A remarkable empirical regularity is that the city size distribution in many countries is well approximated to a Pareto distribution. This claim is so widely accepted that it has gained the status of a law, Zipf’s Law, or a rule, the Rank-size Rule. It has also inspired extensive researches mainly in the fields of economic geography and regional science. The urbanization process has mainly taken place since 1978 with significant processes of industrialization and economic growth in China. Many researchers have studied the characteristics of city scale distribution in different regions according to Ordinary Least Squares (OLS). The spatial econometric analysis of urban system is still scarce. This article adopts spatial econometric models to analyze the Rank-size Rule and evolution mechanisms of urban system in China’s middle area through population data of prefectural-level cities from 1985 to 2009. Firstly, cross-sectional distribution of urban population is analyzed by means of nonparametric estimations of density functions. Evolution of the shape of urabn population cross-sectional distribution shows the existence of convergence trends. Secondly, the linear regression equation is estimated by OLS. Then spatial autoregressive model and spatial error model are estimated. The results show that the estimation over time of the q parameter displays an increasing trend from 1985-1990, then decrease until 1995, from which it starts to augment. Zipf’s exponent estimated by spatial lag model is smaller than OLS. It indicates that the size distribution of urban system is more convergent because of significant spatial dependence between cities. Thirdly, we explore the mechnism between the spatial dependence and city size distribution. Spatial interaction caused by the agglemation of production factors, industrial adjustment and innovation diffusion provides the basis of spatial dependence. It affects the evolution of urban system and makes urban size distribution more convergent. Finally, the article concludes with a summary of key findings and puts forward some recommendations.
随着“中部崛起”战略的实施, 中部地区的城市快速发展并引起广泛关注。为增进对中部地区城市体系发展规律的认识, 根据1985~2009 年城市人口数据, 利用非参数密度估计方法得到该地区地级以上城市的Kernel密度图, 发现城市规模的核密度曲线不断右移, 城市整体规模日益扩大;采用空间计量模型对该地区地级以上城市的位序-规模特征进行分析, 结果显示城市间的空间依赖性使空间滞后模型估计的Zipf 指数值比OLS估计结果要小, 表明考虑空间效应的城市体系规模分布更为集中。随后进一步解析空间依赖性影响城市规模结构演化的内在机制, 认为要素集聚、产业调整和创新扩散等造成的空间相互作用提供了空间依赖性赖以存在的基础, 影响城市体系的演化和位序-规模变动, 使城市体系规模分布更趋均衡。结论对于明晰城市在区域城市体系中的定位, 确定合理的发展战略具有参考价值。
Regional specialization and division degree of manufacturing industries are measured by Krugman index and location quotient index in Central China in 2000, 2004 and 2008. And then, the situation and evolution of cooper-competition relationship among six provinces in Central China are discussed by the cooper-competition model composed of Markov chains. Results show that the manufacturing industries specialization degree among provinces in Central China had been improving, but the disparity of inter-provincial division level was quite remarkable, especially the division degree of manufacturing industries were higher between Shanxi and other provinces than others which is closely related to the energy resources advantages and the manufacturing industries structure. Regional specialization range among provinces which possess circumjacent geographical position or similar resources advantages was lower than the not. Cooper-competition analysis shows that the complementary cooperation relationships between Shanxi and other central provinces were strongest, while competitive relationship among other provinces and the polarization trend of cooper-comptition were more and more prominent. Markov chains analysis shows that the transformation of cooper-competition relationship only occurred between the adjacent types. During the process of cooper-competition relationship transformation, the probability of shifts to powerful complementary cooperation type or powerful competing type was higher that others and the polarization of cooper-competition relationship among provinces in Central China was becoming remarkable gradually. From this, it can be seen that under the Central China′s emerging strategy background, harmony and ordered regional specialization and division pattern should be constructed through taking the development advantages of every province, letting down the bars of administrative boundaries, and breaking the market protection and reducing the cost of transaction. The regional linkage and cooperation should be strengthened and the regional cooperation mechanisms should be established, including governments, enterprises and other organizations in order to achieve comprehensive linked and integrative development in Central China.
