A REVIEW OF PHYSICAL GEOGRAPHY IN SOUTH ASIA     

Vishwas S. Kale  M.A.  M.Phil.  Ph.D. 《Singapore journal of tropical geography》1994,14(2):212-228

The development of physical geography in South Asia has generally followed the British and European trends. Diverse themes from denudational chronology to palaeoflood geomorphology have attracted the attention of geomorphologists, particularly in the last 25 years. In addition, geographers’ interest in climatology and biogeography became pronounced during the 1980s. Major methodological shifts in the late 1960s in the west have affected geographical studies in South Asia. These shifts include the use of methods of quantification, remote sensing data, and the increased importance of field and laboratory studies. The second notable aspect in recent times is the accelerating interest amongst physical geographers in environmental studies and the applied aspects of the discipline as well as an increased interaction with scientists in cognate fields. An attempt is also made to identify the key research themes that will interest physical geographers in the near future.  相似文献   

Slope-induced changes in channel character along a gravel-bed stream: The Allt Dubhaig,Scotland     

Rob Ferguson  Phil Ashworth 《地球表面变化过程与地形》1991,16(1):65-82

Changes in channel character along a small river in the Scottish Highlands are described using measurements in seven reaches over a 3 km length with no significant tributaries but a decline in slope from 0.02 to 0.00015 because of local baselevel control. This decline in slope is associated with rapid downstream fining of the gravel bed followed by an abrupt transition to a sand bed. The channel pattern alters progressively rather than abruptly, in the sequence (1) near-braided, (2) meandering with active point-bar chutes, (3) meandering with active outer-bank talweg, (4) stable equiwidth sinuous. The changes in channel pattern and hydraulic geometry are predicted better by rational approaches based on critical shear stress or other physical concepts than by purely empirical discriminant or trend equations. Measurements in five reaches confirm a downstream decrease in shear stress and the amount and calibre of bedload. It is argued that the downstream changes in channel character in this stream are induced by profile concavity inherited from deglacial conditions, are typical of many streams in mountainous areas and can be understood in terms of slope-induced changes in hydraulic properties.  相似文献   

Robustness of variograms and conditioning of kriging matrices   总被引：1，自引：0，他引：1  

Phil Diamond  Margaret Armstrong 《Mathematical Geology》1984,16(8):809-822

Current ideas of robustness in geostatistics concentrate upon estimation of the experimental variogram. However, predictive algorithms can be very sensitive to small perturbations in data or in the variogram model as well. To quantify this notion of robustness, nearness of variogram models is defined. Closeness of two variogram models is reflected in the sensitivity of their corresponding kriging estimators. The condition number of kriging matrices is shown to play a central role. Various examples are given. The ideas are used to analyze more complex universal kriging systems.Research performed while on leave at Centre de Geóstatistique et de Morphologie Mathématique, Fontainebleau.  相似文献   

Catastrophic events reveal the dynamic nature of salt-marsh vegetation in Southern California   总被引：1，自引：0，他引：1  

Joy B. Zedler  Jordan Covin  Chris Nordby  Phil Williams  John Boland 《Estuaries and Coasts》1986,9(1):75-80

Recent hydrological disturbances, including flooding, dry-season streamflow, and drought, greatly altered coastal wetland habitats in sourthern California. At Tijuana Estuary, a six-year study of salt-marsh vegetation patterns during these rare conditions documented substantial temporal variability in plant growth and distribution. Important to cordgrass (Spartina foliosa Trin.) dynamics were the amount and timing of streamflows, which reduced soil salinity and alleviated stresses on plant growth. Poorest growing conditions occurred in 1984 when both river and tidal flows were lacking; soils had low moisture and extreme salinities (avg.=104‰ in September). Plant stress was documented in 1984 as high mortality (62% fewer stems than in 1983) and reduced height (19% less than in 1983). Cordgrass height was greatest in 1980 following winter flooding (20% increase over 1979); densities were greatest in 1983 with summer freshwater influxes (60% increase over 1982). A carbon allocation model is proposed to explain the varied responses.  相似文献   

Changing patterns of population distribution in Zimbabwe     

Zinyama L  Whitlow R 《GeoJournal》1986,13(4):365-384

This paper critically evaluates the causes and consequences of changes in population distribution in Zimbabwe during the colonial period and since independence in 1980. Five main aspects of population geography are examined. Firstly, by way on background on contemporary patterns of settlement and land use, the history of tenure policies is outlined. Secondly, the distribution of the African population as revealed in the 1982 census is described and major changes between the census years of 1962, 1969 and 1982 are discussed. Thirdly, changing patterns of settlement and land use within the peasant farming areas (Communal Lands) are examined in the context of increasing population pressures. Fourthly, trends in the growth of the main urban centres and the process of urbanisation of the African population are described. Fifthly, post-independence development policies directed at effecting changes in the distribution of population are discussed with particular reference to the land resettlement programme. The present distribution of population is seen as the product of interacting political, economic and environmental factors, knowledge of which is essential in devising appropriate development strategies to achieve a more equable balance of population and resources.  相似文献   

A three-dimensional geophysical model of the crust in the Barents Sea region: model construction and basement characterization   总被引：2，自引：0，他引：2  

Oliver Ritzmann  Nils Maercklin  Jan Inge Faleide  Hilmar Bungum  Walter D. Mooney  Shane T. Detweiler 《Geophysical Journal International》2007,170(1):417-435

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Editorial: papers presented at JONSMOD 2006     

Phil Dyke 《Ocean Dynamics》2007,57(4-5):237-237

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Flow and deposition of pyroclastic granular flows: A type example from the 1975 Ngauruhoe eruption,New Zealand     

Gert Lube  Shane J. Cronin  Thomas Platz  Armin Freundt  Jonathan N. Procter  Cargill Henderson  Michael F. Sheridan 《Journal of Volcanology and Geothermal Research》2007

Small-volume pyroclastic density currents (PDCs) are generated frequently during explosive eruptions with little warning. Assessing their hazard requires a physical understanding of their transport and sedimentation processes which is best achieved by the testing of experimental and numerical models of geophysical mass flows against natural flows and/or deposits. To this end we report on one of the most detailed sedimentological studies ever carried out on a series of pristine small-volume PDC deposits from the 1975 eruption of Ngauruhoe volcano, whose emplacement were also witnessed during eruption. Using high-resolution GPS surveys, a series of lateral excavations across the deposits, and bulk sedimentological analysis we constrained the geomorphology, internal structure and texture of the deposits with respect to laterally varying modes of deposition.  相似文献   

SCAP meeting no.10     

Mike Bode  Phil Charles  Carlos Frenk 《Astronomy& Geophysics》2001,42(2):2.27-2.28

Mike Bode , Phil Charles and Carlos Frenk report the minutes of the tenth meeting of the Standing Conference of Astronomy Professors, held at the RAS, Burlington House on 30 January 2001.  相似文献   

Editorial     

Phil Potts  Mireille Polv 《Geostandards and Geoanalytical Research》2001,25(1):5-5

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