Study on Urban Construction Land Suitability Evaluation in Southwestern Mountainous Areas of Yunnan Province Based on the Strategy of "Protecting Farmland in Flatland Areas and Constructing Mountainous Cities" : A Case in Lianghe County

According to the particularity of towns＇ construction in the southwestern mountainous areas of Yunnan Province, this study has built constructive land suit- ability evaluation index system which is different to flat area. Then this study deter- mined single evaluation factors index and comprehensive suitability index using ＂ex- treme conditions method＂ and ＂suitability index method＂, and analyzed and assessed the constructive land suitability on each evaluation unit polygons and its suitability level by using GIS software. Taking Lianghe County of Dehong Dai-Jingpo Au- tonomous Prefecture as an example to evaluate land suitability in Lianghe County＇s main towns around the gentle slope, the results show, in the evaluation area, the area of land suitable for construction and unsuitable for construction respectively ac- count 73.58% and 26.42%. And first-class, second and third-class of land suitable for construction should be composited at the ratio of about 11：49：40. The suitability evaluation index system and method developed in this paper is applicable for evalu- ating the construction land suitability in mountainous areas of southwest Yunnan Province, and will provide theoretical and technical support for land policy measures which strengthen the protection of farmland and promote the scientific development of urbanization in Yunnan Province and even similar mountainous areas of the whole China.

Agricultural land loss in China's urbanization process

In China, urbanization of agricultural land around city agglomerations increases rapidly. Rapid urbanization of agricultoral land affects food supply, land value and ecological balance in the society. In China, the urban built-up area had increased by 40% from 1996 to 2003. This increase came predominantly from farmland surrounding the cities. How the ongoing urbanization of China affects its agricultural land is the focus of this paper. In current studies, we have found that population density; urbanization degree and personal income are key factors that influence the urbanization process. Based on this, relation model has been established and to predict the general trends of the urban area expansion in China in 2020.In 2020, the constructed urban area of China would be increased by 1.3 times compared wtth 2003. In 2020, this study anticipates the conversion of about 32,562 sq. kin. agricultural land of China for urban use.

Using negative exponential function to characterize built-up land density along slope gradient for 19 urban areas in China

In China,numerous cities are expanding into sloping land,yet the quantitative distribution patterns of urban built-up land density along the slope gradient remain unclear,limiting the understanding of sloping land urbanization.In this paper,a simple negative exponential function was presented to verify its applicability in 19 typical sloping urban areas in China.The function fits well for all case urban areas(R^(2)≥0.951,p<0.001).The parameters of this function clearly describe two fundamental attributes:initial value a and decline rate b.Between 2000 and 2020,a tends to increase,while b tends to decrease in all urban areas,confirming the hypothesis of mutual promotion between flatland densification and sloping land expansion.Multiple regression analysis indicates that the built-up land density and the ruggedness of background land can explain 70.7%of a,while the average slope ratio of built-up land to background land,the built-up land density and the built-up land area can explain 82.1%of b.This work provides a quantitative investigative tool for distribution of urban built-up land density along slope gradient,aiding in the study of the globally increasing phenomenon of sloping land urbanization from a new perspective.

Spatial Development Explorations of Middle- and Small-sized Mountainous Cities: A Case Study of Shangluo City, China

Spatial structural features of middle- and small-sized mountainous cities in China were analyzed. Taking Shangluo City for example, problems in the spatial planning of middle- and small-sized mountainous cities were explored, it was stressed that local characteristics should be respected to make plans reasonably, and handle the spatial transition between urban and rural areas properly, so as not to lose the originality of rural areas during the urbanization. The study aimed at providing useful experience for the urbanization.

