| Country | Area (millions ha) | Area irrigated (millions ha) | Length of primary canals (km) | Length of secondary canals (km) | Comments |
|---|---|---|---|---|---|
| Afghanistan | 64.750 | 2.660 | 6 650 | 26 600 | About 70% of the irrigated area is irrigated by canals made by the farmers, with temporary inlets and poorly constructed channels suffering high seepage losses. Heavy silt load in all waters. After the civil war irrigation systems are likely to be in a state of disrepair and their reinstatement must come before fish production can be contemplated. |
| Algeria | 238.174 | 0.345 | 862 | 3 448 | Irrigable area limited to 300 000 ha. Farmers not in tune with irrigation techniques, and their education has been one of the biggest constraints to success. This same constraint would probably apply to the extension of fish production techniques. |
| Angola | 124.670 | 1.830 | 4 575 | 18 300 | Irrigation is still in the early stages of development. Particular attention is being given to the development of groundwater supplies. No immediate prospects for widespread fish production in canals. |
| Argentina | 279.569 | 1.70 | 4 250 | 17 000 | Most (97%) irrigation in arid and semi-arid regions in the west, using surface water conveyed through artificial conduits. Serious silting problems resulting from poor management. No proper control structures on a large number of schemes. Poor conditions for fish culture. |
| Australia | 768.400 | 1.615 | 4 037 | 16 148 | In south Australia irrigation water is supplied by uplift pumps through concrete-lined channels and pipelines. In Victoria open channels are used, as in western Australia where 30% are concrete-lined (in the south). In inland New South Wales, irrigation is by open channels. |
| Austria | 8.385 | 0.040 | 100 | 400 | Irrigation is mostly supplementary using sprinkler methods. About 90% of total irrigated area fed by sprinklers, which are necessarily supplied from pipes. Fish production potential poor. |
| Bangladesh | 14.200 | 2.098 | 5 245 | 20 980 | Much of the irrigated area is supplied from tubewells or small lowlift pumps, water being distributed on demand through quaternary channels. In 1975, 516 000 ha were irrigated in this manner, and more recently there have been extensive programmes for tubewell development. Thus up to a third, if not more, of the total irrigated area in Bangladesh is fed by locally sited tubewells. During the monsoon many irrigation canals are utilized for flood control, hence high flows. However, a large proportion of irrigation systems are suitable for fish production. |
| Botswana | 60.037 | 0.002 | 5.0 | 20 | Limited water resources, which are little developed at present. Fish production potential therefore low. |
| Brazil | 851.197 | 2.400 | 6 000 | 24 000 | Future development should bring extensive areas under irrigation. Irrigation methods vary between open canal systems and sprinkler systems, which are becoming increasingly common for coffee crops. |
| Bulgaria | 11.091 | 1.242 | 3 105 | 12 420 | 37% of irrigation water piped to feed sprinkler systems. Remainder by gravity systems. Extensive reconstruction programme of the fieldwater distribution network is underway to replace open canal network with subsurface pipes. |
| Cambodia | 18.104 | 0.090 | 225 | 900 | The majority of irrigation is for rice cultivation, which generally involves sheet flooding between August and December. |
| Canada | 997.618 | 0.775 | 1 937 | 7 748 | Approx. 60% of irrigated land in Alberta is irrigated by surface methods. Practically all irrigation in the humid areas of Canada is by sprinkler through pressurized systems. Seepage from canals is a general problem and canals are gradually being lined with concrete, asphalt, polythene or sulphurcrete. |
| Chile | 74.177 | 1.257 | 3 142 | 12 568 | Irrigation mainly by traditional methods, including spreading, irrigation furrows, check-flooding, and others. Modern technology is expensive in Chile and through a lack of education among farmers, is only slowly being adopted. Length of canals estimated in 1974 as 44 000 km. |
