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1.
城市地面沉降研究进展及其发展趋势 总被引：12，自引：1，他引：12
地面沉降是城市主要地质灾害之一。随着中国城市化进程的加快，地面沉降规模扩大，危害加剧，本文简述了国内外地面沉降概况，对地面沉降的成因、危害、机制、数学模拟、监测、防治等方面的研究进展进行了综合论述，并指出，建设工程性地面沉降，孔隙水运移机制、地下水和地面沉降模型耦合、地面沉降生态-经济-社会影响评估、地下水采灌优化设计、地面沉降系统防治、地面变形高精度监测、城市化建设与地面沉降的相互关系等，是今后城市地面沉降研究的主要方向。 相似文献
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城市基准地价是我国地价体系的重要部分,它是以城市定级为基础而确定的区域土地使用权的平均价格,需要从消费需求和投资需求等方面分析。该文根据临沂市2009年地价动态监测结果,分析该地区地价和房价还处于较低水平。 相似文献
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北方寒冷地区城市哈尔滨人口城市化与土地城市化协调关系研究 总被引：3，自引：3，他引：0
以哈尔滨市为研究范围,构建了人口城市化、土地城市化指标体系,运用熵值法计算各指标的权重,结合协调发展模型,分别研究了哈尔滨市1997-2014年期间人口城市化的内部协调性、土地城市化的内部协调性以及人口城市化和土地城市化的协调度及协调发展水平,并对人口城市化、土地城市化与协调发展水平进行了研究。结果表明：哈尔滨市的人口城市化内部协调性和土地城市化内部协调性都表现出前期加速,后期平稳的状态,在20世纪90年代,人口城市化内部协调性和土地城市化内部协调性都迅速提高,进入21世纪以后,协调度均保持在0.9左右,波动较小,内部协调度较高;综合人口城市化和土地城市化的协调度和相对发展度来看,除1999-2000年处于高级协调外,在研究期的其余时段哈尔滨市人口城市化和土地城市化基本处于初级协调状态,人口城市化与土地城市化的非同步性,是制约两者协调发展的关键因素,其中人口城市化对协调发展水平的影响更大。 相似文献
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土地问题是城镇化建设的一个突出问题。目前城镇化进程中还存在依赖土地程度过高、土地闲置、浪费、利用率偏低、城乡用地不能统筹、管理粗放等问题。新型城镇化要走集约、智能、绿色、低碳的道路,由速度扩张向质量提升转型,这就要求城镇化进程中土地规划要更加科学、土地利用要更加节约集约,土地管理要更加精细。 相似文献
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家庭联产承包责任制实现了土地所有权和使用权的初步分离,使农民获得了相对独立的承包经营权,极大地调动了农民的生产积极性。然而,随着农村经济社会的发展,人地矛盾日益激化,土地的边际生产力已出现明显的递减趋势,土地小规模家庭经营,农业的比较利益大大下降;同时,农村的剩余劳动力涌向经济较发达的大中城市,城市化进程骤然加剧等,使得土地家庭承包经营这一土地制度逐渐显露出自身的缺陷。在稳定农村土地承包关系的前提下,促进农村土地流转,可以在一定程度上发挥土地的规模效益,促进农村经济社会的健康持续发展。 相似文献
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在城市化与土地利用结构的协调发展成为焦点问题的时代背景下,以新疆乌鲁木齐市为研究区域,采用Johansen协整检验和Granger因果关系分析法,对乌鲁木齐市2000-2015年的城市化水平及5类代表性城市用地结构变化数据进行了处理,并对城市化与用地结构进行了因果关系分析。结果表明：（1）2000-2012年,乌鲁木齐市城市化水平由84.82%降至77.12%,呈下降趋势;2013-2015年由77.73%升至81.62%,呈上升趋势,造成这一现象的主要原因是非农业人口增长速率相对于农业人口增长速率较慢;（2）2000-2015年各类用地所占比例变化情况如下：居住用地比例均在26%以上,明显高于其他用地;工业用地比例较为稳定,均为15%~19%;公共设施用地2014-2015年明显下降,即从平均比例11.46%降至5.03%;城市道路用地比例较稳定,均为5.8%~7.5%;绿地比例呈上升趋势,由20.01%升至30.94%;（3）城市化与居住用地之间的Granger因果关系不明显,工业用地、公共设施用地、城市道路用地是引起城市化的Granger原因,城市化是绿地的Granger原因。对乌鲁木齐市城市化与土地利用结构进行因果关系分析,对城市用地格局的改善、土地利用战略以及有关政策法规的制定具有一定的参考意义。 相似文献
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A spatial-temporal model with Model Maker tool is designed to retrieve Land Surface Temperature (LST) and to describe the changes of urban heat island, as well as urban development. Spectral Radiance, Brightness Temperature, NDVI, and Emissivity are first calculated from TM and ETM+, which are then used to compute LST by using Qin et al.’s mono-window algorithm. The LST is classified based on normalized statistical method, and the normalized heat images are computed between different times. Therefore, the urban heat changes can be shown in the map clearly and directly through an urban heat conversion matrix. Such a model has been applied in this study to obtain the urban heat conversion matrix of South China from 1990 to 2000. The results indicate that the LST increased areas mainly locate along the major roads in the eastern bank of the Pearl River, which is a result of speedy urban expansion and need to be noticed in the future. 相似文献
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Northcote TG 《GeoJournal》1996,40(1-2):127-133
