1. Introduction

2. Literature Review

Table 1. Unit public prices (UPPs) for charging for the use of Union-owned water resources in the Paranaíba River Basin.

Table 1. Unit public prices (UPPs) for charging for the use of Union-owned water resources in the Paranaíba River Basin.

* Unit public prices. Source: Paranaíba River Basin Committee– CBHRP [8].

3. Materials and Methods

4. Results and Discussion

4.1. Bibliometric analysis

The total number of articles found in the Capes journals, which composed the final database, was 81 (Figure 2).

Out of the 81 pre-selected articles, 51 were excluded due to duplication or lack of information. Then, the remaining 30 articles were read, and of these, 10 were excluded for not meeting the central theme of the research question. Finally, 20 articles met the inclusion criteria. Among the articles found, all were published from 2010 onwards and were updated each year, with the latest published in 2022. Articles published in the last 5 years were found, counting from 2015 (1), 2016 (1), 2017 (1), 2018 (3), 2019 (1), 2020 (1), 2021 (1), and 2022 (1), with 2018 being the standout year with the most publications on the subject.

In Table 2, the main conclusions observed in the selected articles on water resources charging in Brazil are presented.

Table 2. Main conclusions observed in the selected articles on water resources charging in Brazil.

Table 2. Main conclusions observed in the selected articles on water resources charging in Brazil.

Studies	Country	Main conclusions
(Alencar, K. et al., 2018)	Brazil	The implementation of water charges in the Rio Grande basin is feasible, indicating irrigation as the activity that most uses water in the basin. Furthermore, it is suggested not to establish a limit for the economic impact on the agricultural sector, or to establish it at a significant value to encourage rational water use.
(Alho da Costa, F., 2022)	Brazil	Charging for the use of water resources can be an important strategy to ensure the sustainable use of these resources in Brazil. The participation of society in the definition of charging policies and water resource management is of great importance to ensure equity and transparency in the process, requiring clear and effective legislation.
(Almeida, M. e Curi, W., 2016)	Brazil	It highlights that integrated water resource management involving the participation of different actors and joint actions is essential to ensure the availability of water for all uses and users. Finally, it is suggested that the implementation of public policies and incentive programs, such as tax reductions for companies that use sustainable practices, can help promote sustainable water resource management.
(Campos, J., 2013)	Brazil	Integrated water resource management is a relatively recent and complex challenge that requires the adoption of conservation measures and rational water use, as well as the promotion of public policies and actions that encourage society's participation in water resource management.
(Demajorovic, J. et al., 2015)	Brazil	Charging for water use can incentivize companies to adopt more sustainable and efficient water practices. The authors point out that charging can stimulate companies to invest in more efficient technologies, reduce waste, and promote water recirculation and reuse. However, water charging is not the sole solution for sustainable water resource management.
(Ferreira, A. F. A. e Oliveira-Filho, E. C., 2021)	Brazil	Farmers have a limited understanding of the importance of paying for water use and how this system can contribute to sustainable water resource management. While some farmers are willing to pay for water use, the majority do not recognize the need to financially contribute to water resource maintenance.
(Ióris, A., 2012)	Brazil	Water resource management in Brazil has a long history marked by progress and setbacks. Despite advances in water resource management in recent decades, significant challenges remain, such as lack of financial and human resources, water pollution, and water scarcity in arid and semi-arid regions
(Ladwig, N. et al., 2017)	Brazil	Charging for water use in irrigated rice production in the southern region of Santa Catarina can have a significant impact on production costs, especially for farmers with lower economic power. The study shows that costs vary according to river flow and users' capacity to pay for water, which can lead to inequalities in agricultural production and water distribution.
(Leite, G. e Vieira, W., 2010)	Brazil	Charging for water use can incentivize companies to adopt more sustainable and efficient water practices. The authors point out that charging can encourage companies to invest in more efficient technologies, reduce waste, and promote water recirculation and reuse. However, water charging is not the only solution for sustainable water resource management.
(Lima, L. et al., 2019)	Brazil	Farmers have a limited understanding of the importance of paying for water use and how this system can contribute to sustainable water resource management. While some farmers are willing to pay for water use, the majority do not recognize the need to contribute financially to the maintenance of water resources.
(Morais, J. et al., 2018)	Brazil	Water resource management in Brazil has a long history marked by progress and setbacks. Despite advancements in water resource management in recent decades, it still faces significant challenges such as lack of financial and human resources, water pollution, and water scarcity in arid and semi-arid regions.
(Odppes, R., et al., 2018)	Brazil	Charging for water use in irrigated rice production in the southern region of Santa Catarina can have a significant impact on production costs, especially for farmers with lower economic power. The study shows that costs vary according to river flow and users' payment capacity, which can lead to inequalities in agricultural production and water distribution.
(Santin, J. e Goellner, E., 2013)	Brazil	The use of the Shapley value can be an efficient methodology for charging for water use in river basins, especially in situations of high complexity and socioeconomic heterogeneity.
Oliveira, V. et al., 2020)	Brazil	Cost sharing is an effective tool for water resource management and can help incentivize the adoption of sustainable practices in the region. Additionally, the study highlights the importance of participation and cooperation among different stakeholders involved in watershed management.
(Resende Filho, M. et al., 2011)	Brazil	Charging for water use can lead to improved technical efficiency in water and input use in agricultural production.

