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[en] All earth dams require protection against erosion due to wave action on the upstream slope and protection against runoff from rain, snowmelt or wave splash on the downstream shell. Erosion protection is a major cost factor in embankment dams, typically varying from 5-15% of the dam cost, although it can approach 50% of embankment cost for long low dikes. The most common type of erosion protection is dumped rock riprap. Current practice in riprap design is based on rational analysis of factors affecting riprap stability, and the performance of existing riprap protection. Historical development of riprap design is reviewed, beginning with U.S. Army Corps of Engineers dams in the 1940s. Riprap design parameters are based on slope steepness and severity of wave action, which depends on reservoir geometry and location. A common cause of riprap deterioration is loss of underlying bedding as a result of inadequate design or segregation of riprap and bedding during construction. The most common form of riprap failures include: loss of filter material through riprap if it is too fine; inadequate rock size to resist wave action, resulting in beaching; segregation during construction, resulting in pockets of undersized rock which can expose the underlying filter, and pockets of oversized rock through which bedding can wash out; breakdown of poor quality stone due to prolonged exposure and wave action; and failure to extend the primary riprap far enough downslope to be below the level of wave action at low reservoir levels. 26 refs., 8 figs
[en] A complex methodology for torrents and erosion and the associated calculations was developed during the second half of the twentieth century in Serbia. It was the 'Erosion Potential Method'. One of the modules of that complex method was focused on torrent classification. The module enables the identification of hydro graphic, climate and erosion characteristics. The method makes it possible for each torrent, regardless of its magnitude, to be simply and recognizably described by the 'Formula of torrentially'. The above torrent classification is the base on which a set of optimisation calculations is developed for the required scope of erosion-control works and measures, the application of which enables the management of significantly larger erosion and torrential regions compared to the previous period. This paper will present the procedure and the method of torrent classification.
[en] The present paper shows the results obtained in the framework of 2 Nuclear Projects, in the topic of application of nuclear techniques to evaluate the erosion rates in cultivated soils. Taking into account the investigations with the 137CS technique, carried out in the Province of Pinar del Rio, was obtained and validated (first time) a methodology to evaluate the erosion impact in a cropland. The obtained methodology includes all relevant stages for the adequate application of the 137CS technique, from the initial step of area selection, the soil sampling process, selection of the models and finally, the results evaluation step. During the methodology validation process in soils of the Municipality of San Juan y Martinez, the erosion rates estimated by the methodology and the obtained values by watershed segment measures (traditional technique) were compared in a successful manner. The methodology is a technical guide, for the adequate application of the 137CS technique to estimate the soil redistribution rates in cultivated soils
[en] This article is a generalization of the results of theoretical studies of the effect of erosion control regimes on the operational properties of mold-forming parts of molds. The main problem is the provision of wear resistance and fatigue strength in the electroerosion processing of these types of products. The analysis showed that the fatigue strength is affected by the processing regimes and the coefficient after the erosion treatment. The index of wear resistance is determined both by the treatment modes and by the physical-mechanical properties of the billet materials. To ensure the operational performance of products, it is necessary to establish the physical picture of the processing of complex profile parts by finding the optimum eroding regime. (paper)
[en] In this paper, the slurry-erosion behavior of carbon steel was investigated. The synergism due to the interaction of erosion and corrosion was further divided into the erosion enhanced by corrosion and corrosion promoted by erosion and effort was made to experimentally measure corrosion-enhanced erosion component. The results indicated that the corrosion rate is promoted with increasing flow rate and the sand concentration. The corrosion-enhanced erosion is caused by the degradation of the mechanical erosion resistance and the non-uniform dissolution of surface. The mechanism of the erosion-enhanced corrosion was discussed in line with the changes in material properties during the erosion-corrosion processes. (author)
