Simulation of groundwater flow and contaminant transport at a landfill site using models

Numerical and analytical modelling studies were conducted for the analysis of groundwater flow and contaminant transport at the Innisfil landfill site in the Town of Innisfil, County of Simcoe, in Ontario, Canada. Previously conducted field studies categorized the upper stratigraphy at the site into three units: upper sand unit, upper silt/clay unit and Intermediate Sand unit. Essentially horizontal groundwater movement in the two sand units and vertical downward flow in the silt/clay unit were reported by the field hydrogeologists. In the following, application of three computer models (FLOWPATH, USGS MOC and POLLUTE) for the simulation of the groundwater flow and contaminant transport processes at the Innisfil landfill site is described. The paper focuses on the calibration of groundwater flow and contaminant transport systems, and demonstrates how the insight gained during the contaminant transport calibration was used to improve the initial groundwater flow characterization of the hydrogeological system.     

Regional search, selection and geological characterization of a large anticlinal structure, as a candidate site for CO2-storage in northern Germany

This paper reports on the regional screening, selection and geological characterisation of a potential on-shore CO₂ storage site (saline aquifer) in north-eastern Germany. The main objective of this study was to identify and investigate a candidate storage site, capable to accommodate the total amount of approximately 400 million tons of CO₂. Such a volume is produced by a modern, lignite-fired power plant within its operation lifetime of approximately 40 years. Within north-eastern Germany, several saline aquifers of Triassic, Jurassic and Cretaceous age have been evaluated with respect to their regional occurrence, storage potential and basic reservoir properties. Subsequent to a ranking, considering different criteria, the anticlinal structure Schweinrich holding suitable saline aquifers of the uppermost Triassic and lowest Jurassic has been selected from a number of identified candidate sites. According to results of the geological site characterisation, including structural geological investigations and 3D reservoir modelling, the structure Schweinrich seems to be a suitable site for industrial large scale CO₂ storage. Further data acquisition (new wells and 3D seismics) and research (more detailed and comprehensive modelling) is needed in order to prove the structural integrity of the storage site and assure long-term safety.     

Recent trends in annual snowline variations in the northern wet outer tropics: case studies from southern Cordillera Blanca,Peru

TL-moments approach has been used in an analysis to identify the best-fitting distributions to represent the annual series of maximum streamflow data over seven stations in Johor, Malaysia. The TL-moments with different trimming values are used to estimate the parameter of the selected distributions namely: Three-parameter lognormal (LN3) and Pearson Type III (P3) distribution. The main objective of this study is to derive the TL-moments (t ₁,0), t ₁?=?1,2,3,4 methods for LN3 and P3 distributions. The performance of TL-moments (t ₁,0), t ₁?=?1,2,3,4 was compared with L-moments through Monte Carlo simulation and streamflow data over a station in Johor, Malaysia. The absolute error is used to test the influence of TL-moments methods on estimated probability distribution functions. From the cases in this study, the results show that TL-moments with four trimmed smallest values from the conceptual sample (TL-moments [4, 0]) of LN3 distribution was the most appropriate in most of the stations of the annual maximum streamflow series in Johor, Malaysia.     

An Analytical Footprint Model For Non-Neutral Stratification

We propose an analytical model for the so-called footprint of scalar fluxes in the atmospheric boundary layer. It is the generalization of formulations already given in the literature, which allows to account for thermal stability. Our model is only marginally more complicated than these, and it is therefore simple enough to be applicable for a routine footprint analysis within long-term measurements. The mathematical framework of our model is a stationary gradient diffusion formulation with height-independent crosswind dispersion. It uses the solution of the resulting two-dimensional advection – diffusion equation for power law profiles of the mean wind velocity and the eddy diffusivity. To find the adjoint Monin–Obukhov similarity profile, we propose two different approaches, a purely analytical one and a simplenumerical error minimalization.     

SELECTION OF SUITABLE METHODS FOR TERRAIN MODELLING FOR RIVER ENGINEERING

LINTRODUCTIONTerrainmodellingisatermtodescribetheprocessofrepresentingthesurfaceoftheEarth.Mathemahcally,theproblemcanbedescribedas;Givenasetofn(3sn相似文献   

Fluid variability in 2 GPa eclogites as an indicator of fluid behavior during subduction

