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1.
地表物质组成与土地沙漠化 总被引：3，自引：1，他引：2
土地沙漠化是在干旱、半干旱地区,由于特定的自然条件和人类不合理地利用自然资源,所引起的环境退化过程。随着这个过程的进一步发展对人类的不利影响越来越大。因此,对土地沙漠化的问题,也越来越得到人们的普遍重视。在内蒙伊克昭盟及宁夏、陕北地区,沙漠化的土地面积,分别占总土地面积的32%、25.2%和45.9%。这说明了在上述地区土地沙漠化是相当严重的。造成土地沙漠化的自然因素,除气候的干旱、多风外,地表物质的组成是其物质基础。而地表物质组成与沉积条件密切相关,因此,不同的沉积环境形成不同的沉积物,其质地性质差异很大。这些不同的沉积物,对土地沙漠化的发生及发展速度、类型和治理措施都有直接关系。因此,研究地表物质组成与土地沙漠化之间的关系是极为重要。 相似文献
2.
DAVID M. THEOBALD 《Geographical review》2001,91(3):544-564
ABSTRACT. A deficiency common to both the historical debates over loss of agricultural land and the current discussions of urbanization and sprawl is a limited understanding of land‐use dynamics beyond the urban fringe. Data aggregated at the county level poorly capture the fine‐grained pattern of land‐use change beyond the dynamic urban‐rural interface. Furthermore, current urban‐based definitions are poorly suited to delineate these areas, and low‐density, exurban land use is difficult to measure using existing land‐cover databases. Urbanization and the conversion of once‐agricultural or other natural resource lands to other uses has traditionally been tracked using urban areas, as delimited in the U.S. census. Urban densities are typically defined as areas with more than 1,000 people per square mile, or 1.6 people per acre (U.S. Census Bureau 2000). Assuming an average of 2.5 people per housing unit, this translates to roughly 0.7 units per acre, or approximately 1 unit per 1.6 acres. The analytical units used in the census, however, both overbound and underbound areas with urban densities. About one‐third of urban areas in 1990 comprised lower‐than‐urban housing density, thanks to overbounding. But, then, one‐third of locations that had urban‐level housing densities failed to be included in urban areas as a result of underbounding, which, if counted, would have constituted another 18 million acres of urban area. An increase over time of the average number of acres required per housing unit in exurban and higher‐density locations occurred in roughly one‐third of U.S. counties from 1960 to 1990 and persisted from 1990 to 2000. In 2000 roughly 38 million acres were settled at urban densities, and nearly ten times that much land was settled at rates from low, exurban density (as low as one house per 40 acres) to higher rates (up to one per 10 acres). This represents a continuing encroachment on land previously given over to other uses—habitat or agriculture. Practitioners of natural resource management need to recognize the ubiquity of exurban development and better incorporate the fine‐scale patterns of land use beyond the urban fringe. 相似文献
3.
城市群作为国家新型城镇化的主体形态,表征其空间结构和组织演变的城镇建设用地具有明显“群态化”特征。借鉴群落生态学理论,利用城镇用地开发速率指数、景观指数、核密度估计等方法,对长三角城市群1978—2017年城镇建设用地的规模分布、形态变化和集聚状态进行探讨,提炼出快速城镇化背景下城镇建设用地的群态化演变模式。研究结果显示：① 随着长三角城镇建设用地的不断增长,城镇建设用地规模表现出从低级向高级逐渐跃迁的层级变动特征和明显的区域分异,汇合成群态化发展的“量”的物质基础。② 在空间发展上,城镇建设用地斑块趋于紧密、均衡,其形态变化由分散、无序逐渐变为集中和规整;在空间集聚上,城镇建设用地热点区向大城市集聚,逐渐打破城市行政界线,呈组团式发展态势,催生出群态化演变的“质”的提升。③ 在40年的快速城镇化过程中,长三角城镇建设用地经历了独立发育模式、优先生长模式、组团嵌套模式和圈层共生模式,最终形成“群内有群、多重嵌套”的群态化模式。本文通过分析城镇建设用地群态化的演变过程,重新解读城市群作为城镇化的主体形态这一现实规律,为推进新型城镇化进程和促进城市群高质量一体化发展提供相关的理论基础。 相似文献
4.
