Oficina Regional de la FAO para América Latina y el Caribe |

IRRIGATION IN BRAZIL 1

Climate

Brazil has a very wide diversification of climate. The agro-climatic regions with their characteristics are described in the following table and their implications for irrigation are explained below.
(i)The south is below the Tropic of Capricorn in the temperate zone, with cool, relatively dry winters and warm, relatively moist summers. It has two well defined characteristics: one is its homogeneous rainfall within the region and the other is the uniform climate, the prevalance of the mesotermic climate. Due to frost, there are few opportunities for out-of-season winter irrigation, and although supplementary summer irrigation can save farmers from crop failures in a dry year, on average it gives only a small increase over the rainfed yields of the typical summer crops of the south: maize, beans and soybean. It has a highly developed, commercially-oriented agriculture which both large and small farmers share.
As a result, irrigation development in the south has instead focused mainly on summer flooding of lowlands for rice production (Rio Grande do Sul). Most of this is large-scale and mechanized, and is closely integrated with cattle production, largely for reasons of weed control. Lowlands are typically only planted with rice once every three years and kept under non-irrigated pasture for the other two. From 1978 to 1988 the Government promoted conventional lowland rice irrigation on a smaller scale, under the Provarzeas programme that is now suspended.
(ii)The southeast region, stretching approximately from the Tropic of Capricorn to 14 degrees south is, like the extreme south, dominated by technically advanced, commercial farmers. Although it also receives most of its rainfall in the summer, winters are milder. Hence, winter irrigation allows the farmer to crop twice instead of once, rotating winter plantings of wheat, peas or beans with rainfed summer crops, which include cotton and sugar cane. There is also supplementary irrigation of summer crops when necessary. Although there is less of the extensive flooded rice typical of the south, the Provarzeas programme has made considerable progress in the last ten years, also in the southeast. Here it encouraged the growth of beans and other crops using supplementary irrigation in winter, in rotation with the main crop of summer flooded rice.
(iii)The centre-west stretches from the fringes of the Amazon basin in the west to the state of Goiás in the east, and from 8 degrees to 24 degrees south. At its westerly extreme it has a relatively well-distributed rainfall of up to 2 500 mm/year and there is little need for irrigation. Further to the east, rainfall decreases to some 1 000 m and irrigation is required during a six-month dry season. However, most of the centre-west is cerrado (savanna) land, potentially productive if the soil's natural acidity and low phosphates are corrected. Since cerrado soil management techniques are newly developed, only over the last decade has much of the region been opened for cultivation, mainly by advanced farmers from further south. Increasing numbers of farmers are taking advantage of the region's many perennial rivers and streams to complement their rainfed cereal, soybean, bean and cotton production with dry-season irrigated cropping. The large properties and level land are well suited to centre-pivot and self-propelled irrigation systems, which have expanded in the last years. Free of winter temperature constraints, irrigation in the cerrado can greatly increase the intensity of this vast, recently occupied area.

(iv)The northeast includes Brasil's semi-arid lands, which have an irregularly-distributed annual rainfall averaging from 750 mm to less than 250 mm. The region contains the country's poorest farmers and large numbers of landless people. Many farmers cultivate for subsistence only. Unlike other regions water resources in most of the northeast are a severe constraint to agriculture. One major river, the São Francisco, dominates the region, but the topography generally requires that its water be extracted by pumping. There are a few other naturally perennial rivers like the Parnaiba (Piauí/Maranhão), and although regulation structures have been built on some seasonal rivers by the Government, many now run dry due to uncontrolled water extraction. There are some lowland areas suitable for flooded rice mainly in the humid coastal strip. Where water constraints can be overcome, the warm northeastern climate favours maize, beans, cotton and sugar cane, as well as year-round multiple fruticulture and horticultural cropping and seed production. Large public-sector irrigation schemes have been constructed and allocated both to entrepreneurs and small-scale settlers, with the aim of overcoming intermittent regional food deficits while creating employment and benefiting the rural poor. Increasing use is being made of drip and sprinkler irrigation in water-scarce areas with fruit trees that are now receiving special attention from the federal and state governments.
(v)The north region covers almost the whole Amazon Region, being the largest extension of hot and humid forest in the world. It occupies almost half of the Brazilian territory. The climate is hot and humid. Irrigation needs are few, and development is limited to a small area of lowland rice.

