is affected by climate change, and water-related extreme events – intensification of droughts and floods, changes in seasonal precipitation and evaporation – threaten the sustainable development of societies and maintenance of ecosystems (Konapala et al. 2020, Padrón et al. 2020, Tabari 2020). Likewise, climate projections indicate a reduction in renewable surface and groundwater resources, intensifying competition among the multiple uses of water and multiple economic sectors (IPCC 2013).

Global water crises – from droughts in the world’s most productive farmlands to the hundreds of millions of people without access to safe drinking water – are among the most significant threats the planet has faced (WEF 2015). Other global risks are inextricably tied to water management and access, extreme weather events, failure of national governance, state collapse or crisis, rapid and massive epidemics, and failure to adapt to climate change. Particularly in Brazil, a country with continental dimensions, water-related problems stem from contrasting vulnerabilities (Debortoli et al. 2016), which undermine local water security. While the Northeast region faces prolonged drought spells, floods are recurrent in some parts of the Southeast and South.

According to Marengo (2007) and Cunha et al. (2019), in the last century, every Brazilian region faced extreme events, and these will become more frequent in the future due to climate change. There are several studies that show these trends for specific regions of the country: Amazon region (Gloor et al. 2013, Correa et al. 2017, Barichivich et al. 2018), Northeast region (Oliveira et al. 2014, Marengo et al. 2017, Cunha et al. 2018), Southeast (Ávila et al. 2016, Zilli et al. 2017, Lyra et al. 2018), and South (Murara et al. 2019). Existing studies have focussed on individual regions of the country; an overview of the main vulnerabilities resulting in water insecurity in the entire country will contribute to developing a national action plan for mitigating water inequalities exacerbated by climate extremes.

To incorporate all water-related challenges, the concept of water security characterizes interactions among water conditions, ecosystem functioning, and societal needs (Scott et al. 2013). Thus, water security entails having access to water in acceptable quantity and quality (OECD 2016) for health, livelihoods, ecosystems, and production, coupled with an acceptable level of water-related risks to people, environments, and economies (Grey and Sadoff 2007). Similarly, it is intrinsically associated with a society’s ability to adapt to extreme events and especially to better predict periods of scarcity (Taffarello et al. 2016). We reviewed and analysed water security in Brazil based on the database of the National Water Resources Information System (in Portuguese, Sistema Nacional de Informações sobre Recursos Hídricos – SNIRH – available at http://www.snirh.gov.br/portal/snirh/snirh-1/acesso-tematico/usos-da-agua#wrapper) implemented by the National Water and Sanitation Agency (in Portuguese, Agência Nacional de Águas e Saneamento Básico – ANA). This is the first attempt to characterize and examine the current and future water security situation in Brazil on a national scale. We are motivated by important discussions that have not been addressed in the literature:

1. What is the current water security situation in the country in terms of water availability and demand?

2. What are the emerging challenges in water security following a development path?

3. What are the prospects for water security in Brazil?

Firstly, we provide a detailed overview of water availability and demand for the main consumptive uses affecting water security in Brazil. This diagnosis is focussed on the peculiarities of each geographic region and hydrographic area. Moreover, based on the coauthors’ expertise, we discuss the current and future challenges concerning regional and national water security, mainly those related to negative impacts caused by climate change. In the conclusion, perspectives are provided to guide the next steps towards overcoming water insecurity in Brazil.

The current discussion aims to contribute to the Panta Rhei global initiative by enhancing knowledge about changes in hydrology and related societal systems (Montanari et al. 2013). Moreover, our discussions contribute to achieving the Sustainable Development Goals (SDGs), particularly SDG-6 (clean water and sanitation), which aims to ensure the availability and sustainable management of water and sanitation for all, which in turn will support many other goals (United Nations 2019) and their viable adaptation strategies (UNEP, 2021).

2 An overview of water security in Brazil

2.1 Water availability

Brazil has a privileged position in the world regarding water resource availability, accounting for about 12% of the world’s freshwater (Shiklomanov et al. 2000). Notwithstanding, this resource varies enormously throughout the country both spatially and temporally. Brazilian water resources can be geographically divided into 12 hydrographic regions spread across the geopolitical divisions, and into six biomes, which are large-scale ecosystems with similar vegetation, soil, climate, and wildlife characteristics: Amazon, Cerrado, Atlantic Forest, Caatinga, Pampas, and Pantanal (Fig. 1). There is high variability in climate characteristics due to the country’s continental proportions. Therefore, water resources are unevenly distributed, leading to local socioeconomic crises due to water scarcity. The water supply system frequently encounters problems of both quality and quantity, mainly in the metropolitan regions of the country such as the cities of São Paulo, Rio de Janeiro, Porto Alegre, Curitiba, Belo Horizonte, Brasília, Manaus, and São Luis (Fig. 1(b)).

