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Irrigation and International Water Agreements

Present State of Irrigation Development

Irrigated area:
It is said that the world’s irrigated area in 1996 was 263 million ha, and that 190 million ha, or 72% of the total irrigated area was in developing countries. When looking at the regional distribution, 175 million ha or two thirds of irrigated area are in Asia.

Irrigation ratio:
The world’s irrigation ratio (irrigated area / cropped area) is 17.3% and the ratio in developing countries is 23.5%. The irrigation ratio is also the highest at 35% in Asia, which includes four countries with particularly high irrigation ratio: China (irrigated area: 69 million ha, irrigation ratio: 50%), India (56 million ha, 33.2%), Pakistan (16 million ha, 77%) and Indonesia (8 million ha, 35%). The irrigated areas in these four countries account for more than half of the total irrigated area in the world, and about two thirds of the irrigated area in developing countries. If only the developing countries are taken into consideration, the irrigation ratio is high at 20 to 40% in Asia, North America, the Near East and North America, and it is quite low at 3 to 6% in Africa (the Sahara and southward) and South America.

Importance of irrigation:
Irrigation is indispensable for agricultural production in the world. This can be seen from the fact that 36% of the world’s agricultural production comes from irrigated farmland, the area of which accounts only for 17% of the total area of farmland, and also from the fact that 60% of grain production in developing countries comes from irrigated farmland.

Drainage and flood prevention:
Besides irrigation, drainage and flood prevention is also important for farmland conservation and crop protection; however, accurate statistical data are very scarce. According to an estimation made by Hikari Tsutsui, the area of farmland provided with facilities for drainage and flood prevention is about 170 million ha, two thirds of which is in developed countries. Among countries with a high irrigation rate, farmland of 47 million ha in the US, 17 million ha in China, 13 million ha in India are said to be provided with such facilities.