Truncation errors of selected finite difference methods for two-dimensional advection-diffusion equation with mixed derivatives

The spread of a passive contaminant in an open-channel reach is considered with use of a two-dimensional advection-diffusion equation with the included off-diagonal dispersion coefficients. This paper presents the calculation of truncation errors, namely numerical diffusion and numerical dispersion for various finite difference schemes. The accuracy of the considered finite-difference approximations is analysed by deriving and studying the relevant modified partial differential equation.     

Prediction of groundwater inflow into copper mines of the Lubin Głogów Copper District

 The Lubin Głogów copper district (lgom) is in an area of copper mining, where ore is mined at a depth of 600–1200 m below surface. Mine dewatering directly influences W-1 limestone aquifer of Permian (Zechstein) age and indirectly impacts a Triassic sandstone aquifer as well as water-bearing sediments interbeded with the coals. The prediction of groundwater inflow into mines has been performed using methods of mathematical modelling. In succeeding steps of the approach, the scheme of the hydrogeological framework was changed starting from the one-layer model up to the four-layer model. The evolution of this hydrogeological schematization is presented in this paper. The latest scheme characterizes such levels of details that allows the following predictions: (1) expansion of depression in all aquifers is influenced by dewatering, (2) the widest extent of depression is in the southern direction, (3) groundwater inflow to the Lubin and Rudna mines will remain at the same level, while the inflow to the Polkowice mine will increase by 25%. Reliable prediction can be achieved by incorporating the entire recharge and drainage area characteristics of the aquifer influenced by mine dewatering into the model. Received: 7 March 1998 · Accepted: 7 December 1998     

Development and Applications of Dome A-DEM in Antarctic Ice Sheet

Dome A, the highest dome of East Antarctic Ice Sheet, is being an area focused by international Antarctic community after Chinese Antarctic Expedition finally reached there in 2005, and with the ongoing International Polar Year (IPY) during August 2007. In this paper two data processing methods are used together to generate two 100-m cell size digital elevation models (DEMs) of the Dome A region (Dome A-DEM) by using Cokriging method to interpolate the ICESat GLAS data, with Ihde-DEM as a constraint. It provides fundamental data to glaciological and geophysical investigation in this area. The Dome A-DEM was applied to determining the ice-sheet surface elevations and coordinates of the south and north summits, defining boundaries of basins and ice flowlines, deducing subglacial topography, and mapping surface slope and aspect in Dome A region. The DEM shows there are two (north and south) summits in Dome A region. The coordinate and the surface elevation of the highest point (the north summit) are 80°21′29.86″S, 77°21′50.29″E and 4092.71±1.43m, respectively. The ice thickness and sub-ice bedrock elevation at north summit are 2420m and 1672m, respectively. Dome A region contains four drainage basins that meet together near the south summit. Ice flowlines, slope and aspect in detail are also derived using the DEM.     

The Influence of Fluctuations of the Solar Emission Line Profileon the Doppler Shift of Interplanetary HLyα Lines Observed by the Hubble–Space–Telescope

In an earlier research the employment of a radiation transport model with angle-dependent partial frequency redistribution, self-absorption by interplanetary hydrogen, realistic solar H_Lyαemission profile, and a time dependent `hot' hydrogen model to analyze 5 interplanetary H_Lyα glow spectra obtained with theHubble–Space–Telescope–GHRS spectrometer, has not resulted in unequivocal determination of a set of thermodynamical parameters of the interstellar hydrogen The residual discrepancies between the model and the data concern the observations performed within an interval of 1 year close to the solar minimum from very similar lines of sight. In this paper we investigate by calculating interplanetary H_Lyα lines with the use of a one hydrogen distribution and several solar H_Lyα line profiles whether this residual may be caused by possible variations in time of the shape of the solar H_Lyα emission line profile which cause variable illuminations of the interplanetary gas. These variations of illuminations cause variations in Doppler shift of the resonant interplanetary H_Lyα line that can amount to ≃ 4 km s^-1in the line peak. Consequently we conclude that without adequate knowledge of the solar H_Lyα emission line profile during spectral observations of the interplanetary hydrogen gas it is impossible to obtain an agreement between models and observations better than by this value. This revised version was published online in July 2006 with corrections to the Cover Date.     

Contamination of tsunami sediments in a coastal zone inundated by the 26 December 2004 tsunami in Thailand

Tsunami sediments deposited in a coastal zone of Thailand by the 26 December 2004 tsunami wave were sampled within 50 days after the event. All surface and ground waters in tsunami- inundated zone revealed significant salinity at that time. The tsunami sediments, composed mainly of fine to medium sand, contain significantly elevated contents of salts (Na⁺, K⁺, Ca⁺², Mg⁺², Cl and SO ₄ ⁻² ) in water-soluble fraction, and of Cd, Cu, Zn, Pb in the bioavailable fraction and As in the exchangeable fraction in relation to the reference sample. The origin of contaminants is marine, as well as litho- and anthropogenic. The salts and Pb, Zn and Cu reveal high correlation to each other and to the mean grain size (pore size and porosity). Serious environmental hazard exists in that region because, due to gentle morphology, there is a risk of migration of the contaminants into ground waters and food chain.     

On the minimum distance between two Keplerian orbits with a common focus

The methods used so far for determination of the closest approach between two orbits are discussed, and corrected versions of two of them are presented.