Source: Authors (2023).

It is evident in the authors' conclusions the importance of charging for water resource use, the need for social participation, the determination of a fair and appropriate value for the purpose, as well as incentives for sustainable practices that allow for consumption reduction and improvement in the quality of discharged effluents.

4.2. Federal water resource charging in the Rio Paranaíba

Table 1 presents the data on the withdrawal and discharge flow (m3), number of users by purpose (Un), and charged amount (BRL) for federal water resources in the Rio Paranaíba (Table 1).

Table 1. Users by purpose, withdrawal and discharge flow (m³), and charged amount according to the purpose of use of water resources extracted from the Rio Paranaíba channel. Year 2021.

Table 1. Users by purpose, withdrawal and discharge flow (m³), and charged amount according to the purpose of use of water resources extracted from the Rio Paranaíba channel. Year 2021.

Purpose	Users by Purpose (Un)	Capture Flow (m³)	Discharge Flow (m³)	Charged Value (BRL)
Public Water Supply	17	284.626.793,76	119.275.453,99	4.901.701,50
Aquaculture in Excavated Tanks	18	2.707.809,05	2.707.809,05	5.696,54
Human Consumption	13	114.548,87	114.548,87	2.428,3
Animal Farming	18	84.575,04	84.575,04	382,33
Sanitation	15	179.616.266,40	80.239.275,29	200.960,02
Industry	27	150.514.764,83	76.497.409,35	2.336.543,73
Irrigation	716	655.348.081,44	473.418.684,75	1.267.277,54
Mining - Sand/Gravel Extraction	11	866.012,00	866.012,00	15.706,45
Mining - Other Extraction Processes	7	24.766.923,28	24.640.923,28	382,33
Others	45	5.908.888,54	5.289.001,82	110.986,74

Source: ABHA [12]

According to the data presented in Table 1, it is possible to observe that the purpose with the highest capture flow is irrigation, followed by public supply and sewage treatment. However, when analyzing the value charged per purpose (Figure 3), it is seen that the highest revenue comes from public supply, followed by industry and irrigation. Therefore, even if the purpose has the highest capture flow, its value charged in the Rio Paranaíba riverbed will be established differently through the value table presented by Normative Instruction n°. 115/2020.

The justification is that irrigation, despite having the highest volume of water intake, its value is based on the market and its real purpose. If its charge increases, it may become unfeasible for activities that use irrigation, especially agriculture, or in the worst-case scenario, it would increase production costs, ultimately affecting the final selling price.

According to Ladwig et al. [13], if the charge increases, agricultural producers will consider water as a significant input cost, which may lead to water rationing to maximize its use, prevent waste, and reuse water in the system. Although the market price is variable, it can be below or above the profit price of the production, which may vary throughout the agricultural year. In other words, if production costs are high, it may be an obstacle to implementing water use charges.

