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Karol Przeździecki Jarosław Zawadzki Zygmunt Miatkowski 《Environmental Earth Sciences》2018,77(17):623
Anthropogenic activities, especially resulting in changes in the water conditions, usually disturb biological and agricultural functions of grasslands, leading to their degradation, often on large areas. Remote sensing observations of such changes in grassland ecosystems evoke a great interest, but they are still a difficult task, especially when performed on industrial and mining areas. This paper presents a new effective method of remote sensing of grassland moisture conditions based on temperature–vegetation dryness index (TVDI) calculated from free Landsat imagery, and employing the TVDI spatial variability estimated from a semivariance analysis. The practical applicability of the method is demonstrated on the example of monitoring of the extensive neighborhood of lignite open-cast mine within a period of a few years. Besides, the developed method was validated at the studied area, using in situ information. Thus, we demonstrated that TVDI may serve as an effective indicator of grassland moisture conditions, even in problematic areas. 相似文献
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A numerical study which takes into account wave dispersion effects has been carried out in the Indian Ocean to reproduce the initial stage of wave propagation of the tsunami event that occurred on December 26, 2004. Three different numerical models have been used: the nonlinear shallow water (nondispersive), the nonlinear Boussinesq, and the full Navier-Stokes aided by the volume of fluid method to track the free surface. Numerical model results are compared against each other. General features of the wave propagation agreed very well in all numerical studies. However some important differences are observed in the wave patterns, i.e., the development in time of the wave front is shown to be strongly connected to the dispersion effects. Discussions and conclusions are made about the spatial and temporal distribution of the free surface reaffirming that the dispersion mechanism is important for tsunami hazard mitigation. 相似文献
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PCBs in fish from the southern Baltic Sea: levels, bioaccumulation features, and temporal trends during the period from 1997 to 2006 总被引：1，自引：0，他引：1
Levels of seven marker polychlorinated biphenyls (PCBs) have been determined in five species of Baltic fish collected during 1997-2006. Downward time trends in the concentrations of heavier congeners of PCBs in different Baltic fish, with the exception of cod, have been observed between 1997 and 2001. In case of sprat and herring samples, the statistical significance of the time trends of the PCBs: 101, 118, 153, 138 and 180 concentrations has been proved. Species-specific bioaccumulation of PCBs has been indicated, and the lowest and highest levels of PCBs (expressed on the basis of lipid weight) have been observed in sprat and salmon samples, respectively. PCB profiles have been found to be similar in all the fish species tested. Sampling location has not been a crucial factor for the observed levels of various PCBs. In some fish species, PCB concentrations are negatively correlated with the fat content but have no relation with the fish length. 相似文献
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An analysis of the mechanism of flow in ice-covered rivers 总被引：1，自引：0，他引：1
Zygmunt Meyer 《Acta Geophysica》2010,58(2):337-355
The paper presents a mechanism of flow of water in an ice-covered river in the case of movable bottom. The analysis is based
upon the principal hydrodynamics equations of turbulent flow in the case of steady uniform motion. It leads to the conclusion
of linear distribution of the turbulent shear stress with depth. It allows to obtain the vertical distribution of velocity
of flowing water under the assumption that at the boundaries (movable bottom and ice) the viscosity of water is greater than
the kinematics viscosity. The relations describing the vertical distribution of velocity of flowing water, as well as the
eddy viscosity coefficient under these conditions, are given. 相似文献