| China, People's Rep. of, | 956.5 | 44.653 | 111 632 | 446 528 | There are over 150 large irrigation systems in China with an area greater than 20 000 ha each. This represents immense fisheries potential and the Chinese already utilize canals for fish production. In the north extensive use has been made of ground water for irrigation. |
| Columbia | 113.891 | 0.470 | 1 175 | 4 700 | 10 000 ha of sprinkler irrigation in Bogota. Deforestation in watersheds is leading to increasing sedimentation problems in irrigation canals. |
| Costa Rica | 5.070 | 0.110 | 275 | 1 100 | Irrigation is on a small scale in Costa Rica. Sprinkler systems are used in some coffee plantations. |
| Cyprus | 0.925 | 0.031 | 77.5 | 310 | The effluent of two sewage plants is used for irrigation. Groundwater is a very important source of irrigation water. Pressurized methods are the most widely used. |
| Czechoslovakia | 12.787 | 0.257 | 642 | 2 568 | The majority of irrigation is by sprinkler methods. Fish production potential low. |
| Denmark | 4.307 | 0.405 | 1 012 | 4 048 | The small size of streams in Denmark negate any large-scale projects. Sprinkler irrigation fed by small pumps is the most common. |
| Dominican Rep. | 4.873 | 0.200 | 500 | 2 000 | Most recent canals are unlined and divert water directly from rivers. Canal capacities vary from 0.17 to 12 m/s. |
| Ecuador | 28.356 | 0.542 | 1 355 | 5 420 | In the mountainous regions irrigation is an ancient practice, but is limited to small-scale schemes because of the difficult terrain. The more modern developments constitute only a few hundred km of canals. |
| Egypt | 100.145 | 2.528 | 6 320 | 25 280 | The Nile is the only river in Egypt, and apart from boreholes and wells is the only water supply. This century has seen the gradual development of perrennial irrigation in the Nile valley, coinciding with the progressive enlargement of the Aswan dam. This reached a climax with the completion of the Aswan High Dam in 1970, when the entire cultivated area of Egypt was placed under perrennial irrigation. Major canals and district supply canals always supplied. Branch and sub-branch canals supplied on a rotation basis. Fish production potential high, and already the subject of field trials. |
| El Salvador | 2.104 | 0.112 | 280 | 1 120 | Few economically feasible reservoir sites. Most irrigation schemes supply only 10 – 200 ha, with the canals being only ditches. Some large schemes planned but implementation delayed. |
| Ethiopia | 122.190 | 0.162 | 405 | 1 620 | Irrigation schemes exist only in the Awash valley, for sugar cane and cotton crops Because of the subsistence nature of agriculture, most irrigation is by small-scale stream diversion. |
| Ghana | 23.854 | 0.008 | 20 | 80 | Some medium-sized irrigation schemes in operation, supplied by direct pumping from the Volta river. Problems with bilharzia and malaria due to the creation of impounded waters. Future potential is high. |
| Greece | 13.199 | 1.110 | 2 775 | 11 112 | 42% of the irrigated area is fed by sprinkler systems. The remaining 52% consists of open surface systems. Most irrigation canals are concrete-lined. |
| Guatemala | 10.889 | 0.077 | 192 | 768 | Fruit plantations developed medium-sized irrigation schemes. National schems are small ranging from under 500 ha to 4 500 ha. |
| Guyana | 21.497 | 0.127 | 317 | 1 268 | Over 40% of the irrigated area is under sugar plantations. The canals are hydraulically oversize, to allow the passage of barges to the factory. Flood irrigation is prevalent. Fish may be lost from the canal. |
| Honduras | 11.209 | 0.087 | 217 | 868 | Most irrigation is of fruit plantations by sprinkler systems. Some of these have main canals feeding pressurized pipes. Others are fed by direct pumping. Fish production potential low. |
| Hungary | 9.303 | 0.163 | 407 | 1 628 | Over 90% of irrigation is by sprinkler methods. Fish production potential low. |
