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So far, the figures given in the text refer to physical areas, which is not the case for irrigated crops which are measured in terms of harvested areas. The same plot can thus be counted several times if it is used for several crops in a year.
Regional distribution of water management methods
|Other cultivated wetlands/ valley bottoms||Flood
|Full or partial control||Spate
|'000 ha||'000 ha||'000 ha||'000 ha||'000 ha||'000 ha||'000 ha||as % of total||as %
|Northern||5 610||305||-||5 915||-||-||5 915||41.5||24.8|
|Sudano-||2 263||212||9||2 484||97||296||2 877||20.2||12.1|
|Gulf of||307||-||163||470||193||730||1 393||9.8||4.0|
|Islands||1 105||-||-||1 105||-||-||1 105||7.7||40.3|
|Southern||1 645||-||-||1 645||182||9||1 836||12.9||8.1|
|Total||11 477||517||180||12 174||1 046||1 038||14 258||100.0||9.9|
The figures on crops in water managed areas are very incomplete and do not allow the establishment of statistical tables by country showing the distribution of the major crops under water management in Africa. However, by using all the information available, information can be obtained on about 10.5 million hectares of crops. This figure corresponds to 75% of the physical area with water control and it can thus be considered as representative of the situation of crops in water managed lands on the continent and in the major regions. Results are summarized in Table 4, in which the different crops have been grouped in six major categories.
Regional distribution of main irrigated crops (partial information)
|Region||Rice||Other cereals||Vegetables||Fodder||Industrial crops||Arboriculture||Total|
|'000ha||'000ha||'000 ha||'000ha||'000 ha||'000 ha||'000 ha|
|Northern||538||2 221||423||1 207||80||459||4 928|
|Gulf of||993||52||168||-||21||6||1 240|
|Total||3 136||3 550||856||1 564||876||510||10 492|
The most widespread crop is rice, which alone represents more than one third of the water managed crop area. However, large discrepancies can be seen between the regions. Cultivated mostly in wetlands and valley bottoms, rice is the predominant crop in the humid zones of the Gulf of Guinea and Eastern Africa. It is also very developed on the plateaus of Madagascar. In the Northern and Southern regions, it represents only a small portion of the total crops under water management. Among the other cereals, wheat and maize are cultivated and irrigated mostly in the countries of the North (Egypt and Morocco) and in South Africa, Sudan and Somalia. Sorghum is cultivated in the Sudano-Sahelian region, mostly as recession cropping.
Vegetables (in the table, root and tuber crops have been included in this category) are present in all regions and almost every single country. On the whole, they represent about 8% of the cultivated areas under water management in Africa. In Algeria, Mauritania, Kenya, Burundi and Rwanda, they are in fact the most widespread crops under water management. Arboriculture, which represents 5 % of the total, is concentrated almost uniquely in the Northern region and is mostly composed of citrus. Industrial crops are located mostly in Sudan and in the countries of the Southern region (mostly cotton and oilseed crops). In this category, one also finds sugar cane, coffee, cocoa, oil and date palm, banana, tobacco and cut flowers. Apart from sugar cane, present in all regions except the Northern, the other crops are generally concentrated in a limited number of countries. Finally, the category grouping fodder crops and irrigated pastures, although it concerns only a very limited number of countries (concentrated in the Northern and the Southern regions) represents an important part of the cultures under water management (15%). Berseem, cultivated almost exclusively in Egypt, represents the most widespread irrigated crop in that country (1 million hectares). Other fodder crops or irrigated pasture are found principally in Morocco and in South Africa, with this last country having most of the irrigated pasture land (220 000 hectares).
Rate of use of equipped areas
One of the most frequently used indicators to assess the rate of intensification of the use of irrigated land is the cropping intensity, or the ratio between irrigated crops (including double and triple cropping) and areas equipped for irrigation. The survey showed, however, that this figure was almost never available or not reliable enough at country level. Another possible indicator is the rate of use of land equipped for irrigation, which is the part of the equipped areas actually used for production at least once in the year. This figure can vary significantly from one year to another, in particular where irrigation schemes have problems of water availability. In Table 9, the average rate of use of irrigated schemes for full and partial control is presented for each of the 30 countries where this information could be found. A regional analysis does not allow consideration of geographical trends in the variation of this value. This is probably due to the fact that it is a factor which is more related to socioeconomic conditions specific to individual countries rather than to criteria related to climate and geography.
For eight out of the thirty countries, the rate of use of equipped areas is recorded to be 100% and more than half of the countries report rates of use above 80%. Conversely, countries like Lesotho, Benin, Angola, Mozambique and Eritrea show rates of use below 50%, the causes of which, very diverse, are described in detail in the country profiles. Overall, the equipped areas of the 30 countries represent 8.3 million hectares. About 1.5 million hectares, or 18% of the equipped area, is not irrigated.
Environment and health
Environmental and health problems in Africa are as serious as in other developing regions. However, in Africa, very little quantitative information is available on this aspect. Salinization of irrigated lands is a serious problem in a number of irrigation projects, such as in Egypt, Namibia, Morocco, Ethiopia and Senegal. Although water pollution by agriculture is not very serious at the continental level, due to relatively low levels of fertilizer application, fertilizer and agrochemical pollution of water resources is reported in the Northern region. Health problems related to water development, particularly vector-borne diseases such as schistosomiasis and malaria, are serious throughout the continent. Approximately 90 to 95 percent of malaria-related deaths in the world are estimated to be in Africa. Again, country-specific data, linking irrigation development and human health, are lacking in many countries. Some of these environmental and health issues, depending on availability and reliability of data, are described in the country profiles.
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