Natural and economic conditions of reclamation developments

The USSR territory is characterized by different natural conditions: in the north and north-east vast areas are under tundra and taiga where long snowy winter is changed by short, cool, often rainy summer.

The south-eastern part of the country, involving some regions of the Transcaucasus, Middle Asia and the southern part of the Kazakh SSR, is located in the desert zone. This zone is characterised by an insignificant amount of rainfall (from 50 to 200 mm) that mainly occurs during non-vegetation period. Effective agricultural practice in this arid and hot zone, with the exception of some mountainous regions is impossible without irrigation. Large areas of sandy deserts and semideserts (over 300 million hectares) are used under seasonal pastures and need water.

In the south, mainly, on the coast of the Black and Caspian Seas there are some regions characterized by subtropical humid climate favourable for cultivation of citrus and tea. These regions need partial drainage.

Among these extreme climate zones there are some other intermediate climatic zones occupying about the same area and having their own economic features.

In the north, immediately in the region of tundra and taiga there starts the zone of excessive humidity, where the amount of rainfall is much higher than evaporation and transpiration of the vegetation cover. Heavy flow of rivers running to the north is formed in this zone. Besides, there is a great number of lakes and swamps here. The total area of swamps, excluding swamps in the very northern regions, exceeds 70 million hectares.

Drainage works required in this zone are mainly carried out in the Byelorussian Soviet Socialist Republic, Baltic Republics, in the north of the Ukraine, in the north-western and central regions of the Russian Soviet Federative Socialist Republic and in Siberia. The soils of this zone are rather poor and effective farming here requires not only drainage but such measures as stone removal, bush cutting and stubbing as well as liming of acidic soils.

Then follows the zone of foliage forests and forest steppe. This zone forms a rather narrow strip stretching throughout the whole country from the Carpathian Mountains and the coast of the Baltic Sea in the west up to the Pacific Ocean in the east. The zone is characterized by more moderate climate, i.e. less severe winter and warm, rather humid summer. In some seasons and years evaporation and transpiration of the vegetation cover may exceed the amount of rainfall but sometimes the latter predominates over evaporation. This is a zone of unsteady wetting and it is characterized (mainly in its southern part) by more fertile soils and favourable conditions for farming. However, some low bogged areas and river flood plains of this zone need drainage improvements, whereas some crops need irrigation during dry periods.

The next zone covering the south-western part of the country and extending up to the coasts of Lake Baikal is the steppe zone. This zone, like the one mentioned before, refers to the areas of unsteady wetting, however, the duration and frequency of droughts here are much higher. In spite of very fertile soils (chernozem) of this zone crop yields, especially grain crops, are low and unstable without irrigation. The probability of droughts in this zone varies from 23 per cent to 54 per cent, i. e. from 2 to 5 years out of 10 years. Therefore irrigation is necessary for effective cultivation of most agricultural crops.

Control of water and wind erosion as well as water-supply are of great importance here.

It is difficult to accurately show the boundaries of the above-given zones, since they are conventional. With a certain degree of approximation, in per cent of the total area of the country covering 22.5 million sq km, the areas of the zones can be shown as follows: polar deserts and tundras — 7.9, forests — 34.0, forest steppe and steppe — 13.9, semi-desert and desert — 13.1, moist subtropics — 0.1, mountains— 31.0.

Thus, the natural conditions of the USSR predetermine the necessity for wide-scale reclamation developments almost in all regions of the country and, particularly, for irrigation of vast dry areas which are more climatically favourable for cultivation of valuable crops. However, to solve this problem is difficult because of unfavourable distribution of water resources within the country. Though the Soviet Union has a world lead in the river flow and fresh-water resources (annual river

How makes up 4,340 thousand cu km), its water resources have uneven distribution and the regions which need water for farming more than any other regions are, as a rule, poorly provided with water. About 3/4 of the river flow is formed in the northern and eastern poorly inhabited regions and drained into the Arctic and Pacific Oceans.

EXERCISES

1. Визначте значеня виділени слів та словосполучень за схожістю з українськими словами:

taiga, tundra, Middle Asia, effective cultivation, subtropical climate, cultivation of citrus, climate zones, transpiration of the vegetation cover, Carpathian Mountains, the steppe zone, chernozem, polar deserts/

2. Випишіть парами слова-пароніми:

exception, severe, uneven, rule, approximate, mild, accurate, exclude, include, former, excessive, latter, insufficient, even.

3. Перекладіть слова, звертаючи увагу на словотворчі суфікси:

1) mountain, mountainous, mountaineer; 2) climate, climatic, climatically; 3) probable, probably, probability; 4) frequent, frequency, frequently; 5) approximate, approximately, approximation; 6) accurate, accurately, accuracy.