Land Reclamation(redirected from Land reclaimed)
land reclamation[′land ‚rek·lə′mā·shən]
(in Russian, melioratsiia, from the Latin melioratio, “improvement”), the organizational and administrative and technical activities directed at the fundamental improvement of land. Land reclamation measures make the soil, hydrologic, and other natural conditions of vast regions more suitable for human economic activity. They help create the water, air, temperature, and nutrient conditions in the soil and the moisture, temperature, and air circulation conditions in the bottom layer of the atmosphere that are favorable to useful flora and fauna. Land reclamation promotes healthful conditions and improves the environment.
Because it gives greater stability to gross harvests and to agriculture in general, land reclamation is very important to this branch of the national economy. It makes it possible to use land resources more productively. Like mechanization and the introduction of chemicals, it is an important factor in increasing agricultural production and promoting scientific and technological progress in agriculture. It opens broad opportunities for increasing yields, establishing a stable feed base for animal husbandry, and bringing desert and swampy lands into use. The technical level of land reclamation is determined by the character of production relations, the level of development of the country’s productive forces, the zonal conditions of different territories, and economic goals.
Classification of lands and types of reclamation. The most common type of land reclamation involves land with unfavorable water conditions. In swamps and excessively wet lands reclamation is aimed at increasing aeration of the soil, improving its temperature, and stimulating the aerobic decay of organic matter. These goals are achieved by draining the land—that is, by removing excess water from the soil cover by means of ditches or pipes that run into streams or other bodies of water. In arid farming regions where there is little precipitation and the rate of evaporation is high, reserves of soil moisture are supplemented by water brought to the fields by artificial means (irrigation ditches or pipes). In deserts, semideserts, and steppes where animal husbandry has developed, pastures are flooded. In many cases this technique is combined with selective oasis irrigation (in deserts, for example). Where there is little water, management of water resources is improved by seasonal and long-term regulation of river flows, which may be accomplished by building a reservoir, by changing the flow within a basin, or by excavating a new channel. In places where rivers have insufficient carrying capacity their channels are regulated. Low-lying areas are improved by siltation. The set of measures designed to improve the unfavorable water conditions of a region is referred to as hydromechanical land reclamation.
Land with unfavorable chemical and physical characteristics is improved by agricultural technology and chemical reclamation measures. In steppe and desert regions saline soils and solonetzes containing an excess of salts, which are harmful to most agricultural crops, are improved by leaching, by applying gypsum, and by deep tillage. Chemical reclamation agents such as gypsum, calcium chloride, iron sulfate, and sulfuric acid help remove soda, the salt most toxic to agricultural plants, from the soil. Liming increases the fertility of acid soils. On sandy soils large quantities of organic fertilizers are applied, legumes are planted, and clay is spread. Sand is applied to heavy soils. The plowing horizon is made deeper on compacted soils. Uneven surfaces are graded.
The reclamation of lands subject to the harmful mechanical action of wind or water entails preventing the erosion of soils by surface water and wind and combating moving sands, landslides, and gullies. On eroded land, reclamation measures aim at reducing the amount and the speed of surface runoff, increasing the soil’s resistance to movement and to water and wind erosion, and establishing obstacles to soil movement and the action of water and wind. Hydraulic engineering methods are applied to achieve these ends. Man-made terraces, water retention ridges, and ditches are built to eliminate soil erosion on slopes, diversion canals are dug along the edges of gullies, hydraulic engineering structures are built to regulate flow and prevent gullying, and shelterbelts are planted.
Characteristics of land reclamation. The duration of its effect distinguishes land reclamation from other measures for improving the land and increasing soil fertility. Consequently, unlike procedures such as autumn tillage, harrowing, and continuous grading of fields, which must be repeated every year, land reclamation is referred to as “fundamental,” “long-term,” or “major” work. For example, drainage systems ensure the long-term removal of excess water from an area. Irrigation systems are long-term structures that supply the fields with the necessary volume of water and make it possible to water agricultural crops whenever necessary. Agricultural technology and shelterbelts also have a positive effect on the soil and on the natural conditions of the land for a long time.
Land reclamation is most effective when different methods are combined and their use is closely linked with the preparation of virgin lands for agricultural use, the improvement of natural pastures, and farming methods. Taken together, all of these activities constitute an integral set of measures to improve the natural conditions of the land. On land requiring drainage, optimal soil moisture conditions are best ensured by two-way regulation—that is, by systems that remove water during the heavy spring rains and supply water during the dry season, thus providing both drainage and irrigation. Where irrigation is necessary, a collection and drainage network is usually built at the same time as the irrigation network, in order to prevent an excessive rise of the water table and possible salinization of the soil. Drained acid soils are limed. Land reclamation must be combined with the correct development and agricultural use of the land (crop rotation, selection of crops and varieties, and cultivation technology, for example).
