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This paper presents a comprehensive review on the interaction between hydrodynamic processes, beach morphology and sedimentology at large scale coastal behaviour along the coastline of Santa Catarina, between Laguna and São Francisco Island, a microtidal east coast swell environment with headland and bay geomorphologies. The parabolic bay shape equation has proven to be a convenient and practical tool for studying the stability of the headland-bay beaches, tombolos, and salients in Santa Catarina. The beaches exhibit different patterns of sediment removal as a function of the degree of beach curvature. In highly curved beaches, there is a well-developed shadow zone and a range of morphodynamic conditions, from a sheltered low-energy beach adjacent to the downdrift headland to a high-energy exposed beach on the straight end of the headland-bay beach. The less curved beaches instead, tend to show more uniform behaviour since they are directly exposed to incident waves. There is no obvious relationship between average wave height and mean grain size, showing the importance of sediment source to characterize the sedimentary distribution patterns in the study area. The analysis of beaches showed that beach morphodynamics and sequence profiles for a bay–headland coast in a microtidal east coast environment is a function of geological inheritance (e.g., distance between headlands and orientation, nearshore and inner shelf morphology, coastal plain morphology, and sediment source), and hydrodynamic factors (wave conditions, oceanic wave exposure and relative tidal range).  相似文献
2.
The equilibrium planform concept (EPC) for bayed beaches has achieved wide currency in coastal morphodynamics. The north coast of Ireland comprises a series of discrete headland-embayment beaches within which waves and currents recycle a finite sediment volume. It is therefore an ideal setting in which to explore the applicability of the concept. Application of the approach to 9 embayment beaches on the north coast of Ireland provides some insights into the application of the concept. The planform of some beaches does correspond to that predicted while others do not. Those whose measured planform does not correspond to the predicted planform can be interpreted through, (a) difficulty in identifying the wave diffraction point, (b) disequilibrium on the beach (sediment scarcity or excess), (c) geological control of beach morphology. The subjectivity in selecting the diffraction point renders alternative explanations difficult and reduces the utility of the approach on natural shorelines, where significant irregularities render identification of such points difficult.  相似文献
3.
The equation most commonly used to describe the bay planform was proposed by Hsu and Evans (1989) and it was obtained through empirical analysis of sand beach planforms.In the last decade interest in gravel sediments increased owing to their greater stability on beaches, compared with sand sediments. Due to the differences between the morphodynamics of sand and gravel beaches, which is strictly influenced by their different hydraulic characteristics, it was necessary to create a predictive instrument for this beach type as well.Therefore, in this study the standard Hsu and Evans equation (1989) was modified in order to make it applicable not only to sand beaches but also to gravel beaches. The shoreline was computed according to a parabolic model in polar coordinates whose coefficients are considered linearly dependent on the wave direction and related to the beach type. The estimation of the free parameters of the model was performed according to a statistical analysis of a shorelines data set of Mediterranean sand and gravel embayed beaches.  相似文献
4.
This note explains a technique used for pre-processing three-dimensional survey data obtained at embayed beaches that exhibit distinct alongshore curvature. Using a log-spiral function fitted to the beach planform, the data is transformed from Cartesian into an alternative alongshore–cross-shore coordinate system. When undergoing this transformation, the curvature in the survey data is effectively removed. This greatly simplifies the application of standard interpolation methods, and in this transformed coordinate system the alongshore and cross-shore directions are now explicitly defined. Using a property unique to the log-spiral, the interpolated data is readily transformed back into the original Cartesian coordinate system for further analyses and interpretation. The practical application and advantages of this technique are then demonstrated using survey data from two embayed beaches in south-eastern Australia.  相似文献
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海滩的稳定性及其演变是砂质海滩研究的重要内容。在全球砂质海滩普遍遭受侵蚀的背景下,分析部分稳定海滩的特征和原因可以为海滩维护和科学管理提供重要参考。本文基于近 11 年 (2010—2020 年) 青岛第一、第三和石老人海水浴场共 8 条典型剖面的实地监测高程数据,对海滩滩肩宽度和单宽体积进行计算对比,研究表明,除石老人海水浴场一个剖面变化较大外,其他剖面的滩肩宽度只变化了 0~14 m,是 11 年前的 0%~23.3%;单宽体积变化了 8.5~46.5 m3,是 11 年前的1.0%~9.4%;海滩剖面垂向扰动范围一般在 30~60 cm 范围内。海滩存在局部小尺度淤积或侵蚀,剖面形态总体较为稳定。海平面变化、台风和风暴潮等自然因素是海岸轻微侵蚀或调整的重要影响因素,但对海滩的优化管理 (包括定期监测海滩、适度展开养护、制定完善的管理政策和加强执行力度等人为因素) 可以应对这些海滩变化,并且已成为近年来该研究海滩保持稳定的关键因素。  相似文献
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