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Authors: Janpïeisov R., Alimbaïev A.K., Minïat V.U., Smagulov T.A.
Title: Dïegradatsiïa pochv gornykh i pustynnykh pastbishch Kazakhstana (Soil degradation on mountain and desert grazing lands in Kazakhstan)
Publisher: Problïemy osvoïeniïa pustyn', N° 4, pp. 19-26, Ashkhabad
| Date: 1990 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata |
| Classification: | 2A1, 2A3, 2B2b, 3C4 |
| Region: | Kazakhstan |
| Summary: | In Kazakhstan, 180 million ha of pastures (66% of the territory of Kazakhstan) are used as grazing land for 36 million sheep, 9.5 million cows and 140,000 camels. There is significant land degradation and erosion as a result of disorganized overgrazing. Wind and water erosion have developed, and barkhans have formed. There is a detailed description in this document of changes in the qualities of various types of soil. A regional and typological analysis is presented, illustrated with a chart (p. 21) showing the indices of each degree of intensification of soil erosion in high, medium and low mountains and in sandy plains. The document discusses the resistance of diverse types of pasture to erosion, but no data is given on acceptable grazing capacity. The most intense erosion is found where herds join together for the winter, and in other locations were herds are concentrated. Degradation and deflation are recorded at 2-4 km from places of animal concentration, and degradation and the formation of barkhans occur along herd routes. |
Author: Kabulov S.K.
Title: Izmïenïeniïe ekosistïem iujnogo Priaral'ïa v svïazi s ponijïeniïem urovniïa Aral'skogo Morïa (Changes in ecosystems south of the Aral Sea resulting from the decrease in water level)
Publisher: Problïemy osvoïeniïa pustyn', N° 2, pp. 77-84, Ashkhabad
| Date: 1979 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | A3-4, 2B2e-f, 3C3, 4A4 |
| Region: | Aral Sea |
| Summary: | In 1977-1978 extensive
studies were undertaken on environmental changes,
particularly in the vegetation, in transections in the
Aral Sea area. There are 3 types of regional change:
|
Author: Kalïenov G.S.
Title: Printsipy sostavlïeniïa karty dïegradirovannoï rastitïel'nosti pustyn' Turkmïenistana i vozmozhnosti ïeïo praktishïeskogo primïenieniïa (Preparation of a map of the degradation of vegetation in Turkmenistan. Possibilities for practical application)
Publisher: Problïemy osvoïeniïa pustyn', N° 1, pp. 10-19, Ashkhabad
| Date: 1989 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 1C1, 1C4 (cartography), 2A3, 2B2c |
| Region: | Turkmenistan |
| Summary: | This map (1: 1,000,000) of
the degradation of vegetation in Turkmenistan has been
drawn up on the basis of changes in the structure of
vegetation and in the floristic composition resulting
from human activities. This map shows existing
vegetation. It was prepared with the aid of satellite
imagery and cartographic materials. The basis of the map
is degradation as shown in the natural vegetation.
Stripping the land of vegetation sets off the chain
reaction of erosion and deflation. The author concentrates on human-induced vegetation changes in deserts and semi-deserts were the vegetation has very slowly regenerated. In the Karakumy Desert, new vegetation covers dunes and takyrs after 20-30 years. It is estimated that climax biocenosis appears after 2000 years. The map records zones where degradation is concentrated and indicates the phases of vegetation degradation and regeneration. The article ends with proposals for the practical application of this map for the protection of vegetation. |
Author: Kaplin V.G. (ed.)