Perhaps nowhere in Canada, if indeed in North America, could two adjacent watershed basins be selected which show such remarkable differences in their historical and recent response to human population growth effects. One — the Fraser — covers some 234,000 km2 (about one quarter of the province of British Columbia) and houses nearly two-thirds of its total population. The other — the Okanagan — forms a small part (some 14,000 km2) of the upper Columbia River drainage in Canada. Native Indian populations at maximum before European contact in the late 1700s were about 50,000 in the Fraser basin and probably less than a fifth of that in the Okanagan. Present total resident populations of the Fraser and Okanagan basins, about 2 million and 1\4 million respectively, have greatly different distributions and thereby effects within the watersheds they occupy. In addition seasonal tourist populations have important and differential impacts within the two watersheds. Expression of these effects on water, fisheries and other aquatic resources of the two basins are explored along with possibilities and suggestions for their sustainable development. The latter, despite some glimmers of hope, will not be tenable without major changes in public attitude, in government policy at all levels, and in other measures which to many may seem impossible. 相似文献
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“两湖一库”是典型的喀斯特高原湖泊,湖库周边生态环境极为脆弱,其土地利用变化对所在区域生态安全/供水安全及社会经济发展带来重要影响。基于“源－汇”理念和黔中“两湖一库”地区1998－2018年4期遥感解译数据,采用土地利用动态度模型分析近20年来“两湖一库”地区土地利用动态演变规律,并运用定量与定性分析相结合的方法探究其驱动力。结果表明:（1）1998－2018年建设用地、林地、未利用土地（主要为暂时性未利用土地）面积不断增加,水域面积波动减少,耕地、草地面积持续减少,其中建设用地和未利用土地在各时段均为变化最活跃的地类。（2）年均综合土地利用动态度由1998－2008年的1.33%提高至2008－2013年的2.4%和2013－2018年的2.3%。近10年各地类间的相互转换较10年前更为活跃。（3）主要的土地利用“源－汇”转换关系表现为耕地转为林地和建设用地、草地转为林地和耕地。（4）各地类加速向建设用地转换,建成区面积迅速扩张,“两湖一库”供水压力进一步增大。（5）人口压力、经济发展等因素是“两湖一库”地区建设用地扩张的主要驱动因素,政策因素对林地和水域面积变化有重要影响。研究结果可以为“两湖一库”地区土地利用、规划及社会－经济－生态协调发展提供参考。 相似文献
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In Nigeria, increasing evidence indicates a deteriorating man-land relationship. Negative changes in landscape quality, lowering both the productivity and aesthetic quality of the natural environment, may have serious effects on the nation's economy. In rural areas, declining soil fertility and soil erosion threaten the ability to produce sufficient food. In urban areas, competition for productive agricultural land has led to its conversion to urban uses. Earth materials required for urban development have been obtained by widespread landscape destruction. Expansion of urban areas into sensitive valley, marsh, and lagoon environments has led to an increased frequency of urban floods and flood damage. A developing conservation ethic must be accompanied by a practicable framework for land use control. 相似文献
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Subglacial landsystems in and around Okanagan Valley, British Columbia, Canada are investigated in order to evaluate landscape development, subglacial hydrology and Cordilleran Ice Sheet dynamics along its southern margin. Major landscape elements include drumlin swarms and tunnel valleys. Drumlins are composed of bedrock, diamicton and glaciofluvial sediments; their form truncates the substrate. Tunnel valleys of various scales (km to 100s km length), incised into bedrock and sediment, exhibit convex longitudinal profiles, and truncate drumlin swarms. Okanagan Valley is the largest tunnel valley in the area and is eroded >300 m below sea level. Over 600 m of Late Wisconsin-age sediments, consisting of a fining-up sequence of cobble gravel, sand and silt fill Okanagan Valley. Landform–substrate relationships, landform associations, and sedimentary sequences are incompatible with prevailing explanations of landsystem development centred mainly on deforming beds. They are best explained by meltwater erosion and deposition during ice sheet underbursts.During the Late-Wisconsin glaciation, Okanagan Valley functioned as part of a subglacial lake spanning multiple connected valleys (few 100s km) of southern British Columbia. Subglacial lake development started either as glaciers