Tree stem (>2 m tall) mortality was assessed following a late dry‐season wildfire across a seasonally flooded elevation gradient at Workshop Jungle, near Darwin, in the Northern Territory of Australia. For all species combined, dead stems had significantly smaller diameter at breast height (dbh) than living stems. Assessment of tree‐stem damage following a tropical cyclone at Cobourg Peninsula, NT, revealed that damaged stems had significantly greater dbh than undamaged stems for all tree species sampled across a boundary between monsoon rainforest and savanna. A greater proportion of stems were damaged by the cyclone than by the fire (28 per cent as against 18 per cent), although there were considerable between‐community differences in the proportion of damaged stems at the two sites. The fire caused little impact (<10 per cent) on total basal area of three different forest communities on the elevation gradient at Workshop Jungle. The cyclone was found to cause >50 per cent damage to total basal area of three different communities on Cobourg Peninsula. It is suggested that the combination of a cyclone followed by an intense fire in storm debris could potentially destroy a monsoon rainforest through its impact on all tree‐size classes. This may explain why some monsoon rainforests rapidly contracted following Cyclone Tracy that destroyed the city of Darwin on Christmas Day, 1974. 相似文献
5.
D.I. Smith 《Applied geography (Sevenoaks, England)》1981,1(1):31-39
An urban land use survey of Lismore, New South Wales, was undertaken to assess the character of buildings affected by the major flood of March 1974. A questionnaire survey was then carried out on a sample of 140 residential houses, 212 commercial establishments and all 26 industrial concerns in the flood-prone area to assess actual flood damage. Potential flood damage was estimated by a professional valuer and by questionnaire information. Comparison of actual and potential damage showed that actual damage was only 52.4 per cent of potential damage in the residential sector, 23.5 per cent in the commercial sector and 6.1 per cent in the industrial sector. It is concluded that the relatively low levels of actual damage reflect the high degree of preparedness by the urban population, particularly in the commercial and urban sector. The results indicate the level of damage reduction feasible given adequate flood warning schemes and appropriate adjustments by the community. 相似文献
6.
研究城市功能用地演替可以揭示出新时期中国城市功能空间演化的特征、趋势与形成机制,为城市管理提供理论依据。本文以张掖中心城区为研究范围,运用GIS工具及方法,定量分析了张掖市1981年以来居住用地、工业用地、公共服务用地三大功能用地的空间演变特征及其动因,进而绿洲城市空间的可持续发展提供指导。研究发现：张掖城市居住用地和公共服务用地呈逐步增加趋势,空间上呈“内聚→外散”的演变趋势,两者均由老城区向四周扩散,而工业用地先增加后减少,空间上呈“混杂→集中”的转变特征,整体上集中于东北部产业园区内。张掖城市功能用地演变是人口经济驱动、宏观政策调控、城市开发与生态环境博弈、交通线路牵引、城市规划引导等共同作用的结果。 相似文献
7.
基于土地利用现状遥感监测数据,采用贝叶斯统计方法对长三角城市群和中原城市群城市建设用地扩张的时空特征及其影响因素进行研究,并探讨两个间差异规律。结果表明:(1)研究期内,两个城市群的建设用地均呈现快速扩张的态势,增长速度均在2000—2005年达到峰值,对应的净增长率分别为36.6%和31.1%。(2)两个城市群城市扩张空间演化过程差异显著,长三角城市群建设用地扩张表现为“点—轴—波式循环”模式,空间异质性较高,出现多个城市扩张热点区域;而中原城市群表现为“点—轴—网”模式,地区间扩张差异较小,温点扩张区域居多。(3)影响两个城市群建设用地扩张的主要因素有经济发展、产业结构、人口规模和居民收入。从影响程度大小的区域对比来看,经济规模、产业结构和居民收入对长三角城市群的影响程度高,人口规模对中原城市群的影响程度高。 相似文献
8.
Biola K. Badmos Grace B. Villamor Sampson K. Agodzo Samuel N. Odai Olabisi S. Badmos 《Singapore journal of tropical geography》2021,42(1):65-84
In this study, the Land Use Dynamic Simulator model was applied to investigate the impact of farm credit as an adaptation strategy to cope with effects of climate variability on agricultural land‐use change and crop production in the Vea watershed in Ghana. The authors identified the determinants of crop choices within the landscape (e.g., farm household and biophysical characteristics of farm plot). The crop choice sub‐model was then linked to the crop yield sub‐model to determine the yields of selected crops. In adapting to the impacts of climate variability, the maize credit adoption sub‐model under the maize cultivation credit scenario was integrated into decision‐making. This was simulated for a 20‐year period, and compared with the business‐as‐usual scenario. Under the simulated maize credit scenario, maize adopters increased from about 20 per cent to about 50 per cent and the area allocated for maize cultivation significantly increased by about 266 per cent. Consequently, the average annual aggregated household crop yield increased by 6.3 per cent higher than in the business‐as‐usual scenario. This simulation study shows that access to maize credit can significantly influence agricultural land‐use change and food availability in the study area. However, although access to farm credit may translate into food availability, the sustainability of this strategy is questionable. 相似文献
9.