Not only in the Rio Paranaíba basin, but according to the survey conducted by Alencar et al. [14], irrigation agriculture is also the sector that most uses water, accounting for 46.4% of the authorized flow in the Rio Grande basin located in the Brazilian Cerrado.

It is necessary to implement new charging mechanisms indicated by the Committees for the Integration of the Paraíba do Sul River Basin (CEIVAP) and the Piracicaba, Capivari, and Jundiaí River Basin Committees (PCJ). These mechanisms' parameters are aligned with the activities existing in the basin, which can be an option to implement the CBH Paranaíba model since the difference in water intake and charges for irrigation can be observed.

Figure 3 shows the distribution of the predominant purposes by the Federal Units that compose the Rio Paranaíba Basin, namely the states of Goiás, Minas Gerais, Mato Grosso do Sul, and the Federal District.

Considering that the data available in the spreadsheet contained the purpose, but occasionally lacked the Federal Unit to which it was intended, it was decided to group this incomplete information into an item called "others". In other words, they are waters taken from the Paranaíba River channel by users, charged and intended for the listed uses, but without cataloging the Federal Unit to which it belongs. It is necessary to improve the internal processes of the Paranaíba River Basin Agency and the control mechanisms of the Paranaíba River Basin Committee, as well as the National Water Agency – ANA.

By far, the main revenue is intended for the purpose of public water supply, accounting for 52.33% and a revenue of R$ 4.9 million (Figure 3), although it is not the main volume captured (m3) since this occurs for irrigation (Table 1). The industry is present in second place with 24.95% and R$ 2.34 million, almost half of the uses and values attributed to public water supply. It is noteworthy that the use of water for irrigation, in third place, with 13.53% and revenue of R$ 1.27 million.

Since public water supply leads the revenue, and mostly comes from urban areas that will also generate proportional discharges, it is worth noting what Leite [15] reports, that an added value could be charged for the use of water associated with its high levels of effluent emissions, serving as a stimulus for this sector to adopt less polluting practices, such as treating their sewage, which is discharged into rivers without any control most of the time. This scenario of the basin with a high level of pollution due to the precarious situation of urban sanitation is verified in cities, in such a way that the effect of sewage discharge into the waters can reach unsustainable levels if the urban sector is not properly charged or stimulated to adopt more rational practices in the use of water.

Even though irrigation is the third largest revenue generator, there is no relation to the volume of water extraction, as it is the leader in water usage. This shows, as stated by Ladwig et al. [13], that the value charged for water will depend on the purpose of its use. In theory, those who consume more or pollute more should pay more for the use of water resources. However, in practice, the analysis shows that the establishment of water charges is associated with the purpose for which it is used.

Regarding industry, as the second largest revenue-generating sector and due to its importance as noted by Demajorovic et al. [16], there is a need to advance in the revision of prices applied to water consumption in the industrial sector, in order to find a value that will influence rational use of water in companies, or even adoption of water reuse. Among the purposes with the highest demand for water usage, according to Odppes et al. [17], increasing the tariff for water usage following the national trend can directly affect the average production cost for the industrial sector, and adopting water reuse or rationalization techniques could be an option.

Thus, Almeida and Curi [18] emphasize that integrated water resources management, involving the participation of different actors and joint actions, is essential to ensure the availability of water for all uses and users. Finally, they suggest that the implementation of public policies and incentive programs, such as tax reduction for companies that use sustainable practices, can help promote sustainable water resources management such as water reuse.

Lima et al. [19] describe that the increase in price related to water charges was low (0.04-0.09% of production costs), indicating that it can be absorbed by the industry. On the other hand, the revenue generated by the basins can be decisive for the implementation of various actions aimed at average water quantity and quality, which is good for the industry itself. By presenting this, it is seen that there is a need for the revision of values, and yet, it should not significantly affect the production cost of industries.

Table 2 displays the charges for the use of water resources according to their purpose and the Brazilian state to which the Paranaíba River Basin belongs.

