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1.
In the north-western part of Szechwan Basin is the famous Chengtu Plain,with an area of 8,000 sq. km. and at 500-700 m. above the sea level. It is a huge alluvial plain formed by cohesion of many alluvial fans, among which the Minking fan is the largest, constituting 2/3 of the area of Chengtu Plain. 相似文献
2.
Do Young Oh 《Urban geography》2013,34(7):1066-1068
In this study, we use a Geographic Information System-based index to measure spatial accessibility of public high schools. The index is applied to the Baton Rouge Metropolitan Statistical Area in 1990, 2000, and 2010. Overall, urban areas had consistently worse accessibility scores compared with suburban and rural areas. High schools with more African American students tended to have poorer accessibility levels. Schools with lower accessibility tended to be associated with poorer average student performance, and the effect strengthened between 2000 and 2010. In developing a better understanding of the accessibility of public high schools, this paper reaffirms the significance of space, place, and race, and challenges the notion of declining relevance of accessibility in Louisiana public education policymaking. 相似文献
3.
In the north-western part of Szechwan Basin is the famous Chengtu Plain,with an area of 8,000 sq. km. and at 500-700 m. above the sea level. It is a huge alluvial plain formed by cohesion of many alluvial fans, among which the Minking fan is the largest, constituting 2/3 of the area of Chengtu Plain. 相似文献
4.
Under the framework of ecological civilisation, the formulation of territorial spatial planning(TSP) and improvement of spatial governance systems are of great practical significance. Since the founding of the People’s Republic of China, land-use planning(LUP) has experienced profound changes, and tremendous research efforts have been made in that field. However, systematic studies on LUP history are scarce.To bridge the existing gap, this study traced back to the emergence of LUP, described its... 相似文献
5.
ABSTRACTExisting theory of urban transformation under neoliberalization describes cities as the institutional arena in and through which neoliberal strategies of urbanism emanate and are contested. Emphasis is placed on the interaction between state and market without paying adequate attention to their internal dynamics. This study of urban transformation in the Beijing metropolis identifies a distinct trajectory whereby commodification of urban land has been actively pursued in response to the decentralization of developmental responsibilities and recentralization of tax revenue collection instituted by the central state. An urban development strategy is practiced whereby land commodification, city planning, and mega event hosting are integrated and mutually reinforcing. The research shows a pattern of land commodification and development dominated by newly developed construction land in the near suburbs, and reveals a picture of increased spatial inequality and intensified social discontent as a consequence of city-centered land development. Contrary to popular perception of the state and market as diametrically opposed principles of political organization, the Chinese state is found to have transformed and reshuffled itself to embrace and take advantage of the market for its developmental agenda. 相似文献
6.
The region under discussion lies in the eastern border of the Tibetan Plateau. andhas been deeply di(?)sected by the Tatu Ho, Yalung Kiang and their triibutaries. Deep canyons and the flat plateaus form strong contrast in topography. Some native terms have been wisely used, such as, Koaga for glaciated mountains and peaks,“Tang” for bare rock region, “Tsu” for alp pasture, “Kan” for precipitous valley slope, and “Lon” for stream channel. 相似文献
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8.
The policy framework claiming to support Indigenous people in remote parts of Australia is in disarray with Commonwealth, state and territory governments proposing closure of remote communities on a range of economic and social policy grounds, but facing significant criticism on economic, environmental, social and cultural grounds. Western Australia's proposal to close 150 remote communities, announced in late-2014, is reviewed and found to reveal a profound failure of geographical literacy. 相似文献
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10.
Seed germination was compared among wild, in situ-managed (wild plants let standing in areas cleared for agriculture), and cultivated populations of the columnar cacti Stenocereus pruinosus, Polaskia chichipe, Myrtillocactus schenckii, and Polaskia chende, species representing a gradient from higher to lower management intensity, respectively. We hypothesized that seeds from cultivated populations have higher water requirements to germinate than seeds of other populations, and that such difference is stronger in species more intensely managed. Germination was evaluated under water potential treatments at 0.0, ?0.2, and ?0.4 MPa. Interspecific differences were identified; germination rates markedly decreased in S. pruinosus and P. chichipe as water potential reduced. M. schenckii seeds germinated better at ?0.2 MPa, and seeds of P. chende in all treatments. Seed germination of wild and cultivated populations was similar in all cases and, therefore, at the population level domestication does not appear to have influenced variations in germination of the studied cacti species. However, experiments to test whether germination of seeds from plants with clear signs of domestication differs with seeds from other plants and their differential germination and seedling survival in wild, in situ-managed and cultivated environments could help to precise the influence of domestication on these plants. 相似文献
11.