《Singapore journal of tropical geography》2018,39(2):281-299
This paper examines spatial and temporal patterns of large to medium‐sized fires across the Indonesian Archipelago using remote sensing, particularly the MODIS fire products, over a 14 years period (2000–13 inclusive) in conjunction with climatic and land data in a GIS. Results showed fires (burned area and number of fires) were detected the most in year 2002 and least in 2010. The extent of burning was correlated with the annual Southern Oscillation Index with most burning occurring during times of sustained negative SOI values, which generally means drier conditions across the region. Most of the detected fires occurred in the middle of the dry season and in drier eastern Indonesia. Across Indonesia, approximately 1.5 per cent of available open vegetation area burned, whereas only 0.5 per cent of forest area burned. Most open vegetation burning was detected in the savanna with an area equivalent to 11.1 per cent of its extent being burned over the 14 years. On Sumba Island, where the pronounced dry season extends for at least four months, open vegetation is the most common land cover type, of which 99 per cent burned by area over the study period making it the island with the most burned areas in the Indonesian Archipelago. 相似文献
10.
基于路网分割的京津冀城乡空间识别及特征分析 总被引：2，自引：1，他引：1
提出一种基于路网分割应用于区域尺度快速识别城乡边界的方法。该方法利用路网与城市空间格局的强耦合联系,通过城乡斑块地理分割与精度计算确定城市斑块的最优解,识别区域城乡空间。以京津冀为例开展方法验证,分析了区域城乡空间格局、路网特征及城市用地经济效率。结果表明,该方法识别精度较高,可用于低成本、快速、高效的区域城乡空间识别;京津冀城市空间格局呈现“大京津、小河北”的差异性,路网密度特征呈现京、津、石3个显著的高密度区域,二者存在高耦合性;2015年该区域城市用地经济效益总体良好,石家庄、保定、和承德3市综合效率值欠佳,需进一步提高土地利用效率。 相似文献
11.
Pankaj Bhardwaj Omvir Singh Dinesh Kumar 《Singapore journal of tropical geography》2017,38(3):293-312
Thunderstorms are one of the most dangerous convective weather events. Despite the recent advances in prediction of convective storms worldwide, thousands of casualties occur annually. In the present study, the authors highlight specifically, thunderstorm‐related casualties reported in India from 1978–2012. Analysis of long‐term data have revealed about 16 308 casualties resulting from 1381 thunderstorm events with an average of 465 casualties occurring annually. The maximum number of casualties were concentrated in north‐eastern and central north‐eastern states. About 80 per cent of total casualties were recorded in West Bengal (23 per cent), Assam (20 per cent), Orissa (14 per cent), Bihar (13 per cent) and Jharkhand (8 per cent) states. The national casualties rate per million population per year and casualties density standardized by area has been found to be 0.50 and 5.07, respectively. Male casualties were found to be more prominent than female and children casualties, probably due to the larger proportion of males performing their work outdoors. The number of thunderstorm events and casualties was observed to be highest during pre‐monsoon season and lowest during winter. It is believed that the findings from this study will help policy makers to draw strategies to cope with the perils of thunderstorms. 相似文献
12.
Nur Hussain S.M. Shahriar Ahmed Amena Muzaffar Shumi 《Singapore journal of tropical geography》2023,44(3):438-458
Urban Heat Island (UHI) refers to a phenomenon whereby urban areas experience higher temperatures compared to the surrounding areas. Remote sensing-based Land Surface Temperature (LST) measurements can be utilized to measure UHI. This study emphasized on geostatistical remote sensing-based hot spot analysis () of UHI in Dhaka, Bangladesh as a way of examining the influences of Land Use Land Cover (LULC) on UHI from 1991 to 2015. Landsat 5 and 7 satellite-based remote sensing indices were used to explore LULC, UHI and environmental footprints during the study period. The Urban Compactness Ratio (CoR) was used to calculate the urban form and augmented characteristics. The Surface Urban Heat Island (SUHI) intensity (ΔT) was also used to explore the effects of UHI on the surrounding marginal area. Based on our investigations into LULC, we discovered that around 71.34 per cent of water bodies and 71.82 percent of vegetation cover decreased from 1991 to 2015 in Dhaka city. Contrastingly, according to CoR readings, 174.13 km2 of urban areas expanded by 249.77 per cent. Our hot spot analysis also revealed that there was a 93.73 per cent increase in hot concentration zones. Furthermore, the average temperature of the study area had increased by 3.26°C. We hope that the methods and results of this study can contribute to further research on urban climate. 相似文献
13.
