Water Availability and Use

Amongst the most significant of the rivers that form the Paraná River are the Grande river, which rises in the Serra da Mantiqueira highlands and runs for 1300 km from east to west, and the Paranaíba River, which is formed by many tributaries, of which the most northern is the São Bartolomeu, which rises in the Serra dos Pirineus highlands, in the vicinity of Brasília.

The initial course of the upper Paraná runs in a southwesterly direction until it reaches the Serra do Maracaju highlands. In this initial stretch, the Paraná River takes in a number of tributaries on both banks, with the most significant of these being the Tietê, Paranapanema and Iguaçu rivers, all on the left bank.

From the confluence of the Paranapanema to the town of Guairá, the Paraná River takes in further, smaller tributaries, amongst these are the Ivaí and Piquiri rivers, on the left bank, and the Ivinheima, Amambaí and Iguatemi rivers, on the right bank. The Iguaçu river joins the Paraná River at the point at which the territories of Brazil, Paraguay and Argentina all converge.

The Paraná River runs for 2,570 km to its estuary at the Prata River, which added to the 1,170 km of the Paranaíba River, its main tributary, gives a total of 3,740 km, being the third longest river in the Americas. The Paraná Hydrographic Region is divided up into nine sub-basins: Grande, Iguaçu, Ivaí/Piquiri, Ivinhema, Paranaíba A, Paranaíba B, Paranapanema, Sucuriú/Verde/Pardo and Tietê (Figure 1).

The Paraná River, in Brazilian territory up to the mouth of the Iguaçu River, records a mean discharge rate of 11,000 m³/s (7% of the national total) and a specific discharge rate of 13 l/s/km². With the exception of the Iguaçu sub-basin (21.8 l/s/km²), all the other sub-basins record specific discharge rates of between 9 and 16 l/s/km², indicating that the water availability is relatively well distributed throughout the hydrographic region (Figure 2).

Figure 2 Specific discharge rates by sub-region

With respect to the groundwaters, metamorphic rocks, which give origin to fractured aquifers, are present in the northern and eastern edges of the Paraná Hydrographic Region, with the wells recording discharge rates in the order of 2 to 7 m³/h and an average depth of 120m. In the remainder of the region, fluviomarine and aeolic sediments associated with basaltic lava predominates. In these sites, the sediments form porous aquifers and possess wells with mean discharge rates in the order of 1 to 15 m3/H and depths of between 100 and 150 m. The Guarani aquifer (839,800 km² in the country) is exceptional within this context, with ground wells that record discharges that can reach 1,000 m³/h and depths which range from 70 to 1,500 m.

 

To implement sewage treatment systems in the main urban centers To develop a program for suitable use and management of the soil and control of erosion, with the aim of preserving the springs and preventing the silting up of rivers. To optimize the use of water in irrigation and industry and reduce the losses in the supply system

Implement a measuring and charging system for water usage in the most critical sub-basins Set up a strategy for preventing floods and protecting vulnerable areas, especially in the Greater São Paulo, Campinas, Curitiba and other main urban centers Settle the issues regarding the need to maintain minimum water volume levels, so as to allow waterway travel on the Tiete-Paraná waterway, and the operational rules of the hydroelectric power plants

The current situation of the Paraná Hydrographic Region in terms of availability and demand is laid out in Table 3, in which it can be seen that the sub-basin of Tiete presents the highest demands arising from irrigation, human and industrial consumption, and the highest demand/discharge ratio (23.7%).

Human demand is 104.2 m³/s, with 55% of this value being concentrated in the sub-basin of the Tiete. Around 90% of the population of the hydrographic region is connected to the water supply network and the average consumption is between 150 and 200 m3/month/inhab.

Industrial demand is 112.8 m³/s, with the greatest demand being in the sub-basin of the Tiete (54% of the total), especially in the metripolitan area of São Paulo.

Irrigation demand is 252.1 m³/s, with the greatest demand being in the sub-basins of the Tiete (206 thousand irrigated hectares) and the Grande river (116 thousand irrigated). The total irrigated area in the Paraná Hydrographic Region is 424,767 ha.

Livestock demand is 43.9 m³/s and has a relatively uniform distribution throughout the hydrographic region, with the highest demand observed in the sub-basin of the Tiete (18% of the total), in most part due to poultry farming activities.

The total water demand is 513.0 m³/s (23% of the demand for the country), with 49% being for irrigation, 22% for industrial use, 20% for human consumption and 9% for livestock watering (Figure 3).

Figure 3 Demand distribution

Figure 4 illustrates the distribution of the demands by sub-basin, where it can be seen that the highest demands for human use, livestock watering, irrigation and industrial use occur in the sub-basin of the Tiete. 

Figure 4 Demand distribution by sub-region.

The region boasts the highest installed energy capacity in the country (40,613 mW, 67% of the national total), as well as the greatest demand (75% of national consumption). There are 148 hydroelectric power plants in the region, with the most noteworthy of these being Itaipu, Furnas, Porto Primavera and Marimbondo. There no longer exists the possibility of new large-scale hydroelectric projects on the main rivers, with the current trend being the development of small, hydroelectric power station projects on smaller rivers.

With respect to river navigability, the Tiete-Paraná waterway is one of the most important, being navigable travel between São Paulo, Goiás, Paraná, Minas Gerais and Mato Grosso do Sul, over a total of 220 municipalities, covering approximately 2,400 km. 5 million tons of cargo was transported on this waterway in 1996. This waterway is particularly important for stimulating the industrialization of the inland areas of the country and integration with the Mercosul member countries.

Industrial and domestic pollution has the greatest impact on water resources in the hydrographic region. The low levels of domestic sewage collection and treatment result in significant pollution burdens, particularly in the vicinities of the main urban centers, thereby affecting the quality of the supply sources. As for the domestic pollution, the urban organic burden potential is 2,666 tons of BOD₅/day (35% of the national total) and is mainly concentrated in the vicinities of the metropolitan region of São Paulo.

Regarding industrial pollution, the concentration of factories in the vicinities of metropolitan regions of São Paulo and Curitiba plays a major part, which does not favor pollutant dilution, as they are located near headwaters.

Events that are considered critical to the water resources, are water supply rationing in the city of São Paulo, due to the increase in demand and lack of headwaters offering good quality water. Interruption to the water treatment systems, due to pollution of the headwaters and complaints from the public regarding the bad odor of the water, caused by algae proliferation, is commonplace in the Tietê sub-basin.

Flooding is common in urban areas, due to drainage problems (soils that have become impermeable and river channeling), as often witnessed in the Tiete (São Paulo) and Iguaçu (Curitiba) sub-basins. Floods in rural areas are a result of the occupancy of river flood plains. Both urban and rural flooding leads to severe economic losses and are a direct result of the significant change of the natural hydrologic behavior.