《The Professional geographer》2013,65(4):458-466
This research tests the spatial mismatch hypothesis by comparing the employment probabilities of central city versus suburban African American males in nine metropolitan areas. Treatment effects models are used to control for the effects of both individual characteristics and residential self-selection on the probability of employment. A positive effect of suburban residential location on employment is found for the residents of Dallas, Los Angeles, New York, and Washington, while no effect is found for the residents of Cleveland, Houston. Jackson, Memphis, and Newark. The general conclusion to be drawn is that the spatial mismatch effect is contingent on the particular characteristics of each metropolitan area. Preliminary analysis shows that metropolitan areas with a spatial mismatch effect are large in terms of total population and total land area, and have less efficient transportation systems. 相似文献
12.
《Geomorphology》2004,57(1-2):41-51
Dust samples, collected monthly for 15 years from 50 urban sites in 10 cities in Gansu Province, China, provide information on modern rates of dust deposition in the desert and Gobi areas and in the Loess Plateau. Dust deposition is highest during spring months and lowest during autumn months, in both the desert and Gobi areas and the Loess Plateau. There is a significant positive correlation between dust deposition and dust event, and an inverse correlation between dust deposition and precipitation. The 15-year mean maximums in the desert and Gobi areas and the Loess Plateau are 498.64 and 327.02 t km−2 year−1, respectively, and the mean minimums are 290.22 and 180.86 t km−2 year−1, respectively. Drought may have a widespread, major influence on the modern rates of the dust deposition. 相似文献
13.
Sedimentation rates in the Wanggang salt marshes, Jiangsu 总被引：1，自引：0，他引：1
WANGAijun GAOShu JIAJianjun PANShaoming 《地理学报(英文版)》2005,15(2):199-209
1 IntroductionLand-ocean interaction in coastalzone is one of the key m atters of the International G eosphereand Biosphere Program (IG BP). The key problem s of the second phase in the next decadeinclude the m aterial cycle, the system evolution process … 相似文献
14.
《Norsk geografisk tidsskrift. Norwegian journal of geography》2012,66(3-4):193-197
Located at approximately 150 m above the present base level, the caves of Niaux, Lombrives and Sabart are an old drainage system, which worked between the Vicdessos and Ariège Valleys. In these caves, three successive sedimentary units were studied in detail. Each unit consists of two parts: the lower deposit is detrital, of fluvial origin, and testifies to a hydrological working of the conduit system; the upper deposit of each unit is mostly speleothems, corresponding to a draining of the conduits as the palcokarst evolved above base level. This is similar to the present environment of the caves. Only the speleothems from the upper part of each unit were dated by the 230Th/234 U method. The dates, from 27 samples, are in good agreement with Europe and North America data. The data from the middle (250 to 200 ka BP) and upper (90 to 20 ka BP) fluvial sediments correspond to major glacial events, which re-activated the karst system. Two further events resulted in a lack of carbonated sedimentation, the first between 350 and 290 ka BP, the second between 175 and 130 ka BP. Comparing the data from other places, these two events can be related to glacial periods of minor importance in the study area, because of the lack of erosion and of detrital sediments. The oldest detrital sediments are covered by speleothems older than 350 ka BP and, partly, older than 720 ka BP (from paleomagnctic data to be confirmed); from sedimentary data, they may not be related to a glacial event. They are perhaps contemporary with the area's initial cave formation. 相似文献
15.
Spatial-temporal scales effects are general among human-nature interactions.However, the laws and mechanisms of the interaction between humans and the environment at different spatial-temporal scales remain to be identified. The Hexi Corridor in Northwest China is located in the eastern section of the Silk Road and is one of the world’s first long-distance cultural exchange centers. Here we present a comprehensive dataset of the Hexi Corridor, including changes in environments, population, wars,... 相似文献
16.
Global climate change has been evident in many places worldwide. This study provides a better understanding of the variability and changes in frequency, intensity, and duration of temperature, precipitation, and climate extremes in the Extensive Hexi Region, based on meteorological data from 26 stations. The analysis of average, maximum, and minimum temperatures revealed that statistically significant warming occurred from 1960 to 2011. All temperature extremes displayed trends consistent with warming, with the exception of coldest-night temperature(TNn) and coldest-day temperature(TXn), which were particularly evident in high-altitude areas and at night. Amount of precipitation and number of rainy days slowly increased with no significant regional trends, mainly occurring in the Qilian Mountains and Hexi Corridor. The significance of changes in precipitation extremes during 1960–2011 was high, but the regional trends of maximum 5-day precipitation(RX5day), the average precipitation on wet days(SDII), and consecutive wet days(CWD) were not significant. The variations in the studied parameters indicate an increase in both the extremity and strength of precipitation events, particularly in higher-altitude regions. Furthermore, the contribution from very wet precipitation(R95) and extremely wet precipitation(R99) to total precipitation also increased between 1960 and 2011. The assessment of these changes in temperature and precipitation may help in developing better management practices for water resources. Future studies in the region should focus on the impact of these changes on runoffs and glaciers. 相似文献
17.