Especially in arid regions, the climate may be improved by land reclamation. Owing to the evaporation of moisture from the soil and vegetation, irrigation increases the humidity of the layer of air near the ground. This, in turn, reduces the temperature and mitigates the effect of droughts.
Currently, most reclamation projects encompass tens and hundreds of thousands of hectares (ha). When vast areas such as these are involved, it becomes more important to make a scientifically sound choice of reclamation measures that will not have negative effects on nature and natural resources. For example, if an area’s irrigation system is incorrectly designed, the soil may be salinized or eroded, and marshes may develop. Improper drainage may make the land under forests, meadows, and other agricultural lands too dry. The creation of reservoirs without regard for groundwater conditions may cause the water table to rise and may result in the development of marshy lands and the deterioration of sanitary conditions. Where the rules of land reclamation are not followed, rivers and bodies of water become polluted, fish die, and fishing becomes less profitable. Before a land reclamation plan is drawn up, the area is surveyed. Topo-graphicgeodetic, geological, hydrogeological, soil, geobotanical, climatologic, and other studies are included in the survey. Theories on the biosphere, biological communities, and conservation are of enormous practical importance in planning land reclamation.
Land reclamation requires significant capital expenditures. However, these are repaid in a few years by the increase in the economic fertility of the improved lands—that is, by the rise in their productivity. In the USSR, for example, the yield of cereal crops on irrigated lands is 1.5–2 or more times higher than on nonirrigated lands, and the alfalfa yield, 4–5 times greater. Liming increases the yield of grain by an average of 3–4 quintals per ha, potatoes by 15 quintals, and sugar beets by 60. Land reclamation has a favorable effect on the efficiency of agricultural production. The productivity and profitability of agriculture rise, as do output and income per unit of labor input and per ha, owing to intensive crops, increased yield, and repeated plantings. The income from farming irrigated and drained lands is significantly higher than the income from farming unimproved lands.
Land reclamation abroad. Land reclamation originated several millennia ago. Considerable areas were irrigated in Mesopotamia, ancient Egypt, and India from around 5000 to 3000 B.C. Drainage was also developed in these countries. Land reclamation measures were implemented in China (irrigation, drainage, siltation, and river control), Korea, Algeria, the Arabian Peninsula, and Central Africa before the Common Era. In some countries land reclamation declined temporarily during certain periods, and improvement structures were destroyed and lands abandoned. At the turn of the 19th century there were 8 million ha of irrigated lands in the world. Large-scale irrigation facilities were built in India, Egypt, the western USA, and Italy during the 19th century. By the beginning of the 20th century there were 48 million ha of irrigated land and about 20 million ha of drained land in the world.
During the 20th century land reclamation measures have been characteristic of agricultural development throughout the world. There were about 121 million ha of irrigated land in the world during the 1950’s, and by 1972, more than 225 million. The largest irrigated areas are in Asia (more than 150 million ha, not counting the USSR). In China there are 74 million ha of irrigated land (67.7 percent of the cultivated land), in India, 37.6 million ha (27.3 percent); in Pakistan, 11.97 million ha (41.6 percent); in Iraq, 4 million ha (53.4 percent); and in Japan, 3.4 million ha (56.6 percent). With Soviet technical assistance irrigation is developing in Afghanistan, where 813,000 ha (10.46 percent of the cultivated land) are now irrigated. The Jalalabad irrigation system, which will supply water to 31,000 ha, and the Sardeh system, which will irrigate 19,000 ha, are under construction, and a plan has been drawn up for the irrigation of 330,000 ha in the northern regions.
In the Americas, 28 million ha are irrigated: 19.7 million ha in the USA (20.3 percent), 4 million ha in Mexico (22 percent), 1.3 million ha in Chile (46.2 percent), 1.15 million ha in Argentina (4 percent), 1.08 million ha in Peru (5.5 percent), and 627,000 ha in Canada (2.5 percent). In the USA the Franklin D. Roosevelt Reservoir was built under a plan for the Columbia Basin. Its waters irrigate 200,000 ha and will make possible the expansion of irrigated land to 400,000 ha. Canada is building an irrigation system that will draw water from the Saskatchewan River and will ensure the irrigation of 200,000 ha. In Mexico a reservoir with a volume of 13 billion cu m is being built on the Grijalva River to irrigate 500,000 ha, and on the Fuerte River irrigation systems that water 250,000 ha have been built.