[en] Understanding the sediment source is very significant for erosion control in small watersheds. On the Loess Plateau of China, over 110 thousands of check dams were constructed in the past 60 years, which played an important role in controlling soil loss and also kept much information of erosion and sediment yield in the past. The objective of this investigation is to identify the sediment source by the 137Cs tracing method in a small watershed in the Loess Hilly Region of China. Fifty-five sampling sites were selected from the watershed (44 from the inter-gully area, 7 from the gully sides and 4 from the reference sites), and a total of 114 soil samples were collected from three sediment profile cores at the Sidizui watershed check dam constructed in 1959. Based on the erosion rate from the inter-gully area by the 137Cs models, and the total erosion amount deposited in the check dam since 1963, the relative contributions of sediment from the inter-gully area and gully area were estimated during 1963–2013. By comparing the difference of 137Cs activities of surface soils from the check dam (deposited in the 2011–2013 flood events), the inter-gully and gully areas, the relative contributions of sediment derived from the two source areas to the flood sediment during recent years (2011–2013) were estimated by a simple mixing model. Results showed that the erosion rate from the inter-gully area was about 3054 t/km2 a during 1963–2013, and the relative contributions of sediment from the inter-gully area and gully area were estimated to be 27 and 73%, respectively. The sediment from the inter-gully area was about 20% of the total sediment yield amount to the 2011–2013 floods, and from the gully area it was about 80%. The relative contribution of sediment from the inter-gully or gully area was not a fixed value in the watershed. Both of the inter-gully erosion and gully erosion should be simultaneously controlled, and more erosion control measures on the gully area should be taken in the subsequent watershed management in order to reduce the erosion amount in this region.
[en] Three values are used to calculate the thickness change rate: the initial value the thickness of the wall of the pipeline element, the final thickness at the date of inspection and the interval of time between the dates of the determination of thickness. There are two ways to select the interval of time: in the case of one operational control, the time interval is determined between the date of commissioning of the pipeline element and the date operational control, in the case where several operational controls the time interval can be determined between the dates neighboring controls. Various issues related to the definition of erosion-corrosion wear speed, the speed of formation of deposits on the basis of operational controls and indicators based on the use of corrosion with different exposure times are examined
[ru]Для расчета скорости изменения толщины используются три величины: начальная толщина стенки элемента трубопровода, конечная толщина на дату контроля и интервал времени между датами определения толщин. Используется два способа выбора интервала времени: в случае проведения одного эксплуатационного контроля интервал времени определяется между датой ввода элемента трубопровода в эксплуатацию и датой проведения эксплуатационного контроля, в случае, когда проведено несколько эксплуатационных контролей, интервал времени может быть определен между датами соседних контролей. Рассматриваются различные вопросы, связанные с определением скорости эрозионно-коррозионного износа, скорости формирования отложений на основе данных эксплуатационного контроля и на основе использования индикаторов коррозии с различным временем экспозиции
[en] Superficial erosion is one of the main soil degradation agents and erosion rates estimations for different edaphic climate conditions for the conventional models, as USLE and RUSLE, are expensive and time-consuming. The use of cesium-137 anthropogenic radionuclide is a new methodology that has been much studied and its application in the erosion soil evaluation has grown in countries as USA, UK, Australia and others. A brief narration of this methodology is being presented, as the development of the equations utilized for the erosion rates quantification through the cesium-137 measurements. Two watersheds studied in Brazil have shown that the cesium-137 methodology was practicable and coherent with the survey in field for applications in erosion studies. (author)
[en] Reservoir sedimentation has been recognized as an important environmental threat in the Moldavian Plateau of Eastern Romania. Measurements of the 137Cs content of reservoir and, sometimes, floodplain sediments have been used to estimate the rate of sedimentation over the past 13-36 years. The estimated mean sediment accumulation rates in the reservoirs from three geomorphological subunits vary between 2.6 and 7.9 cm/year with an average rate of 4.6 cm/year after April 1986. Strong relationships were established between the individual sedimentation rates and the drainage area within the southern and central part of the Moldavian Plateau. The shape of the 137Cs depth profile was used as the main approach. Taking into account that the standard pattern is in the form of a cantilever and based on burial magnitude of 137Cs peak derived from Chernobyl two chief patterns of reservoir sedimentation were identified, shallow and deep buried cantilever, respectively. (author)