Figure 1. Brazil’s location in South America, where (a) shows the water balance status over the Brazilian hydrographic regions and (b) provides additional information on the biomes and the main Brazilian cities in the geopolitical divisions of microregions

The Amazon (AMZ) and Parana (PRN) regions represent distinct portraits of water-related problems caused by the heterogeneous distribution of water resources. The AMZ accounts for 4.5% of the country’s population and provides about 80% of the total surface water availability in Brazil. Conversely, the PRN is the most economically developed region in the country, notwithstanding that it represents 5% of the total surface water availability and is home to 32% of the Brazilian population (the most populous hydrographic region). To overcome mainly the lack of water supply, several cities in Brazil rely on groundwater as the only or a complementary source of freshwater. For instance, about 17% of Brazilians rely exclusively on groundwater, which in turn, also contributes to surface water endurance during drought spells (Hirata et al. 2019). The last water resources report issued by the ANA estimates there are 2.4 million wells in the country (ANA 2019a). Groundwater availability in the Brazilian territory is equivalent to around 18% of the total surface water, although it is also unevenly distributed due to varying hydrogeological characteristics and aquifer yield. Specifically, in the semiarid Northeast of Brazil, the combined soil salinity and low drainage capacity of the crystalline formation that dominates the area severely limits the available groundwater resources.

Although water quality and quantity are often treated separately, we need to provide humans and the environment with both clean (quality) and sufficient (quantity) water supply, as noted in many water security definitions (Witter and Whiteford 1999, UNESCO 2013, OECD 2016, Strickert et al. 2016). Thus, the integrated water balance – quality and quantity – is fundamental for assisting effective management actions and policies for ensuring water security at a national level. Figure 1(a) presents an integrated quali-quantitative analysis (see Supplementary material Fig. S1 for further information on the classification from satisfactory to critical water availability) in which the Eastern Northeast Atlantic (EOR), São Francisco (SFO), and East Atlantic (ALT) regions stand out for presenting a high level of water insecurity (critical quality and quantity availability). These hydrographic regions, along with the Parnaiba region (PBN), are located in the Brazilian semiarid region, one of the world’s most densely populated dryland areas (Marengo 2008). Despite its natural hydroclimatic characteristics, climate change projections predict an intensification of droughts in the Brazilian semiarid region (Marengo et al. 2017). Therefore, to manage water resources, considering climate change uncertainties is of paramount importance for overcoming the current and future water vulnerabilities.

The Uruguay (URU) and South Atlantic (ASU) hydrographic regions, located in the Brazilian South, face recurrent challenges in terms of water availability in adequate quantities to meet public demand (see Fig. 1(a)). In this case, water quantity is a major component undermining water security, therefore, strengthening conflicts over the multiple uses of water. For instance, balancing water demand and availability in this region is key due to large rice fields that are cultivated under flooded conditions. Meanwhile, climate change projections show an increase in the precipitation pattern and in water availability in the region (Chou et al. 2014, Ribeiro Neto et al. 2016, Almagro et al. 2017, Avila-Diaz et al. 2020). Yet this increase will affect agricultural production, since the increase in precipitation has the potential to increase soil erosion rates (Almagro et al. 2017). Hence, it is essential to incorporate these projections in water resource management.

2.2 Imbalance between supply and demand for consumptive water uses

Here we use two important concepts related to the consumptive uses of water: water withdrawal and water consumption. We define water withdrawal (or water abstraction) as the total amount of freshwater withdrawn from a surface water or groundwater source, that could return or not to the water source. Water consumption, on the other hand, is defined as that portion of water withdrawal that was consumed and does not return to the original water source. Understanding these concepts is crucial to evaluate water stress, as water withdrawal could indicate the level of competition and dependence on water resources. Additionally, water consumption is essential to evaluate water shortage and scarcity (Gleeson 2017).

