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1996 | Buch

Conclusions and Recommendations Kapitel lesen Erstes Kapitel lesen

The Inter-Relationship Between Irrigation, Drainage and the Environment in the Aral Sea Basin

herausgegeben von: Dr Marinus G. Bos

Verlag: Springer Netherlands

Buchreihe : NATO ASI Series

Enthalten in: Professional Book Archive

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Über dieses Buch

The irrigated area in the Aral Sea basin totals about 7. 5 million hectare. Part of the water supplied to this area is consumed by the irrigated crop; the remainder of the supplied water drains to the groundwater basin, to downstream depressions, or back to the rivers. During its use, however, this drained part of the water accumulates salts and chemicals. The disposal of this polluted water causes a variety of (environmental) problems. If the percentage consumed water of the total water supply to an irrigated area (the so-called overall consumed ratio) can be increased, less water needs to be drained. This alleviates part of the related (environmental) problems. Further, if the overall consumed ratio for the above 7. 5 million hectare is improved, less water needs to be diverted from the rivers. Hence, more water can flow towards the Aral Sea. As mentioned above, part of the non-consumed irrigation water drains to the groundwater basin. Commonly, the natural discharge capacity of this basin is insufficient to handle this imported water. As a result, the groundwater table rises towards the land surface causing waterlogging. In (semi-)arid zones this waterlogging triggers a soil salinity problem resulting to a significant reduction in crop yields. The artificial increase of the discharge capacity, and lowering of the groundwater table, solves the soil salinity problem.