Main characteristics of the agro-climatic regions of Brazil
Average values	South	South-East	Centre-West	North-East	North
Temperature (° C)	14 - 18	24 - 18	26 - 22	20 - 28	24 - 26
Annual rainfall (mm)	1250 - 2000	900 - 4 400	1250 - 3000	250 - 2000	1500 - 3000

Water Resources

For general purposes, Brazil can be divided into:
(i) three river basins namely the Amazons, Tocantins and São Francisco; and
(ii) two basin complexes:
- The Plata river that has three Brazilian sub-river basins (Paraná, Upper Paraguay and Uruguay);
- The remaining rivers flowing into the Atlantic that are divided into several basins.

Figure1 Map of Brazil showing the main river basins with their
water resources characteristics

Basin name	AREA (km2)	P (mm/y)	E (mm/y)	Q (m3/s)	q (l/s/km2)
1 Amazon in Brazil	3935000	8735,7	4918,8	3784,4	30,8
2 Tocantins-Araguaia	757000	1256,6	884,2	372,1	15,6
3 North and Northeast	1029000	1533,0	1239,6	285,4	8,8
4 San Francisco	634000	580,7	490,7	89,9	4,5
5 East Atlantic	545000	321,0	246,2	137,2	8,0
6 Paraná-Paraguay	1245000	2139,9	1656,7	387,6	9,9
7 Uruguay	178000	278,9	148,1	130,9	23,3
8 Southeast Atlantic	224000	312,3	176,7	135,6	19,2
TOTAL	8547000	15158,1	9761,0	5323,1

The Amazon and the Tocantins-Araguaia basins in the north account for 56 percent of Brazil's total drainage area. The Amazon River, the world's largest river in volume of water and second longest after the Nile, is navigable by ocean steamers as far as Iquitos in Peru. The Paraná-Paraguay river system drains the south-western portion of the state of Minas Gerais. Brazil's two southernmost states are drained through the Uruguay River also into the Plata River. The São Francisco River is the largest river entirely within Brazil, flowing for over 1 609 km northward before it turns eastward into the Atlantic. The last 277 km of the lower river is navigable for ocean-going ships.
The internal surface water resources, understood as the average water production within Brazil, is 5 323 km3/y. The inflow of the Amazon to Brazil is 2 807 km3/y, so that the total surface water resources in the country reach, on average, 8 172 km3/y. The outflow from Brazil into the Plata River is 518 km3/y. The data shown in Figure 1 illustrates the great hydrological diversity of the Brazilian territory. It also shows that the lowest water availability ratio, both per person and per area, is in the semi-arid region of East Atlantic 1 and in the São Francisco River Basin.