Total water consumption has steadily increased in Brazil, comprising the main consumptive uses such as irrigation, human and animal consumption, industrial purposes, power generation and mining. At the national level, annual water consumption increased by 17 billion m³ from 1950 to 2000, an average annual growth of 8.7%. However, the average annual growth in the subsequent years, from 2000 to 2017, declined from 8.7% to 3.9%. According to ANA’s projections, the average annual growth in water consumption may continue to decrease, reaching 1.1% per year, over the period from 2017 to 2030 (Fig. 2). Despite the decrease in the relative annual growth rate in recent years, water consumption reached 36.5 billion m³ in 2017. Irrigation accounts for 52 and 68.4% of total water withdrawal and consumption, respectively, urban and rural supply for 25.5 and 11%, industry for 9.1 and 8.8%, livestock for 8 and 10.8%, thermopower for 3.8 and 0.2%, and mining for 1.6 and 0.8% (Fig. 2). The Northeast and Southeast regions accounted for 23% and 34%, respectively, of the total national water withdrawal and consumption. Conversely, both regions have experienced historical cases of drought spells and water shortages, such as the most severe drought, which was recorded in the Northeast from 2010 to 2018 (Marengo Orsini et al. 2018, Pontes Filho et al. 2020), and the unprecedented drought mainly faced by São Paulo and Rio de Janeiro (two of the most important states in the Southeast) in 2014 and 2016 (Nobre et al. 2016). In this context, a supply–demand water resources imbalance reveals the high water supply vulnerability affecting the socioeconomic sectors in these regions, which have endured an increase in the frequency and magnitude of extreme events according to Marengo (2014).

Figure 2. Total water consumption and withdrawal, where (a) shows the water consumption per use type from 1930 to 2030, and (b) provides additional information about water withdrawal per region and water consumption per water use type in 1950, 2000 and 2017, and projected for 2030

The water consumption for the agricultural sector is highly representative, with mainly irrigation and livestock production representing 80% of the total water accounted for by the consumptive uses (Fig. 2). Brazil is currently the world’s largest exporter of beef and the second-largest beef producer; also, livestock production is a booming sector and already accounts for 6% of the gross domestic product (GDP), an increase by 45% over the last 5 years (da Gomes et al. 2017, O’Donoghue et al. 2019). Although this number is substantial, only one-eighth of the total water used by agricultural activities is attributed to livestock. Since 1960, irrigation has been mainly responsible for water withdrawal in the country, accounting for 52% of total withdrawal in 2017. For instance, water withdrawal for irrigating rice crops increased from 1 to 12 billion m³ in the URU and ASU hydrographic regions, even though its national contribution to total water withdrawal decreased from 76% to 36% during the period from 1950 and 2017. The continuous growth of the consumptive water uses, along with the low water availability in the EOR, SFO, ALT, URU, and ASU hydrographic regions, suggests a high pressure on the Brazilian water supply system, therefore, leading to water insecurities.

Water withdrawal for irrigation increased by 32 billion m³ from 1950 to 2017, due to agricultural expansion. Zalles et al. (2019) reported that the cropland extent more than doubled in the Cerrado biome from 2000 to 2014, mainly in the states of Maranhão, Tocantins, Piauí, Bahia (the agricultural frontier collectively known as MATOPIBA), Mato Grosso, Mato Grosso do Sul, and Pará. Furthermore, grain cultivation increased by 80% in these areas between 1996 and 2006 (Merten and Minella 2013). Irrigation is of paramount importance for allowing crop cultivation in semiarid regions or regions with prominent drought spells, such as the Midwest of Brazil (ANA 2018). Since 1950, water withdrawal for irrigation has increased by 36% in the Midwest (mostly covered by Cerrado biome) and the Northeast (Caatinga and Cerrado biomes). It is important to highlight the semiarid region (Northeast Brazil)’s dependency on irrigation for agricultural production: it alone is responsible for 27% of all irrigation withdrawals in the country. An increasing trend is expected, considering adverse climate change scenarios (Martins et al. 2019), to sustain productivity in those regions.

The urban and rural water supply services are the second-largest water use in the country. Despite the large withdrawal value (25.5% of total) (Fig. 2(b)), approximately 80% returns to water bodies as sewage, of which only 46.3% is treated although about 75% is collected (Brazil Ministry of Regional Development 2019). Compared with the other regions, the Midwest and Southeast present the highest treatment rates of 54 and 50%, respectively. In contrast, sewage treatment is applied to 22 and 36% in the North and Northeast regions, respectively. These lower sewage treatment rates not only degrade water quality, negatively impacting the population’s health, but also intensify disputes among the multiple water uses downstream of the effluent discharge, in regions already highly vulnerable to water scarcity. This also reflects the quali-quantitative aspect of water insecurity faced by most of the country’s metropolitan regions (see Fig. 1(a)).