Title: Mïetody izuchïeniïa biogïeotsïenozov pïeschanoï pustyni (Methods of analyzing the biocenosis of sand deserts)
Publisher: Akadïemiïa Naouk Turkmïenskoï SSR (Academy of Sciences of Turkmenistan), Ylym, Ashkhabad, 180pp.
| Date: 1990 | Language: Russian |
| Available: | BiL Moscow, WGiSR UW Warsaw |
| Classification: | 2A3, 2B2c, 3C4, 3C2 |
| Region: | Central Asia, Turkmenistan, Karakumy Desert |
| Summary: | The issue of desertification is only marginally discussed in this collection of ten articles on methods of studying the flora and fauna of deserts. There is isolated information on land degradation dispersed throughout, in particular on pp. 14-16, and equally dispersed information on revegetalization. Overgrazing has been an important factor in land degradation since the 1930's. During the last few decades, this has brought about sand dune formation. This process is particularly intense near housing developments where trees and bushes have been cut for fuelwood. Studies have been carried out in the eastern part of the Karakumy Desert. Sands there cover 6,700 km2, or 23.1% of the total area (results obtained from analyzing satellite imagery), 70% of which are the result of human activity. On page 16, there is a discussion of the slow rate of revegetalization on dunes, a necessary process for the transition to the next stage of ecological evolution (the longest period, which lasts 100 years, is between psammophyte shrub formation on semi-stabilized dunes and that of sand acacia). |
Author: Khalmuratov P.
Title: Pïeschanyïe massivy plato Ustiurt i ikh ratsional'noïe ispol'zovaniïe (Sand massifs of the Ustyurt Plateau and their rational exploitation)
Publisher: Karakalpakstan, Nukus, 108 pp.
| Date: 1989 | Language: Russian |
| Available: | BiL Moscow |
| Classification: | 0, 2A3, 2B2b, 2B2e, 3C4, 4A2, 4A4 |
| Region: | Kazakhstan and Uzbekistan (Ustyurt Plateau) |
| Summary: | Description of the natural
environment in general and the plant cover in particular
on the Ustyurt Plateau (east of the Caspian Sea).
Pastoral potential is analyzed. Regional differences are
emphasized. The author does not describe the
desertification process and hardly mentions degradation.
He does however refer several times to the appearance of
new barkhans and of moving sands on heavily overgrazed
lands. He is opposed to prolonged grazing near wells and
describes an example of very advanced degradation near a
well where animals stayed throughout the year (Kuscha,
100 km2 of degraded land near one well, p.
45). In contrast, on neighbouring lands where animals grazed only in autumn and winter, the vegetation remained in good condition. |
Author: Kharin N.S.
Title: Aktual'nyïe problïemy bor'by s opustynivaniïem aridnykh tïerritoriï (Current issues in combating desertification in arid lands)
Publisher: Problïemy osvoïeniïa pustyn', N° 1, pp. 8-14, Ashkhabad
| Date: 1985 | Language: Russian |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 1A, 1D, 2A, 2B, 3C, 5 |
| Region: | Central Asia, Turkmenistan |
| Summary: | Each year in the world 50-70% of fertile lands degenerate into deserts. International organizations, in particular UNEP and FAO, have an important role in combating desertification. This text gives information on conferences and international declarations as well as definitions of desertification. Several factors in desertification are specified. In the Karakumy region, pastures degrade after 5-8 years of intense use. The regeneration of vegetation after second degree desertification takes 6 years; after the third degree is reached it takes 17 years. Water erosion (in the Kopet-dag foothills) and wind erosion (in the 13 million hectares of sand dunes in Turkmenistan) are also mentioned. In the V.I. Lenin (Karakumy) Canal zone, desertification processes have lessened. In the year 2000 in the entire country desertification will become less intense and, in some places, degradation will begin to disappear. Desertification is also caused by droughts. In Turkmenistan in every 10-year period there is an average of 3 low-yield years, 4 years of normal yields, and 3 high-yield years. |
Definition: Desertification is currently seen as the degradation of arid ecosystems resulting in a decrease in biological productivity. Factors of desertification are long-term climate changes, variations in short cycles (less than 10 years), droughts, a decline in the vegetation and an increase in the albedo.
Author: Kharina I.N.