The annual recharge of groundwater is estimated at 95 km3/y. The volume of stored groundwater in Brazil less than 1 000 m deep and with good quality for human uses is estimated at 112 000 km3, with very variable extraction rates. These range from less than 5 m3/h in the metamorphic rocks of the semi-arid northeast and recent deposits to 1 000 m3/h in the sedimentary rocks. There are around 200 000 wells being exploited, with drilling of about 10 000 wells a year. Approximately 61 percent of the Brazilian population is supplied for domestic purposes from subsurface water.
The northeast region deserves special emphasis because of (i) its semi-arid climate with low precipitation (average of 600 mm/y) and high potential evaporation (2 000 mm/y) and (ii) predominance of metamorphic rocks with low capacity to accumulate groundwater. The rivers have intermittent flow, except for the São Francisco and Parnaíba. The limited surface water availability has resulted in over-exploitation of the aquifers since early this century. In the last 30 years, however, there has been much concern to survey, evaluate and use the water resources of the region better. The region has a surface of 1.6 million km2 (20 percent), comprises nine federal units and had a population of 43.9 million (27 percent) in 1996. The region is divided into 24 river basins, the water resources of which vary between 820 and 850 m3/inhab./year in Pernambuco and Fortaleza to 30 000 m3/inhab./year in Gurupi.
The Treaty of the River del Plata entered into force in 1977 and worked for several years as a political interconnection among the countries of the southern cone (Argentina, Brazil, Bolivia, Paraguay and Uruguay). Its main objectives are the wise use of water resources; regional development with preservation of flora and fauna; physical, fluvial and terrestrial integration; and promotion of greater knowledge of the basin, its resources and potential.
The Amazon Cooperation Treaty (TCA) was signed in 1978 by Brazil, Colombia, Ecuador, Guyana, Peru, Surinam and Venezuela and entered into force for Brazil in 1980. The basic scope of the TCA is to promote the harmonic development of the Amazon, in order to allow an equitable distribution of the benefits, to improve the quality of living of its peoples and to achieve the full incorporation of their Amazon territories to the respective domestic economies.
Other treaties include: (i) the Cooperation Agreement for the Use of Natural Resources and Development of the Quaraí River Basin; and (ii) the Treaty for the use of Shared Natural Resources of the Bordering Stretches of the Uruguay River and its tributary, the Pepiri-Guaçu River, between Brazil and Argentina.

Lakes and dams

The consumption of electric energy stood at 258 000 GWh in 1996. The installed capacity is 57 640 MW, 93 percent of which is from hydrolectric power stations and 7 percent from thermoelectric power stations. The percentage contribution of the hydroelectric power stations for energy generation (97 percent) is greater than the percentage of the installed potential (93 percent) because thermoelectric power stations are inoperative for long periods of time, only being activated mostly during dry periods, when reservoirs become dangerously low. The Itaipu power plant, the largest hydroelectric plant in the world (power production is 12 600 MW divided equally between Brazil and Paraguay), is located on the Paraná River on the Paraguay-Brazil frontier, not far from Iguaçu Falls. New hydrolectric power stations are to be built in several of already inventoried places, making a total of 107 307 MW of installed generating power in the next few decades. The Brazilian hydroelectric potential is around 258 686 MW, of which only 21 percent is being exploited.

Water withdrawal

Theoretically, the country has ample water resources in six of its eight major water basins to supply all foreseeable long-term irrigation requirements. In 1996, the average consumption of irrigation water was 12 629 m3/ha per year. Only in the northeast and in the eastern tributaries of the São Francisco basin is irrigation development constrained by water availability. Already, 0.04 km3/of desalinated water are use for livestock and domestic purposes in the northeast region. Local water shortage also occurs in some small watersheds in the southeast and south where irrigation development and water consumption for industry and municipal use have been relatively uncontrolled. In these areas, as well as on some rivers in the northeast and along some tributaries of the São Francisco river, water use would have to be controlled and regulated if economic losses and degradation of quality are to be avoided.

Fig. 2 Water withdrawal by sector in Brazil 1996

Irrigation and drainage development

The irrigation potential of Brazil is estimated at 29.3 million ha (see following table). This includes only areas where irrigation can be developed and excludes the areas of high ecological value in the northern region (Amazonas and Tocantins basin). In the savanna areas (cerrados) of the centre-west region, the potential for irrigation has expanded substantially in recent years, following recent advances in soil management and irrigation techniques applicable in that region. The irrigated area in 1998 was 2.8 million ha, which represents 5.7 percent of the cultivated area.

