Karstification below dam sites: a model of increasing leakage from reservoirs   总被引：1，自引：3，他引：1  

W. Dreybrodt  D. Romanov  F. Gabrovsek 《Environmental Geology》2002,42(5):518-524

Unnaturally steep hydraulic gradients below foundations or across abutments of dams may cause solutional widening of fractures in karstifiable rocks of carbonates or gypsum. This could cause increasing leakage which may endanger the performance of the construction. To investigate this problem recent models on natural karstification have been applied. We have performed numerical simulations of leakage below a model dam with a grouting curtain reaching down to 100 m below its impermeable foundation of 100 m width. Water is impounded to a depth of 100 m. The dam is located on a terrane of fractured rock dissected by two perpendicular sets of fractures with spacing of 5 m, and with a log-normal distribution of their initial aperture widths of about 0.02 cm. In the first state of karstification these fractures widen slowly, until a pathway of widened fractures below the grouting has reached the downstream side with exit widths of about 1 mm. This causes a dramatic increase of leakage, and turbulent flow sets in. After this breakthrough at time T, in the second state of karstification, dissolution rates become even along these fractures and cause widening of about 0.1 cm year^-1 for limestone, and at least of 1 cm year^-1 for gypsum. This leads to an increase in leakage to excessive rates within 25 years for limestone, but only 5 years for gypsum. We have performed a sensitivity analysis of breakthrough time T for the various parameters which determine the problem. The result shows breakthrough times in the order of several tens of years for both limestone and gypsum. We have also modelled leakage to caves or karst channels 200 m below the bottom of the reservoir, which could induce the formation of sinkholes. The model can be extended to more realistic settings. In conclusion, our results support the prediction that increasing leakage at dam sites can be caused by recent karstification which is activated after filling the reservoir, possibly leading to serious problems within its lifetime.  相似文献   

ELF plasma waves in hot and cold plasma fluxes observed by Prognoz-8 in the magnetospheric tail     

J. Blecki  B. Nikutowski  P. Koperski  B. Popielawska  K. Kossacki  S. A. Romanov  S. P. Savin 《Annales Geophysicae》1994,12(10-11):1006-1017

We present Prognoz-8 observations of low-frequency plasma waves (2-105 Hz) associated with plasma fluxes near the outer boundary of the plasma sheet. These plasma fluxes were different from the regular plasma sheet boundary layer and consisted of tailward flowing warm proton and cold oxygen beams accompanied by rather cold electrons (T _e less than 100 eV). Observed plasma characteristics were used in the numerical solution of the dispersion relation for the ion-beam acoustic instability. Detailed analysis shows that this instability can be a source of observed emissions at frequencies up to 25 Hz.  相似文献   

Manifestation of the El Niño effect in the Indian Ocean     

V. I. Byshev  Yu. A. Ivanov  V. G. Neiman  Yu. A. Romanov  I. V. Serykh  V. E. Sklyarov  A. D. Shcherbinin 《Doklady Earth Sciences》2008,418(1):140-144

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Icebergs in the Southern Ocean and Factors Defining Their Distribution     

Yu. A. Romanov  N. A. Romanova 《Russian Meteorology and Hydrology》2018,43(3):178-187

Using the data of ~58 000 ship observations of Antarctic icebergs in 1947–2014, the map of average summertime concentration of icebergs (namely, of their number within a circle with the radius of 15 nautical miles) in the Southern Ocean was constructed. The main features of the iceberg distribution are revealed, and their possible reasons are investigated. It is shown that in the open ocean sea currents play a key role in the iceberg distribution. Wind effects are pronounced when ocean currents are weak or absent. According to the authors’ estimates, wind plays a decisive role only in the formation of one wide quasimeridional tongue of high iceberg concentration in the Weddell Sea. It is difficult to assess the impact of Antarctic glaciers’ productivity on the iceberg distribution, because currents, wind, and breaking and jamming of icebergs in shallow water areas cause their rapid redistribution. The clear physical explanation of the main features of iceberg concentration distribution on the constructed map indicates that it provides a rather real pattern.  相似文献   

A compact form for the analytic description of temperature dependence of saturation vapor pressure over plane surfaces of water and ice     