基于MapInfo的大连市主城区可建设用地测算研究

随着城市化进程的推进以及人口的持续增加,对城区大量的土地资源进行开发建设,导致出现土地资源匮乏的问题。为更好辅助城市规划、经济建设、社会发展以及环境保护等方面,本文以大连市主城区为例,基于DEM图像与相关数据,运用MapInfo和ArcGIS地理信息系统平台,建立覆盖大连市主城区全域的50 m×50 m面状矢量格网,作为地形分析的基础格网,对大连市主城区地形进行海拔高程和坡度分析。以海拔高程60 m,坡度25%为基准统计大连市主城区不受地形因素制约的可建设用地区域。在将主城区划分为可建设用地区域与限制建设用地区域的基础上,统计各市辖区的可建设用地区域所占比例和面积。从整体上看,可建设用地区域占整个主城区的50.034%,其中中山区、西岗区、沙河口区、甘井子区的可建设用地区域比例依次为50.561%、64.509%、73.570%、45.679%。为使统计结果更好地支持对大连市开发建设的研究,进一步对各街道可建设用地区域进行统计分析。

InSAR技术支持下的长沙市2015—2021年地面沉降监测分析

长沙市是长江中游地区重要的中心城市,地质条件脆弱、土质疏松,土体在施工和降雨作用下极易固结压实,造成地面形变,威胁建筑物和基础设施的稳定。地面沉降是长沙市地质灾害的主要原因之一。为了监测长沙市近几年的地面沉降情况,本文使用MCTSB-InSAR方法,利用151景Sentinel-1SAR影像数据,获取了长沙市主城区2015—2021年的地面沉降结果。经分析发现,最大累计沉降量约为250 mm,最大沉降速率约为80 mm/a,绝大部分区域平均沉降速率在30 mm/a以下;长沙市整体稳定,局部有不均匀沉降发生,沉降区域主要分布在主城区外围,主要由工程施工引起。

极端环境隧道建造面临的主要问题及发展趋势

聚焦艰险山区、深水海域与城市敏感区3类极端环境,全面梳理和总结了在此环境下隧道建造面临的主要问题、相关技术突破和未来发展趋势。针对艰险山区中极高地应力、高地温、高海拔以及活动断裂带等极端条件,总结分析围岩和隧道的变形机制、破坏机制及防护措施,并指出未来可通过大数据、机器学习等手段建立更精准的预测模型,以实现隧道建造过程的实时监控和风险评估;针对深水海域中高水压、高烈度地震、强侵蚀环境等极端条件,分析多因素耦合下沉管法及盾构法隧道管片及接头的劣损和破坏机制,总结提升其力学和耐久性能的主要技术措施,并提出未来仍需针对海底隧道管片接头的防水、抗震及抗侵蚀性能开展更深入的研究,以形成完整的理论和技术体系;针对城市敏感区隧道穿越既有隧道、敏感建构筑物、地下障碍物等挑战,总结分析盾构法和顶管法施工环境响应规律、地层变形评估方法和控制技术措施,提出未来可采用机器学习等技术辅助隧道建设,以提升预测和控制的准确性,减小建设过程对城市环境的扰动。目前,相关研究成果为极端环境下的隧道工程建设提供了重要支撑,但部分技术仍需进一步在实践中完善并形成规范,以指导后续的工程建设;而随着新一代信息技术的发展,未来隧道建造必将朝着数字化、智能化、自动化的方向发展,从而保障极端环境下隧道建设的安全、绿色、高效。

从“以机适地”到“改地宜机”的丘陵山区农业机械化路径优化

丘陵山区耕地面积、农作物播种面积均占全国耕地面积及农作物播种面积的1/3,涉及农业人口近3亿人,研究如何推进农业机械化以实现农业强国至关重要。从丘陵山区农业机械化发展的内在逻辑出发,比较分析“改地宜机”与“以机适地”,探讨丘陵山区从“以机适地”到“改地宜机”的农业机械化转换动力,结合Hotelling模型测算政府支持丘陵山地“改地宜机”的补贴标准,并对国内外案例进行分析解读。研究表明,“以机适地”的小型化农机对农业生产率改进有限,丘陵山区农业现代化、建设农业强国的根本出路在于“改地宜机”为大动力、高效率农机作业创造土地条件。为提高农业经营主体参与“改地宜机”意愿,政府应根据宜机化改造耕地条件采取差异化财政补贴,降低农业经营主体“改地宜机”投入成本、缩短投资回本年限,其中坡度在2°以下、2°~6°、6°~15°的补贴标准分别为15 000元/hm^(2)、30 000元/hm^(2)和45 000元/hm^(2),对坡度超过15°以土地原则应退耕还林还草,不宜高成本进行宜机化改造。针对国内外丘陵山区“改地宜机”的农业机械化经验及存在的问题,提出积极稳妥推进丘陵山区“改地宜机”的对策建议。