Industry is another sector with significant water consumption, which has increased by 310% from 1950 to 2017. It accounts for 9% of the total water withdrawal, approximately 6 billion m³ per year; the actual consumption is approximately 55% of the water withdrawn. Specifically, the food industry is responsible for about 56% of the total water consumed by the sector, highlighting the Southeast region which is responsible for 47% of the total industry consumption in Brazil (ANA 2019a, 2019b). The mining industry also accounts for a large water consumption volume, mainly in the Southeast and North regions. Together, these regions are responsible for 80% of the total water used for mining. The water demand for mining activities is equivalent to supplying the entire Brazilian rural population (ANA 2019b). Although Brazil is one of the largest producers of iron ore, bauxite and aluminium oxide, niobium, and phosphate, mining activities do not offset negative social and environmental impacts on health, welfare, deforestation, and water pollution (Milanez and Puppim de Oliveira 2013). A potential alternative for overcoming the high rates of withdrawal and consumption by industry is water reuse. Even though the Brazilian Sanitation Act 99984 and the National Basic Sanitation Plan (PLANSAB) (Brazil Ministry of Regional Development 2013) establish the promotion of water reuse, this is still a limited practice in Brazil (Brazil Ministry of Cities & IICA 2016). In addition to reducing costs of water supply and treatment, reusing water in industry may reduce pressure on water resources (Freedman et al. 2016), contributing to water security in Brazil.

The last representative water use is for power generation, mainly from thermopower. This electricity source represents 3.8% of the total withdrawal in the country, but it only consumes 0.2% of what is withdrawn. Nonetheless, this percentage is important, because more than 70% of Brazil’s energy is supplied by hydropower plants. Thermopower plants play a key role in supporting the energy supply as a flexible and safe alternative to hydropower generation during water shortages. For instance, about 27% of the energy supply relied mainly on thermoelectric plants during the 2014–2016 water crisis in the Southeast. Nonetheless, the water use by thermopower is expendable, since this energy source can be replaced by renewable energies that do not need water, such as solar and wind sources.

3 Main challenges in the Brazilian context

In the previous sections, we discussed the uneven distribution and heterogeneous needs of water resources among the Brazilian macroregions. Over the last two decades, water withdrawal increased by 80%, and projections show a further increase of 30% by 2030 to meet the population growth and, consequently, future demand for water, food, and energy. The growth in water demand indicated by projections and historical data is intrinsically linked to the pattern of increase in the CO₂ emissions in the country (Fig. 3), mainly due to the population growth and economic development. Figure 3 does not depict a scenario of proportional economic and emissions growth. Whereas emissions increased by 80% from 1990 to 2014 (from 600 to 1080 Mt CO₂), the GDP only increased by 50% in the same period (from US$ 8000 to US$12 000 per capita). Furthermore, there is still a positive trend in CO₂ emissions, indicating that Brazil will possibly fail to comply with the 2025/2030 Nationally Determined Contributions (NDCs) under the Paris Agreement goals. When also considering a post-COVID-19 impact scenario, the agricultural sector is expected to increase despite the fall in emissions from the industry and energy sectors due to a potential economic recession (CAT 2020). This indicates the paramount importance of legal apparatus implementation to meet the Brazilian NDC targets, especially in light of the unprecedented fires in the Pantanal and Amazon biomes. Deforestation in the Amazon has also reached the highest rate since 2008 and has shown a steep rise since 2017 (INPE 2020a, 2020b).

Figure 3. Correlation of data on water demand, CO₂ emissions, population growth, gross domestic product (GDP), Nationally Determined Contributions (NDCs), and national water regulations from 1990 to 2030. National water regulations: (a) Act 9433/1997: National Water Resources Policy; (b) Act 11445/2007: National Guidelines for Basic Sanitation; (c) Act 12187/2009: National Policy on Climate Change; (d) Act 12608/2012: National Policy for Civil Protection and Defense; (e) Water Security National Plan; (f) Act 14026/2020: Update of the Basic Sanitation Act. *Data are in constant 2010 US dollars (1USD = 1.76 Brazilian Real - BRL). Sources: CAT (2020), IBGE (2020), World Bank (2020)