| India | 328.759 | 44.350 | 110 875 | 443 500 | Most of the large irrigation schemes constructed in the last century are supplied directly from rivers, whilst of the modern schemes, a much higher proportion are fed from impounded waters. Most canal systems are unlined. Weed growth in canals is a serious problem. Fish production potential very high. |
| Indonesia | 190.435 | 7.260 | 18 150 | 72 600 | Most irrigation occurs on Java and Bali islands. Due to the rugged terrain small schemes tend to dominate, especially on Bali. Older schemes on Java were fed by diversion weirs, but new schemes tend to be based on reservoir storage. Fish production potential good. |
| Iran | 164.800 | 5.740 | 14 350 | 57 400 | Over 20% of the irrigated area is fed by Kanats, underground water courses. Large-scale schemes use open canal systems. A serious problem is the high seepage rate from the canals, which are largely unlined. |
| Iraq | 43.492 | 1.750 | 4 375 | 17 500 | Surface irrigation methods are used almost exclusively. Siltation and weed growth are problems in the canals. Water flow in the major rivers is highly seasonal, and many irrigation schemes take water directly from the rivers. |
| Israel | 2.077 | 2.750 | 6 875 | 27 500 | The irrigation system in Israel consists of an interconnected national network, and is highly organized. Irrigation water usage is constant throughout the year. Apart from the main elements of the National Water Carrier (NWC), irrigation is by pressurized methods. Fish production in canals already being investigated. |
| Italy | 30.123 | 3.020 | 7 550 | 30 200 | Italy has many medium-sized and some large irrigation projects, both of diversion and storage types. 23% of the irrigated surface is supplied with sprinkler irrigation, whilst surface irrigation accounted for the remaining 77%. |
| Jamaica | 1.099 | 0.034 | 85 | 340 | Most irrigation schemes serve sugar cane and fruit plantations, although sprinkler irrigation is used in some schemes, surface irrigation still prevails. |
| Japan | 37.700 | 32.950 | 82 375 | 329 500 | Japan has a great many irrigation schemes, which are largely surface systems due to the large areas of rice paddy. Fish production potential high. |
| Jordan | 9.774 | 0.043 | 107 | 428 | Length of irrigation canals (excluding farm channels) is 500 km. There is a national programme for the concrete-lining of canals to prevent seepage losses. Little potential for widespread fish production. |
| Kenya | 58.265 | 0.040 | 100 | 400 | The development of irrigation in Kenya is not far advanced, the largest schemes being under 200 000 ha. There are substantial areas under rice paddy. |
| Korea, Rep. of | 9.886 | 1.240 | 3 100 | 12 400 | Most irrigated land is under rice paddy, of which about 770 000 ha are fed by intermittant irrigation and 312 000 ha by continuous irrigation. There are a number of very large irrigation projects in the Republic of Korea, which feature extensive canal networks. Fish production potential good. |
| Laos | 23.680 | 0.120 | 300 | 1 200 | Irrigation projects are few in number and small to medium-sized. They are used for rice paddy irrigation. |
| Lebanon | 1.040 | 0.086 | 215 | 860 | Water resources heavily used, but inefficiently managed. Most irrigation projects centre on the Litani River. |
| Libya | 175.954 | 0.236 | 590 | 2 360 | All surface water resources in Libya are seasonal. Considerable ground water resources exist. Little development of these at present, and any future development likely to be to piped schemes. |
| Madagascar | 58.704 | 0.860 | 2 150 | 8 600 | Main crops are rice, sugar cane and cotton. Open irrigation systems prevail. Siltation in the canals is a major problem. |
| Malawi | 11.848 | 0.018 | 45 | 180 | No recent information on types of schemes. Main crop is sugar cane. |
| Malaysia | 32.975 | 0.336 | 840 | 3 360 | Main crop is rice. Irrigation mainly by open channels. Fish production potential good. |
| Mali | 124.000 | 0.195 | 487 | 1 948 | Main irrigated crop is rice. Irrigation systems characterised by open channels. |
| Malta | 0.032 | 0.001 | 2.5 | 10 | Most irrigation by piped groundwater. Almost no fish production potential. |
