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1.
城市地理分形研究的回顾与前瞻   总被引:57,自引:7,他引:57  
刘继生  陈彦光 《地理科学》2000,20(2):166-171
简要地回顾了城市地理学的分形研究历程,重点介绍了国内分形城市和城市体系的研究成果,对比了中外有关研究的异同,指出了存在的问题和未来的发展方向,论述了城市地理分形研究的意义和前景。  相似文献   

2.
Based on various data,it can be concluded that eight monsoonal temperate glaciers in China were in stationary or ad-vancing between 1900s~1930s and 1960s~1980s,and were in retreating during 1930s~1960s and 1980s~present under the background of climate warming.The total glacier area has reduced by 3.11 km2 with a mean front altitude rise of 3.2 m/yr and 4 glaciers have disappeared in Mt.Yulong during 1957~1999.Mass balance records indicated that glaciers had suf-fered a constant mass loss of snow and ice during the last several decades,and the accumulated mass balance in Hailuogou basin in Mt.Gongga was 10.83 m water equivalent in the past 45 years with a annual mean value of-0.24 m,and the value at Baishui glacier No.1 was-11.38 m water equivalent in the past 52 years with-0.22 m/yr.The inverse variation between mass balance and temperature in China and the Northern Hemisphere reflected that climate warming is mainly corresponding to constant ice and snow mass loss in the past 50 years.The change of the glaciers’ surface mor-phology has occurred since the 1980s,such as enlargement of glacier-lake and ice falls,resulted from the accelrative cli-mate warming.  相似文献   

3.
Global and Regional Water Availability and Demand: Prospects for the Future   总被引:1,自引:0,他引:1  
One of the most pressing global issues currently facing mankind is the increase in world population and its impact on the availability of freshwater. Recent estimates of water stocks and flows through the world's hydrologic cycle and their spatiotemporal variability illustrate the nature of current and projected water disparities throughout the world. As all such problems manifest themselves at smaller scales, a major challenge in freshwater assessments is how to handle this on different geographical scales. Increasing use of water is creating water shortages in many countries that are projected to have significant population increases in the next 25 years. Humankind is projected to appropriate from 70% to 90% of all accessible freshwater by 2025. Agriculture is the dominant component of human water use, accounting for almost 70% of all water withdrawals. Hence, many of the solutions to water-related food and environmental security come from within agriculture by increasing the efficiency and productivity of water use. Many factors significantly impact the increasing water demand, including population growth, economic growth, technological development, land use and urbanization, rate of environmental degradation, government programs, climate change, and others. Demand management, not increasing supply availability, is the realistic way forward. Although, thanks to market forces, the threatened exhaustion of nonrenewable resources has not happened, renewable resources, such as freshwater, remain problematic because they are vulnerable to human overuse and pollution. Climate change adds further risks and uncertainties to the global picture requiring the adoption of adaptive management in water resources based on monitoring and reevaluation. Although climate change may be perceived as a long-term problem, it needs to be addressed now because decisions today will affect society's ability to adapt to increasing variability in tomorrow's climate. If we are to balance freshwater supply with demand, and also protect the integrity of aquatic ecosystems, a fundamental change in current wasteful patterns of production and consumption is needed. Recognition of the links between rapidly growing populations and shrinking freshwater supplies is the essential first step in making water use sustainable.  相似文献   

4.
近年来有关温室气体,特别是CO2浓度上升导致的全球气候变暖将引起灾难性后果的理论,已成为全球关注和讨论的重点.本研究通过分析和总结器测资料和最近2000 a来温度序列,得出如下观点和结论:1)全球变暖是客观存在的,但是全球升温的幅度存在不确定性;2)人类活动和自然因素共同影响着气候变暖,仅从自然因素方面考虑未来存在降温的可能,因此未来温度的变化趋势很难预测;3)过去2000 a来冷暖变化频繁交替,最近100 a来的升温速率是否是过去2000 a中最大的时期存在不确定性.因此,在得出明确结论之前,需要进一步加大研究力度,明确这些不确定性.  相似文献   

