Naryn River Research Articles

Effects of projected climate change on the glacier and runoff generation in the Naryn River Basin, Central Asia

Climate change is a major environmental concern and the melting processes of the glaciers and snow-packs are sensitive to climate change. The ultimate effect of the future changes on the glacier and hydrology is unclear and poorly investigated for Central Asia. Here, we use results from the latest ensemble of climate models in combination with a glacier-enhanced Soil Water Assessment Tool (SWAT) hydrologic model to assess the hydrological impact of climate change in the Naryn River Basin, Central Asia. Results indicate that small glaciers suffer from larger relative area losses than large glaciers. Only 8% of the originally glaciated area for small glaciers will retain glaciers by 2100 for RCP8.5. The rate of area retreat for small glaciers (with an area <1 km(2)) will slow down for the period 2066-2095, while the glacier area shrinkage is projected to accelerate for large glaciers throughout the twenty-first century. In all cases, glaciers will recede but net glacier melt runoff will reach peak in about 2040. Decreases in future runoff are projected in combination with a negative change in precipitation, snowmelt and higher evapotranspiration. Glacier melt is mainly derived by future temperature changes, while the runoff and snowmelt component are determined by future precipitation. The timing of peak runoff is advancing about one month as a result of earlier snowmelt due to the warming temperature. Runoff is projected to increase during the spring and decrease for the summer season for the future periods. Thus water availability on the time will likely undergo significant changes. (C) 2015 Elsevier B.V. All rights reserved.

On the question of the interrelation between variations in crustal electrical conductivity and geodynamical processes

The behavior of the variations in the crustal electrical conductivity in a wide range of periods is studied from the data of magnetotelluric soundings (MTS) during the Kambarata experiment (a strong industrial explosion to construct the blast-fill dam on the Naryn river), as well as at Aksu, a stationary geophysical monitoring point. The concept of the interrelation between the stress-strain state of the medium and the change in the apparent electrical resistivity, which is based on the idea of the redistribution of mineralized solutions between the crack networks, is confirmed experimentally. A procedure of azimuthal monitoring is developed, which allowed us not only to identify the anomalous changes in the module and phase of apparent resistivity but also to establish the directions of their maximum increases and decreases (the axes of compression and tension). For 34 points of deep MTS in the territory of Central Tien Shan, the depth intervals in the upper crust that are most sensitive to the changes in the stress-strain state of the medium are established. The variations in the electrical conductivity are compared with the solar-lunar tidal impacts. It is shown that by analyzing the recorded time series, it is possible to recognize the characteristic signs of the changes in the stress-strain state of the medium that are caused by seismic events.

Creation of the dam for the No. 2 Kambaratinskaya HPP by large-scale blasting: analysis of planning experience and lessons learned

Results of complex instrument observations and video taping during large-scale blasts detonated for creation of the dam at the No. 2 Kambaratinskaya HPP on the Naryn River in the Kyrgyz Republic are analyzed. Tests of the energy effectiveness of the explosives are evaluated, characteristics of LSB manifestations in seismic and air waves are revealed, and the shaping and movement of the rock mass are examined. A methodological analysis of the planning and production of the LSB is given.

Geochemical features of Uranium isotopes in waters of the Toktogulsky reservoir

Proportions of water mix of different genesis influencing feeding ofrivers of the Toktogulsky reservoir were calculated basing on the results of study of uranium content and ratio of its even isotopes. Constancy of ratio of uranium isotopes in the waters of the Toktogulsky reservoir was shown, which can be used as a natural indicator during assessment of pollution of waters of the Naryn River basin by lower uranium tailing dumps.

Placement of the dam for the no. 2 kambaratinskaya HPP by large-scale blasting: some observations

Results of complex instrument observations of large-scale blasting during construction of the dam for the No. 2 Kambaratinskaya HPP on the Naryn River in the Republic of Kirgizia are analyzed. The purpose of these observations was: to determine the actual parameters of the seismic process, evaluate the effect of air and acoustic shock waves, and investigate the kinematics of the surface formed by the blast in its core region within the mass of fractured rocks.

