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991.
AquantitativeanalysisontheEgyptianMediterraneanwaters¥M.A.SaidandF.M.Eid(ReceivedSeptember21,19931accfeptedJanuary15,1994)Abs... 相似文献
992.
Although the Yellow River Delta and Bohai Sea coastal zone are long distance and different environment with Po River Delta and Adriatic Sea coastal zone, the comparison of data of two different areas and the evolution trend of two areas are quite similar. The influence of natural climatic changes on the evolution of the deltas and coastal zones exists both in ancient and modern times. The cold/wet period occurred in 1300—1400A. D. and 1550 —1850 A.D. within this"large scale" climatie cycle, and shorter periods (10— 35 years) of cold rainy weather alternated with warm/dry period are known as "Bruckner cycles" which have influence on the evolution of the deltas and coastal zones. 相似文献
993.
Q. J. Huggett A. K. Cooper M. L. Somers A. R. Stubbs 《Marine Geophysical Researches》1992,14(1):47-63
GLORIA side-scan sonographs from the Bering Sea Basin show a complex pattern of interference fringes sub-parallel to the ship's track. Surveys along the same trackline made in 1986 and 1987 show nearly identical patterns. It is concluded from this that the interference patterns are caused by features in the shallow subsurface rather than in the water column. The fringes are interpreted as a thin-layer interference effect that occurs when some of the sound reaching the seafloor passes through it and is reflected off a subsurface layer. The backscattered sound interferes (constructively or desctructively) with the reflected sound. Constructive/destructive interference occurs when the difference in the length of the two soundpaths is a whole/half multiple of GLORIA's 25 cm wavelength. Thus as range from the ship increases, sound moves in and out of phase causing bands of greater and lesser intensity on the GLORIA sonograph. Fluctuations (or wiggles) of the fringes on the GLORIA sonographs relate to changes in layer thickness. In principle, a simple three dimensional image of the subsurface layer may be obtained using GLORIA and bathymetric data from adjacent (parallel) ship's tracks. These patterns have also been identified in images from two other systems; SeaMARC II (12 kHz) long-range sonar, and TOBI (30 kHz) deep-towed sonar. In these, and other cases world-wide, the fringes do not appear with the same persistence as those seen in the Bering Sea. 相似文献
994.
995.
A simple sand trap is used to measure swash and backwash bedload transport rates on intertidal profiles. Data from sixty-eight beach experiments are used to calculate a mean value of 12.78 kg m?4s?2 for the calibration coefficient in the Bagnold beach equation. 相似文献
996.
The first map of the sea bed morphology and sedimentary features within the RMSTitanic search area is proposed from the interpretation of SAR side-scan sonar images. Downslope sedimentary features such as erosional
furrows and crown scarps constitute a 7 km wide instability corridor. A large field (15 km2) of asymmetrical sediment waves indicating a downslope transport is identified. Current-induced features corresponding to
associated sand ribbons and barchan dunes resulting from the Western Boundary Undercurrent action are mapped. The morphology
of theTitanic Canyon is also precised from the SAR images. Finally, the origin of the sea bed features is discussed in an attempt to link
each bed form to a sedimentary process. 相似文献
997.
Descriptive Analysis and Classification of Benthic Communities in Some Mediterranean Coastal Lagoons (Central Italy) 总被引:3,自引:0,他引:3
Abstract. Benthic samples were taken seasonally at 32 stations in five coastal lagoons of Central Italy (Fogliano, Monaci, Caprolace, Fondi, and Lungo) during a two-year period (1982–1984). Composition and distribution of benthic populations in each lagoon as well as seasonal trends of species richness, density, diversity, and redundancy are presented and discussed.
The faunal differentiation appeared to be mainly due to the different degree of water exchange, both with marine and continental systems. 相似文献
The faunal differentiation appeared to be mainly due to the different degree of water exchange, both with marine and continental systems. 相似文献
998.
Geological and geophysical surveys of active submarine volcanoes offshore and southeast of Epi Island, Vanuatu, New Hebrides
Arc, have delineated details of the structure and acoustic stratigraphy of three volcanic cones. These submarine cones, named
Epia, Epib, and Epic, are aligned east-west and spaced 3.5 km apart on the rim of a submerged caldera. At least three acoustic
sequences, of presumed Quaternary age, can be identified on single-channel seismic-reflection profiles. Rocks dredged from
these cones include basalt, dacite, and cognate gabbroic inclusions with magmatic affinities similar to those of the Karua
(an active submarine volcano off the southeastern tip of Epi) lavas. 相似文献
999.
1000.
Seismic reflection profiling demonstrates the importance of mass movement in the north-central California Borderland. Bulk
properties of surficial hemipelagic sediments in the Santa Barbara, Santa Cruz, and San Nicolas basins show that different
types of mass-transported sediments have different properties, although their general sedimentologic characteristics are very
similar. Slump deposits have moderate water contents (48% wet weight basis), high plasticity indices (46%), and moderate activities
(1.6). For debris flows these values are low: 28%, 5%, and 0.3, respectively, and for other types (liquefied flow, mudflows,
and turbidities) the values are high: 54 to 63%, 49 to 58%, and 1.2 to 1.5, respectively. 相似文献