advanced over a pre-existing sub-aerial lake (catch lake) or by incremental production and storage of basal meltwater. High geothermal heat flux, geothermal springs and/or subglacial volcanic eruptions contributed to ice melt, and may have triggered, along with priming from supraglacial lakes, subglacial lake drainage. During the underburst(s), sheetflows eroded drumlins in corridors and channelized flows eroded tunnel valleys. Progressive flow channelization focused flows toward major bedrock valleys. In Okanagan Valley, most of the pre-glacial and early-glacial sediment fill was removed. A fining-up sequence of boulder gravel and sand was deposited during waning stages of the underburst(s) and bedrock drumlins in Okanagan Valley were enhanced or wholly formed by this underburst(s).Subglacial lake development and drainage had an impact on ice sheet geometry and ice volumes. The prevailing conceptual model for growth and decay of the CIS suggests significantly thicker ice in valleys compared to plateaus. Subglacial lake development created a reversal of this ice sheet geometry where grounded ice on plateaus thickened while floating valley ice remained thinner (due to melting and enhanced sliding, with significant transfer of ice toward the ice sheet margin). Subglacial lake drainage may have hastened deglaciation by melting ice, lowering ice-surface elevations, and causing lid fracture. This paper highlights the importance of ice sheet hydrology: its control on ice flow dynamics, distribution and volume in continental ice masses. 相似文献
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J. U. Obot Dr. 《GeoJournal》1981,5(3):243-249
Calabar was selected for settlement by the Efik people in 1600 because of its suitability for controlling the slave trade. It did not develop into a major urban centre till the 1970s. This was because of poor transportation development. The available water transport was poorly run by a privately managed British Company, the Elder Demster.With the creation of a state capital in 1967 the government developed ferry services. Theses did not only encourage the migration of people from the rural areas to the newly created state capital for employment in the government and industrial establishments, but triggered off urbanization processes. The opening of a land route in 1978 increased population migration, concentration and urbanization.The increased population is not accompanied by increased food supply. Food is scarce and very highly priced especially the protein-rich foods. The low labour productivity is not unconnected with the prevalent malnutrition and undernourishment in the municipality. Here the government is reminded of its responsibility in meaningful planning that will take care of the necessary food supply now lacking in the area. 相似文献
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20世纪90年代上海中心城区的地面沉降在地下水开采量没有增加的情况下出现了新一轮的增长。与此同时,上海进行了大规模的城市化建设。通过对中心城区地面沉降量与工程建设进行相关性分析发现,近年来中心城区的地面沉降量与工程建设具有相关性。目前城市化建设引起地面沉降的现象已受到关注,但尚缺乏对城市化进程引起地面沉降机制的系统研究。针对上海市城市化进程引起地面沉降的因素进行分析探讨,城市化进程引起的沉降包括建筑物荷载及交通荷载等外荷载引起的沉降,基坑开挖、降水及隧道施工等工程施工引起的土体压缩,以及隧道渗漏,周边地区对地下水补给量的减小,地下构筑物挡水效应等引起的地下水位持续下降而诱发的沉降 相似文献
