Irrigation features

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From 1955 to 1975 the annual growth of the irrigated area was almost 3% <ref name="Bruce"> Bruce Sundquist, 2007. Chapter 1- Irrigation overview. In: The earth's carrying capacity, Some related reviews and analysis. On line: [http://home.windstream.net/bsundquist1/ir1.html] </ref> . From 1970 to 1982 the growth rate was some 2% per year, and from 1983 to 1994 about 1.3% per year. The growth rate of irrigated area is decreasing.
From 1955 to 1975 the annual growth of the irrigated area was almost 3% <ref name="Bruce"> Bruce Sundquist, 2007. Chapter 1- Irrigation overview. In: The earth's carrying capacity, Some related reviews and analysis. On line: [http://home.windstream.net/bsundquist1/ir1.html] </ref> . From 1970 to 1982 the growth rate was some 2% per year, and from 1983 to 1994 about 1.3% per year. The growth rate of irrigated area is decreasing.
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The following table, taken from reference <ref> R.J.Oosterbaan, 1989, Effectiveness and Social/Environmental Impacts of Irrigation Projects: a Review. In: Annual Report 1988, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 - 34 . Download from web page : [http://www.waterlog.inf/articles.htm] , or directly as PDF : [http://www.waterlog.info/pdf/irreff.pdf] </ref> , shows the irrigation development in the world between 1955 to 1983, distinguishing developed from developing countries:
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The following table, taken from reference <ref> R.J.Oosterbaan, 1989, Effectiveness and Social/Environmental Impacts of Irrigation Projects: a Review. In: Annual Report 1988, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 - 34 . Download from web page : [http://www.waterlog.info/articles.htm] , or directly as PDF : [http://www.waterlog.info/pdf/irreff.pdf] </ref> , shows the irrigation development in the world between 1955 to 1983, distinguishing developed from developing countries:
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The developed countries witnessed a relatively greater increase than the developing nations.
The developed countries witnessed a relatively greater increase than the developing nations.
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== Water use ==
== Water use ==
Irrigation schemes  in the world use about 3500 km<sup>3</sup> water per year, of which 74% is evaporated by the crops <ref name="Bruce"/>  . This is some 80% of all water used by mankind (4400 km<sup>3</sup> per year). <br />
Irrigation schemes  in the world use about 3500 km<sup>3</sup> water per year, of which 74% is evaporated by the crops <ref name="Bruce"/>  . This is some 80% of all water used by mankind (4400 km<sup>3</sup> per year). <br />

Revision as of 10:08, 19 May 2010

This page shows statistical data on irrigation of agricultural lands world wide.
Irrigation is the artificial abstraction of water from a source followed by the distribution of it at scheme level aiming at application at field level to enhance crop production when rainfall is scarce.

Terms & Synonyms

Official WHO Definition

Other Definitions

Contents

Interpretations and Explanations

Irrigated area

The next table gives an overview of irrigated areas in the world in 2003 [1] .
Only the countries with more than 10 million ha of irrigated land are mentioned.

Area (106 ha)  
India   57
China   54
Pakistan   19
Asia (*)   188
USA   22
World   277

(*) Including India, China en Pakistan

There are 4 countries with 5 to 10 million ha irrigated land: Iran (7.7), Mexico (6.3), Turkey (5.1), and Thailand (5.0).

The 16 countries with 2 to 5 million ha irrigated land are: Bangladesh (4.7), Russia (4.5), Indonesia (4.5), Uzbekistan (4.3), Spain (3.8), Brazil (3.5), Iraq (3.5), Egypt (3.4), Rumania (3.0), Vietnam (3.0), Italy (2.8), France (2.6), Australia (2.6), Japan (2.6), Ukraine (2.3), and Kazakhstan (2.1)

Area per application method at field level

Furrow irrigation
Furrow irrigation

94% of the application methods of irrigation water at field level is of the category surface irrigation [1] , whereby the water is spread over the field by gravity.

Of the remaining 6%, the majority is irrigated by methods requiring energy, expensive hydraulic pressure techniques and pipe systems like sprinkler irrigation and drip irrigation, for the major part in the USA. The source of irrigation water in these cases often is groundwater from aquifers. However, the exploitation of aquifers can also be combined with surface irrigation at field level.

In relatively small areas one applies subirrigation whereby the water infiltrates into the soil below the soil surface from pipes or ditches. This category includes tidal irrigation used in the lower part of rivers where the tidal influence is felt by permitting the river water to enter ditches at high tide and allowing it to infiltrate from there into the soil [2].

Basin irrigation for a rice crop
Basin irrigation for a rice crop

In relative rare cases one uses labor-intensive methods like irrigation with watering-cans and by filling dug-in porous pots (pitcher irrigation) from where the water enters the soil by capillary suction.