Inhaltsverzeichnis

Frontmatter
Conclusions and Recommendations
Abstract
During the above NATO Advanced Research Workshop, Wageningen, 4 through 7 January 1995, the participants subscribed to the two main principles as accepted at the Conference of Heads of Central Asian States (11 January 1994), and also supported at the Donor’s Meeting in Paris (24 June 1994). They are:
  • It is necessary to work out measures for successful development of the Aral Sea Basin by making joint decisions related to socio-economical problems of the Region giving full consideration to environmental requirements.
  • Concentration of efforts on improvement of the ecological conditions near populated areas surrounding the Aral Sea, as well as the exposed bottom of the sea in these areas, creating a new stable ecological system in the basin with proper protective measures in the Amudarya and Syrdarya deltas.
Marinus G. Bos
The Interrelationship between Irrigation, Drainage and the Environment
Abstract
The intended effect of irrigation, a human intervention, on the natural environment is twofold: (i) it changes the land surface and the hydrology of the irrigated area; (ii) it affects the soil moisture-solute-groundwater regime of the irrigated area: water and solutes that would not be present naturally are brought to the area by means of canals. Two important non-intended consequences within the irrigated area are the risk of waterlogging and the risk of salinization. Waterlogging occurs when more water is entering the area than is discharged. The groundwater table will rise, and eventually can approach the soil surface, thereby rendering the topsoil unsuitable for root growth. Salinization occurs when more salts are entering the area than are leaving the area. Downstream of the irrigated area two further consequences are: the decreased river discharge, and the return flow of polluted water (both agricultural and urban).
M. G. Bos, R. van Aart
Environmental Benefits of Reducing Collector-Drain Runoff and Ways to Improve Irrigation Water Quality in the Rivers of the Aral Sea Basin
Abstract
Agriculture in the Central Asian Republics is suffering for several reasons, the main ones being the deficit of water for irrigation and the deterioration of water quality. Land reclamation and water management development in Uzbekistan, and in all the Central Asian Republics, were based on the availability of sufficient irrigation water of good quality in the years from 1960 to 1970. Sufficient supplies of water for irrigation created favourable conditions for regulation and maintenance of the soil-water-salt regime during these years, even with natural drainage. Improvement of irrigated lands, including those that were newly developed, was ensured by the installation of modern drainage systems (mostly subsurface horizontal and vertical drainage), and also by the annual maintenance of the irrigation systems and the collector-drains.
Vadim Berdjansky, Igor Zaks
Planning for Drainage Development in the Aral Sea Basin
Abstract
The Aral Sea basin is a closed drainage system encompassing about 690,000 km2. The basin is primarily within five countries of the former USSR (Kazakhstan, Kyrgyz Republic, Tajikistan, Turkmenistan, and Uzbekistan) whose rivers flow to the Aral Sea. The Sea is the ultimate disposal site for all runoff and discharges within the basin. Because of large developments for irrigation, increased population, and industrial intensification, the Aral Sea has shrunk since 1960 from 68,000 km2, to about 37,000 km2. and its level has dropped by about 14 m. The Aral Sea salinity level has increased nearly three times, to that of sea water, and serious environmental damage has been caused by increased loadings of agricultural chemicals, municipal wastewater, and industrial effluents in the basin.
Walter J. Ochs, Lambert K. Smedema
Impressions and Findings of a Study Tour to Karakalpakia in Central Asia
Abstract
The Aral Sea and the surrounding regions are experiencing extensive environmental degradation with major economic consequences in the five republics that share the basin — Kazakhstan, Uzbekistan, Kirghizia, Tajikistan and Turkmenistan. The area of the Aral Sea has been reduced by more than 40% and its volume by over 65% in 30 years. Total river flow into the Sea has dropped from 40 km3 in 1960 to less than 5 km3 in 1985. The salt content has increased from 10 g/l before 1960 to 28 g/l in 1989 and to 35 g/l in 1991.
Peter Wolff
Drainage Development in the Arid Zones of Central Asia
Abstract
Irrigation has been the foundation of agriculture in Central Asia since ancient times. The earliest proof of irrigated agriculture is found in sources dating from the fifth century B.C. The scale and size of the remains of old irrigation systems (canals, dams) are surprising. By the seventh century A.D., the irrigated area in Central Asia was more than 2 million ha, but most of this area had good natural drainage conditions, with groundwater outflow exceeding infiltration and inflow of groundwater. The local population practised irrigation in areas of unsatisfactory natural drainage (deltas, lowlands, alluvial plains). They used the so-called “dry drainage” system, in which cultivated lands occupied no more than 25% of the total irrigable area, and evaporation from the remaining area helped to maintain the groundwater balance. This method was connected with extensive land use in old Horesm, Bactria, and other lowland territories in Central Asia. We find remains of artificial drainage systems (“zaur”, open shallow collectors of 1.5 to 2.5m depth) only in plains immediately next to the foothills, where gravel-and-sand layers covered by clay and loam are susceptible to waterlogging and salinity under the pressure of artesian water.
Victor Dukhovny
Choice of Envelope Materials for the Rehabilitation of the Drainage Network in Uzbekistan
Abstract
About 2 million ha of the total 4.3 million ha of irrigated land in Uzbekistan have subsurface drainage systems. The total length of this drainage network exceeds 40,000 km. Almost half of the network requires rehabilitation because of overage materials and poor maintenance. The rate at which drainage systems are being rehabilitated should be increased significantly to prevent the loss of soil fertility due to salinisation.