Title: Ekspïertnaïa sistïema po opustynivaniiu na pïersonal'nom komp'iutïerïe (Using the PC computer in desertification analysis)
Publisher: Problïemy osvoïeniïa pustyn', N° 5, pp. 54-60, Ashkhabad
| Date: 1990 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata |
| Classification: | 1C4 (computer) |
| Region: | - |
| Summary: | General information on
deserts and on the advantages of computers. This text
presents a programme in the "prolog" language
which has been used to accumulate data on the condition
of vegetation in the Karakumy Desert. Data can be stored
on the type of desert, the dimensions of the area
examined, the number of shrubs, the area of grass
coverage, and the floristic composition (number of
species and names of plant associations). The computer
adapts all these data to categories of desertification. The author gives a practical example of dialogue with the IBM PC. |
Author: Kiïevskaïa R.K., Nïekrasova T.F., Mozhaïtsïeva N.F.
Title: Vliïaniïe aridizatsii na galogïeokhimichieskiïe protsïessy nizovïev Syrdarii (The Influence of aridification on salt formation processes in the Syr-Darya river valley)
Publisher: Problïemy osvoïeniïa pustyn', N° 6, pp. 23-28, Ashkhabad
| Date: 1980 | Language: Russian |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2A2, 2B2b, 3C3 |
| Region: | Kazakhstan (Syr-Darya river valley) |
| Summary: | A reduction in the stream flow of the Syr-Darya has caused widespread changes in the vegetation and soil in the river delta: the drying up of a large area of hydromorphic soils, deterioration of their geophysical features, and a decrease in real and potential fertility. In addition, the cessation of overflows (which formerly lasted several days) has caused intense salinization in non-irrigated soils, considerably modifying the salt formation on irrigated lands in the lower Syr-Darya basin. The author also examines the influence of aridification on salt formation processes which occur in the Syr-Darya delta. |
Conclusions:
1. The regulation of the stream flow of the Syr-Darya and the cessation of overflows has caused widespread salinization in hydromorphic soils and changed their salt content.
2. The accumulation of salt in the banks near the riverbed has extended towards moister soils in the Syr-Darya basin above the delta. In the driest part with the least favourable hydrogeological conditions, salt accumulation has spread to regions near canals, to the mouths of rivers, and to riverbanks with hydromorphic soils already showing a high level of salinization.
3. The development of irrigation and the ensuing processes of aridification, accompanied by the cessation of overflows, has brought about a change in the type of salt accumulating in large areas. Sulphato-chloric and chloric types have replaced sulphate and chloro-sulphate types.
Author: Kirsta B.I.
Title: Problïema Aral'skogo Mor'ïa i Karakumskiï Kanal' (Problems of the Aral Sea and the Karakumy Canal)
Publisher: Problïemy osvoïeniïa pustyn', N° 5, pp. 10-17, Ashkhabad
| Date: 1989 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2A4, 2B2f, 2D |
| Region: | Turkmenistan, Aral Sea |
| Summary: | For many years there has
been a reduction in the level of the Aral Sea, a
considerable deficit of water in the Syr-Darya and
Amu-Darya rivers and the mineralization of these waters. The author questions the current opinion that the reduction in the level of the sea is due to the construction of irrigation systems and the Karakumy Canal. Kirsta cites historical evidence, contemporary observations, and evaluations for the years 1956-1986 which show that the collection of water for irrigation is 18-24% of the total quantity of water coming from the lake, which is not very significant. At the same time, improvement projects do not decisively influence the intensification of mineralization in the water of the middle and lower streams of the Amu-Darya. However, the author stresses the need to modernize the canals in order to diminish water infiltration and evaporation. Kirsta also proposes economizing water. |
Authors: Knïazïeva L.A., Olovïannikova I.N. (eds.)
Title: Povyshïeniïe produktivnosti polopustynnykh zïemïel' sïevïernogo Prikaspiïa (Increase in the productivity of semi-arid lands north of the Caspian Sea)
Publisher: Naouka, Akadïemiïa Naouk SSSR (Academy of Sciences of the USSR), Moscow, 197 pp.