Spatial differences and driving forces of land urbanization in China

Land urbanization plays an important supporting and restriction role in the rapid and sustainable development of urbanization in China, and it shows distinctive spatial heteroge- neity. Applying urban area as the basic research unit and urban construction land area as the core indicator, this paper establishes the conceptual framework and calculation method for the quantity and rate of land urbanization process. The study evaluates the spatial differen- tiation pattern of absolute and relative process of land urbanization in 658 cities in China from 2000 to 2010. The spatial distribution of cities with rapid land urbanization process is dis- cussed, and the contribution rate and its spatial heterogeneity of major land use types are examined with the aid of GIS. The main conclusions are as follows： （1） Land urbanization in China shows a clear spatial difference. The greater the city scale, the faster its land urbani- zation. The cities with rapid land urbanization show a significant pattern of central distribution in coastal regions and a scattered distribution in the inland regions. （2） Over the last 10 years, the average quantity of land urbanization in the 656 cities was 3.82 km2, the quantity of land urbanization is differentiated by administrative grade. The average rate of land urbanization was 6.89%, obviously faster than the speed of population urbanization. The rate of land ur- banization reveals a pattern of differentiation between coastal and other cities. （3） In the past 10 years, the two primary land use types associated with land urbanization in China are residential and industrial, with a combined contribution rate of 52.49%. The greater the scale of the city, the more significant the driving effect of industrial land. In small- and medium-scale cities of the western and central regions, the growth of residential land is the primary driver of land urbanization, while in coastal urban agglomerations and cities on important communica- tion axes, the growth of industrial land is the main driver. （4） Overall, urban population ag- glomeration, industrial growth and investment are the three drivers of land urbanization in China, but cities of different scales have different drivers.

Detecting spatio-temporal changes of arable land and construction land in the Beijing-Tianjin corridor during 2000–2015

Rapid peri-urbanization has become a new challenge for sustainable urban-rural development worldwide. To clarify how unprecedented urban sprawl at the metropolitan fringe impacts urban-rural landscape, this study took the Beijing-Tianjin corridor of Beijing-Tianjin-Hebei metropolitan area, one of the largest urban clusters in China, as a typical example. By using Landsat-based landscape metrics and a practical methodology, we investigated the landscape changes and discussed the potential reasons in the context of rapid peri-urbanization of China. Specifically, multi-temporal land use maps derived from Landsat images were used to calculate landscape metrics and analyze their characteristics along the urban-rural gradients. The practical methodology was used to monitor spatio-temporal characteristics of landscape change in large metropolitan areas. The results showed that landscape patterns in the area had changed greatly from 2000 to 2015 with characteristics of construction land sprawl and arable land shrinkage. The intensity and scale of landscape changes varied along the urban-rural gradients. Sampled plots in urbanized areas and rural areas demonstrated distinguishable landscape patterns and significant differences. Urban areas had more heterogeneous and fragmented landscapes than rural areas. Peri-urban areas in general experienced higher levels of land diversification than rural areas. Rural residential land appeared to be more aggregated near Beijing and Tianjin cities. Besides, our findings also indicated that urban expansion was largely responsible for landscape patterns.The findings of this study potentially provide strategical insights into landscape planning around mega cities and sustainable coordinated urban-rural development.