城镇土地集约利用研究 总被引：47，自引：1，他引：47
小城镇发展战略地位的确立，加速了城镇化进程，城镇化过程中的用地粗放与人均耕地锐减之间的矛盾，是提出城镇土地集约利用的依据。从城镇土地集约利用内涵界定入手，分析了城镇土地集约利用的必要性，探讨了城镇土地集约利用定量评价的原则，从城镇存量土地产出率、土地利用强度、土地投入强度和土地可持续度4个方面建立了城镇土地集约利用评价指标总系统。指出城镇发展与土地集约利用的途径。 相似文献
14.
Land expansion of mountain cities in China is not systematically studied yet. This study identified 55 major mountain cities at and above prefecture level, and analyzed the land expansion characteristics and driving forces, based on visually interpreted data from TM images in 1990, 2000, 2010 and 2015. From 1990 to 2015, total built-up land area of the mountain cities increased by 3.87 times, 5.56% per year. The urban land growth was apparently accelerated after 2000, from 4.35% per year during 1990–2000 increased to 6.47% during 2000–2010 and 6.2% during 2010–2015. Compared to the urban population growth, the urban land expansion rate was 44% higher. As a result, the urban land area per capita increased, but it was still within the government control target, and also was much lower than the average of all cities in China. Urban development policy, changes to administrative divisions, GDP and population growth, and road construction were identified as the major driving forces of land expansion. Terrain conditions were not found a relevance to the urban land expansion rate during 1990–2015, but had a significant impact on the layout and shape, and also probably on the urban land efficiency. 相似文献
15.
深圳城市规划对土地利用的调控效能 总被引：4，自引：0，他引：4
城市规划实施效能研究已开始由定性走向定量,引入GIS空间分析技术,利用相关政府部门提供的资料和实地调查资料,以深圳为案例从定性与定量角度系统全面地开展了城市规划对土地利用的调控效能研究。研究结果表明城市规划对土地利用调控效果显著:①城市规划对深圳城市空间结构的控制与引导十分有效,使得其在快速发展过程中仍然保持良好的城市空间结构。②城市规划对特区土地利用的调控效果较好,城市建设基本按照规划进行;而城市规划对特区外土地利用基本失控,城市建设无序蔓延,城市规划没有起到应有的调控作用。③城市规划管理对土地利用也具有重要的调控作用,《建设用地规划许可证》的规划审批用地挤占了大量耕地、园地、林地和水域等,引起了深圳各区域土地利用的巨大变化。 相似文献
16.
基于凸壳原理的杭州城市扩展形态演化分析 总被引：6，自引：1，他引：5
在城市化快速推进的背景下,探索凸壳原理在城市扩展形态识别中的应用价值,并借此分析杭州市主城区1985~2010年间城市扩展形态演化规律及其机理,以期为控制城市扩展形态,指导未来城市土地开发活动提供借鉴。研究发现,凸壳原理在城市扩展形态识别上简单而明确,通过确定已有城市建设用地的凸壳,将城市所有可开发用地明确区分为凸壳内用地和凸壳外用地2类,为采取差别化的空间管理政策提供依据。构建了基于凸壳原理的城市扩展形态计算机识别方法,有利于在城市扩展模拟中实现城市扩展形态影响因素的定量化表达。1996年之前,杭州市建设用地和凸壳面积增长缓慢,城市形态相对紧凑;1996年之后,建设用地快速增长,城市不均衡扩展加剧,凸壳面积陡增,城市形态紧凑程度下降。总体来看杭州市城市扩展类型属于外延型,随着凸壳面积的增加,城市填充潜力随之增强,为促进杭州市城市紧凑化发展,应该严格控制凸壳外的城市土地开发。沿主干道的城市开发是城市形态外延式发展的主要因素,已有建设用地周边以及城市内部次要道路沿线的城市开发,以及城市中心的集聚作用和规划对城市开发的控制是城市形态填充式发展的主要因素,而郊区化发展和“东扩西进”等城市空间发展政策促使特定时期城市外延式发展。 相似文献
17.