| Mexico | 197.255 | 4.900 | 12 250 | 49 000 | There are over 40 000 km of irrigation canals in Mexico, over 10 000 km being main canals, representing considerable potential for the development of fisheries. |
| Myanmar | 44.655 | 1.250 | 3 125 | 12 500 | Irrigation mainly by open systems, although some pressurised systems exist. |
| Nepal | 14.08 | 0.650 | 1 625 | 6 500 | Rice is the main irrigated crop, by open channel systems which are therefore compatible with fish production. |
| Netherlands | 3.719 | 0.535 | 1 337 | 5 350 | Irrigation in the Netherlands is only supplemental in nature. Distribution is therefore by pressurised systems and involves only small volumes of water. |
| New Zealand | 26.868 | 0.265 | 662 | 2 650 | Being a country enjoying a relatively high standard of living, there is unlikely to be any demand on the irrigation water resources for fish production. |
| Nicaragua | 13.000 | 0.083 | 207 | 830 | All irrigation schemes are private, and are associated with plantations (banana, sugar cane, etc.) and therefore the introduction and control of fish production schemes could be problematic. 25% use pressurised systems. |
| Nigeria | 92.377 | 0.850 | 2 125 | 8 500 | Limited water resources. Main irrigated crops are rice and wheat. |
| Pakistan | 80.394 | 16.040 | 40 100 | 160 400 | 50% of the irrigated area is fed by open canal systems. The remaining area is fed by tubewells, streams and seasonal canal systems. |
| Panama | 7.708 | 0.030 | 75 | 300 | Most irrigation is associated with private plantations. |
| Peru | 128.522 | 1.220 | 3 050 | 12 200 | Open canal systems predominate. |
| Philippines | 30.000 | 1.450 | 3 625 | 14 500 | Weed growth and siltation are significant problems, and lack of finance restricts canal maintenance in many cases. |
| Portugal | 9.196 | 0.632 | 1 580 | 6 320 | Most schemes are open systems, although new developments use pressurised systems. |
| Puerto Rico | 0.890 | 0.039 | 97 | 390 | Most important irrigated crop is sugar cane, fed by open channel systems. |
| Saudi Arabia | 214.969 | 0.420 | 1 050 | 4 200 | The majority of irrigation water is supplied from groundwater sources, either by pumping or from natural springs. Due to the high evaporation rate, much of this is distributed through pipes or underground channels. |
| South Africa | 122.104 | 1.128 | 2 820 | 11 280 | Whilst some major irrigation schemes designed to harness surface waters are planned or under construction, this resource is limited and most developments are likely to be based on groundwater utilization. Developments of this type usually use pressurized distribution systems. |
| Spain | 50.478 | 3.220 | 8 050 | 32 200 | Spain has a very well developed irrigation system, comprising a number of large gravity fed systems. |
| Sri Lanka | 6.561 | 0.607 | 1 517 | 6 070 | Rice forms the major irrigated crop. Sri Lanka has a number of large reservoir-based irrigation schemes. The potential for fish production in these systems lies largely in the reservoirs, but there must also be considerable potential for development of the irrigation channels. |
| Sudan | 250.581 | 1.860 | 4 650 | 18 600 | Irrigation water derives from two sources in Sudan, the Nile and the extensive aquifers which underlie most of the country. Gravity flow systems from the Nile will have the most potential for fish production, but water management practices may render only the main canals suitable. |
| Swaziland Syria | 1.736 18.518 | 0.062 0.652 | 155 1 630 | 620 6 520 | Sugar cane is the main irrigation crop, fed by gravity flow systems which may be suitable for fish production. The largest irrigation schemes are government built, those which are gravity fed having concrete-lined main and secondary canals. |
| Taiwan (Prov. of China | 3.598 | 0.496 | 1 240 | 4 960 | Rice paddy accounts for 57% of irrigated crops, by area. Fish production potential good. |