喀斯特山区城市群耕地时空演变特征及驱动因素分析

厘清城市化背景下喀斯特山区城市群耕地现状及影响因素,对推进区域可持续发展和保障粮食安全具有重要意义。以黔中城市群核心经济区为例,基于2010年、2020年耕地数据,利用变化轨迹分析法、耕地指数、空间自相关和地理探测器等方法,探究喀斯特山区城市群耕地时空演变特征及其驱动因素。结果表明:从整体看,黔中城市群核心经济区耕地分布表现为“中部贵阳市低,周边高”的特点;从县域看,研究期内县域耕地分布均以300~500 km^(2)为主。黔中城市群核心经济区耕地同时具有转出和转入的变化特征,但耕地转出面积明显大于转入,使得研究区耕地减少2 309.37 km^(2)。黔中城市群核心经济区耕地转入、转出具有明显的空间集聚特征,且均以高-高聚类为主。影响黔中城市群耕地时空分布的主要因素为经济因素,但随着社会经济发展,经济因素的影响程度有所降低,影响因素逐渐趋于多元化。为最大程度控制黔中城市群耕地减少,建议在发展经济的同时要合理规划土地利用,保障耕地安全。

长株潭城市群生态绿心地区乡村建设用地减量策略研究

随着我国土地供需矛盾的日益突出,建设用地从“宽供给”逐渐走向“总量减量、盘活存量”发展的新阶段。基于长株潭城市群生态绿心地区乡村建设用地持续蔓延扩张,用地规模难以控制的问题,本文通过总结我国城乡建设用地政策演变与相关实践经验,以长株潭城市群生态绿心地区为例,深度剖析乡村建设用地减量发展面临的困境,并从规划编制体系、具体实施路径、政策创新三个方面提出减量化策略,即“完善规划编制,构建‘全链条’减量治理体系”、“精准识别减量区域,推进‘精细化’减量实施路径”、“创新减量政策,探索‘生态+减量’协同治理模式”,以期为我国跨区域城郊地区乡村空间治理提供参考。

西南山区公路施工期土地利用遥感监测研究

为实现对西南山区公路建设期土地利用的监测,获取公路施工区域周边土地利用变化情况,本研究以多时相卫星遥感影像为数据源,选取云南某高速公路施工区为研究区域,通过分析研究区公路施工前期、中期和后期的施工区域遥感影像数据,获取公路施工期土地利用变化情况。研究发现,利用遥感技术可较好地获取山区公路施工期土地利用的变化情况,可满足公路施工期间土地保护的环境监测要求。

基于GIS空间分析法的西南山区城镇建设用地适宜性评价——以盘州市为例

对西南山区盘州市的城镇建设用地进行适应性评价,为西南山区及盘州市的城镇规划、土地开发、城镇开发边界划定等提供理论价值参考。根据盘州市自然环境及其实际情况,选取高程、地形坡度、地形坡向、地形起伏度4项因子,基于GIS空间分析法进行了综合评价。结果表明:城镇建设用地适宜性评价等级以低和较低等级为主,其中低等级的区域面积占总区域的56.27%,较低等级的区域面积占总区域的20.88%。住宅类城镇建设用地适宜性评价等级也以低和较低等级为主,其中低等级的区域面积占总区域的73.96%,较低等级的区域面积占总区域的14.68%。评价结果揭示了盘州市城镇建设用地及住宅类城镇建设用地适宜性评价等级及其空间分布特征,其中适宜性的较高、高等级的城镇建设及住宅类城镇建设用地土地较少,而高等级均只占全区面积的1%左右,因此在利用该等级区域土地应需十分珍惜。

北京山区建设用地扩展及其与耕地变化关系研究

基于土地利用详查和变更数据并利用两期土地利用现状图,分析比较了北京山区建设用地空间变化历史形态,力求准确测算建设用地扩展的时空特征及其差异;并对山区建设用地景观格局动态变化进行分析,探讨了其与耕地变化的相关关系。研究结果表明山区建设用地扩展程度逐年增强,圈层性与不规则性并存,并对耕地保护产生巨大压力;将来,必须制定科学的土地利用规划对建设用地扩展进行调控,防止大量优质耕地被占用。

