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Majority of existing simulation models is composed for simulate the pollution spreading (concentration) only downstream from the pollutant source. Consequence of this is that these models strictly require all the initial and boundary conditions (discharges, location and concentration of the pollutant). However, opposite problems may occur in practice: pollution concentration time courses in specific cross-section profile along a watercourse are known (e.g. based on the on-line monitoring), but pollution source location, as well as the pollution amount, are unknown. Such task is called „inverse“ task. The objective of this task is to determine the location of pollution source as well as the total pollution amount and time course of pollution efflux. A unique pollution source identification in river systems is very unlikely because of the river system tree structure and its branching but result of inverse task can be a selection of regions with high probability of source location. Paper presents a modelling study, focused on localisation of the pollution source of the rivers. The study is based on a real field experiment, however on a single river section without branching. [ABSTRACT FROM AUTHOR]

Nowadays a typical task in water quality modelling is to simulate the pollution spreading downstream, i.e. initial and boundary conditions are known. However, in practice opposite problems may occur: pollution concentration time courses in specific locations are known (e.g. based on the on-line monitoring), but the position of the pollution source is unknown. This type of task can occur in case of accidental pollution and is named as an inverse task. Particular importance has the inverse task application in urban environment - in sewer systems. Inverse task can be solved by water quality monitoring in different sewer profiles, based on simple presence of the monitored pollutant. An interesting approach to solve the inverse task is to monitor the hydrodynamic dispersion in sewer system, assuming discontinuous and instantaneous pollution sources (similar to a single toilet flush). A unique pollution source identification in sewer systems is very unlikely because of the sewer system tree structure and its branching, but result of inverse task can be a selection of regions with high probability of source location. Such approach can help to monitor and localise human activities in urban environment. [ABSTRACT FROM AUTHOR]

General topic of this paper is numerical modelling of pollution dispersion in streams and use of some modelling approaches for the inverse task. Inverse task means a modelling technique, which is focused on the localisation of unknown pollution source. Such task is called „inverse”, because typical common models or equations are rather focused on the pollution spreading simulation, whereas the pollution source location is known. To solve such inverse problem various approaches can be used, but in all cases a prerequisite is to know pollution concentration time courses in the monitored stream section. One of the simplest approaches for solving the inverse task is to perform a large number of plausible simulations and to compare the simulated concentration time courses with the monitored one. The best fit can determine the distance of the pollution source. For such inverse task solution, a simple and fast modelling method should be used, but on the other hand the method should be as precise as possible. This paper proposes an improvement of the analytical method, which can be used for the inverse task solution. [ABSTRACT FROM AUTHOR]

One of the main tasks of water management is to achieve good water quality. Important auxiliary tools in this case are mathematical models that currently are incorporated in almost every numerical model, used to solve problems in everyday practice of water management and engineering. A dispersion coefficient is one of the crucial input parameters of transport processes. The paper is focused on determination of dispersion coefficients in sewers, as in prismatic and straight stream channel with relatively constant roughness of streambed. Field experiments were performed in a straight sewer sections under dry weather flow conditions, i.e. with relatively low pipe filling, discharges and velocities. Consequently, the dispersion coefficient in a sewer line with various direction changes was determined. In the end of the paper the observed effect of "dead zones" is described, which theoretically should not occur in conditions of our experiment (prismatic channel with no obstacles). Paper also discuss this topic and explain its root cause. [ABSTRACT FROM AUTHOR]