5.
正From July 31st to August 1st, 2018, the International Workshop on Cryospheric Changes and Their Regional and Global Impacts,co-sponsored by the State Key Laboratory of Cryospheric Science of Northwest Institute of Eco-Environment and Resources (NIEER), Chinese Academy of Sciences,People's Government of Dunhuang City,the International Association of Cryospheric  相似文献   

6.
新经济地理学和经济地理学的对话——回顾和展望   总被引:2,自引:0,他引:2  
克鲁格曼获得2008年诺贝尔经济学奖,使得新经济地理学成为众人瞩目的焦点,也引起了经济地理学家对新经济地理学的再次关注.本文在介绍克鲁格曼在美国地理学年会专题报告的基础上,回顾比较了经济地理学家和经济学家眼中的新经济地理学,最后探讨了新经济地理学和经济地理学在理论前沿和政策研究方面的融合潜力.克鲁格曼在2010年美国地理学年会上全面回应了经济地理学家对新经济地理学的批评,并以经济学家的身份阐述了新经济地理学和传统经济地理学在学术范式和学术方法方面的差异,有助于消除经济地理学家对新经济地理学的误解.尽管新经济地理学的模型仍然存在很多不足,但是学者们仍然在努力完善模型,试图使模型的假设更加符合现实,从而结论更加可靠.新经济地理学的发展可以为经济地理学的学术实践提供新的视角.另一方面,尽管经济地理学家的视角和研究范式不同于经济学家,但是,传统经济地理学的研究更加贴近实际,更能够揭示现实世界的丰富性和复杂性,从而可以为新经济地理学的抽象研究在理论和实践卜提供思路.在涉及政策方面的研究.新经济地理学面临的最大问题是其模型的假设严重偏离现实,因此其政策推论的可靠性值得商榷.同时,传统经济地理学的案例研究非常具体而全面,但是案例的特殊性使得其难以得到一般化的结论.在两者都存在各自的局限性的情况下,鼓励两者的交流和合作必然有助于经济地理研究的深入,并且可以为区域发展提供更加合理的政策建议.  相似文献   

7.
Growth Rates of Global Energy Systems and Future Outlooks   总被引:1,自引:0,他引:1  
The world is interconnected and powered by a number of global energy systems using fossil, nuclear, or renewable energy. This study reviews historical time series of energy production and growth for various energy sources. It compiles a theoretical and empirical foundation for understanding the behaviour underlying global energy systems’ growth. The most extreme growth rates are found in fossil fuels. The presence of scaling behaviour, i.e. proportionality between growth rate and size, is established. The findings are used to investigate the consistency of several long-range scenarios expecting rapid growth for future energy systems. The validity of such projections is questioned, based on past experience. Finally, it is found that even if new energy systems undergo a rapid ‘oil boom’-development—i.e. they mimic the most extreme historical events—their contribution to global energy supply by 2050 will be marginal.  相似文献   

8.
近50 年来天山地区典型冰川厚度及储量变化   总被引:8,自引:2,他引:6  
冰川储量变化与冰川水资源量变化以及冰川对河川径流的贡献量密切相关。在GPR-3S技术支持下, 本研究基于雷达测厚数据、不同时期的高分辨率遥感影像、地形图及实测资料, 分析了天山三个典型地区四条代表性冰川近期厚度及储量变化特征, 并通过对比探讨了造成变化差异的可能原因。结果表明, 1962-2006 年乌鲁木齐河源1 号冰川厚度平均减薄0.15m a-1, 冰储量亏损26.2×106 m3, 冰川末端平均退缩3.8 m a-1;博格达峰南坡的黑沟8 号冰川在1986-2009 年间, 冰舌平均减薄0.57 m a-1, 冰储量损失了25.5×106 m3, 末端平均退缩11.0 m a-1;位于博格达峰北坡的四工河4 号冰川在1962-2009 年间冰舌平均减薄0.32 m a-1, 冰储量亏损14.0×106 m3, 末端平均后退8.0 m a-1;1964-2008 年间, 托木尔峰青冰滩72 号冰川冰舌平均减薄0.22 m a-1, 由此至少造成冰储量亏损14.1×106 m3, 末端退缩达40.0 m a-1。对比分析显示, 青冰滩72 号冰川消融退缩最为强烈, 黑沟8 号冰川次之, 与乌鲁木齐河源1 号冰川、科其喀尔冰川相差不大, 稍大于四工河4 号冰川和哈密庙尔沟冰川。这种差异可能与区域气候变化和冰川物理特征有直接关系。  相似文献   

