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951.
The physical basis of the linkage between magnitude and timing of channel flow hydrographs and drainage network morphometry is reviewed. Small Hortonian and structurally Hortonian networks are analysed using numerical runoff simulation. For Hortonian networks the variability of the geometry of individual channels and subcatchments within each Strahler order has generally little effect upon the overall character of the hydrograph in channels of higher order. If the network is also structurally Hortonian, the analysis of the simultaneous formation, travel, and concentration of the hydrographs in all channels of the network can be simplified to a sequence of one representative hydrograph per channel order. This approach is used in this study. Three major runoff processes control the flow hydrograph characteristics: the overland flow process which determines the water supply to the drainage network; the channel flow process which translates the hydrograph in space and time; and the drainage network process which concentrates and magnifies the flow at the junctions of the drainage network. Functional relations for the hydrograph peak, timing, and flow velocity are presented. For a given uniform rainfall and infiltration rate, the peak of the channel flow hydrograph is shown to increase geometrically with channel order, and its magnitude is directly related to the bifurcation ratio. The travel time of the peak also increases geometrically with channel order, and it is directly related to the channel length ratio over velocity ratio. The flow velocity of the peak changes in a downstream direction as a function of the bifurcation and slope ratio. It was also found that for negligible channel storage the channel flow and drainage network processes do not contribute significantly to the observed nonlinear response of a watershed to precipitation. 相似文献
952.
953.
《The Professional geographer》1988,40(1):116-131
Books reviewed in this article: Boundary Control and Legal Priniciples . Curtis M. Brown , Walter G. Robillard and Donald A. Wilson . Lost Initiatives: Canada's Forest Industries, Forest Policy, and Forest Conservation . R. Peter Gillis and Thomas R. Roach . The Navajo Atlas: Resources, People, and History of the Dine Bikeyah . James M. Goodman . The City and the Sign . M. Gottdiener AND Alexandros Ph . Lagopoulos , EDS. The Comfortable House: North American Suburban Architecture 1890–1930 . Alan Gowans . Arabic-Islamic Cities. Building and Planning Principles . Besim Salim Hakim . Contemporary Climatology . Ann Henderson -Sellers and Peter J. Robinson . A Trace of Desert Waters . Samuel G. Houghton . Geography, Resources and Environment. Vol. 1: Selected Writings of Gilbert F. White. Vol. 2: Themes from the Work of Gilbert F. White . Robert W. Kates AND Ian Burton , ED. Spatial Dimensions of Unemployment and Underemployment (A Case Study of Rural Punjab) . Gopal Krishan . Maps of the Holy Land: Cartobibliography of Printed Maps, 1475–1900 . Compiled by Eran Laor , assisted by Shoshana Klein . The Geography of Third World Cities . Stella Lowder . A Perspective on U.S. Farm Problems and Agricultural Policy . Lance Mc Kinzie , Timothy G. Baker AND Wallace E. Tyner . Soil Erosion and Its Control. R.P.C . Morgan , ED Geopolitics . Patrick O'Sullivan . Landscape, Meanings and Values . Edmund C. Penning -Rowsell AND David Lowenthal , EDS. 相似文献
954.
955.
Jean-Jacques Macaire Christian Di-Giovanni Florent Hinschberger 《Comptes Rendus Geoscience》2005,337(8):735-744
Accumulation of organic matter in fens of fluvial valleys is often related to a low terrigenous matter delivery and to palaeoenvironmental conditions inducing low mechanical erosion. These assumptions come from the interpretation of contents in organic (MO) and mineral (MM) matters in sediments, expressed in percents, and then exactly anticorrelated. Calculation of mass accumulation rates of MO and MM , expressed in g?m?2?yr?1, shows that and generally are not anticorrelated and that high values of and could appear simultaneously. That expression of MO and MM accumulation makes it possible to precise the climatic and human impact on sedimentation. To cite this article: J.-J. Macaire et al., C. R. Geoscience 337 (2005). 相似文献
956.
Geochemical discriminations of sandstones from the Mohe Foreland basin,northeastern China: Tectonic setting and provenance 总被引:5,自引:0,他引:5
Andrey A. Sorokin 《中国科学D辑(英文版)》2005,48(5):613-621
The Mohe region near the border area of China with Russia is in Heilongjiang Province. Topographically the area consists of lower mountains or hills situated at the northern end of the Da Hinggan Mountains. Struc-turally the Mohe basin rests on the north margin of the Ergun Block, and the Mongol-Okhotsk Orogen is lo-cated to the north of the basin. Due to poor access conditions and good vegetation coverage, previous researches on the basin are much weak with few spe-cial geological inves… 相似文献
957.
