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[en] From the viewpoint of engineering and environmental assessment, this paper briefly represents some essential concepts concerning mixing behavior in a natural stream and experimental results and theoretical researches which domestic and international scientists have conducted in this field. Formulae are recommanded for predicting the transverse mixing coefficient, the longitudinal dispersion coefficent, the non-uniform dilution factor, the mixing distance and concentration of pollutants, longitudinal spread scale and elapsing time of a pollutant cloud. The applicability of this method is also discussed
[en] Operators of dams in Canada and the U.S. are steadily shifting from construction of new facilities to the maintenance and repairs of existing ones. This paper emphasized the importance of prioritizing maintenance activities on embankment dams whose maintenance needs vary from structure to structure. Two parallel procedures were developed, one for monitoring devices and the other for defense groups. Both procedures are intended to be used together to rate the condition of the embankment dams. The term 'defense groups' is used to refer to the collection of physical components on dams to prevent adverse conditions from occurring that would result in an uncontrolled release of the reservoir. The priority rankings and condition indices developed by means of this procedure reflects the judgment of a panel of engineers and geologists who implement them. They are not to be interpreted as an index of dam safety. While the process is sufficiently well developed to warrant wide-spread distribution, it is considered to be still in the developmental stage. Therefore, it should be used in conjunction with other parallel processes evaluating structural, mechanical and electrical features of the structure under consideration. 6 refs., 7 tabs
[en] Highlights: • Present day methods deliver new knowledge about socio-ecological past of the lake. • Long term investigation reveals shifting goal setting of restoration over time. • Different, intertwined temporal scales complicate lake restoration endeavors. • Interannual weather variability influences restoration endeavors. • Prevailing understandings influence the anticipated futures of the lake. - Abstract: The history and future of the restoration efforts at the hypereutrophic southern Finnish lake, Tuusulanjärvi, are investigated. The interdisciplinary study is conducted within a modified DPSIR- framework, which allows us to both trace back and envision the future of the dynamics of the complex socio-ecological processes involved in restoration. The study covers the time period from the early 1970s up to 2030. The longitudinal study integrates environmental historical, limnological, and futures studies. The analyses reveal the multiple time scales of social and ecological processes present in long term restoration, the changing perceptions of and emphasis on restoration goals and outcomes over time, and the challenges that incidental and uncertain parameters, such as weather conditions, pose to sustainable and efficient restoration endeavors.
[en] The uniquely rich hydrological and archipelagic nature of Finland creates versatile opportunities for spending of leisure time. As various uses of waterways compete with each other, it is difficult to compare advantages and disadvantages of operations in view of various interests. This is why efforts have been made to develop methods to make the effect commensurable. Usability of shores is one important factor in the assessment of recreation use of waterways. When influence of water level changes in usability of shores is estimated, shore and bottom slope and quality, and uses and user numbers of the shores must be known. In several assessment methods, usability of shore is depicted by distance of the shifted shoreline (due to the changed water level) from the 'good' status. The studies on changes in the recreation value or usability of shores should be started by making efforts to classify and estimate various effects separately. If the value is wished to be given as one figure, the calculation basis applied, the weights and the used value functions must be stated clearly with the results. It is equally important to make a sensitivity analysis, i.e. to study effects of changes in uncertain input data on the results
[en] Present article is devoted to environmental assessment of Kafirnigan River during the flood period. Physicochemical and microbiological parameters of selected samples of Kafirnigan River have been determined and analysed.
[en] This paper introduces three quantitative indicators to conduct research for characterizing Northeast China cold vortex persistence activity: cold vortex persistence, generalized “cold vortex,” and cold vortex precipitation. As discussed in the first part of paper, a hindcast is performed by multiple regressions using Northeast China precipitation from 2012 to 2014 combination with the previous winter 144 air-sea system factors. The results show that the mentioned three cold vortex index series can reflect the spatial and temporal distributions of observational precipitation in 2012–2014 and obtain results. The cold vortex factors are then added to the Forecast System on Dynamical and Analogy Skills (FODAS) to carry out dynamic statistical hindcast of precipitation in Northeast China from 2003 to 2012. Based on the characteristics and significance of each index, precipitation hindcast is carried out for Northeast China in May, June, July, August, May–June, and July–August. It turns out that the Northeast Cold Vortex Index Series, as defined in this paper, can make positive corrections to the FODAS forecast system, and most of the index correction results are higher than the system’s own correction value. This study provides quantitative index products and supplies a solid technical foundation and support for monthly precipitation forecast in Northeast China.
[en] The response of rectangular large-mouthed harbours to exciting monochromatic plane waves, particularly to waves with rays not orthogonal to the straight coastline, has been numerically investigated. Some of the transversal modes are found to be strongly excited, though in narrow frequency bands. The first transversal mode is quite relevant, especially in harbours with transversal size greater than the length. It can be reasonably suspected that the mechanism of excitation may be rather different from that prescribed by the theory in the case of narrow mouth. Particularly, it has been found that the eigenmodes of the basin with zero elevation on the entrance line play a primary role in determining the harbour response, especially in the excitation of the pure transversal modes. (author)