Water ‘banking’ in Fergana valley aquifers—A solution to water allocation in the Syrdarya river basin?

The Syrdarya river is an example of a transboundary basin with contradictory water use requirements between its upstream and downstream parts. Since the winter of 1992–93, the operational regime of the upstream Toktogul reservoir on the Naryn river – the main tributary of the Syrdarya – has shifted from irrigation to hydropower generation mode. This significantly increased winter flow and reduced summer flow downstream of the reservoir. Consequently, excessive winter flow is diverted to the saline depression called Arnasai, while water for summer irrigation is lacking. This study suggests to store the excessive winter flows temporarily in the upstream aquifers of the Fergana valley and to use it subsequently for irrigation in summer. It is estimated that groundwater development for irrigation could be practiced on one-third of the irrigated land of the valley, and conjunctive use of groundwater and canal water on another third; the rest will remain under canal irrigation. This strategy will lower the groundwater table and create aquifer capacity for temporal storage of excessive water—“water banking”. This use of the term is only one of many concepts to which “water banking” or “groundwater banking” is applied. In this paper, the term is applied for temporary storing of river flow in subsurface aquifers. Pilot modeling studies for the Sokh aquifer – one of the 18 aquifers of the Fergana valley – supported that this strategy is a feasible solution for the upstream–downstream issues in the Syrdarya river basin. Field studies of water banking are required to determine the scale of adoption of the proposed strategy for each aquifer of the Fergana valley.

Radionuclide contamination in the Syrdarya river basin of Kazakhstan; Results of the Navruz Project

As part of an international collaboration (the Navruz Project) between Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, and the United States of America on transboundary river monitoring, the Radiometric Laboratory of the Institute of Physics in Kyrgyzstan measured the isotopic composition of uranium (as measured by g, the ratio of activities of 234 U/ 238 U) for the water of the Naryn River basin. This ratio varies from 1.5 to 1.9 due to natural causes. The results point to the lack of the technogenic uranium along the Naryn River through territory of the Kyrgyz Republic and to the contamination of the Mailuu-Suu River by technogenic uranium from tailing dumps in the area. The share of technogenic uranium transported to Uzbekistan does not exceed 30p, and the total uranium content is considerably lower than the maximum admissible concentration (MAC) and is almost an order of magnitude lower than that of potable waters of the Chui Valley of Kyrgyz Republic.

Architecture of the Toktogul hydroelectric station on the Naryn River

Architecture of the Toktogul hydroelectric station on the Naryn River

Damming the Naryn River channel at the Tashkumyr hydroelectric station

The experience of damming the mountain river Naryn at the site of the Tashkumyr hydrostation under conditions of a narrow rock canyon with an unusually high location of the inlet sill of the water outlet structure in the presence of considerable drops on the embankment, exceeding 10 m, permits making the following conclusions: 1. Under the confined conditions of a complex mountain relief with a limited length of the damming stretch related to the layout of the structure hampering the organization of additional accesses to the river, the pioneer one-embankment method with dumping of the material into the water primarily from two banks is recommended as the main method for damming the channel of a mountain river. This method requires, in comparison with the two-embankment, smaller expenditures of means and times for preparation and conduction of works on damming and provides a reliable embankment even with unusually large drops. 2. When reaching the maximum unit power of the flow in the gap it is quite effective to use an upstream hydro development (hydrostation) for reducing the discharges to minimum values. Temporary disconnection of the hydrostation for reducing the discharges being released and, as a consequence, reducing the volume of damming material and shortening the time of conducting damming works, as a rule, is always justified. 3. Prototype investigations established that the method of laboratory investigations of damming in the presence of considerable drops on the embankment, just as for small drops, is completely reliable and allows with sufficient accuracy hydraulic substantiation and selection of a reliable and economical damming method with determination of the quantity of damming material.