About 7 million ha are irrigated in Africa: 2.9 million ha in Egypt (the entire cultivated area), not counting 126,000 additional ha under development near the Aswan Reservoir; 2.5 million ha in the Sudan (11.1 percent); 760,000 ha in Tunisia (11.8 percent); and 500,000 ha in Syria (16.2 percent). In Europe irrigation has developed primarily in the Mediterranean countries. In Italy, 3.15 million ha are irrigated (11.4 percent). In Spain, 2.3 million ha (11.4 percent) are irrigated, and the construction of irrigation systems for 1.2 million additional ha is planned. Major irrigation systems are under construction in Bulgaria, where 1 million ha (21 percent) are already irrigated. In France 2.5 million ha (12.5 percent) are irrigated, and a plan has been developed to irrigate 240,000 ha in the lower Provence and lower Languedoc basins. Irrigated lands occupy 1.27 million ha in Australia (9.1 percent), but the scarcity of water inhibits the development of land reclamation.
Land reclamation by drainage is most highly developed in the USA, Canada, India, Hungary, Poland, Japan, Great Britain, and the Netherlands. As of 1971 there were more than 100 million ha of drained lands in the world. A number of countries, including the USA, the Federal Republic of Germany, France, Czechoslovakia, and Poland, use agricultural technology and chemical methods of land reclamation and plant shelterbelts.
The USSR.HISTORY. Land reclamation originated in very ancient times on Soviet territory (Central Asia and Transcaucasia). In many regions of Turkmenia, Uzbekistan, and Armenia archaeologists have found the ruins of irrigation systems dating from 4000–2000 B.C. Various crops were planted on irrigated lands in the lower reaches of the Syr Darya and Amu Darya beginning in the eighth-seventh centuries B.C.
In European Russia in ancient times there were a few isolated attempts to drain swampy lands in Novgorod, Vladimir, Moscow, and other principalities, but organized land reclamation work dates from the early 18th century, when land was drained in connection with the building of St. Petersburg and the development of the shores of the Gulf of Finland by Peter I. Land reclamation was done on a small scale by individual pomeshchiki (landlords), but the reclamation of peasant lands became possible only after the abolition of serfdom in 1861. By the beginning of the 20th century there were 3.8 million ha of irrigated land and 2.5 million ha of drained land in Russia, and by 1917, 4.1 million ha and 3.2 million ha, respectively.
After the October Revolution of 1917 new prospects for organized land reclamation opened. In May 1918, V. I. Lenin signed a decree appropriating 50 million rubles for irrigation in Turkestan. The great importance of improving peasant lands was noted in the resolution of the Eighth Party Congress (1919) on Lenin’s report and in the GOELRO plan. The development of land reclamation in the USSR began in the first five-year plan (1929–32). By 1941 the area of improved lands was more than 11.8 million ha. Between 1945 and 1965 old improvement systems were restored and partially modernized, and new ones were built near the Volga-Don, Kuban’-Egorlyk, and Terek-Kuma canals, in the Vakhsh and Gissar valleys, on the Barabinskaia Steppe (Western Siberia), and in Estonia, Latvia, and Lithuania.
CONTEMPORARY CONDITIONS. The May 1966 Plenum of the Central Committee of the CPSU played a special role in the development of land reclamation in the USSR. After the plenum, land reclamation was begun on vast areas (for example the Golodnaia and Karshinskaia steppes, the lands along the Northern Crimea and Karakumy canals, the Kakhovka irrigation system on the Dnieper, the nonchernozem zone of the European RSFSR, the Baltic region, and Western Siberia). By 1971 the area of irrigated land reached 11.1 million ha, and that of drained lands, 10.2 million ha. More than 22 million ha were limed between 1966 and 1970. All the rice produced in the USSR (1,279,000 tons in 1970, or almost 2.5 times as much as in 1965), as well as all the cotton, is raised on reclaimed lands, as are more than 30 percent of the vegetables and a significant percentage of the grapes, fodder crops, and sugar beets. More cereal crops, including winter wheat and corn, are being planted on irrigated and drained lands. In 1971 cereal crops occupied 3.9 million ha of improved land.
Under the ninth five-year plan (1971–75) the expansion of irrigated and drained lands and the improvement of meadows, pastures, and other agricultural lands continued. A great deal of work was done to increase the supply of water to the land, and the reconstruction of existing irrigation systems was basically completed. In 1971–72 about 1 million ha were brought under irrigation, and 1.2 million ha were drained. For the first time major regions of irrigated cereal crops (primarily wheat) are being established in the Ukraine, the Northern Caucasus, and the Volga Region. The construction of rice cultivation systems in the Kuban’, in Astrakhan and Rostov oblasts, in Uzbekistan, and in the Kara-Kalpak ASSR will make it possible to increase rice production significantly. (In 1972 the rice harvest was 1,647,000 tons.) One of the main challenges is the further development of irrigated farming in the cotton-growing regions (the Karshinskaia, Sherabadskaia, and Golodnaia steppes, the Karakumy Canal zone, and the Fergana Valley). Drained lands are located chiefly in the Baltic region, the Poles’e in the Ukraine and Byelorussia, the Meshchera Lowlands in the central European USSR, the Colchis depression in Georgia, and the Amur Valley in the Far East.
