In 2000 year scientists from four Central Asian countries: Kazakhstan, Uzbekistan, Kyrgyzstan and Tajikistan decision about joint radio-ecological monitoring of the transboundary rivers of the Central Asia, project «NAVRUZ» was accepted. The project was carried out under aegis of Sandia National Laboratories of the USA. Collaborator of the «NAVRUZ» project there was Doctor Howard Passell who is as well collaborator of this project too. During project performance the contents of natural and technogenic radioactive nuclides (137Cs, 40K, decay series of 238U, 235U, 232Th) and toxic admixtures (U, Pb, Se, Sb, As, Be, etc.) was studied in objects of biosphere of the transboundary rivers of the Central Asia. Research has been continued within the limits of ISTC projects. Two projects have been executed in territory of Tajikistan it is Т-1000 and Т-1163. On a site of Sandia National Laboratories the database about the concentration of radioactive nuclides, toxic elements and other parameters of the basic rivers of the Central Asia has been made. Unfortunately, in connection with completion of projects the database was not updated in last five years.
The main goal of the proposed project is to conduct a radio-ecological, hydrological and geochemical investigation of the Syr-Darya River basin in Tajikistan. The current state of the Kayrakum water reservoir, of the Syr-Darya River and its lateral inflows will be studied. Bathymetric surveys will be made of the reservoir and river and the information used to construct topographic maps of the reservoir bottoms. Actual volumes of the Kayrakum water reservoir will be calculated. Soil, sediment, and water samples will be taken for chemical and radiochemical analysis to obtain information on the extent of contamination. The mechanism of sedimentation in the Kayrakum water reservoir will be studied and used to model the accumulation of sediments in this reservoir.
The Syr-Darya River is one of the main rivers of Central Asia. Originating in the mountains of Kyrgyzstan, it passes through Uzbekistan, Tajikistan and Kazakhstan. The Syr-Darya River strongly impacts all social and environmental aspects of the life of the population living in the river basin. The Syr-Darya River empties into the Aral Sea, but due to extensive agriculture and economy development of the Central Asian countries, the volume of water delivered to the Aral Sea reduced by more than an order of magnitude since the 1950s. The shrinking of the Aral Sea has become as a global problem and has led to a large environmental impact.
The water from the Syr-Darya River is used primarily for irrigation, industrial and domestic uses. Most of the water is used for irrigation. In the 20 century Central Asian countries faced with a demographic explosion: every 30-40 years, the population of these countries has doubled, and this trend is continuing. As a result of population growth the use of new land for agriculture and resettlement of the population is necessary. But the use of outdated technologies and irrigation systems leads to large of water loss and water pollution in the mainstream of the Syr Darya River.
At least two factors should be noted relating to the water problem in Central Asian today: 1) growing tension in relations between the neighbor Central Asian Countries in the management of regional water resources; 2) environmental changes caused by global warming, drying up of the Aral Sea, and as a result, the process of desertification.
Syr-Darya River moves a large amount of silt. The most part of the sludge is made during the floods on May and June (more than 60%). Kayrakum water reservoir began active silt accumulation since its filling with water started in1950. Most actively silt accumulation continued from 1950 to 1973. In 1973 the accumulation of water and, respectively, sludge started in new Toktogul and Andijan water reservoirs, located in the upstream. Since then, the main suppliers of silt in the Kayrakum reservoir became the side feeders of the Syr Darya. According to preliminary calculations, Kayrakum water reservoir accumulated more than 680 million tons of sludge. Washing of reservoir shore also contributed to the process of silting. There were observed sand dunes in the eastern part of the reservoir at the beginning of flooding. At present both dead and useful volumes of the reservoir was reduced.
Now destiny of Kayrakum reservoir often discussed, including the problem of cleaning from the silt. Taking into account the enormous mass of accumulated silt and poor budget of Tajikistan it is evident that clean-up of the reservoir will remain at the stage of discussions. In the meantime, the reservoir will accumulate silt, and its functionality will change. The reservoir was created for seasonal regulation of water consumption. It gradually was loses irrigation capacity. Now reservoir can regulate water flow monthly. Step-by-step it will go on weeklong regulation and derivation mode.
To determine the true volume of water reservoir it is necessary to survey the detailed bottom relief by Acoustic Doppler Profiler SonTek ADP. This will provide a three-dimensional model of the reservoir that makes possible to calculate the true value of the dead and the working volume of the reservoir.
It will be interesting to collect information about the water debit of the Syr-Darya River. This work must be performed in different seasons. Water of the river consumed for irrigation and urban use of Sughd region towns of Tajikistan. At the same time side feeders bring water into the Syr-Darya.
Water quality will be evaluated during the express-tests on some physical-chemical parameters such as temperature, salinity, conductivity, dissolved oxygen, pH, eH, turbidity, etc.