| Date: 1989 | Language: Russian |
| Available: | BiL Moscow, BiV Kiev |
| Classification: | 2B2h, 5C1, 5C2 |
| Region: | Russia (north of the Caspian Sea) |
| Summary: | Results of studies carried
out during the years 1970-1985 in the station of
Dzhanynbek north of the Caspian Sea, approximately 30 km
north of Lake Elban. The agricultural use of saline soils (which cover half of this region) is impossible without their restoration. Modern irrigation leads to salinization and waterlogging. The rise in the water table and soil salinization (up to 500 m from canals) are the result of irrigation projects of the last decade. The best results in desalinization can be obtained from tree plantation. An improvement in the hydrological situation is possible (as trees retain snow) from the planting of protective strips 10-20 m wide along canals. Forests are useful for biodrainage, soil desalinization and snow retention. Agricultural land use is possible without irrigation, with high, stable cereal yields. The productivity of the land depends on the location of the protective forest strips, the distance between the strips and the age of the trees. |
Author: Kolobov N.V., Murakaïeva S.A.
Title: Zasukhi na tïerritorii Tatarskoï ASSR (Droughts in the Tatar Autonomous Republic)
Publisher: Izdatïel'stvo Kazanskogo Univïersitïeta (University of Kazan), Kazan', 140 pp.
| Date: 1980 | Language: Russian |
| Available: | WGiSR UW Warsaw |
| Classification: | 3B, 4B |
| Region: | European Russia (Tatar Republic) |
| Summary: | This publication is about droughts - their frequency, their regularity and their relation to atmospheric circulation over Eurasia during the period from 1926 to 1975. A classification of droughts and a description of ensuing economic losses (particularly in cereal cultivation) are given. Although this work is concerned with problems close to desertification, desertification as such is not mentioned. |
Author: Kolodin M.B.
Title: Ispolzovaniïe i okhrana vodnykh rïesursov Srïednïeï Azii (The use and protection of water resources in Central Asia)
Publisher: Problïemy osvoïeniïa pustyn', N° 4, pp. 41-47, Ashkhabad
| Date: 1978 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2A4, 5D2a |
| Region: | Central Asia |
| Summary: | In the years 1913-1980,
water consumption in the entire Soviet Union increased
6-7 times, agriculture being the largest consumer. The most critical water deficits have been recorded in Central Asia and in the Aral Sea basin, leading researchers to study the possibility of diverting Siberian rivers. It has been calculated that 200 km3 of water per year could be supplied; the cost of transporting 1 km3 of water is hundreds of millions of roubles. A mathematical model for river diversion has been prepared. The project cannot be completed before the 21st century. The purification and desalinization of drainage water is also mentioned in this document. |
Author: Kopïekov C.B.
Title: Drïevnïeantropogïennyïe landshafty Prisarykamyshskoï dïelty Amudar'i (Landscapes past and present affected by human activities in the Prisarykamyshskaïa delta of the Amu-Darya)
Publisher: Problïemy osvoïeniïa pustyn', N° 2, pp. 33-39, Ashkhabad
| Date: 1984 | Language: Russian |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 1C2, 1C3, 2D, 3C2 |
| Region: | Turkmenistan, Uzbekistan |
| Summary: | This document analyzes the distribution and dating of soils affected by irrigation and human use during previous centuries. Current land use is also analyzed. The author finds that the youngest soils are the most useful. This historical study of soils covers the period from the 13th to 19th centuries. In some cases the same lands have been irrigated and cultivated during several different periods of history. When cultivation is interrupted, the lands transform into deserts (takyrs), sometimes overtaken by sand dunes. In the central Daoudan region, the irrational cutting of shrubs which retain sands on soils used for cultivation has caused these areas to change into moving dunes, and the soil with high agricultural utility to disappear. |
Authors: Korniïenko V.A., Kiïevskaïa P.K., Nïekrasova T.F., Mozhaïtsïeva N.F.