多中心空间结构对城市地价影响研究 总被引：1，自引：0，他引：1
城市地价的飞速上涨和成本提高,对企业选址、个人购房带来越来越重要的影响,城市多中心发展能否有效抑制地价亟待实证检验。基于2008年和2013年全国285个地级及以上城市的微观土地出让数据,分析城市空间结构对地价的影响。研究发现：① 多中心空间结构能有效抑制城市过高地价,但会显著提升城市低段地价和城市整体平均地价;② 城市多中心空间结构对商住用地地价提升作用显著,但对工业用地作用不显著;③ 反映土地需求的城市人口密度对于城市综合地价具有显著提高作用,增加人均建设用地面积能有效降低城市综合地价,土地等级和出让方式等地块特征因素对交易地价影响也十分重要。因此,地方政府引导城市多中心化发展既能提供给企业、个人更多的用地选择,有效缓解城市主中心地价过高问题,也能推动城市次中心建设,促进城市均衡发展。 相似文献
18.
珠江三角洲城镇建筑覆盖近期变化研究 总被引：17，自引：5，他引：12
基于遥感与地理信息系统技术,从1988年与1998年两个时期研究区域的TM卫星影像提取各城镇的实际建筑覆盖区面积等专题信息,并利用Arc/Info802建立珠江三角洲乡镇级空间数据库。在此基础上重点对珠江三角洲城镇建筑覆盖近期变化的空间扩展特性,并就企业、交通设施、人口、区域经济与行政体制等驱动因子进行了初步综合分析。研究表明20世纪末珠江三角洲城镇建筑覆盖总体圈层格局相对稳定,核心增长与交通指向扩展非常显著,城镇建筑覆盖区增长总量与增长速率空间分布不一致,城镇扩展强度指数空间分布也显示出核心增长与交通轴向增长显著的特征 相似文献
19.
Land use and land cover change in Greater Dhaka, Bangladesh: Using remote sensing to promote sustainable urbanization 总被引：12，自引：0，他引：12
This study evaluates land use/cover changes and urban expansion in Greater Dhaka, Bangladesh, between 1975 and 2003 using satellite images and socio-economic data. Spatial and temporal dynamics of land use/cover changes were quantified using three Landsat images, a supervised classification algorithm and the post-classification change detection technique in GIS. Accuracy of the Landsat-derived land use/cover maps ranged from 85 to 90%. The analysis revealed that substantial growth of built-up areas in Greater Dhaka over the study period resulted significant decrease in the area of water bodies, cultivated land, vegetation and wetlands. Urban land expansion has been largely driven by elevation, population growth and economic development. Rapid urban expansion through infilling of low-lying areas and clearing of vegetation resulted in a wide range of environmental impacts, including habitat quality. As reliable and current data are lacking for Bangladesh, the land use maps produced in this study will contribute to both the development of sustainable urban land use planning decisions and also for forecasting possible future changes in growth patterns. 相似文献
20.
基于2000、2015年中国东中部地区261个地级市统计与土地利用数据,运用空间自相关模型,变异系数和三元协调度模型分析其城市人口、GDP和城市建设用地的空间集聚态势和非均衡变化过程,揭示人口城市化与土地城市化的协调程度。结果显示：（1）城市人口、GDP和建设用地的Moran’s I指数均为正值且2015年的值大于2000年的值,显示出明显的空间集聚特征,且在2000—2015年集聚特征不断加强;（2）城市人口密度和人均GDP的变异系数分别从2000年的1.38和0.91下降到2015年的0.96和0.70,地均GDP从1.32上升到1.77,表明城市人口密度和地均GDP的差异在逐步减小,但地均GDP的不均衡性却在增大;（3）2015年,共有171个地级市城市用地规模增长弹性系数小于1.12且人均城市用地小于115m2,但有104个地级市地均GDP在1000元/m2以下,表明虽然绝大部分地级市城市化规模和速率都在可控范围之内,城市用地经济产出仍然相对较低;（4）90%以上地级市的城市人口、GDP和城市建设用地三者在两个研究时间段内处于协调发展状态。 相似文献