N. P. Romanov 《Russian Meteorology and Hydrology》2017,42(1):27-37

A possibility is studied of extending the range of action of the simple three-parameter formula (ITS-90 scale) proposed in the previous work of the author [2] for the dependence of saturation vapor pressure E on temperature T within the range of 250 to 490 K. The results demonstrated that the dependence ln[E(T)/E(T _bas)] = (T - T _bas)[A - B(T - T _bas) + C(T - T _bas)²]/T with four sets of coefficients A, B, and C obtained using one base temperature Tbas equal to the temperature of triple point of water T _t = 273.16 K and two additional base values T _bas2 = 473.16 K and T _bas3 = 623.16 K makes it possible to approximate rather accurately the initial experimental and computed data in the temperature range from the point of homogeneous freezing of 235 K to the critical temperature of 647 K for liquid water and from 193 K to T _t for ice. A procedure used for obtaining the inverse function T(E) by solving the third-degree algebraic equation is validated. A hypothesis is proposed for the physical substantiation of additional base points in the form of “a noticeable appearance of dimers at the point T _bas2 and their 100% concentration at the temperature T _bas3.”  相似文献   

Shaping the Rwenzoris: balancing uplift,erosion, and glaciation     

Georg Kaufmann  Matthias Hinderer  Douchko Romanov 《International Journal of Earth Sciences》2016,105(6):1761-1778

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Nonlinear low frequency cut-off of the spectrum of the lower hybrid magnetospheric plasma turbulence     

Yu.V. Golikov  V.F. Kovalev  A.B. Romanov  M.A. Savchenko  V.V. Pustovalov  V.P. Silin 《Planetary and Space Science》1977,25(11):1027-1030

By solving the nonlinear equation of the magnetized plasma in the weak turbulence limit the level of the spectral energy density of the lower hybrid oscillations expanding in the plasma of the Earth's polar magnetosphere, is found. As an approximation the instability which initiates turbulence is considered in a plasma with two interpenetrating beams of nonrelativistic electrons with velocities along the geomagnetic field. The saturation of the instability is due to induced scattering of the oscillations by electrons and ions of the plasma.The spectral distribution of the lower hybrid turbulence has a maximum near the low frequency boundary.  相似文献   

Compressional wave events in the dawn plasma sheet observed by Interball-1     

O. Verkhoglyadova  A. Agapitov  A. Andrushchenko  V. Ivchenko  S. Romanov  Yu. Yermolaev 《Annales Geophysicae》1999,17(9):1145-1154

Compressional waves with periods greater than 2 min (about 10–30 min) at low geomagnetic latitudes, namely compressional Pc5 waves, are studied. The data set obtained with magnetometer MIF-M and plasma analyzer instrument CORALL on board the Interball-1 are analyzed. Measurements performed in October 1995 and October 1996 in the dawn plasma sheet at −30 R_E ≤ X_GSM and |Z_GSM| ≤ 10 R_E are considered. Anti-phase variations of magnetic field and ion plasma pressures are analyzed by searching for morphological similarities in the two time series. It is found that longitudinal and transverse magnetic field variations with respect to the background magnetic field are of the same order of magnitude. Plasma velocities are processed for each time period of the local dissimilarity in the pressure time series. VeloCity disturbances occur mainly transversely to the local field line. The data reveal the rotation of the veloCity vector. Because of the field line curvature, there is no fixed position of the rotational plane in the space. These vortices are localized in the regions of anti-phase variations of the magnetic field and plasma pressures, and the vortical flows are associated with the compressional Pc5 wave process. A theoretical model is proposed to explain the main features of the nonlinear wave processes. Our main goal is to study coupling of drift Alfven wave and magnetosonic wave in a warm inhomogeneous plasma. A vortex is the partial solution of the set of the equations when the compression is neglected. A compression effect gives rise to a nonlinear soliton-like solution.  相似文献   

Spectrophotometric and iodometric methods for the detection of hydrogen sulfide in the Black Sea: Comparison of the results of analysis     

S. K. Konovalov  A. S. Romanov 《Physical Oceanography》2000,10(4):365-377

We discuss the results of analysis of published data and field and laboratory investigations aimed at the solution of the problem of comparabilityof the results of detection of hydrogen sulfide in the Black Sea by spectrophotometric and iodometric methods. We show that the reproducibility of the results of spectrophotometric analysis is higher than hat of the iodometric method only in the case where the content of sulfide in a sample is less than 10–30 μMl⁻¹. When larger concentrations are involved, the traditional iodometric analysis proves to be the most precise and reliable method for the detection of hydrogen sulfide in the Black-Sea waters. Translated by Peter V. Malyshev and Dmitry V. Malyshev  相似文献   

Anomalous Heating of the Solar Atmosphere in the Epoch of the Solar Activity Minimum     

Romanov  K. V. 《Geomagnetism and Aeronomy》2019,59(8):1121-1127

Geomagnetism and Aeronomy - The article studies the physical mechanism of the generation of a steady stream of weak shock waves at the photospheric level during the epoch of the solar-activity...  相似文献