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ANDRÉ RENAUD 《水文科学杂志》2013,58(2):109-116
Abstract The authors give data of water infiltrations in horizontal and vertical columns, and in a two dimensional model. The soils are two mixtures of sand and loam, and a natural sandy loam. The characteristics of these soils are given in the article. As a conclusion, the two dimensional problem can be approached by a linear combination of data in horizontal and vertical columns. 相似文献
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Charles W. CARLSTON 《水文科学杂志》2013,58(3):62-84
ABSTRACT Sir Charles Cotton (1964) has pointed out that in an earlier paper (Carlston, 1963) which related drainage density to hydrology, there was insufficient emphasis on the role of climate in its effect on drainage density. Re-examination of the relation of drainage density to base flow in the 15 basins originally described has revealed additional evidence that base flow is affected by precipitation or recharge (a climatic variable), while varying inversely with drainage density. Within the climatic region studied in the earlier paper (the Humid Subtropical Climate of the eastern U. S.), no evidence could be found that amount or intensity of rainfall affected the intensity of flood runoff or the scale of drainage density. In comparison with other climates, however, such as the Marine West Coast Climate, it is possible that the less intense precipitation of a marine climate may result in lower runoff intensities and lower drainage densities, however the lower mean temperatures of such climates may develop soils of generally higher infiltration capacity which would produce lower drainage densities. A progressive increase in aridity results in a decrease in soil and vegetal cover which greatly magnifies the range of drainage densities characteristic of semi-arid regions. In such regions, where the land sur-face has a good infiltration capacity rainfall sinks readily into the dry soil (although recharge to ground water may be negligible), and runoff is virtually zero, as is drainage density, Impermeable terranes devoid of vegetal and soil cover reject the rain, runoff is briefly total and drainage density may be greatly magnified, as in the South Dakota Badlands, where drainage density runs into the hundreds. Arid or Desert Climates should produce erosional landforms with generally high drainage densities, though not reaching the magnitudes of drainage density found in the semi-arid badlands where rainfall intensities are much higher. 相似文献
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郭祥云 《地震地磁观测与研究》2011,32(3):173-176
中国地震局地球物理研究所中国数字地震台网数据管理中心(CDSN DMC)根据美国地震联合研究会数据管理中心(IRIS DMC)发布的2011年3-4月全球地震动态,通过修订给出以下监测结果.2011年3-4月全球共发生M≥5.0地震886次,其中3月717次,4月169次.在3-4月发生的886次地震中,东半球共计780次,西半球共计106次.东半球发生M5.0-5.9中强震715次,M6.0-9.9强震65次,西半球发生M5.0-5.9中强震102次,M6.0-7.9强震4次.其中7级以上地震全球共4次,最大一次地震发生在日本本州东岸远海,发震时间2011年03月11日05∶47∶321,Mw=9.1. 相似文献
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《地震工程与工程振动》2008,28(6)
著名地震工程学家George W.Housner教授于2008年11月10日逝世。世界地震工程界的一颗巨星陨落了!对于他的溘然长逝,我们表示深切的悼念。 相似文献
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L. Olayinka ASSEEZ 《水文科学杂志》2013,58(3):61-62
Abstract When a river flows into a reservoir, the solid materials it carries sink to the bottom thus reducing the potential reservoir capacity. The suspended load of eight major western rivers flowing into Kainji Lake was determined as a part of the investigation of the suspended sediment of the reservoir. The sediment content in each sample was determined in parts per million. On the whole the results of this study is in agreement with the previous conclusion that the sediment load of the Niger was low. A range of 29–221 ppm was observed within the reservoir whereas the concentration in the inflowing rivers varied from 122–953 ppm. It was however not possible to determine the total sediment load because discharge data were lacking. The data presented herein confirm the earlier conclusion that the rate of silting is slow but indicate that locally high rate of sediment supply should give cause for anxiety regarding the possible growth of deltas as the months of these rivers. The full potential of this study is difficult to assess at this stage but it has revealed a number of problem areas worth looking into in future years. A number of future studies believed to be capable of giving the necessary data for operation and management of the reservoir are recommended. 相似文献
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W. B. Langbein 《水文科学杂志》2013,58(2):34-36
Abstract Sampling in undisturbed soils of clearcuts and adjacent unlogged virgin forests in western Oregon indicates that clear cutting results in reduced soil moisture depletion and accelerated recharge. 相似文献
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Dubovikov and Canuto (Dubovikov, M.S. and Canuto, V.M., Complete Eulerian-mean tracer equation for coarse resolution OGCMs. Geophys. Astrophys. Fluid Dyn., 2006, 100, 197–214), after averaging the tracer conservation equation in density coordinates and transforming to height coordinates, concluded that present ocean models are missing important terms in their mean tracer equations. Here we point out some errors made by Dubovikov and Canuto (2006) in their isopycnal averaging procedure. We draw on the temporal-residual-mean (TRM) theory and show that when the isopycnal averaging and coordinate transformation are performed correctly, the tracer equations of present ocean circulation models are recovered. We therefore conclude that present ocean circulation models are not neglecting the leading order terms identified by Dubovikov and Canuto (2006). 相似文献