Land reclamation requires heavy construction work, especially earth moving. Powerful bulldozers, excavators, scrapers, continuous-operation digging machines, and concrete pourers are used at land improvement sites. In the USSR a large-scale base has been established in the construction industry for land reclamation work, in particular, plants for the production of reinforced-concrete goods (for example, slabs for canal facings, chutes, pipes, and elements of hydraulic engineering structures). Increasingly, new building materials are being used, including plastics (polyethylene drainage pipes and polyethylene film for antifiltration screens in canals and reservoirs).
Land reclamation science. Until the 1890’s scientific work in land reclamation was done by individuals, but after the drought of 1891 the state paid greater attention to land reclamation. From 1894 to 1900 an expedition under the direction of V. V. Dokuchaev developed a system of measures to improve agriculture and, in particular, to change water conditions in the southern part of the country (the southern Ukraine, the Volga Region, the Crimea, and the Caucasus). Dokuchaev’s work laid the foundation for land reclamation science in Russia. Between 1907 and 1916 the number of experimental stations specializing in irrigation farming and in bringing marshes under cultivation became more numerous in various regions of the country. Special scientific research organizations were set up primarily to take inventories of water resources and establish norms and methods for using them. (In 1910 a hydrometrical organization was founded, and in 1912, a hydromodular organization.)
Under Soviet power a network of planning and research institutes for land reclamation has been organized. Among these organizations are the A. N. Kostiakov All-Union Institute of Hydraulic Engineering and Land Reclamation, the Byelorussian Scientific Research Institute of Land Reclamation and Water Resources, the Ukrainian Scientific Research Institute of Hydraulic Engineering and Land Reclamation, the Northern Scientific Research Institute of Hydraulic Engineering and Land Reclamation, the Southern Scientific Research Institute of Hydraulic Engineering and Land Reclamation, and the Georgian Scientific Research Institute of Hydraulic Engineering and Land Reclamation.
Scientific research in land reclamation is also done at the Institute of Geography of the Academy of Sciences of the USSR, the Soil Institute, the Institute of Water Problems, the republic academies of sciences, and land improvement experimental stations. Methodological work is done by the section of hydraulic engineering and land reclamation of the V. I. Lenin All-Union Academy of Agricultural Sciences. Important work in land reclamation science has been done by A. N. Kostiakov, A. A. Cherkasov, S. K. Kondrashev, A. N. Askochenskii, S. F. Aver’-ianov, V. A. Kovda, B. A. Shumakov, K. K. Gedroits, I. I. Antipov-Karataev, G. N. Vysotskii, and L. P. Rozov.
The results of large-scale planning and surveying and scientific research are summarized in the Master Plan for the Comprehensive Use of the Water and Land Resources of the USSR (completed in 1970), which includes the Master Plan for the Development of Land Reclamation Until 1985 and a prognosis for the period through the year 2000. In the future the principal task of land reclamation science will be to develop methods of controlling the natural interactions of soil, water, the atmosphere, and plants. The USSR participates in the work of the International Commission on Irrigation and Drainage, which collects, analyzes, and summarizes data on the development of reclamation throughout the world and arranges exchanges of information. The USSR also takes part in the work of the Committee on Water Problems of the UN Economic Commission for Europe, the Regional Conference on Water Resources and Development of the UN Economic Commission for Asia and the Far East, and other organizations.
Since 1949 the theoretical and practical journal Gidrotekhnika i Melioratsiia (Hydraulic Engineering and Land Reclamation) has been published in the Soviet Union. Land reclamation specialists are trained at land reclamation (water and land reclamation) institutes and technicums and in the water and land reclamation departments of agricultural institutions of higher education.
REFERENCESRozov, L. P. Meliorativnoe pochvovedenie, 2nd ed. Moscow, 1956.
Cherkasov, A. A. Melioratsiia i seVskokhoziaistvennoe vodosnabzhenie, 4th ed. Moscow, 1958.
Kostiakov, A. N. Osnovy melioratsii, 6th ed. Moscow, 1960.
Shumakov, B. A. Oroshenie v zasushlivoi zone Evropeiskoi chasti SSSR. Moscow, 1969.
Shubladze, K. K. Melioratsiia zemel’. Moscow, 1970.
F. N. BONCHKOVSKII