Fluid activity ratios calculated between millimeter- to centimeter-scale layers in banded mafic eclogites from the Tauern Window, Austria, indicate that variations in a _{H 2 O} existed between layers during equilibration at P approximately equal to 2GPa and T approximately equal to 625°C, whereas a _{CO 2} was nearly constant between the same layers. Model calculations in the system H₂O–CO₂–NaCl show that these results are consistent with the existence of different saturated saline brines, carbonic fluids, or immiscible pairs of both in different layers. The data cannot be explained by the exisience of water-rich fluids in all layers. The model fluid compositions agree with fluid inclusion compositions from eclogite-stage veins and segregations that contain (1) saline brines (up to 39 equivalent wt. % NaCl) with up to six silicate, oxide, and carbonate daughter phases, and (2) carbonic fluids. The formation of crystalline segregations from fluid-filled pockets or hydrofractures indicates high fluid pressures at 2 GPa; the record of fluid variability in the banded eclogite host rocks, however, implies that fluid transport was limited to local flow along individual layers and that there was no large-scale mixing of fluids during devolatilization at depths of 60–70 km. The lack of evidence for fluid mixing may, in part, reflect variations in wetting behavior of fluids of different composition; nonwetting fluids (water-rich or carbonic) would be confined to intergranular pore spaces and would be essentially immobile, whereas wetting fluids (saline brines) could migrate more easily along an interconnected fluid network. The heterogeneous distribution of chemically distinct fluids may influence chemical transport processes during subduction by affecting mineral-fluid element partitioning and by altering the migration properties of the fluid phase(s) in the downgoing slab.     

Retrograde evolution of eclogites: evidences from microstructures and 40Ar/39Ar white mica dates,Münchberg Massif,northern Bavaria

Phengites from eclogites and pegmatites (3T, 2M₁, coarse-grained and recrystallized) of the Münchberg Massif (Weissenstein and Oberkotzau) have been dated by the ⁴⁰Ar/³⁹Ar method. 3T-micas from the eclogites yielded plateau and isochron ages of 365±7 Ma. 2M₁-micas show disturbed degassing spectra. Micas from pegmatites show a slight excess Ar component, with an isochron age of 353 to 351±3 Ma. An age component of approximately 300 Ma was also detected. In combination with age values from the literature, the cooling history of the Münchberg Massif from eclogite-facies conditions (390 Ma) to cooling below 350°C (350 Ma) is documented. The age component of 300 Ma is attributed to a low-grade stage of mineral growth accompanied by a transitional ductile-brittle deformation. The petrological effects include formation of pumpellyite-prehnite-facies minerals, frequently precipitated in microcraks and cleavage planes of earlier formed minerals. This stage has to be seen in conjunction with the intrusions of the Fichtelgebirge granite.     

Carbo-Permian pteridophyll leaf fragments from an amphibolite facies basement, Tauern Window, Austria

Graphitic schists from the Pennine Basement, Tauern Window, Austria, contain fragments of pteridophyll leaves. They are preserved, despite the overall strong deformation and metamorphism at amphibolite facies conditions (˜ 525°C, 750°100 MPa), due to a particular strain path with volume loss by pressure solution. They were determined as cf. Callipteridium sp. indicating a Permo-Carboniferous age. This depositional age is similar to radiometric age data obtained for the intrusion of nearby metagranitoids, indicating either tectonic contacts between the metagranitoids and the graphite schists, or a very active and rapidly changing tectonic regime during the Hercynian event.     

The shot-sensor method of measuring currents in shallow estuarine waters

A current measuring device, the Shot-Sensor, was developed as a low cost alternative to measuring water flow speeds and directions using conventional, more expensive instrumentation. The device releases stainless steel shot of known size and settling speed into a flowing water mass. As the shot settles, it is dispersed by currents and ends up in settling traps. Mean current speed and direction can be calculated from the patterns of dispersal and the percentages of shot of various sizes in the traps. Determination of precision and accuracy indicate that the Shot-Sensor can measure within a few cm s^?1 of more expensive meters and may be suitable for some shallow-water applications. Speed range of the Shot-Sensor is presently limited between 3 and 40 cm s^?1, but further development could allow this range to be extended.     

Experimental Na-K distribution between amphiboles and aqueous chloride solutions, and a mixing model along the richterite – K-richterite join

The cation exchange equilibrium has been investigated by hydrothermal experiments at 700 and 800°C at 200 MPa. To avoid equilibration problems of conventional exchange experiments, we synthesized amphiboles with an excess fluid allowing exchange between solid and fluid during the experiment. The exchangeable cations Na and K were provided as excess 1 to 2n chloridic solution. These exchange syntheses can be described by the reaction equation with ^(aq) for hydroxides and chlorides in aqueous solutions and _{( s )} and _{( p )}?=?start and product fluid. The amphiboles grew in presence of the exchange fluid and adjusted their stoichiometry in equilibrium with the fluid phase. The solid products consist of more than 99% amphibole (Na,K-richterite_ss) with traces of diopside and quartz. The amphiboles are up to 1?mm long and often ≈ 40 μm thick. Detailed EMP- and HRTEM-observations show that they are chemically homogeneous and structurally wellordered. The experimental results give consistent phase relations in the reciprocal ternary system Na-richterite–K-richterite–NaCl–KCl. We analysed the product fluid with AAS- and ICP-methods. The Na-K distribution coefficients between fluid and amphiboles of the richterite–K-richterite join are close to unity at 700°C and 800°C at 200 MPa. Small systematic deviations are explained by a symmetric solution model for the A-position of the amphiboles. Using ideal mixing for H₂O-NaCl-KCl fluids, a mixing model for the system richterite–K-richterite is presented. We suggest that the composition of richterite solid solutions can be used as a sensor for NaCl/KCl-ratios in metamorphic fluids.