Kurpsai hydroelectric station on the Naryn River

1. 1.The composition of the structures and type of dam of the Kurpsai hydrostation were adopted in close connection with the specific characteristics of sequence-type construction on mountain rivers. Among the advantages of sequence-type construction under these conditions are: the possibility of using ready-made industrial facilities with a debugged technology; the absence of a need to construct a residential village at the construction site; construction is carried out by an organization staffed by people who have gained invaluable experience in concreting during the construction of the Toktogul hydrostation. The realization of these advantages greatly shortened the preparatory period and volume of preparatory works and accelerated the creation of the hydrostation by a minimum of 3–4 years. 2. The gravity dam of the Kurpsai hydrostation was designed for a definite technology of its construction (the Toktogul method). The design of the dam is distinguished by an economy of its profile and high technological efficiency. One outlet — the deep spillway — was left in the dam, the penstocks were extended beyond the dam profile to its downstream face, the construction of the seals of the contraction joints is substantially simplified, the network of drainage galleries is distributed over the height of the dam, the drainage pump house is extended beyond the dam profile, and rooms in the dam, stairways, and elevator shafts are reduced to a minimum. Since the Toktogul method permits the good use of the possibilities of the zonal distribution of concrete, material is used economically in the Kurpsai dam — the consumption of cement in concrete of the internal zone for grade M-150 was reduced to 180 kg/m3 of concrete. 3. During construction of the Kurpsai hydrostation the technology of concreting in single-layer blocks from the upstream to the downstream face of the dam was improved considerably. Among the measures simplifying the process of concreting we must include the elimination of pipe cooling of the dam, the use of a practically uncooled concrete mix with a temperature to +24°C in the summer, automation of the compaction of the concrete mix, and elimination of the removal of the laitance from the horizontal joints in the internal zone of the dam.

Tectonics and seismicity of the Toktogul Reservoir Region, Kirgizia, USSR

The 214 m high Toktogul Dam will impound a 19.5‐km3 reservoir on the Naryn River in central Kirgizia. The reservoir lies along the Talas‐Fergana fault, a major tectonic feature of central Asia. The nature of Cenozoic movements along the fault is in debate; however, there is considerable evidence of present‐day right‐lateral movement. The region is one of moderate to high seismicity. A magnitude 7.6 earthquake occurred in 1946, approximately 65 km from the dam, near the intersection of the Talas‐Fergana fault and Chatkal ranges. Construction of the dam was completed in 1975 and by late 1979 the water level in the reservoir reached three fourths its final planned depth. Low‐magnitude, induced earthquakes began as the water level first exceeded 100 m in late 1977. A microearthquake survey using portable instruments was carried out in July‐August 1978 and a seven‐station telemetered network was installed in October 1978. The largest of the induced earthquakes has been of magnitude 2.5; the activity is in the immediate vicinity of the dam at very shallow depths (2–5 km) and is related to water level. Preliminary analysis of data gathered during 1978–1979 shows a zone of activity, extending to 5 km depth, supporting geological evidence for an active reverse fault beneath the dam and parallel to the canyon of the Naryn River. Where the reservoir crosses the Talas‐Fergana fault, 15 km upstream from the dam, the water level has not yet reached 100 m and seismicity along the Talas‐Fergana has not shown any significant change related to filling of the reservoir.

Temporary tunnel with a lightweight lining at the Kurpsa hydroelectric station

1. Consideration of the hydrological situation in the basin of the Naryn River and the presence of the unfilled upstream reservoir of the Toktogul hydrostation made it possible to reduce the design discharge during construction at the Kurpsa site and to reduce the cross section of the temporary tunnel. 2. A careful analysis of the engineering-geologic conditions along the route of the temporary tunnel (made after driving the upper level) and investigations of the cohesion of gunite with the rock mass made it possible to use a lightweight gunite lining instead of the earlier planned reinforced-concrete lining over a considerable length of the tunnel. 3. The use of the lightweight gunite lining made it possible to dam the Naryn River 8 months earlier and to start on the construction of the main structures. A considerable reduction in the cost of the finished tunnel was obtained. 4. Experience in operating the tunnel of the Kurpsa hydrostation after it was put into service made it possible to introduce corrections (design cohesion of gunite with rock) in the “Instructions on Designing Hydraulic Tunnels” SN-283-73.

