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环渤海地区城市规模扩张与质量增长的时空演变及耦合特征 总被引：1，自引：0，他引：1
城市规模扩张与质量增长是当前中国城镇化发展所面临的重要矛盾,如何推动两者的协同演进成为区域城市系统可持续发展的重要命题。本文以中国经济第三个增长极——环渤海地区为研究区,在城市系统理论认识的基础上,构建多维度融合的城市规模与质量测度体系,利用泰尔指数和脱钩模型对城市规模扩张与质量增长的时空演变过程及其耦合关系进行深入分析,并从系统内部性和外部性角度探讨了城市系统高质量运行的影响机制。研究表明：①2000—2019年环渤海地区城市规模扩张与城市质量增长均持续攀升,并呈现出一定的空间格局特征,其中京津冀呈“同心圆”的高-中值分异格局,山东半岛呈“中轴-两翼”的中-高值集聚格局,辽东半岛呈“突变式”的低-中-高三区共存格局。②环渤海地区城市规模扩张与质量增长的区域差异性总体降低,并以区域内差异占据主导,城市规模扩张的差异性降幅为山东半岛>京津冀>辽东半岛,城市质量增长的差异性降幅为京津冀>辽东半岛>山东半岛,不同区域内城市系统演化趋势复杂多样。③环渤海地区城市规模扩张与质量增长的脱钩类型经历了“SND-WD”为主向“WD-SD”为主的变化过程,脱钩状态整体趋于耦合的良性发展,脱钩程度表现为京津冀>山东半岛>辽东半岛。④环渤海地区城市规模扩张与质量增长及其耦合趋优是城市系统内部性和外部性要素综合作用的表现,不同要素通过长效调控、有条件作用和缓慢调节等过程性影响和有效性干预的方式,驱动不同城市系统由规模扩张转向质量增长。 相似文献
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1956-2010 年甬江流域降水变化特性分析 总被引：2，自引：0，他引：2
近几十年气候变化加剧了一些地区的水资源时空分布不均匀性, 使水灾害事件呈突发、频发、并发、重发趋势。本文选取中国东南沿海的甬江流域为研究对象, 基于近55 年日过程降雨资料(1956-2010 年), 采用集中度分析和Mann-Kendall(MK)趋势检验等统计学方法, 分析甬江流域降水的变化特性。结果显示, 甬江流域20 世纪80年代后, 年降水集中度呈现显著(置信水平95%)的下降趋势, 汛期降水量占年降水量比重减少, 其中5 月份降水量比重下降最为明显;而非汛期降水量占年降水量比重增加, 1 月份降水量比重增加最为明显;50~100 mm/d级别的暴雨总量稳定且有增加趋势。总体上, 甬江流域降水年内分布呈现坦化趋势, 不同量级暴雨变化趋势有利于洪水资源化, 因此结合合理的工程措施可以有效地增加该区域的水资源可利用量。 相似文献
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Zeng Yishan Wang Fengzhen He Zongli Liu Guoping Wang Chengqiang Hao Jicheng 《《地质学报》英文版》1986,60(4):43-55
On the basis of the mechanism of formation of mineral inclusions, it may be assumed that a certain relation exists between the compositions of fluid inclusions in various minerals formed at the same stage of hydrothermal activity. In order to study the genetic relationships between different minerals in the Bayan Obo iron deposit, the compositions(K~+, Na~+, Ca~+, Mg~+, F~+, Cl~+, CO_2~(2-), ΣSO_4~(2-) and pH) of inclusions in fluorite(23), hematite(13), magnetite(3), sodium pyroxene(2) and dolomite(5) from the main mine and the eastern mine were determined by using the vacuum decrepitation and leaching methods, and cluster analyses of the data on the compostions were made. The Q-mode cluster analysis indicates that some iron oxide minerals in the deposit are related to dolomite of sedimentary origin, while others are related to fluorite and sodium pyroxene--products of hydrothermal activity. The R-mode cluster analysis shows that the components of the leaching solution may be divided into two groups: one includes CO_2~(2-), Mg~(2+) and H~+(pH), which are obviously associated with dolomite; the other comprises Na~+, K~+, Ca~+, F~+, Cl~+ and SO_4~(2-), which may possibly represent the composition of hydrothermal solutions.The reaction of the Na-F-Cl solution(pH 4.72) with hematite dolomite at 300℃ and 5 × 10~7 Pa and under alternately"static and dynamic" conditions produced large amounts of hematite and fluorite and small amounts of smectite and Na(Fe) silicates, and the hematite-fluorite assemblage accords with the actual geological conditions in the deposit. From a comparison between the compositions of"static" and"dynamic" solution samples, it may be known that the flow reaction facilitates the migration of Fe, F, Ca and other components as well as Na-metasomatism(Na and Si are fixed in a solid phase).The study of the compositions of mineral inclusions and simulation experiments on hydrothermal metasomatism have provided new evidence for the hypothesis of metamorphosed-sedimentary and hydrothermal-remoulding origin of the Bayan Obo deposit, and pointed out emphatically that hydrothermal metasomatism plays an important role in the formation of the mineral deposit, particularly in the main and the east mine. 相似文献