9.
我国固沙植物引种的历史及展望   总被引:10,自引:0,他引:10  
本文通过对我国固沙植物引种工作近三十五年历史的回顾,总结了工作取得的成就,其中包括:发掘野生固沙植物资源和引进国外固沙植物的概况.选引的固沙植物在我国沙漠改造利用和沙漠化防治工作中所起的作用,固沙植物引种驯化的理论和方法,并根据上述工作基础,对引种机构、研究水平和深度,以及研究内容等方面的发展进行了预测。  相似文献   

10.
The Great Silk Road is a trade route linking the East and West which gave impetus to the development of ancient society, and Kazakhstan is the heart of the trade route. At the initial stage, intensive transaction of goods took place between the West and East through The Great Silk Road. This paper reviewed the history of development of the Silk Road and suggested that today to construct the "New Silk Road", Kazakhstan should face many issues, and take many steps to become a Eurasian hub through taking full of advantages. Above all, developing mechanisms of integration and sustainable development is our urgent need.  相似文献   

11.
Understanding the Changing Planet lacks the spark of wonder and synthesis that initially attracted me into geography. Its structure around compelling questions reflects disciplinary fragmentation and the model of interdisciplinary science favored in the late twentieth century. It is suggested that geography can move beyond the “big tent with three poles” approach, to a twenty-first-century hyperdisciplinary model where content, science, analysis, and synthesis blur and a new bottom-up science can emerge. In this science, new theory and even grand unified theory might be possible. As discussed in Understanding the Changing Planet, the Web and the emergence of volunteered geographic information are examples. This would make study of the whole earth and its systems “a respectable object for scholarly efforts.”  相似文献   

12.
近10年来中国耕地资源的时空变化分析   总被引:105,自引:5,他引:100  
根据中国资源环境数据库中的耕地数据以及20世纪80年代末期、1995年和2000年3期覆盖全国时间跨度约为10年的遥感数据,对中国耕地时空变化进行分析。总趋势表明,近10年来我国耕地资源总量有所增加;东部及沿海地区优质耕地迅速减少;东北地区和内蒙古自治区耕地大量开垦;水田旱地转换明显。利用GIS方法将耕地变化数据与中国生态环境质量数据进行叠加,表明近10年来耕地的生态环境质量下降了。近10年耕地动态变化的空间分布表现出13种动态格局。对80年代末至1995年 (前5年) 和1995年至2000年 (后5年) 这2个时间段内的耕地变化进行对比分析,表明了前5年与后5年耕地变化的动态格局有空间上的相似性,但前后变化幅度相差较明显。近10年来气温的升高与中国水田北移有较好的一致性,而降水的减少对西北地区耕地的撂荒和开垦有明显作用。中国经济的发展所导致的城市化过程使得大量耕地被占用。近10年来相关的耕地政策对控制耕地面积的减少有作用,但耕地的总体质量却下降了,这直接影响了粮食产量。  相似文献   