长沙市区建设用地扩张的时空特征

以不同时段的遥感影像资料为数据源，借助GIS技术对空间数据的统计及分析功能，提取出6个时期长沙市建成区变化的相关数据信息。在此基础上，利用扩张速度、扩张弹性、分维数、玫瑰图等方法分析长沙市区1986-2004年建设用地扩张的时空特征。结果表明，近20年来，长沙城市建设用地扩张了将近1倍，尤其是2002-2004年，建设用地扩张趋势最为明显。现阶段城市的扩张主要表现为低密度填充式的蔓延，城区扩张方向的主要方位是NW270°～295°和SE165°～180°。建设用地扩张的驱动因素除经济发展及人口增长因素之外，政策也是重要的影响因素，尤其是近年来政策因素的作用更为突出。未来长沙城市的空间发展将是多中心组团式的扩张，城市扩张方向日趋合理化。

劳动力析出对生态脆弱区耕地撂荒的影响

研究目的:以宁夏南部山区为例,研究农业劳动力析出对生态脆弱区耕地撂荒的影响。研究方法:二分类logistic回归模型。研究结果:撂荒耕地面积与劳动力外出数量、时间及农户所拥有的耕地总面积呈正相关;耕地中的坡耕地和旱地首先被撂荒。研究结论:劳动力析出会促使农户撂荒部分质量差的耕地;这种撂荒行为有助于生态环境的自然恢复。

城市建设用地生态适宜性评价的潜力—限制性分析——以大连城市化区为例

城市建设用地生态适宜性评价是合理利用我国有限土地资源的一项基础性工作,本研究的特色是以大连城市化区为例在归纳GIS方法应用的基础上,将目前国内广泛采用的单纯权重叠加法推广到加权的潜力—限制性分析法。该方法的主要优点是把评价要素分为生态潜力和生态限制性两大类,通过取大原则和成对明智比较法分别确定权重,从而更加科学确定土地利用生态适宜性等级。结果表明,大连可做高强度开发的城市建设用地面积约为850.46km2,约占总面积的6.28%;可在指导下进行适度开发利用的土地面积为1835.97 km2,占总市域面积的13.56%;而不宜作为建设用地的土地(不适宜和中低适宜区)面积为10851.92km2,约占总市域面积的80.16%,即城市建设用地的影响范围应该控制在区域的20%土地利用类型中,另外80%的土地不适宜进行城市建设的开发。根据上述结果,全区规划分为优化建设区、重点建设区、限制建设区和禁止建设区,并提出用地分区发展管制对策。

北京山区建设用地扩展空间分异分析

根据目前描述建设用地扩展空间分异所用各种指数，结合山区扩展实际情况，提出了扩展程度指数的概念。并基于土地利用详查和变更数据，测算了1993～1996，1996～1999，1999-2002三个不同阶段山区建设用地的扩展变化率、扩展强度和扩展程度等指数，分析了北京山区不同类型建设用地的扩展特征及其空间差异。结果表明：20世纪90年代以来，北京山区的建设用地发生了剧烈变化，建设用地扩展程度逐年增强，郊区城市化正向远郊区扩散。山区尚处于城市化的初级阶段，建设用地扩展存在不规则性，区域差异明显。扩展变化率、扩展强度和扩展程度等指数的结合使用更全面准确地描述了山区建设用地扩展及其空间分异状况。

长江三角洲地区城市空间扩展研究

城市化是建设用地扩展的主要驱动因素,分析建设用地时空演化格局已成为学者研究城市化过程的重要视角。采用空间自相关等方法,测度了1985年以来长江三角洲地区城市空间扩展的集聚特征并分析其演变过程;并结合格网建设用地密度频率的变化特点,将空间划分为不同的景观梯度地带,以此研究城市空间在不同地带中的扩展特点。研究结果表明,长三角城市空间扩展聚集程度先降后升,城市化区域融合趋势明显,并在城市空间扩展中表现出以上海、南京和苏州等为代表的3种模式,反应了长三角内部不同的经济发展特点。此外,在不同景观梯度下,长三角城市空间扩展表现出典型的阶段性特征。2000年以前在各个景观梯度下城市空间扩展差异较小,表现为较强的拓展性扩展;2000年以后,在城市核心区扩展强度加强,表现为填充式扩展加快。同时,城乡过渡区面积增加迅速,表明随着城市空间扩展的加速,长江三角洲地区城市土地不集约利用现象已较为突出。