Paper describes the measurement methodology of tracer field experiments at lowland channel, as well as the obtained results from these measurements and their analysis. During the measurements we found, that there is a large portion of so called dead zones, i.e. zones with transient storage of pollutant (tracer) in the investigated channel reach. These zones significantly distort the measured tracer concentrations time course. The paper deals with determination of dispersion coefficients from mentioned field tracer experiments in a stream with dead zones. The values of these coefficients are specific input data for numerical models simulating the pollution spreading in water environment. In the case of natural streams one-dimensional model is sufficient to obtain indicative values of transported pollution concentrations. Therefore, this paper is focused to the methodology and results for determination of the longitudinal dispersion coefficient. The measurements, tracer experiments and their evaluation were performed on straight channel reach of the Šúrsky channel, situated close to the village Svätý Jur (Slovakia). The field measurements were made in 50 up to 500 m long straight channel reach with relatively prismatic cross section profile. The channel bed was 4-5,5 m width at water level, max. depth was in the range 0,4 - 0,8 m, velocity 0,21-0,36 m.s-1 and a discharge was 0,38-0,43 m3.s-1. The range of determined longitudinal dispersion coefficient was 0,63 - 0,82 m2.s-1 . [ABSTRACT FROM AUTHOR]

A simulation model for water quality in the river Drava is presented in this paper, including the space extent of the model, modelling of physical, chemical and biological processes in the river, as well. Simulation of water quality was performed using the software MIKE 11 (Danish Hydraulic Institute). The main goal of the study was the simulation of the water quality for quasi-steady state in two scenarios of the short-term changes in water quality. We simulated in scenario no. 1 two-day failure of the waste water treatment plant in the agglomeration Belišće, in the second scenario, we simulated the impact of waste water from combined sewer overflows in the Osijek agglomeration. [ABSTRACT FROM AUTHOR]

Water quality modelling is currently very effective and important tool in context of the task to ensure the required quality of water resources, respectively, to achieve (maintain) good water status according the Water Framework Directive (2000/60/EC). Mathematical models of water quality are an important tool for integrated water management, planning and protection. Integral part of such models is the modelling of fundamental physical processes affecting water quality - advection and dispersion. This paper documents results of measurements of the dispersion coefficient within the scientific project APVV 0274-10. Measurements in this project have been performed in various surface water bodies in Slovakia - lowland streams with low turbulence (drainage, irrigation channels), as well as in mountain streams with a high degree of turbulence. Within the field experiments both longitudinal, so as the transverse dispersion coefficients were measured. [ABSTRACT FROM AUTHOR]

Green roofs have many advantages: improving the roof thermal insulation, noise absorption, temperature and humidity control in cities (urban microclimate), fire resistance and protection of roof structural surface layers against UV- radiation. The most important green roof ability, which appears as a key feature in terms of rainwater management in urban catchments is the ability of rainwater detention and retention. To increase the retention capacity of green roofs are being used in addition to the drainage layer and the storage layer, which in hydrological terms significantly change the properties of these roofs. Apart from this - there is a need to develop and use green roof growing substrates that minimize leaching of nutrients and other contaminants while still providing adequate physical and chemical properties for plant growth. Organic matter included in the substrate is very beneficial for plant growth, but when it decomposes it may leach nutrients. Components such as recycled waste materials and by-products have a potential, but concentrations of contaminants must be considered. This paper describes preliminary results of a scientific project VEGA 1/0691/13, focused on experimental research of the hydrological function of green roofs in urban areas with regard to the reduction and the detention of rainfall runoff, which may be one of the crucial factors for sustainable urban development. Another objective of the research is to test the filtration ability of green roofs, rainwater runoff quality and possible use of green roofs as a supplementary source of service water in urban areas. At the same time waste materials are tested, which could be used for the substrate layer for green roof plants. As a suitable material a mixture of dry sludge from municipal waste water treatment plant and peat substrate is tested. Other experiments are focused to the option to add simple filtering device directly into the roof structure, or their placement in the outflow area. Therefore another objective of the project is to explore the use of possible filtration materials (e.g. natural zeolite). This material has excellent absorption ability and together with an activated carbon filter it could create an effective system for green roofs runoff pollution reduction. We assume that water collected this way can be in some cases a valuable source of service water and can be used in many private or commercial applications. [ABSTRACT FROM AUTHOR]