The dismantling of the Brazilian environmental policy not only affects the world’s climate but also threatens water security by contributing to increasing the frequency and magnitude of droughts and floods. Marengo et al. (2017) showed a tendency for longer periods with consecutive dry days, more frequent and intense dry spells, and droughts in the Northeast region, corroborating the work of Marengo et al. (2009) and Jenkins and Warren (2015). In the southeastern region, there may also be an increase in the average temperature and a decrease in total precipitation, while cloudbursts and short events may become more frequent, exacerbating interannual rainfall variability (Chou et al. 2014, Viola et al. 2015). The frequency of rainy days and extreme daily precipitation events has increased in São Paulo state. Similarly, precipitation has been more concentrated and sporadic in Rio de Janeiro and Espírito Santo states, where observed data indicate positive trends in the intensity of extreme daily rainfall (Zilli et al. 2017). All those climate change scenarios in the Brazilian regions will trigger conflicts for water allocation and will negatively affect communities that are already vulnerable to extreme events (Marengo et al. 2017, de Jong et al. 2018). Furthermore, these changes in the rainfall regime may cause a shift in the crop production cycle and thus worsen existing situations of agricultural drought. For instance, the current expansion of Eucalyptus plantations located in the South and Southeast (e.g. Carriello et al. 2016) might further aggravate water security in a region that has experienced recent scarcity. There are also, however, studies indicating increases in productivity under climate projections as a positive impact of climate change (Elli et al. 2020).

Climate change is one of the main challenges regarding water security worldwide. Nonetheless, the National Water Security Plan (PNSH) (ANA 2019c) does not consider climate change scenarios and models in defining its objectives and developing its strategies. This represents a major limitation in the conceptualization of the plan, jeopardizing National water security. The plan needs to explicitly introduce climate change with water-adaptive strategies, like nature-based solutions and insurance mechanisms (UNEP, 2021). Doing so, a new generation of water-policy models in defining objectives and challenges could address feasible perspectives. Although uncertainties remain related to the future climate, several countries are already struggling to overcome the negative impacts of climate change on the environment, society, and economy. Thus, water policies and action plans have to account for possible climate scenarios to address the current and future challenges (Ayensu 1999).

The PNSH aims to reduce the negative impacts of droughts and floods on water resources, using a set of infrastructure improvements, by 2035. Although investing in infrastructure is necessary, the adoption of non-structural measures is vital to minimize environmental and socioeconomic losses (Kundzewicz et al. 2002, Simonovic 2002, Horn and Elagib 2018, Watanabe et al. 2018). Since water governance needs to integrate human needs with ecosystem functioning (Tundisi and Tundisi 2016), involving society in the development of feasible mitigation and adaptation measures is fundamental to dealing with future climate uncertainties. Furthermore, investing in more precise and accurate prediction of extreme events will help society make better decisions, consequently reducing vulnerabilities to impacts of climate change. Thus, cooperation between researchers and decision-makers is crucial and has the potential to deliver robust solutions for the current and future needs (Mason and Calow 2012).

Evidence shows that higher community involvement in governance contributes to increasing the sustainability of water resources (Tsuyuguchi et al. 2020). In Brazil, a more democratic and participatory management of water resources was legalized and incentivized with the establishment of the National System of Water Resources Management (from the Portuguese Sistema Nacional de Gestão dos Recursos Hídricos – SINGREH) by the Water Act 9433/1997. Notwithstanding, there are still some management failures (Veiga and Magrini 2013, Neto et al. 2018), such as the unequal distribution of river basin committees over the hydrographic regions. These committees are deliberative and collegial organizations for river basin management in Brazil, lying at the heart of the participatory management at local and regional scales. The main challenges converge to the lack of governance at the local scale, where, for example, small dikes and drilling wells are implemented without any governance due to management being focussed on macro-systems. Thus, it is necessary to strengthen the local management system through more independent and active basin committees, dialoguing with macro-governance.

Brazil has made little effort to align the apparatus of the government with national and international climate-change policies. In addition, there is a general lack of investment in building resilience, and there is no municipal policy related to preparation for, education on, and mitigation of medium- and long-term impacts of water-related climate extremes. The complexities involved require political will to support the development and execution of policies aimed at better understanding, mitigating, and adapting to current and future challenges in water resources. It is worth emphasizing the importance of integrated management encompassing all Brazilian regions and their particularities. Still, the integration of legal frameworks for water resources (Act 9433/1997), basic sanitation (Act 11445/2007 and Act 14026/2020), climate change (Act 12187/2009), and civil defence (Act 12608/2012) is missing. Further, we need to implement active regulatory mechanisms (top down) and community action with citizen science (bottom up) to manage the sector’s water demand.