| Tanzania | 94.509 | 0.129 | 322 | 1 290 | Irrigation is still in the early stages of development in Tanzania and a significant proportion of land is irrigated by traditional means which are not suitable for fish culture. |
| Thailand | 51.400 | 3.900 | 9 750 | 39 000 | Thailand has many large irrigation schemes, of the gravity flow type, which present considerable potential for fish culture. |
| Tunisia | 16.316 | 0.260 | 650 | 2 600 | Most Tunisian waters are saline, and future developments plan to utilize sprinkler irrigation systems, in order to minimize overwatering. |
| Turkey | 77.798 | 2.170 | 5 425 | 21 700 | Much of the irrigation in Tukey is under State control, although the private sector accounts for a significant proportion of total irrigated area. Gravity systems predominate, often in association with sprinkler systems. |
| Uganda | 23.604 | 0.009 | 22.5 | 90 | Until recently irrigation in Uganda was confined to sugar and tea plantations. Pilot plants have been recently established to test sprinkler and surface irrigation of various crops. Sprinkler systems may well dominate irrigation methods in the future. |
| USSR | 2 240.220 | 20.467 | 51 167 | 204 670 | The Soviet Union has a very extensive irrigation network with thousands of kilometres of main and secondary canals which could be used for fish production. |
| USA | 936.336 | 18.102 | 45 255 | 181 020 | Whilst the USA has considerable irrigation resources, economic conditions are such, as in many industrialized nations, that they are unlikely to be utilized in the context of fish production - with the exception of sport fishing. |
| Venezuela | 91.205 | 0.326 | 815 | 3 260 | Venezuela has limited water resources, and a geographically concentrated population. Thus the potential for irrigation development, and associated fish production, is small. |
| Vietnam | 32.956 | 1.790 | 4 475 | 17 900 | The main irrigated crop is rice, which lends itself well to integrated fish production, both in the paddy and associated irrigation canals. |
| Yemen | 52.797 | 0.309 | 772 | 3 090 | Traditionally flood irrigation is practised. This is seasonal and relatively little control can be exerted over the water resource. There is considerable potential for the development of groundwaters, but such developments do not integrate well with fish production. |
| Yugoslavia | 25.654 | 0.148 | 370 | 1 480 | About 35% of irrigated land is fed via pressurized systems, and the pace of irrigation development is slow. |
| Zambia | 75.261 | 0.020 | 50 | 200 | Irrigation development is at an early stage, and there is therefore little fisheries potential at present. |
| Zimbabwe | 39.076 | 0.180 | 450 | 1 800 | Pressurised systems supply 30% of irrigated land, and much of furrow irrigation is for plantation crops. Fish production potential low. |
Notes: Most of the information included in this table has been extracted from two texts: Framji et al. (1981) and FAO Production Yearbook 1988. Much of it is based on information supplied before 1981 and may therefore not be completely up to date.
The length of irrigation canals in each country has been calculated on the basis of 2.5 km of primary and 10 km of secondary canals per 1 000 ha. This is a commonly used approximation and is based on a standard 5 000 ha irrigation scheme. However these estimates must be used with some caution. Canal widths vary so much from scheme to scheme that it may have proved too misleading to calculate water area in primary and secondary canals from the date contained in this table.
The comments as to the potential for fish production in irrigation systems for particular countries, are very general and meant only as a rough guide. They represent the authors' interpretation of the information available to them.
The list of countries in this table is not exhaustive. Countries have been omitted mainly due to lack of information. A number of industrialized countries have also been omitted (although a representatie selection has been retained) on the grounds that canal-based fish production for food would not be of any significance, bearing in mind their relatively advanced economies.