Title: Naouchnyïe osnovy ekologichïeskogo prognoza opustynivaniïa gidromorfnykh landshaftov (Ecological forecast for desertification on hydromorphic lands)
Publisher: Problïemy osvoïeniïa pustyn', N° 2, pp. 13-21, Ashkhabad
| Date: 1983 | Language: Russian |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 1C4 (phytogeography), 2A3, 2B2a, 4A2 |
| Region: | Aral Sea |
| Summary: | This text is concerned with
desertification in the Aral Sea region. In the plains of
the Amu-Darya, with an area of 10.4 million ha of
pastures and prairies, there is a decline in productivity
on 783,000 ha (1978). Along the Syr-Darya,
desertification affects an area of 6.2 million ha and
aridification touches 846,000 ha. On the part of the Aral
Sea region within Kazakhstan, there is salinization on an
area of 6,030 km2 of sandy plains. In 1960 in the Syr-Darya delta, 1,414,000 ha of land was covered with hydromorphic soils with grass and reed plant associations. This region, with a yield estimated at 10-50 q/ha, supplied 3.6 million tonnes of grasses for the production of straw and animal feed. By 1975, the productivity of aridified land decreased to 4.5 - 11 q/ha and that of decertified land to 2 q/ha maximum; animal feed production was no more than 800,000 tonnes. The authors present the succession of plant associations on drying lands: delta, plains reaching to the sea, watersheds. In most cases, 13-16 years after the cessation of the water supply, plant associations form which are typical of desert landscapes (takyrs, sand dunes). For each stage, information is given on the production of animal feed, on soil salinization, and occasionally on hydrological conditions. There is emphasis on the possibility of using information about plant succession in the economic planning of Kazakhstan. |
Author: Kotliakov V.M.
Title: The Aral Sea Basin. A Critical Environment Zone.
Publisher: Environment, vol. 33, N° 1, pp. 4-9 and 36-38
| Date: 1991 | Language: English |
| Available: | BiL Moscow, IG RAN Moscow |
| Classification: | 2A1-4, 2B2f, 2D, 3C3, 4A, 4C |
| Region: | Aral Sea |
| Summary: | From 1960 to 1989 the level of the Aral Sea declined from 53.3 to 39 metres, its area from 67.9 to 37.0 thousand km2, its volume decreased by three, and the volume of river water flowing into the sea by eight- from 40 to 5 km3. Before the decline in its level, the Aral Sea influenced the climate of the region within a 100-200 km perimeter. During the last two decades, the area of reed-covered plains regularly flooded by waters from the Amu-Darya has decreased from 550,000 to 20,000 ha and the yield from pastures has declined approximately 20%. In the last 15 years, cases of typhus have increased almost 30 times and cases of hepatitis 7 times. A significant number of babies are born underdeveloped and sickly, and the infant mortality rate is more than 50 per 1000. This article contains a general map of the Aral Sea region, showing rivers, canals and irrigated lands. |
Authors: Kovda V.A., Lobova E.V.
Title: Aridnyïe pochvy, ikh gïenïezis, gïeokhimiïa, ispol'zovaniïe (Soils of arid regions origins, geochemistry, utilization)
Publisher: Naouka (Academy of Sciences of the USSR), Moscow, 268 pp.
| Date: 1977 | Language: Russian (summary in English) |
| Available: | IG RAN Moscow, WGiSR UW Warsaw |
| Classification: | 0 (soils), 2A1, 3C2, 3C4 |
| Region: | Turkmenistan, Uzbekistan, Kazakhstan, Asia (Afghanistan, India, Mongolia), East Africa |
| Summary: | In this collection of 15
articles, 8 are concerned with the Soviet Union and the 7
others are general or are concerned with other regions.
The issue of desertification is treated superficially;
the concept does not even appear in the text. The
chemical characteristics of soils and their absorption
capacity are emphasized, as are agricultural management
and the use of various types of water. The authors point out the degradation of certain pastures in Uzbekistan due to poor grazing practices and to deforestation. There is an extensive analysis of the possibility of planting saxouls (Halaxylon aphyllum) which flourish in saline soil (p. 123). Overgrazing also leads to the activation of wind processes. In the Karakumy Canal region, barkhans have appeared where there were none in the 1940's. In 1962, in the central Fergana region, the steppes were ploughed and canals were filled with water; the sandy soil was to be seeded in the spring of the following year. However, by autumn the terrain had deteriorated into a sea of sand with barkhans (near Mazgïalana). |
Authors: Kurakova L.I., Milanova I.V.