Earthquake-controlled event deposits and its tectonic significance from the Middle Permian Wandrawandian Siltstone in the Sydney Basin,Australia 总被引:3,自引:0,他引:3
DU Yuansheng G. R. Shi & GONG Yiming . Faculty of Earth Sciences China University of Geosciences Wuhan China . School of Ecology Environment Deakin University Victoria Australia 《中国科学D辑(英文版)》2005,48(9):1337-1346
Earthquake is a disaster event resulting from rapid and intensive crustal vibration caused by fault activity, volcanic eruption, or block dilapidation. Heezen and Ewing[1] and Heezen and Dyke[2] were the first to note earthquake-related mass movement and associated deposits in connection to the turbidity currents and submarine slumps triggered by the Grand Bank Earthquake in 1929. Seilacher[3] defined redeposited sedimentary beds, disturbed and modified by earth- quakes, as seismite. Since t… 相似文献
958.
Guangyou?ZhuEmail author Shuichang?Zhang Yingbo?Liang Jinxing?Dai Jian?Li 《中国科学D辑(英文版)》2005,48(11):1960-1971
The northeastern area of Sichuan Basin, southwestern China, is the area with the maximal reserve of natural gas containing
higher hydrogen sulphide (H2S) that has been found among the petroliferous basins of China, with the proven and controlled gas reserve of more than 200
billion cubic meters. These gas pools, with higher H2S contents averaging 9%, some 17%, are mainly distributed on structural belts of Dukouhe, Tieshanpo, Luojiazhai, Puguang,
etc., while the oolitic-shoal dolomite of the Triassic Feixianguan Fm. (T1f) is the reservoir. Although many scholars regard the plentiful accumulation of H2S within the deep carbonate reservoir as the result of Thermochemical Sulfate Reduction (TSR), however, the process of TSR
as well as its residual geological and geochemical evidence is still not quite clear. Based on the carbon isotopic analysis
of carbonate strata and secondary calcite, etc., together with the analysis of sulfur isotopes within H2S, sulphur, gypsum, iron pyrites, etc., as well as other aspects including the natural gas composition, carbon isotopes of
hydrocarbons reservoir petrology, etc., it has been proved that the above natural gas is a product of TSR. The H2S, sulphur and calcite result from the participation of TSR reactions by hydrocarbon gas. During the process for hydrocarbons
being consumed due to TSR, the carbons within the hydrocarbon gas participate in the reactions and finally are transferred
into the secondary calcite, and become the carbon source of secondary calcite, consequently causing the carbon isotopes of
the secondary calcite to be lower (−18.2‰). As for both the intermediate product of TSR, i.e. sulfur, and its final products,
i.e. H2S and iron pyrites, their sulfur elements are all sourced from the sulfate within the Feixianguan Fm. During the fractional
processes of sulfur isotopes, the bond energy leads to the 32S being released firstly, and the earlier it is released, the lower δ 34S values for the generated sulphide (H2S) or sulfur will be. However, for the anhydrite that participates in reactions, the higher the reaction degree, the more
32S is released, while the less 32S remains and the more δ 34S is increased. The testing results have proved the process of the dynamic fractionation of sulfur isotopes. 相似文献
959.
In a sequence of glacigenic sediments at Aberdaron, Foraminifera were obtained from samples located specifically in order to differentiate between opposing models of depositional environment. All the diamict samples yielded remarkably uniform assemblages, with similar numbers of benthic specimens and benthic species per unit weight of sediment, similar planktic : benthic ratios, and similar ratios of clearly allochthonous to possibly autochthonous elements. This is precisely as predicted by the terrestrial model of sedimentation, where all of the sediments are interpreted as being derived from the melting of glacier ice rich in marine debris entrained during passage along the Irish Sea Basin. The results lend no support to a glacial marine model, since no faunal responses to increasingly distal sedimentary environments are observed. However, the fauna is dominated by the Foraminifera Elphidium excavatum (Terquem) forma clavata Cushman, which is commonly assumed to indicate glacial marine conditions. The modern distribution of similar assemblages suggests that it is just as likely to represent the cold, reduced salinity conditions that would have prevailed in the northern Irish Sea Basin for much of the Quaternary. 相似文献
960.