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Summary Methods are outlined for determining the hydraulic properties of an aquifer, namely, the transmissivity and storativity from a well located near one or more impermeable barriers. The procedures are based on the theory of the nonsteady radial flow toward a well steadily discharging from an aquifer of semiinfinite areal extent. Two different flow systems have been considered, namely a well near an impermeable barrier and a well located between two impermeable barriers. 相似文献
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Geochemical research on C—O and Sr—Nd isotopes of mantle-derived rocks from Shandong Province,China 总被引:1,自引:0,他引:1
This paper presents systematic studies on the C—O and Sr—Nd isotopic compositions for Cretaceous Badou carbonatites, Fangcheng
basalts, and Jiaodong lamprophyres and Paleozoic Mengyin kimberlites in Shandong Province, China. Paleozoic kimberlites have
normal and uniform C—O isotopic compositions with δ13C and δ18O in the range of −4.8‰—−7.6‰ and +9.9‰—+13.2‰, respectively. However, Cretaceous three different types of mantlederived rocks
have quite different C—O isotopic compositions, indicating that the mantle sources are probably partially contaminated with
organic carbon-bearing crustal materials. These Cretaceous rocks show uniform and EMII-like Sr—Nd isotopic compositions and
also indicate that the mantle sources were affected by recycled crustal materials. Comparative studies of C—O and Sr—Nd isotopes
reveal that the lithospheric mantle beneath the eastern North China Craton had different isotope characteristics in the Paleozoic,
the early Cretaceous, and the Tertiary time. This demonstrates that the lithospheric mantle beneath the region underwent at
least twice reconstructions since the Paleozoic. Available data imply that the first reconstruction mainly happened during
the Triassic-Jurassic time with gradual changes and the second in the Cretaceous with abrupt changes. Results also show that
the early Cretaceous (especially at 120-130 Ma) was perhaps the key period leading to the dramatic change of the Mesozoic
geodynamics on the eastern North China Craton. 相似文献
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A. E. SCHEIDEGGER 《水文科学杂志》2013,58(4):87-92
Abstract It is shown that a thermodynamic analogy can be set up for structurally cyclic as well as for noncyclic river nets that satisfy Horton's law of stream numbers. In the latter case, the microcanonical formalism of statistical thermodynamics has to be used. 相似文献
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Sergio E. Serrano 《水文科学杂志》2013,58(1):177-205
Abstract Mathematical models are the means to characterize variables quantitatively in many groundwater problems. Recent advances in applied mathematics have perfected what is now called Adomian's decomposition method (ADM), a simple modelling procedure for practical applications. Decomposition exhibits the benefits of analytical solutions (i.e. stability, analytic derivation of heads, gradients, fluxes and simple programming). It also offers the advantages of traditional numerical methods (i.e. consideration of heterogeneity, irregular domain shapes and multiple dimensions). In addition, decomposition is one of the few systematic procedures for solving nonlinear equations. By far its greatest advantage is its simplicity of application. It may produce simple results for preliminary simulations, or in cases with scarce information. The method is described with simple applications to regional groundwater flow. Many applications in groundwater flow and contaminant transport are available in the literature. Editor D. Koutsoyiannis; Associate editor Xi Chen Citation Serrano, S.E., 2013. A simple approach to groundwater modelling with decomposition. Hydrological Sciences Journal, 58 (1), 1–9. 相似文献
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Disaggregation of the seismic hazard has become a popular technique to convey information on the main sources contributing
to the hazard at a particular site. Recently published work adopts geographic disaggregation analysis of seismic hazard as
a tool to identify dominant rupture scenarios for municipalities in Mainland Portugal. The authors conclude that the seismic
hazard in South and Central Portugal is dominated by the seismicity that takes place offshore, around 70km WSW of Cape S.
Vicente, both for the return periods of 475 years and 975 years. Whilst recognizing the merits of the approach taken and the
utility of the tools developed, we take issue with this last conclusion. We consider that the proposed disaggregation returns
a picture of the biases in the hazard analysis, more than any real feature of the distribution of relevant seismogenic sources. 相似文献