Design of directed blast at the Kambaraty damsite on the Naryn River

Design of directed blast at the Kambaraty damsite on the Naryn River

Seismic stability of the Toktogul dam

1. Investigations of oscillations of the Naryn River canyon at the site of the Toktogul hydrodevelopment during passage of seismic waves presented to us a detailed picture of the movement of the canyon flanks, permitting a reduction in the design accelerations of the flanks and refinement of the seismic load on the dam. 2. Investigations of the shear stability of the Toktogul dam showed that for the adopted seismic load the dam is highly stable. 3. Theoretical and model investigations of the stresses and strains in the dam for different directions of approach of the seismic wave showed that the intensity of the dynamic tensile stresses in the upstream face does not exceed the static compressive stresses. Thus, tensile stresses do not occur on the upstream face at the given level of the seismic load. 4. Investigations of the character and form of failure of dam models under a seismic load revealed considerable strength reserves of the dam, which permit partial or complete elimination of the placement of indentations in the concrete on the downstream face of the dam.

To the builders, assemblers, operators, and all participants in the construction of the Toktogul hydroelectric station on the Naryn river in the Kirgiz SSR

To the builders, assemblers, operators, and all participants in the construction of the Toktogul hydroelectric station on the Naryn river in the Kirgiz SSR

Investigation of the stability of the Toktogul dam using a geomechanical model

1. Investigations on a geomechanical model lead to an analysis of the character of shear resistance of a concrete dam being constructed under complex geologic and topographic conditions. 2. Investigations showed that sectioning of the dam mass by deformation joints adopted for the conditions of the Toktogul station provides integrity of the upstream face against considerable nonumiform deformations of the foundation. 3. Since the deformation of the canyon fractures in shear was overstated on the model, the results obtained apparently correspond to more severe initial conditions than actually occur. 4. The failure diagram indicates that a considerable volume of the rock foundation is involved in resistance to shear. This is determined to a considerable extent by the location of the dam on a bend of the Naryn River. 5. A preliminary analysis and calculations of the possible methods of stability loss led to a well-founded section of the parameters of the initial prototype used for modeling.

Hydrotechnical complex on the Naryn river

Hydrotechnical complex on the Naryn river

Bottom release fractures in the valley of the Naryn River at the site of the Toktogul hydro development

Bottom release fractures in the valley of the Naryn River at the site of the Toktogul hydro development

Construction of high earth coffer dams in two stages on mountain rivers with flood overflow at an intermediate elevation

1. The erection of coffer dams in two stages with overtopping at an intermediate elevation removes the existing limitations in the time of erection and permits increasing the total height of the coffer dams, thus decreasing the sizes of diversion structures, and often shortening the construction time of hydrocenters. 2. In the case of the Toktogul’sk HES the decision to pass the flood through the tunnel and over the crest of a partially erected earth coffer dam made it possible to dam up the Naryn River at the beginning of 1966, and thereby to begin preparatory work in the pit of the dam one year ahead of time. 3. The earthen 30-m high Stage I coffer dam, through which a discharge (600 m3/sec) exceeding the design value by 30% was passed, withstood the flood without any damage. This shows the dependability of the adopted design of the spillway coffer dam and the good quality of the work. 4. The successful passage of the flood at the Toktogul’sk through the partially erected earth coffer dam makes it possible to recommend this method for other projects. The maximum effect can be expected in the construction of earth or rock-filled dams, where the coffer dam, as a rule, becomes part of the dam. 5. The 1966 flood at the Toktogul’sk HES passed with discharges exceeding those of the design and with heads lower than the design; this requires a special analysis of the discharge capacity of tunnels and pipes of large cross sections.