Catálogo de publicaciones - libros

A large number of models for simulating water flow and solute transport in the unsaturated zone are now used for a wide range of applications in research, management, and risk assessment of subsurface systems. Many models of varying degree of complexity and dimensionality have been developed during the past several decades to quantify the basic physical and chemical processes affecting water flow and contaminant transport in the unsaturated zone. Modeling approaches range from relatively simple analytical and semi-analytical solutions, to complex numerical codes. In this paper a brief overview of more widely used analytical and numerical models is given. Some typical problems in which the numerical codes have been applied are also identified.

In this paper we discuss numerical techniques involved in dynamic data driven application simulations (DDDAS). We present an interpolation technique and update procedures. A multiscale interpolation technique is designed to map the sensor data into the solution space. In particular we show that frequent updating of the sensor data in the simulations can significantly improve the prediction results and thus important for applications. The frequency of sensor data updating in the simulations is related to streaming capabilities and addressed within DDDAS framework (Douglas et al., 2003). We discuss the update of permeability and initial data.

Spreading of spilled oil in soil is investigated regarding accidents on railway routes and damage of pipelines along the Georgian section of the Transport Corridor Europe-Caucasus-Asia (TRACECA). Processes controlling the penetration of oil into soil are studied applying analytical and numerical models of oil infiltration. Some analytical solutions are given and analyzed. Results of numerical calculations for conditions foundalong TRACECA are presented.

Dam-break sediment flow is an especially rapid unsteady flow, important in terms of risk assessment, mainly observed in flow-type landslides and dam breaks. The paper presents MUDEP, a computational model under development in IST, Lisbon, Portugal, to model such flows, using the l-D explicit differential TVD MacCormack scheme to solve the adapted St-Venant equations. The function calculating the friction slope varies according to the rheological model. In order to verify the results, experiments were performed in a tilting flume, using a highly viscous oil to simulate the expected laminar behaviour of such flows. The fluid was suddenly released down a slope by the removal of a gate. The comparisons of the computational and experimental results demonstrate the validity of the developed model.

Soil is increasingly affected by applied agrochemicals, atmospheric pollutants, sewage sludge, and manures which can have adverse impacts on soil quality. The European Commission has embarked recently on a Thematic Strategy for Soil Protection that identifies eight threats to soil in Europe of which contamination and decline in organic matter are accorded high priority. To identify changes in soil quality it is important to have some baseline against which to measure that change. In the UK, a National Soil Inventory was made to provide an unbiased inventory of soil resources in Great Britain. Soil samples were taken on a national UTM grid and analysed for a range of physical and chemical properties. About 40% of the grid points in England and Wales were resampled providing an ideal data set from which to identify changes in soil properties, an essential requirement for ‘monitoring’. Geostatistics have been used to estimate the temporal change in several metal concentrations and in soil organic carbon (OC), the major constituent of soil organic matter. In almost all cases, a normally distributed random variable with outliers is shown to be a suitable statistical model to study the change in metal concentrations. A map of change in lead concentration, identifying ‘hotspots’, shows how these methodologies can be applied. It is also shown that the variation of the change in organic carbon is not spatially structured but that the rate of change depends on the initial OC level in the soil.

1992, uncontrolled landfills in Izmir were closed on the ground that they threat the public health and Harmandalı ý Hazardous Wastes Landfill Area has been put into service by Izmir Metropolitan Municipality. Harmandalı Region, which was selected as a sanitary landfill area, has an area of approximately 900 000 m2 and is located in the border of the city Izmir. Izmir is the third biggest city of Turkey with a population of 3.5 million. In this study, the probable impacts of Harmandalı Sanitary Landfill Area on groundwater quality have been investigated. In order to predict the effect land disposal site, “Computer Model of Two-Dimensional Solute Transport and Dispersion in Groundwater” has been applied to the Harmandalı area by using the available data. The results of the model have been controlled after eight years by groundwater analysis in the area.

The necessity to handle efficiently large-scale air pollution models in order to be able to resolves a series of comprehensive environmental tasks is discussed. It is emphasized that the choice of fast and, at the same time, sufficiently accurate numerical methods is very important, but not sufficient. It is also necessary to exploit efficiently the cache memory of the computer under consideration and/or to be able to carry out parallel computations. The particular model used is the Unified Danish Eulerian Model (UNI-DEM), but most of the results can also be applied when other large-scale models are used. The use of UNI-DEM in several comprehensive air pollution studies is discussed in the end of this paper. The investigation of the impact of future climate changes on air pollution levels in some European countries is among the most important studis inwhich UNI-DEM has until now been used.

Some typical drawbacks are analyzed for numerical schemes used in environmental modeling. A new approach for constructing finite volume schemes on a cubed sphere is presented. A locally one-dimensional implicit scheme for the linear advection equation is developed and studied in detail.

Combined emission rate and chemical state optimization by fourdimensional variational data assimilation is presented. Using an adjoint nesting technique, a model setup focussing on the Berlin area is employed, enabling to analyze constituents with strong spatial gradients like NO and NO2. Possible requirements for satellite observations to be used for tropospheric chemical state estimation are shortly discussed.

The problems related to practical realization (as a computer program) of difference schemes for solving the diffusion equations that describe pollutants transport in river water are considered in this paper. In particular, the problem of optimum choosing of the algorithm parameters on which depend the accuracy, the time and the possibility of practical realization of the equation solution are considered. The demand to reduce as much as possible the time and the errors of calculations, and also the simplicity of the functions of certain classes used in mathematical models and the degree of correspondence to real physical conditions are considered as criteria of optimality.