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The Okanagan Centre section is the stratotype for marine oxygen isotope stage (MIS) 4 sediments (Okanagan Centre Drift) in the southern interior of British Columbia, Canada. Previous work suggested that these sediments record two glacial and two interglacial cycles. This study reports on detailed sedimentological and geochronological investigations of lithostratigraphic units comprising the Okanagan Centre sequence, revealing successive deposition of subaqueous and subaerial outwash, a subglacial till and glaciolacustrine sediments during MIS 4. A limiting optical age of 113 ± 8 ka defines the base of this sequence. Sedimentological, paleopedological, optical dating and tephrochronological data from sediments near the middle of the sequence reveal soil development (MIS 3) in eolian sediments deposited on a river terrace overlying a deglaciated surface. Within these sediments, identification of Mt. St. Helens set C tephra suggest sedimentation between 50 and 35k 14C a BP. Optical dating corroborates the tephrochronology and suggests that this surface formed after ～52 ± 7 ka. The record of MIS 2 glaciation is restricted to deglaciation, and overlies MIS 3 sediments above an unconformity possibly related to regional subglacial meltwater erosion. Eolian sediments containing Mt Mazama set O tephra (～7.62k cal a BP) cap the sequence. 相似文献
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地面沉降是普遍存在的一种地质灾害。人类经济社会的发展,尤其是城市化进程日趋加快,一些人类不合理的活动导致了地面沉降频繁发生,给生产、建设和人民生活造成极大的危害。要防治地面沉降发生,必须认清其产生的根源,方能收到药到病除的效果。本文采用归纳分析的方法,将地面沉降划分为5种类型,依据其产生的不同根源,有针对性地提出了预防和治理的措施。 相似文献
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Dynamics of land use/cover changes and the analysis of landscape fragmentation in Dhaka Metropolitan, Bangladesh 总被引：3，自引：0，他引：3
Rapid urban expansion due to large scale land use/cover change, particularly in developing countries becomes a matter of concern since urbanization drives environmental change at multiple scales. Dhaka, the capital of Bangladesh, has been experienced break-neck urban growth in the last few decades that resulted many adverse impacts on the environment. This paper was an attempt to document spatio-temporal pattern of land use/cover changes, and to quantify the landscape structures in Dhaka Metropolitan of Bangladesh. Using multi-temporal remotely sensed data with GIS, dynamics of land use/cover changes was evaluated and a transition matrix was computed to understand the rate and pattern of land use/cover change. Derived land use statistics subsequently integrated with landscape metrics to determine the impact of land use change on landscape fragmentation. Significant changes in land use/cover were noticed in Dhaka over the study period, 1975–2005. Rapid urbanization was manifested by a large reduction of agricultural land since urban built-up area increased from 5,500?ha in 1975 to 20,549?ha in 2005. At the same time, cultivated land decreased from 12,040 to 6,236?ha in the same period. Likewise, wetland and vegetation cover reduced to about 6,027 and 2,812?ha, respectively. Consequently, sharp changes in landscape pattern and composition were observed. The landscape became highly fragmented as a result of rapid increase in the built-up areas. The analysis revealed that mean patch size decreased while the number of patches increased. Landscape diversity declined, urban dominance amplified, and the overall landscape mosaics became more continuous, homogenous and clumped. In order to devise sustainable land use planning and to determine future landscape changes for sound resource management strategies, the present study is expected to have significant implications in rapidly urbanizing cities of the world in delivering baseline information about long term land use change and its impact on landscape structure. 相似文献
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Faced with a shortage of land suitable for agricultural use and a burgeoning urban population, the Province of British Columbia was the first Canadian government to take direct action to control farmland alienation. The problems and successes of this unique program are analyzed and discussed. 相似文献