Irrigation potential (in thousand hectares) by regions
	Lowlands"Varzeas*" (1 000 ha)	Highlands (1 000 ha)	Total Area (1 000 ha)
North Northeast Southeast South Centre-West	8 000 100 750 1 500 3 000	5 300 900 3 400 2 200 4 200	13 300 1 000 4 150 3 700 7 200
Total	13 350	16 000	29 350

Varzeas are seasonally-flooded or flood-prone lowlands.
Irrigation started in Brazil in the last century, in Rio Grande do Sul and in the semi-arid region of the northeast. By the end of the 1960s, the Group for Integrated Studies on Irrigation and Agricultural Development (GEIDA) was created to enlarge the overall knowledge of natural resources. It created various programmes such as the Pluri-annual Irrigation Programme (PPI) in 1969, and the National Integration Programme (PIN) in 1970. Many opportunities were given for private investments on irrigation and drainage: (i) the National Programme for Rational Use of Flood Plains (PROVARZEAS); (ii) the Programme to Finance Irrigation Equipment (PROFIR); (iii) the conception of "entrepreneurial lots" in public irrigation projects; and (iv) the implementation of the sub-sectoral Irrigation I Project. In 1984 a new period started characterized by the establishment of important programmes such as the Northeast Irrigation Programme (PROINE) and the National Irrigation Programme (PRONI), both in 1986. In that period, the Government's role was limited to the accomplishment of large works (transmission and distribution of electrical energy and macro-drainage) while the private entrepreneurs were in charge of the other investments. In 1995, the new Government started preparing the National Policy on Irrigation and Drainage. Figure 3 shows the evolution of irrigation areas in Brazil. The area under irrigation was estimated at 2.87 million ha in 1998.

Figure 3 Irrigation evolution in Brazil

Irrigation techniques differ within Brazil. In the south, southeast and centre-west, rice paddies, as well as some vegetable and orchard crops, are irrigated by simple flooding or using furrow irrigation. Over 790 000 ha of paddy rice are grown with basin irrigation in Rio Grande do Sul. Water is diverted from numerous small streams and conveyed to the farm-gates through earth canals. At least 1.5 million ha in Brazil are estimated to be under traditional systems of this sort. They are used where water availability is ample. This technology, together with proper land preparation and some mechanization, yields a good return. Modern irrigation technologies, which have a higher water-use efficiency and require less labour, are preferred by large farmers in the cerrados, for crops such as wheat, soybean, maize, and cotton, and by the producers of vegetables and fruits near the metropolitan areas in the northeast. These technologies, which are increasingly used in private and public irrigation schemes, range from mobile sprinkler lines to state-of-the-art modern centre-pivot and other self-propelled irrigation equipment. In the northeast there is a strong increase in the use of micro-irrigation equipment, due to the water scarcity in the area. In recent years, the area with surface irrigation has decreased and that with sprinkler irrigation for grain production and micro-irrigation for fruit and vegetables has increased. Total efficiency of water use is estimated, on average, at 40-65 percent for surface, 60-85 percent for sprinkler and 78-97 percent for micro-irrigation methods.

Irrigated agriculture can be divided into public and private schemes:
Public schemes that represent 160 000 ha (6 percent of the total irrigated area in 1996). Most of these public irrigation schemes are in the northeast region, 107 115 ha in 1996. The size of the irrigation schemes varies between 42 and 22 000 ha. Most of the investments are made by Government, which then allocates plots from 4 to 8 ha to poor or landless farmers (settlers). In addition, there are some medium-size plots (from 8 to 32 ha) usually for professionals (agrarian technicians) and large-size plots (from 25 to 500 ha) for enterprises. Public irrigation systems depend on water supplies that have been developed using Government (usually Federal Government) funds. The total cost of development of public irrigation projects in the northeast is approximately US$ 8 600/ha, US$ 9 650/ha and US$10 150/ha for surface, sprinkler and micro-irrigation, respectively. The water charge in 1998 according to the Company for the Development of the São Francisco Valley (CODEVASF) had two components: one to recover the investment cost of the irrigation and drainage system and the other to cover the operation and maintenance costs. The first depends on surface area and values range between US$ 2 and 9 per ha. The second depends on water consumption and values vary between US$ 1.5 and 15 per 1000 m3. CODEVASF has experienced that it is easier to cover operation and maintenance costs in the irrigation systems with larger plot areas than in ones with smaller plot areas.