Karl-Dag Vorren 《Norsk geografisk tidsskrift. Norwegian journal of geography》2017,71(2):114-121
The author studied the causal relationships between palsa formation, the maintenance of palsas, their final thawing, and climate. His main approach was to compare his observations with other researchers’ observations of recent palsa formation and degradation, and the use of relevant palaeoclimatic data. A more than 10 km2 large palsa mire complex in Sør-Varanger Municipality, northern Norway, was studied in terms of vegetation and stratigraphy 50 years ago, and then observed between 2005 and 2015, when the final palsa thawing occurred. The decisive climatic factor for the maintenance of existing palsas – annual mean temperatures below -1 °C, stated earlier by researchers – seemed to be valid also in the studied case. However, the results showed that new palsa formation may require a series of consecutive years with temperatures between -1 and -2 °C in annual mean temperatures. There is a possibility of detecting former palsas (i.e. since thawed) by stratigraphic investigations in cases of lateral erosion of palsas. Stratigraphic corings and field observations in the selected study area did not indicate earlier periods of palsa thawing prior to the modern one. The author concludes that the present thawing thus reflects a reversal of the final cooling stage of the present interstadial (Holocene). 相似文献
18.
Using the observed data from 184 stations over the Yunnan-Guizhou Plateau (YGP) from 1961 to 2005, the long-term trends in sunshine duration, cloud amount, dry visibility (Vd), dry extinction, and water vapor over the YGP are analyzed. The results show that 85% of the stations recorded shortening annual sunshine duration, with the decrease rates between ?12.2 and ?173.7 h/10yr. Results of Mann-Kendall tests indicate that, among the stations with decreasing sunshine duration, 63.7% of them experienced an abrupt change that started in the 1970s and peaked in the 1980s. This decreasing trend has reversed in the early years of the 21st century. The cloud cover and water vapor content in the mid and lower levels over the YGP had no obvious changes during the study period. The annual averages of Vd declined from 34 km in the 1960s to 27 km at present. The annual mean dry extinction coefficient trended upward, from 0.176 to 0.190, on the YGP from 1980 to 2005. Analyses of cloud cover, water vapor, atmospheric visibility, and dry extinction coefficient revealed that emitted tropospheric aerosols (including air pollutants) resulting from increased energy consumption over the YGP could be a major factor influencing the reductions of sunshine duration and atmospheric visibility. 相似文献
19.
Ranchettes are low-density, rural parcels typically from thirty-five to seventy acres that have proliferated across the Rocky Mountain West. They consume large amounts of land and increase fragmentation, leading to potentially negative impacts on the ecology and cultural identity of local places. Although many anecdotal accounts decry the rise in ranchettes, few studies measure their prevalence or spatial patterns. We use archival and contemporary land ownership data to measure ranchette development in La Plata County, Colorado, an amenity-rich county popular for recreation, retirement, and ranchettes. Results show continual yet slowing growth across the decades with patterns of growth spreading in a contagious effect around initial nodes of development. 相似文献
20.
Karin Holmgren Jan Risberg Johan Freudendahl Mussa Achimo Anneli Ekblom Joao Mugabe Elin Norstr?m Sandra Sitoe 《Journal of Paleolimnology》2012,48(2):311-322
Stratigraphic variations in diatom composition and phytolith abundance in a sediment core from a small, hydrologically isolated waterbody, Lake Nhauhache, Mozambique, provide evidence of water-level fluctuations over the past ~2,300?years. Ten AMS radiocarbon dates on bulk sediment samples show that the lake came into existence about 2,300?years ago and that it has dried out since then, but only for brief time periods. Changes in the diatom assemblage composition indicate that lake level fluctuated in response to shifting humidity conditions. The changes reflect wetter conditions ca. 300 BC?CAD 800, more variable conditions between AD 800 and 1150, a distinct dry phase within the time span AD 1150?C1700 and a return thereafter to more humid conditions until present. There is general agreement between the Lake Nhauhache record and other records from the Southern Hemisphere summer rainfall region. This suggests that sediments from small interdunal lakes, which are abundant along the coast of southern Africa, provide reliable, regional paleoenvironmental information about an area from which more such data are needed. 相似文献