An important tool for monitoring of the process of silting could become a geochemical study of soil and bottom sediments around the reservoir and in the River. Study on distribution of macro and micro elements in soil/bottom sediments samples can provide information on place of silts origin, knowledge of macro and micro-elements transition in the system soil-water-bottom sediments and a number of other interesting factors. Geochemical study can also identify land areas and water reservoirs contaminated with heavy metals, inorganic toxins and radioactive elements. Such a study becomes particularly urgent, taking into account Chkalovsk uranium Mountain-metallurgical enterprises, as well as uranium factories located in the upstream of the Syr-Darya and accumulated more than 50 million tons of uranium production wastes.
In 1958 in territory tail depositories of Mayluu-Suu large technogenic crash was occur. As a result of crash in waters of Mayluu-Suu and further to Sir-Darya has arrived more than 100 thousand cubic meter of a waste of uranic production. A part of heavy metals, including thorium, molybdenum, selenium, arsenic and others could reach and fall out in a bottom deposit in the Kayrakum water conservation reservoir. In those days the Kayrakum water conservation reservoir was the unique filter the settler on a centre and supreme of watercourse of Sir-Darya.
Researches will help to understanding the differences between old (till 1973) and young bottom deposits. Till 1973 the large bulk of silt was formed in headwaters of inflows of Sir-Darya in Naryn and Karadarya, and after the beginning of accumulation of water in Toktogul and Andizhan water conservation reservoirs there was a jump of character of taken out silt. Lateral inflows of Sir-Darya and Naryn started play the role of basic supplier of silt, this factor must be reflected in the element composition of silt.
Analysis of concentration of elements in the beginning of the water conservation reservoir, along its shores and in its end will allow learning character of sedimentation of metals along its shores. Heavy metals will be mainly precipitated in the water conservation reservoir beginning. The water conservation reservoir to be in a dynamic regime, seasonally raises and decreases (to 7 meters) water line that obviously can lead to mixing and redistribution of bottom sediments. In the course of long accumulation of bottom sediments there could be a gravity separation of minerals. Heavy metals and minerals could appear in the bottom layer; in too time lights minerals could drift on a water traffic route.
Process of distribution of elements in soils strongly is influenced by geologic features of locality. Some elements can be found on the northern shore and in too time other elements can mainly founds on the southern shores.
The Physical-technical Institute (PhTI) named after S.U. Umarov of Academy of Sciences of the Republic of Tajikistan has sufficient experience in implementing projects of the International Science and Technology Center (ISTC) T-1000 and T-1163, to meet the objectives set in this project proposal. In particular, PhTI has the experience of using Ultrasonic Profiler SonTek ADP for high-precision measurements of water discharge, bottom relief of rivers and reservoirs, as well as experience of use the device Hydrolab for measuring physical-chemical parameters of water quality. In frame of regional experiment Navruz (Kazakhstan, Kyrgyzstan, Uzbekistan, Tajikistan and the United States) the Physical-Technical Institute monitored for over 10 years (1999-2009) radiation-ecological condition of the Transboundary Rivers and their main feeders. Objects of research were water samples, water suspensions, sediments, aquatic vegetation and coastal soils.
During of the project implementation is planned using of Ultrasonic Doppler Profiler SonTek ADP (made in USA) to measure the water discharge and the bottom reliefs. This method has the advantage of accuracy and efficiency in comparison with mechanical method used in the region now. Is planned to use modern equipment of Hydrolab Company (USA), which allows measuring about 10 physical-chemical water quality parameters directly from the research point, whereas the methods used now, need a sampling, their transportation and analysis in the laboratory. For the measurement of radioactive elements gamma-spectrometer, produced by “CANBERRA” Company, and for element analyses the x-ray fluorescent analyzer will be used.
Scope of Activities:
- Development of technical specifications, schedules and routes of expeditions.
- Prepare and conducting of field work.
- Radiometric and elemental analyses.
- Processing and data analysis.
- Scientific management of the project
Expected result:
- Identification of sites contaminated by radioactive isotopes, heavy and toxic metals and evaluation of the degree of pollution.
- Information on the distribution of radioactive isotopes and trace elements in soil samples, bottom sediments and water.
- Comparison of obtained results with the old data saved up on a site of Sandia National Laboratory and definition changing of pollution in the time.
- Generation of a 3D model of the Kayrakum water reservoir bottom relief and bottom profiles of Syr-Darya River in Tajikistan.
- Calculation of the actual volume of Kayrakum reservoir.
- Calculation of the seasonal water balance of the Syr-Darya River.
- Information on the mechanism of the sedimentation in the Kayrakum water reservoir, the origins of silt, and prediction of additional further silt accumulation in this reservoir.