The rest of Brazil´s irrigation (94 percent) has been developed by private individuals or companies. Private development has received technical support from the Government, especially under the PROVARZEAS programme and financial assistance through targeted credit lines. It comprises many forms of irrigation ranging from small to large-scale, and from simple to highly sophisticated irrigation. Investment costs of private irrigation are considerably lower than in the public sector, ranging from US$ 1 600/ha for surface irrigation to US$ 2 650/ha for sprinkler irrigation and US$ 3 150/ha for micro-irrigation. Generally, investment costs of private irrigation are higher in the northeast than in the other regions due to the difficulty for accessing perennial sources of water. Average costs of operation and maintenance range from US$ 35 to 95/ha. Costs can also be broken down into off-farm investment costs (water pumps, electrical support, conveyance, roads), that vary from US$ 4 500/ha to US$ 7 000/ha, and on-farm investment costs that vary between US$ 650/ha for simple surface irrigation methods to US$ 2 500/ha for micro-irrigation.

In 1997, irrigation contributed an estimated 18 percent of total crop production in weight, and some 29 percent of total farmgate value (since irrigated crops are relatively high-value).

Average yields of rainfed and irrigated crop are given in Figure 4.

The range of crops grown under irrigation is diverse. In addition to basic commodities such as wheat, maize, rice, beans, soybeans and cotton, high-value crops are also grown whenever markets permit, like vegetables (some of them on a semi-industrial scale) near the important urban markets of the industrial southeast. The same markets are supplied off-season with fruits, onions, melons and other vegetables from the northeast. Expansion of tomato paste and other vegetable processing factories in the arid zones of the northeast has created market opportunities for large-scale and small-scale irrigators, who increasingly export their fruit and off-season vegetables to Japan, Europe and the United States. Yields of crops vary widely throughout the country.

There has been a great diversity of performance between the public and private irrigation sectors. Public irrigation generally tended to progress slowly and fall short of performance expectations while private irrigation, especially in recent years, has expanded fast and often given high profits. However, direct comparisons are difficult due to regional differences in irrigation needs and opportunities, the special social needs of the impoverished northeast and the different institutional arrangements for public and private development. In 1990 FAO, World Bank and the Government of Brazil undertook in a detailed study to estimate the economic efficiency of Brazil's irrigation. On the basis of information collected, eleven different models of irrigation farming were defined to represent irrigation in Brazil. The results showed that public schemes were systematically less economically efficient than private schemes, and that basic commodities (cereals, cotton, beans, soybeans) would give a much lower return than fruits and vegetables. Under these conditions, the public schemes of the northeast, growing staple food, yielded a very low return. Net economic benefit generated per 1 000 m3 of water averaged around US$ 20 for low-value crops and US$ 50-400 for high-value crops, while net economic returns per year were, on average, around US$ 250 for low-value crops and US$ 2 000/ha for high-value crops.

Little information is available in drainage, salinity and waterlogging in Brazil. The surface with drainage equipment is around 1.28 million ha, mostly in the areas with irrigation equipment. Within the framework of the PROVARZEAS programme in the 1980s, around 400 000 ha were drained. Average costs of drainage development in 1996 range between US$ 1 600 and 1 800 per ha for open drainage, and from US$ 2 300 to 2 700 perha for subsurface drainage.

The natural saline areas in Brazil are quantified on average at 86 million ha, located especially in the driest areas with average precipitation below 1 000 mm/y. The area salinized by irrigation is estimated at 15 000 ha, mostly in the northeast.
The extension of the areas with natural waterlogging, called "varzeas", is 13.35 million ha. Up to now, waterlogging problems caused by irrigation practices have only been recorded in the Nupeba project for an area of 170 ha. CODEVASF is in the process of designing and implementing a drainage system to prevent waterlogging.