With the rapid spread and expansion of big cities, the increasing of traffic congestion is one of the main problems in the process of urban development, which becomes a hot research topic. With the time geography method, this article discusses the formation mechanism of traffic congestion under the perspective of spatio-temporal agglomeration of residents’ daily activities with a case of Guangzhou. The results show that, motile co-existence is the root cause of traffic congestion, while the agglomeration of spatio-temporal paths cause motile co-existence. Guangzhou residents’ activities are conditioned by space and time constraints, which forms the motile co-existence. The urban space and road structure enhance the agglomeration of spatio-temporal paths, so as to form the coexistence of daily activities and traffic congestion. Therefore, path cluster is the fundamental cause of traffic congestion under the constraints of time and space. In conclusion, residents’ daily activities are constrained by time and space, when the constraint reaches to a certain degree, the spatio-temporal agglomeration and motile co-existence will be produced, and finally forms traffic congestion. Good traffic management can only make traffic congestion tend to get better but cannot solve the problem of traffic congestion in essence. The structure of urban space, traffic lines, traffic control, and the situation of transportation supply and demand in some degree affect traffic congestion through motile co-existence. With the situation of transportation supply and demand at a roughly balanced level, the basic measures to solve the problem of traffic congestion lies in resolving the agglomeration of residents’ daily activities.
在RS/GIS技术的支持下,选择南四湖流域典型市域——济宁市为研究区,基于多源数据,揭示了研究区1987~2008年的土地利用时空变化特点,进一步构建“隐患-状态-免疫”的生态安全评价指标体系,采用组合赋权法确定指标权重,应用改进TOPSIS模型实现了100 m×100 m栅格水平上的生态安全综合评价。结果表明：研究区土地利用变化较为剧烈且具有独特的区域特色,其总体特征为耕地、林地、草地和未利用地的面积持续下降,建设用地急剧扩张,水域面积则先降后升;20 a来,研究区生态安全状况经历了先恶化后改善的变化趋势,南水北调工程的实施、环境治理和生态建设加大是2000年后研究区生态安全好转的主要驱动力;研究区生态安全状态空间差异明显,东部山地丘陵区和南四湖区最好,中部和西北部地区最差,其余区域基本处在预警状态。研究结果可为研究区生态建设和土地生态安全格局的制定提供依据。
The research on ecological security of land use is the core of IGBP and IHDP, which can provide a lot of guidances on the regional ecological construction and sustainable development. Based on RS and GIS technology, taking typical Jining City in Nansi Lake watershed as the study area, the paper analyzed land use change in Jining City from 1987 to 2008, and then an evaluation index system was established on basis of “Hazard-State-Immune” model. AHP and entropy methods were used for determining index weights, finally improved TOPSIS method was used to evaluate ecological security on 100 m×100 m grid scale in the year of 1987, 2000 and 2008. The results of the study were as follows: 1） the change of land use in study area from 1987 to 2008 was great, and had typical regional characteristics. The areas of farmland, woodland, grassland and unused land kept decreasing, construction land expanded largely, water area first decreased and then increased. 2） In the past 20 years, ecological security in study area changed from deterioration to improvement, experiencing V-shaped process, and the main reasons of improvement since 2000 were implementation of the South-to-North Water Transfer Project as well as enhancement of ecological construction. 3） The spatial difference of land ecological security in research area was obvious, the best places were located in the eastern hilly area and Nansi Lake, the worst places were located in the middle area, and the remaining areas were in a warning state.This study revealed temporal evolution and spatial distribution of the land use and ecological security in Jining city, which played a conducting and reference role in ecological construction, regional sustainable development, and improving water quality standards of the East Route of the South-to-North Water Transfer Project.
：It is significant to quantitatively analyze the direct and indirect effects of driving factors on urban land use structure for macro-control and optimization of urban land use. Method of path analysis was employed. The results indicate: 1) Direct effect of population growth to the proportion of residential is 0.446, the indirect effects are -0.189, 0.221, -0.042 through economic development,industrial structure change and transport infrastructure development;the indirect effects of economic development,industrial structure change are 0.420, 0.309 through population growth. 2) The direct effects of industrial structure change and economic development to the proportion of industrial are -1.357, 1.236, respectively; the direct effects to the proportion of public service land are 1.387, -1.100;the indirect of population growth to the proportion of industrial land and public service land are 1.163, -1.036 through economic development, but the effect direction is opposite. 3)economic development ,transport infrastructure development and industrial structure change are the main driving factors of the proportion the green space; the indirect (0.451) is bigger than the indirect effect (-0.117) of population growth to the proportion of green space through economic development. 4) economic development,industrial structure change, population growth and their coupling effect are the main driving factors of urban land use structure.