Nikolay Goroshkov, Aurika Galustyan
The Construction and Effectiveness of Combined Drainage Systems
Abstract
Land drainage is becoming increasingly important owing to continued irrigation and because less promising soils were cultivated. This particularly in areas with potentially saline groundwater, facilitating salt accumulation in many irrigated soils. The water and salt balance in the top soil has become more complicated with the growing shortage of irrigation water in most arid countries and the pollution of water in their rivers. Therefore, there is a marked tendency to investment in improved performance of irrigation and drainage systems.
Pulat Umarov
The Contribution of Horizontal Subsurface Drainage to Solving the Aral Sea Economic and Environmental Problem
Abstract
There are 7.6 million hectares of irrigation development along the rivers Syr Darya and Amu Darya in Central Asia. Approximately one-half of this was developed since 1960. As a result, the volume of water reaching the land-locked Aral Sea has reduced dramatically, so that in only 30 years the level of the Aral Sea has fallen by 15 metres, the volume has decreased by 70%, and the salinity has increased so much that the once-productive fishery is now dead. The level of the Sea continues to drop at a rate of 0.3 m per year. Irrigation is estimated to consume 98 km3 of water per year (Bos 1995) or an average application rate of 1.24 m. Subsurface drainage has been installed in a large portion of the Aral Sea irrigation area but with widely spaced tubes, generally 800 m apart, installed at depths of 2.5 to 3.5 m.
David B. Chalcroft
Flow through Wetlands for Controlling Water Quality in Discharges from Irrigated Areas
Abstract
The shrinking and salinization of the Aral Sea as a result of the diversion of waters from the two rivers flowing into it, the Syr in the Northern, and the Amu in the Southern part of the Aral Sea, has, together with conversion for agriculture, caused the disappearance of most of the wetlands in the deltas of both rivers. (The term wetland is here used according to the widely accepted “Ramsar” definition. This definition describes a wetland as an area of marshland permanently or temporary wet or covered with water the depth of which does not exceed 6 meters.)
Jan C. Post Sr., Walter J. Ochs
Comparing Surface and Subsurface Drainage in Rice Irrigation Systems of Kazakhstan
Abstract
The rice irrigation systems of Kazakhstan are situated mostly in the basins of the rivers Syr Darya, lli, and Karatal. The rice fields cover more than 103 000 ha. In 1992, the average yield was 4.7 tons/ha. An increase in rice production depends on the modernization of existing irrigation systems, the reclamation of soil in the irrigated areas, and the rational utilization of water resources to protect them from pollution and over-exploitation.
A. A. Dzhumabekov
Environmental and Economic Benefit of Subsurface Horizontal Drainage Construction
Abstract
In Uzbekistan, as in other arid regions, land that is irrigated needs drainage. For this purpose subsurface horizontal drainage is widely used. Three methods of construction have been developed such as: trench method with narrow trench, with a wide trench and the trenchless method. Each of these methods influence to environmental condition of soils in a different manner. Most damage is caused by the wide trench method and the least by the narrow trench. For each of these methods the optimal construction cost can be calculated in a similar way. The costs are influenced by local engineering and geologic conditions. These conditions are divided into three groups, according to soil condition in vertical walls of trench as follows: stable and unstable above water conditions and unstable under water condition. In stable soils the most efficient and widely used method is the narrow trench, for which technology and equipment are available, including drainage machine with an active trencher.
Berdjansky Vladimir, Berdjansky Vadim
Improving Drainage Water Quality by Constructing Wetland Ecosystems in the Catchment Area of the Amu Darya, Aral Sea Region
Abstract
According to the definition of wetlands by the Ramsar Convention, wetlands can be defined as Ecosystems dominated by marshes, peatland and other ecotopes influenced by ground-and/or surface water. The water depth of open water must be within 6 meter.
Peter Veen, Anatoly Krutov
Irrigation Systems, Water Use Efficiency and Environmental Impacts
Abstract
Recently, there has been an increasing concern about the effective and efficient use of water for agriculture and water conservation in general. The promotion of effective water use and on farm water management was identified as an important contribution to the management strategy needed to address problems of water scarcity and practising intensive agriculture on environmentally sound grounds. Moreover, given the limitation to further expansion of irrigated land in most countries, a large part of the future food requirements will need to be covered from a more efficient and sustainable use of irrigation water (FAO 1993). Therefore, full intensification of agriculture in irrigated lands, while taking all possible precautions against the environmental problems that could follow this approach, is the challenge of the immediate future. This of course affects the needs and modes of future irrigated agriculture.
I. Papadopoulos
Measures to Increase the Efficiency of Irrigated Lands in Kyrgyzstan
Abstract
In January 1994 there was about 1.1 million ha irrigated land in Kyrgyzstan. This area is situated at elevations ranging from 500 m to 3300 m above sea level. Annual precipitation varies from 180 mm in the eastern Tien Shan mountains to 1000 mm in the Kyrgyz and Fergana mountains. In the most populous valleys, it ranges from 100 to 550 mm. Average temperatures in the valleys range from 28 °C in July to -18 °C in January. Absolute temperatures have an even wider range; from a high of 43 °C in summer to a low of -54 °C in winter.