4 Concluding remarks and future perspectives

Ensuring sufficient and clean water for human consumption and economic activities and reducing the risks associated with critical events – droughts and floods – are at the heart of water security. The recent crises in water supply, such as those faced by the metropolitan regions of São Paulo and Rio de Janeiro, have broadened the discussion on water security in large population centres supplied by complex systems (Kelman 2015, Taffarello et al. 2016, Mohor and Mendiondo 2017, Zhang et al. 2018, Gesualdo et al. 2019). Despite the advances, there is still an urgent need for water security in other regions besides the large urban centres, such as the North and Northeast, where most of the population is subject to vast water inequality. The project to integrate the São Francisco River basin with the others in the Northeast region (PISF) is a potential opportunity to alleviate water inequalities affecting communities in the Brazilian semiarid region, consequently ensuring water security. The PISF is a water infrastructure project of water abstraction from the São Francisco River to distribute it to the states of the semiarid region. Although the objective is to guarantee water security in the region, it has been a great challenge to integrate all local needs and conflicts due to multiple uses.

If the environmental policies follow the course of the last few years, we expect an aggravation of water stress and a rise in water conflict in regard to the projected increase in frequency of extreme events all over Brazil. In the agricultural sector, more water conflicts may emerge in the future, mainly when contrasting the possible decrease in annual rainfall with the expansion of irrigated area by 45.6 Mha estimated by the National irrigation Policy (Act 12787). Multsch et al. (2020) suggest that an expansion of irrigated areas without considering climate change would strongly impact surface water resources, resulting in 26.0 Mha being under critical and very critical water scarcity in all regions of Brazil, except Amazonia. Besides the negative impacts on agriculture, water supply, and industry, climate change risks hydropower generation, the main energy source in Brazil. Ensuring water security depends on participative management, flexibility to adapt to current and future climate change, and – mainly – political will. Climate variability and anthropogenic pressures have made the Brazilian biomes more vulnerable, risking ecosystem functioning and water availability. There has recently been a breakthrough in Brazilian environmental policy, with the approval of the National Policy for Payment for Environmental Services (PES). The PES is an instrument that can be used to encourage adaptation to climate change.

Future investments in drinking water supply and sewage are estimated at US$*24.074 and US$35.849 billions, respectively, according to the National Plan for Basic Sanitation (Brazil Ministry of Regional Development 2013). Urban areas will require approximately 95% of each amount. These investments are required to meet the goals of universal basic sanitation in Brazil by 2033 and the related SDGs. Besides water supply and sanitation, a legal policy for water reuse needs to be developed. Notwithstanding that the new legal framework for basic sanitation (Act 14026/2020) invokes the potential reuse of water from wastewater and rainfall, there are still no regulatory instruments defining, for example, thresholds for water quality parameters at the national scale. Therefore, the Brazilian government urgently needs to move towards integrated risk management, focussing on optimizing water use and storage (ANA 2018), whether on a macro scale or on a local scale. This requires planning and implementation of adequate water infrastructure and non-structural measures for water resource management.

Acknowledgements

This paper was developed within the framework of the “Panta Rhei – Everything Flows” scientific decade (2013–2022) of the International Association of Hydrological Sciences (IAHS). The authors acknowledge the graduate programme in Hydraulics and Sanitary Engineering – PPGSHS (USP-EESC) – for the scientific support, and Dr Denise Taffarello for discussions and suggestions. In addition, we acknowledge the feedback from the reviewers, which was valuable in improving the manuscript.

Disclosure statement

No potential competing interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This study was supported by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior do Brasil (CAPES) - finance Code 001, and regular funding to post-graduate program in Hydraulics and Sanitation of University of Sao Paulo, São Carlos School of Engineering by the Brazilian National Council for Scientific and Technological Development (CNPq). Also, by the National Institute of Science and Technology for Climate Change Phase 2 (INCT-II) under the CNPq Grant 465501/2014-1, the São Paulo Research Support Foundation (FAPESP) Grant 2014/50848-9 and the CAPES Grant 16/2014.

Notes

*Data are in constant March 2020 US dollars (1 USD = 5.07 Brazilian Real - BRL)