13.
14.
本文从全球角度和历史经验论述金融中心发展,尤其是国际金融中心发展的条件、路径和制约因素,并综合"金融地理"、"金融法学"及"时区理论"的观点论述国际金融中心发展及增长。本文并对香港及内地金融中心(上海、北京、深圳)在后金融危机的时代及中国的伟大崛起中的发展机遇,及在全球金融网络的位置及角色和前景作出展望,并对上海建设国际金融中心作出建议。  相似文献   

15.
火山活动是影响全球气候变化的重要因子之一.强烈的火山喷发会向大气圈排放大量的火山灰、水蒸气和SO2等气体,尤其是SO2能在平流层中形成气溶胶,并停留很长时间,减少太阳对地表的辐射量,影响局地或全球气候.地质历史记录表明,火山活动与气候冷期有密切的联系,现代观测和模拟资料也显示火山活动后的一年至几年内,火山周围地区甚至全球产生不同程度的降温.现有研究表明,在火山喷发的活跃时期,火山气体喷发物对地球气候系统的影响程度可能超过CO2等气体产生的温室效应.  相似文献   

16.
17.
利用封闭湖泊流域进行古降水量重建的历史、现状及未来   总被引:1,自引:3,他引:1  
回顾了利用封闭湖泊流域进行古降水量重建的简单历史,重点论述了其理论与方法的特点及发展源流;在此基础上,结合作者近几年在青藏高原开展的这方面的研究工作,对季风区进行此项研究的可能方法、理论依据及其初步应用进行了分析,重点阐述了其存在的缺点与不足及未来的改进方式。  相似文献   

18.
<正>The modern geopolitical situation clearly demonstrates the development of two opposite directions.The first one includes the formation of a common global space,which unites the interests of individual countries that have similar political goals.The formation of the military alliance of NATO and countries of the European Union that seek to dominate in the world politics is a remarkable example of such  相似文献   

19.
This article presents an extensive comparative review of the emergence and application of geodemographics in both the United States and United Kingdom, situating them as an extension of earlier empirically driven models of urban socio-spatial structure. The empirical and theoretical basis for this generalization technique is also considered. Findings demonstrate critical differences in both the application and development of geodemographics between the United States and United Kingdom resulting from their diverging histories, variable data economies, and availability of academic or free classifications. Finally, current methodological research is reviewed, linking this discussion prospectively to the changing spatial data economy in both the United States and United Kingdom.  相似文献   

20.
The global ski tourism market has been in a relatively mature period. However, passenger flows are stagnating in many countries and the growth perspectives are not very appealing. This change of the tourism market troubled the entire ski industry with new challenges, leading to the ski tourism industry model established in the 20th century failing to meet the current development needs. According to multiple data sources, including relevant industry reports and the latest data from internetm, this article based on a variety of these reports and the latest data from website, analyzed the ski tourism market’s both sides of supply and demand, systematically summarized the evolution of ski tourism industry since the 21st century, discussed the process of the ski tourism industry’s development and the economy’s growth, and revealed the relationship between the influencing factors of ski tourism market’s potentials. Meanwhile, the main problems and challenges in the ski market were also summarized. The results showed that global ski tourism had entered a mature stage since the beginning of 2000. Moreover, there was a specific correlation between skiing participation rate and GDP, which varied with the regional economic level and the maturity degree of skiing industry. Despite some impacts from COVID-19, the ski industry in most regions exhibited signs of recovery in 2021. The Winter Olympic Games in China have brought new opportunities to the skiing industry and have been expected to encourage global participation in skiing. However, some existing ski resorts in different countries and regions may not significantly contribute to the future development of global ski tourism, and the potential growth of ski tourism market might be small and mainly concentrated in China. At present, the biggest threat to the ski market is baby boomers having long been the bulk of ski resort visitors. The ski market is faced with this aging problem and the widespread phenomenon of ski culture fault. How to meet the needs of this new generation of customers who lack ski backgrounds or cultures is a severe challenge for all emerging and existing ski resorts around the world. Besides, public transport accessibility, service quality and resorts operation capacity have also been the improvement direction of the ski market in dire need.  相似文献   

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