Ivan Duyunov
The Use of Decision Support Systems in Water Management
Abstract
Water managers, those responsible for the management of surface water and groundwater in a certain area, are tasked with reconciling divergent needs for optimum socio-economic benefits. In the past, water management questions were largely one-dimensional. Farmers, for example, wanted more water for irrigation: how could more water be extracted from the river? However, we have learned in the last decades that the consequences of such a change should be taken into account and balance with the other water related issues. Is their still enough water left for the other functions such as navigation? Does the new distribution of water effects the downstream lakes or seas? How can silting-up of the water intake and irrigation canals be avoided? These last questions also illustrate the interaction between water and land. Increasingly, more is demanded and more often. Typically, “what if?” questions require multi-dimensional answers.
Jean-Pierre R. A. Sweerts, Peter C. G. Glas
Conjunctive Water Management for the Aral Sea Basin
Abstract
Arid and semi-arid regions of the world have one thing in common: a water shortage. In these areas, there is always more land than water. It is not possible to provide all the land in an arid basin with a water supply sufficient to grow crops, and at the same time provide for all existing historic and naturally established water uses. The Aral Sea Basin developed a natural equilibrium between precipitation and evapotranspiration during the 14 000 years (Micklin 1991) since the last filling of the Sea. In that long period there was sufficient water in the established equilibrium of the basin to provide for natural vegetation, with enough left over to make a sea. The recent introduction of irrigation into, and adjacent to, the Aral Sea Basin has resulted in a significant change in the natural hydrologic equilibrium of the area.
Lyman S. Willardson
Drainage Problems and Solutions in the San Joaquin Valley of California, U.S.A.
Abstract
The western part of the San Joaquin Valley is a fertile irrigated area of 907,000 hectares. The climate of the area is arid with irrigation water provided by surface flows from the adjacent Sierra Nevada Mountains, from federal and state water projects importing water from outside the valley and from a vast groundwater basin beneath the farm lands.
Joseph C. McGahan
The Use of Specific Environmental Publications for Local Capacity Building for Irrigation and Drainage Projects Within the Aral Sea Basin
Abstract
HR Wallingford, in conjunction with the International Commission on Irrigation and Drainage (ICID) and the United Nations Food and Agriculture Organisation (FAO), have been involved over the last few years in preparing an environmental checklist and a guide to environmental impact assessment (EIA) for use specifically in irrigation and drainage (l&D) work. The purpose of both these documents is to enable in-country professionals, with an l&D background, to systematically take environmental issues into account. The checklist is a tool to guide data collection and assist in scoping environmental studies, a process which is further elaborated in the guide. They both make it much easier for planners and managers to take environmental issues into account in an integrated manner when actions are first proposed. This paper sets out the procedures described in the existing documents and makes suggestions for how to use and adapt them to suit the Aral Sea Basin.
This paper proposes that a systematic format for assessing the environmental effects of actions at all levels would firstly minimise negative effects and maximise positive ones and, secondly, provide a means of collating information on environmental impacts and thereby improve environmental management. A nesting arrangement of procedures would have to be adopted to suit the scale of activity being undertaken. For, example, local drainage developments would require less data collection and fewer analyses than a regional irrigation management plan. The strength of the proposed approach is that standard forms and procedures could be usefully used by professionals who are not necessarily environmental experts. Very large projects funded by international aid would almost certainly require fullscale EIA’s as a condition of the loan. The guide to EIA in I&D, as developed, would be of value in these cases.
It has been stated repeatedly that the Aral sea crisis cannot be managed without extensive training and with most work being carried out by existing personnel. The Checklist, published in 1993, has proved of great value as a teaching tool as well as useful in the field. Training in its use is also a learning experience in understanding environmental issues. The development of documents for use in the Aral Sea basin, that are straightforward to use and written in a familiar language, would help to disseminate knowledge, contribute to the proposed monitoring programme and make use of available data at all levels. This would help local decisions to be environmentally sustainable locally and environmentally considerate for other users of the basin.
T. C. Dougherty
Irrigation and the Environment of the Aral Sea Basin
an annotated bibliography
Abstract
“Heavy withdrawals of irrigation water from the Syr and Amu, the Aral Sea’s two main tributaries, have for all practical purposes eliminated their spills and led to a sharp decrease in the level of the Sea. This and the disruption of ecological equilibrium in this immense region have had catastrophic consequences for both the inhabitants of the region and for the environment.”
L. A. Trouw
Metadaten
Titel
The Inter-Relationship Between Irrigation, Drainage and the Environment in the Aral Sea Basin
herausgegeben von
Dr Marinus G. Bos
Copyright-Jahr
1996
Verlag
Springer Netherlands
Electronic ISBN
978-94-009-1770-5
Print ISBN
978-94-010-7290-8
DOI
https://doi.org/10.1007/978-94-009-1770-5