Table 2. Total values charged for water resources (BRL) according to the purpose of use and the federal unit belonging to the Paranaíba River Basin. Year 2021.

Table 2. Total values charged for water resources (BRL) according to the purpose of use and the federal unit belonging to the Paranaíba River Basin. Year 2021.

Federation Units	Charged Value (BRL)
Distrito Federal	4737768,55
Goiás	2430934,15
Minas Gerais	1943371,74
Mato Grosso do Sul	68464,44
Outras	185935,91

Notes.: Absence of data that designates the UF, therefore, they were classified as others. Source: ABHA [12].

Of the federal charges in the channel of the Paranaíba River, the Federal District, despite having a smaller area than the state of Goiás, stands out in revenue, with almost double the amount collected. Goiás has approximately 2/3 of the Paranaíba River Basin, which has its channel dividing with the state of Minas Gerais in its greatest extension. Goiás's responsibility is amplified in this scenario, and it should improve management mechanisms, especially regarding the charging for the use of water resources.

It can be observed that there are values recorded, but without reference to which state the users belong, demonstrating that the data requires greater control in entering the information in the spreadsheet provided by ABHA – Multisectoral Association of Water Resource Users of the Araguari River Basin.

At the federal level, the charging is still being instituted, meaning it is in the process of evolution, and the last milestone was precisely the beginning of charging in the Paranaíba River basins in 2017, only 20 years after the establishment of the PNRH, which makes the basin's charging management susceptible to failures, as well as adjustments for improvement. According to Alho da Costa [2], in terms of the profile of the main users in each basin, there is a different majority-demanding agent, in the case of the Paranaíba River, it is the sanitation activity, usually related to public service, and it is rare for a private demander to be the most expressive within the context being analyzed.

Seeking to identify the municipal units most associated with the demand for water, the purpose of use, and the total collected, the federal capital stands out (Table 3).

Table 3. Municipalities with the highest demand for water resources in the Rio Paranaíba riverbed and their main purpose.

Table 3. Municipalities with the highest demand for water resources in the Rio Paranaíba riverbed and their main purpose.

Municipalities	Predominant purpose of water resource use
Brasília	Irrigation
Catalão	Irrigation
Araporã	Irrigation
Santa Vitória	Irrigation
Davinópolis	Mining - Other Extraction Processes
Itumbiara	Irrigation
Ouvidor	Mining - Other Extraction Processes
Chapadão do Céu	Irrigação
Goiânia	Sanitary Sewage

Source: ABHA [12].

It can be noticed from the predominant uses that irrigation is especially important in the areas surrounding Brasília, Santa Vitória, Araporã, and Catalão, suggesting the need for improved control and monitoring of these predominantly agricultural activities. For municipalities whose main activity is irrigation, Ladwing et al. (2017) states that cost can naturally be a limiting factor for staying in the agricultural business, especially when profits are reduced. On the other hand, following the function of the charging instrument, if the values are too low, the amount collected will not be sufficient for the environmental maintenance of SINGREH and the necessary investments in improvement actions in the hydrographic basin.

According to Ferreira and Oliveira-Filho [20], many farmers have a limited understanding of the importance of paying for the use of water and how this system can contribute to sustainable management of water resources. Although some farmers are willing to pay for the use of water, the majority do not recognize the need to contribute financially to the maintenance of water resources.

Nevertheless, attention should be given to adopting strategies for other purposes that aim to minimize the use of water resources, such as a possible value, using averages of what is charged in other basins as an example, to show the real value to users of water resources from the Paranaíba River channel and consequently compare and adjust with the values reached, which are already charged and adequate to the needs of the channel or basin, as according to Resende Filho et al. [21], charging for water use can lead to an improvement in the technical efficiency in the use of water and other inputs in agricultural production.

Starting from the purpose with the highest usage, which is irrigation, an important point in terms of charging rule is the exemptions that may generate externalities that will negatively impact the economic situation of the basin. For example, in the case of irrigation in properties with the "small farmers" fiscal module, the producers may be exempt from the charge for the use of water [2].

5. Conclusions

6. Patents

References

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