The 96% surface irrigation knows the following methods of spreading the water over the field after it has been admitted through the inlet [3] :

  • spate irrigation, which may occur in hilly regions in dry zones where small rivers produce spate floods; ditches and bunds are built to guide the water to the fields to be irrigated; the number of fields irrigated at each flood event depends on the duration and intensity of the flood
  • flood-plain irrigation, which may occur in dry zones in larger river plains, where the river has high discharges during a short season only; bunds are constructed to retain the river floods and the lands are being planted to crops when the floods recede (flood recession cropping)
  • border-strip irrigation, in which the water moves over a graded strip of land with a mild slope and the water infiltrates into the soil while the wetting front advances; borders are made along the strip to prevent the water of spreading out to neighboring fields
  • level-basin irrigation, in which the water is set up on the soil surface quickly on leveled plots and given time to infiltrate; the basins are surrounded by borders to retain the water
  • furrow irrigation, in which the water moves over the field in furrows between ridges on which the crop is planted; the water infiltrates into the soil form the furrows; the furrows can be made both in sloping and flat land
Terraced rice fields in Yunnan province, China.
Terraced rice fields in Yunnan province, China.

The first four forms of irrigation come in the category of flood-irrigation, because the entire surface of the cropped area is wetted. With furrow irrigation, the surface of the ridges remain dry.

Basin irrigation can be used both in flat areas and sloping lands. In the latter case, terraces have to be made. The spectacular terraces pictured were made by hand, a tedious job, and they are an amazing world heritage.

Rice grown in the flooded basins of terraces (paddy fields) is often irrigated continuously whereby the water flows from one field to the other, making sure that the rice plants remain submerged. The main reason of the submergence is weed control, but the rice needs to be of a variety that tolerates or even prefers to grow in water.

Areal growth

From 1955 to 1975 the annual growth of the irrigated area was almost 3% [4] . From 1970 to 1982 the growth rate was some 2% per year, and from 1983 to 1994 about 1.3% per year. The growth rate of irrigated area is decreasing.

The following table, taken from reference [5] , shows the irrigation development in the world between 1955 to 1983, distinguishing developed from developing countries:

1955   1983   Increase
106 ha      % of WT     106 ha     % of WT     106 ha      % of 1955
Developed countries   28 23 61 29 33 118
Developing countries   93 77 152 71 59 63
World total (WT)   121 100 213 100 92 76
India+Pakistan   33 27 55 26 22 67
China   31 26 45 21 14 45

The developed countries witnessed a relatively greater increase than the developing nations.

Water use

Irrigation schemes in the world use about 3500 km3 water per year, of which 74% is evaporated by the crops [4] . This is some 80% of all water used by mankind (4400 km3 per year).
The water used for irrigation is roughly 25% of the annually available water resources (4400 km3) and 9 % of all annual river discharges in the hydrological cycle.
River discharges occur for the major part in regions with humid climates, far removed from the regions with (semi)arid climates, where irrigation water is most needed. Compared to the 8600 km3 of annual river discharge in the drier climates, the yearly water use for irrigation is 40%

irrigation    
use
all uses     usable  
resources    
total supply
Quantity of water in km3/year   3 500 4 400 14 000 40 000
Irrigation as a percentage (%)   100 80 25 9

Economical significance

The irrigated area occupies world wide about 16% of the total agricultural area, but the crop yield is roughly 40% of the total yield [4] . Hence, the productivity of irrigated land is 3.6 times that of unirrigated land. The monetary value of the yield of irrigated crops is some 6.6 times that of unirrigated crops. In irrigated land one grows crops with higher market values.

External links

References

  1. 1.0 1.1 International Commission on Irrigation and Drainage (ICID). Download PDF file : http://www.icid.org/imp_data.pdf
  2. R.J.Oosterbaan, 2004. Improvement of tidal irrigation, drainage and reclamation of salinized land under date palms in Abadan Island, Iran. 20 pp. Download from web page [1] or directly as PDF : [2]
  3. Wynn R. Walker, 2007. Irrigation: Surface. In: Stanley W. Trimble (Ed.), Encyclopedia of Water Science, Vol I, p. 678-683. On line: [3]
  4. 4.0 4.1 4.2 Bruce Sundquist, 2007. Chapter 1- Irrigation overview. In: The earth's carrying capacity, Some related reviews and analysis. On line: [4]
  5. R.J.Oosterbaan, 1989, Effectiveness and Social/Environmental Impacts of Irrigation Projects: a Review. In: Annual Report 1988, International Institute for Land Reclamation and Improvement (ILRI), Wageningen, The Netherlands, pp. 18 - 34 . Download from web page : [5] , or directly as PDF : [6]

See also

External Resources

Attachments

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