The article selects 3 large index systems such as competitiveness of resources product, market service as well as tourism security, and uses entropy method to give weight to the 3 big index systems so as to measure urban tourism competitive potential of the Changjiang River Delta horizontally. Combined with SSM model, this article calculates longitudinally the structure deviation component and competitiveness deviation component of urban tourism competitive potential index factors from 1998 to 2008. At the same time, the structure effect and the competitiveness effect of index factors are evaluated on the basis of longitudinal calculation. The results show that there are significant differences in the temporal patterns of urban tourism competitive potential of the Changjiang River Delta. The urban tourism competitive potentials of 4 central cities including Shanghai, Nanjing, Hangzhou and Suzhou are higher, which form the spatial pattern of 4 culminations. Moreover, the difference of urban tourism competitive potential displays the expanding trend. However, it occurs that there is unreasonable situation of the structure of index factors, which does not match entirely with the corresponding tourism competitive potential. Specifically, the whole competitiveness of market, service, traffic carrying capacity and economic development support of Shanghai is very strong. On one hand, the basis of image competitiveness is better while the competitive potential has the decreasing trend. On the other hand, the basis of resources competitiveness is better while the state begins to decline. The significant characteristics of Hangzhou City are that the competitiveness of image and product has the good development, which has the better basis and the large competitive potential. For Nanjing, its competitiveness of market, resources and product has the better basis and its status advances distinctively while other indexes appear the declining trend. The competitiveness of image and service of Suzhou City develops rapidly and has the prominent advantageous position. Therefore, through the two clear contrasts between the horizontal aspects and the longitudinal aspects, the weaknesses and defects of the different urban tourism competitive potential indexes are reflected and the performance of the different urban tourism competitive potential is shown objectively and accurately. As a result, the article provides the quantitative basis and the theoretical reference for advancing the different urban tourism competitive potential of the Changjiang River Delta.
地形起伏度作为影响人口分布的重要因素之一,是人居环境自然评价的一个重要指标,在小尺度人居环境自然评价方面也具有较高的准确性和实际应用价值。基于关中-天水经济区栅格数字高程模型,采用窗口分析等方法,利用ArcGIS软件空间分析模块中的邻域分析,提取了基于栅格尺度的关中-天水经济区地形起伏度,并从比例结构、空间分布和高度特征3个方面系统分析了关中-天水经济区地形起伏度的分布规律及其与人口分布的相关性。研究结果为: ①关中-天水经济区的地形起伏度以中低值为主,地形起伏度小于2.4的区域占总面积的96.66%,其中平地比例占总体的32.4%;地形起伏度越高的地区,平地比例越低,反之亦然。②关中-天水经济区的地形起伏度呈现南北高中间低的空间格局,最高值为宝鸡市太白县,最低值为关中平原;经度上的变化规律不是很明显,纬度上的地形起伏度无论从南到北还是从北到南都是先下降后增高的。③随着海拔高度的增加,地形起伏度呈现逐渐升高趋势,但变化幅度不大。 ④地形起伏度对区域人口分布有较强的影响,关中-天水经济区近90%的人口居住在地形起伏度小于1.5的地区,人口密度与地形起伏度的曲线拟合度非常高。
With the degeneration of environment and acceleration of urbanization, human environment has attracted great attention worldwide. As one of the key factors, the relief degree of land surface is an important indicator for natural evaluation, and it also has high accuracy and practical application in small scale residential environmental evaluation. Based on lattice digital elevation model of scale 1∶25 0000 in Guangzhong-Tianshui economic region, using the window analysis and spatial analysis model of ARCGIS software, this article extracts the relief degree of land surface and population distribution in Guanzhong-Tianshui economic region. From the characteristics of proportion, spatial distribution and height, it also systematically analyzes the discipline of the relief degree of land surface and its relationship with the distribution of population in Guanzhong-Tianshui economic region. The study has shown that: 1) The relief degree of land surface in Guanzhong-Tianshui economic region is dominated by middle and low value, and its topographic area is less than 2.4 occupying 96.66% of the total area, and the average proportion occupying 32.4% of the whole area. The higher is the relief degree of land surface, the lower is the proportion of plains, and vice versa; 2) The relief degree of land surface in Guanzhong-Tianshui economic region presents such spatial patterns that the south and north are higher and the middle is lower, and there is the maximum value in Taibai Country in Baoji City and the minimum value in Guanzhong plains. The variation is not apparent on the longitude, and the degree of latitude increases after the first drop no matter from South to North or from North to South;3)As the altitude increased, the degree presents a rising trend but has not much change; 4) The relief degree of land surface has a strong impact on the regional distribution, nearly 90% residents in Guanzhong-Tianshui economic region lived in the area where less than 1.5 degree, the curved fitting of population density and topographic is very high; 5)The relational area of topographic and population distribution have significant difference, the topographic has obvious relation with population distribution, but the relationship of the topographic is smaller in four countries in Shangluo and Tianshui cities. To sum up, the relief degree of land surface can better reflect the topographic feature and reveal its regularities of space in Guanzhong-Tianshui economic region. Empirical research shows that, as one of the key factors, the relief degree of land surface is an important indicator for natural evaluation; it also has high accuracy and practical application in small scale residential environmental evaluation. In summary, the RDLS model established in this paper can not only reflect the natural environment suitability for human settlements in Guanzhong-Tianshui economic region, but also can illustrate the spatial distribution rules of it very well.