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以亚洲高山区为研究区,在对2000—2020年逐日MODIS积雪产品进行去云处理的基础上提取了每一水文年的积雪日数（snow-covered days, SCD）、积雪开始日期（snow onset date, SOD）、积雪结束日期（snow end date, SED）和积雪持续日数（snow duration days, SDD）等积雪物候参数,并分析了积雪物候时空动态特征及其与气候变化的响应关系。结果表明：亚洲高山区积雪物候空间差异较大,并呈现出主要受海拔影响的垂直地带性分布规律。研究区SED主要集中在3—6月,在低海拔区SED出现在3月份及以前,而高海拔山区则推迟到6月份及以后;SOD主要集中在9—12月,高海拔山脉及高纬度地区的SOD出现较早,而低海拔区的SOD多出现在11月及以后。近20年,研究区SDD主要呈缩短趋势,在13.5%的区域呈显著缩短,而仅7.4%的区域为显著延长;SED主要呈提前趋势,在15.8%的区域显著提前,而仅8.8%的区域为显著推迟;SOD主要呈推迟趋势,在11.4%的区域表现为显著推迟,在8.2%的区域为显著提前。亚洲高山区积雪物候年际变化对气候变化的响应关系明显,积雪累积期气温是影响SOD年际变化的主导因子,而融雪期气温是影响SED年际变化的主导因子;气温的上升,导致了SOD的推迟、SED的提前和SDD的缩短。 相似文献
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Interannual and seasonal variation of flow velocity in Koxkar Baxi Glacier from 2014 to 2020北大核心CSCD
Glacier flow is a key factor in understanding the nature of glaciers, and it is also one of the main research contents of glacier dynamics, which can provide basic support for rational utilization of glacier resources and early warning of glacier disasters. There are many mountain glaciers located in the west of China. The study on the spatiotemporal variation of surface velocity of glaciers also has great significance for the social and economic development of the western China. Koxkar Baxi Glacier, locates on the southern slopes of the Tomur Peak, is a typical dendritic glacier. In order to obtain the conditions of Koxkar Baxi Glacier’flow rates and its variation to further reveal the future of the variation of glacier, the spatiotemporal variability of glacier velocity was surveyed using correlation(COSI-Corr)method on Landsat imagery from 2014 to 2020. The results show that: (1)The average annual flow velocity of the Koxkar Baxi Glacier was 0. 04~0. 05 m·d-1 during 2014 to 2020. (2)The glacier reaches its maximum flow velocity near the center part, and the velocity decreased towards both lateral margins. In a longitudinal profile, ice flow velocity in the accumulation area increased down to the equilibrium line, while decreased towards the glacier terminal. The maximum velocity with 0. 17~ 0. 20 m·d-1 was found near the equilibrium line altitude. (3)The glacier flow velocity in warm seasons were 16. 67% faster than that in cold seasons. (4)The glacier flow velocity from 2014 to 2020 showed a slight decreasing trend, and the average flow velocity decreased 0. 01 m·d-1. (5)Temperature and precipitation had certain influence on the seasonal fluctuation and interannual variation of the flow velocity of the glacier. © 2022 Science Press (China). All rights reserved. 相似文献
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入湖冰川受冰湖作用影响,物质损失速率高于其他类型冰川,并导致冰湖进一步扩张,冰湖溃决风险增加。建立入湖冰川物质变化序列,对揭示不同类型冰川对气候变化的响应特征,以及评估冰湖溃决风险研究具有重要意义。基于中国地面气象要素驱动数据集和实测气象数据,采用冰川表面能量-物质平衡模型估算了冰川表面物质变化,并结合冰川流动和末端退缩特征,重建了1989-2018年龙巴萨巴冰川物质变化序列。结果表明,近30a龙巴萨巴冰川总物质损失为0.315km^(3)w.e.,平均物质变化速率为-0.114km^(3)w.e.·a^(-1)。冰川平均表面物质平衡为-0.26m w.e.·a^(-1),表面消融是冰川物质亏损的主要贡献因素。气温变化对冰川表面物质损失的影响高于降水;冰川表面物质平衡对夏季气温和降水变化的敏感性强于其他季节;表碛覆盖加速了冰川表面消融,且较薄的表碛厚度会加剧冰川表面物质损失。 相似文献
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冰川跃动是多种冰川灾害的主要致灾因子,近年来与冰川跃动相关的冰崩、冰川垮塌、冰川泥石流等灾害的发生频率不断增加,使其成为国际国内冰川学研究的热点。依据对现有文献的统计发现,全球总计约有1 850条跃动冰川,主要分布于环北极地区和亚洲高山区,其中我国西部约有跃动冰川146条。跃动冰川可通过其特殊的表面形态标志,跃动前后冰川末端位置、表面高程和运动速度的变化,以及跃动产生的地貌学和沉积学特征来进行鉴别。跃动冰川的特殊运动模式主要由其内部和底床特性决定,包括冰内/冰下的热力学、水力学与形变等参数及变化过程等。现有大多数跃动冰川研究是基于各类遥感技术,主要着眼于跃动冰川表面变化,并据其对冰川跃动的可能机制进行分析。由于遥感方法精度有限且受天气、地形条件等的制约,同时无法获取冰内/冰下关键参数,因此野外现场观测在这些参数获取方面仍具有不可替代的作用。受限于冰内/冰下参数野外观测数据的缺乏,目前对冰川跃动机理的认识仍局限于早期提出的水力学和热力学两种机制,无法解释同一区域具备不同跃动机制的冰川共存,以及部分冰川跃动从冰川下部发起等问题。同时,在气候变化对跃动冰川的影响研究以及冰川跃动的模拟和预测等方面还有较大欠缺,需要在未来研究中重点关注。 相似文献
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