Title: Antropogïennyie landshafty tropichïeskikh pustyn' (Tropical desert landscapes affected by human activities)
Publisher: Problïemy osvïeniïa pustyn', N° 5, pp. 3-9, Ashkhabad
| Date: 1973 | Language: Russian (summaries in English and Turkoman) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2A, 2B1, 3C |
| Region: | Africa, Asia (with the exception of Central Asia), Australia |
| Summary: | According to climatic
criteria, deserts cover 36% of the total land area of the
world; according to soil criteria, the figure is 43%. As
a result of the intense exploitation of the resources of
steppes and savannahs, more and more territory is
degenerating into desert. The principle factors are the
following: animal husbandry of herds too large for the
given area (especially in the case of goats),
deforestation by local populations to meet their needs in
wood, and soil salinity in irrigated regions. Examples
from various regions of the world are given: the Sahara,
Lake Turkana (in Kenya and Ethiopia, with an increase in
desert area of 10 km2 per year), Iran,
Rajasthan, Australia. Methods of combating the formation
of deserts are also discussed: rational irrigation,
installation of nomads in cooperatives specially created
for them. The authors identify three types of human activity influencing landscape: a) overgrazing as practiced by nomads, b) stationary animal production (Australian type), c) irrigated agriculture in oases. |
Authors: Kurbanov O.R., Arnagïel'dyïev A.
Title: Dinamika rïel'ïefa v zonïe vtoroï ochïerïedi Karakumskogo kanala (Dynamics of the relief in the second zone of the Karakumy Canal)
Publisher: Problïemy osvoïeniïa pustyn', N° 3, pp. 21-27, Ashkhabad
| Date: 1982 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2A1, 2B2c (Karakumy Canal), 3C4-5 |
| Region: | Turkmenistan |
| Summary: | This article discusses,
among other topics, the wind relief which is created
beside the Karakumy Canal. Ordinarily, sands and lands on
the canal banks become rapidly covered with vegetation,
but there are exceptions. Several factors are involved in
addition to human activity: soil composition, depth of
sands, the wind, etc. Local changes not connected to the Karakumy Canal occur near wells. A research mission in 1948-1949 found that there are barkhanized sands around wells in an area of 0.5 km in diameter. In the late 1970's satellite imagery showed the existence of over 60 patches of sand dunes around wells near the Murgab oasis and on the Yelchilïeska plain. The majority of these patches have a diameter of 1-3 km, others of 3-7 km, which proves the intensification of relief changes (resulting from human activity) in the Karakumy Canal region. Several schematic maps are included. |
Authors: Kurochkina L.I., Ishankulov M.C., Korniïenko
Title: O granitsakh vozdïeïstviïa snijïeniïa urovnïa Aralskogo Morïa naokruzhaiushchuïu srïedu (The limits of environmental effects caused by the reduction in level of the Aral Sea)
Publisher: Problïemy osvoïeniïa pustyn', N° 2, pp. 25-33, Ashkhabad
| Date: 1979 | Language: Russian (summary in English) |
| Available: | BiL Moscow, IG RAN Moscow, KR FAK Alma Ata, WGiSR UW Warsaw, UAM Poznan |
| Classification: | 2B2f, 2C, 4A4 |
| Region: | Aral Sea |
| Summary: | The decrease in the level of
the Aral Sea has activated the process of
desertification. In the Syr-Darya valley and in the lower
Syr-Darya basin, the strip of land affected indirectly by
the hydrological situation covers 100 km. The over-collection of water for projects during the years 1960 1971 caused the water table to lower 3 - 4.5 m and has brought on the emergence of salt, since drainage water was not washed by the river. The ecosystems of prairies and riverside forests over an area of 2.5 million ha have undergone intense degradation. The coastal zone of the sea (a belt 5 to 20 km wide), formerly underwater, is a land devoid of soil and vegetation, remaining under the influence of saline water. Wind activity affects the area. In the former coastal zone, 20 50 km wide, intense desertification processes are recorded. The third zone identified is composed of Eocene clays with an altitude of up to 80 m. It is characterized by the association of xerophyte, halophyte, and desert vegetation, and by the development of shrubs. The lowering of the water table and of the level of the sea has caused a decrease in the level of the erosion base. |