Nowadays, researches on flood vulnerability assessment focus on social vulnerability to flood at administrative-division level, which can not present spatial distribution of vulnerability within assessing units and scaling effect of vulnerability. According to the features of human-environment system of Poyang Lake Economical Ecological Zone, fifteen indicators were selected to develop a composite index of flood vulnerability. The result indicated that the majority of the study area was moderately vulnerable to floods. High and extremely vulnerable areas were located at the lakeshore area of the southeast and the southwest of Poyang Lake, the buffer area of main rivers and the paddy fields. We analyzed the spatial distribution of flood vulnerability from the distribution of exposure, sensitivity and adaptive ability. The study was to develop a method to identify flood vulnerability at a grid level, which presented the spatial distribution of vulnerability within assessing units and at borders among units. It will supply policy makers with scientific grounds to establish multi-scale policy of flood protection.
The Ellison-Glaeser (EG) index and the CR5 index were used to give a dynamic calculation and analysis of the industrial agglomeration level of China in the article based on the data of five branches of China′s mineral resources industry, which conclued the coal industry, oil and gas industry, non-metal industry, ferrous metal industry and non-ferrous metal industry from 2000 to 2009. The results showed that during 2001 to 2009, the mineral resources industry on the whole had developed to a relatively high level but at a relatively slow speed. The EG index of the four branches of the mineral resources industry was calculated as above 0.05 in 2009 except for that of the non-metal mineral industry; the five branches′ CR5 index presented an apparent agglomeration, which held at a level of 0.6 in most conditions. The oil and gas industry had the highest average value of 0.657, and the lowest was the non-metal mineral industry, which was only 0.512. On the other hand, from an industrial perspective, the calculation results of the EG index revealed great differences in agglomeration level and uneven developments among the five mineral resources branches. The branch which was heading for the top position of the EG index was the ferrous metal industry with an average value of 0.102 , which was five times as that of the non-metal industry. The coal industry came in at second and the nonferrous metal industry and oil and gas industry were at No.3 and No.4. The last position was held by the non-metal industry with an average value of only 0.028, which was the only mineral resources industry that did not present a high agglomeration level. In addition, there were some differences in the variable range of agglomeration levels among the five mineral resources industries. In contrast, the oil and gas industry had the maximal increase slope of 85.17%, while the non-metal mineral industry′s development was comparatively slow, which had presented an evident decline since 2008. The slow or negative increase slope would make high agglomeration levels hard to sustain. However, the CR5 index showed that the difference among the five branches of the mineral resources industry was relatively small. All five industries presented relatively low or negative increase amplitude; the coal industry was the biggest among the industries at only 4.41%. The reason being that the non-metal mineral enterprises of the first five ones in turnover, enjoyed a geographical agglomeration resulting in the non-metal mineral industry showing a high agglomeration level. This narrowed the differences of agglomeration levels between this and the other branches.
通过对汉江上游的考察,在多个地点发现古洪水滞流沉积层夹在古土壤层与坡积石渣土层或坡积角砾层中。选择白河段JJTZ剖面进行沉积学和水文学研究。对于采集的全新世古洪水滞流沉积样品,进行沉积学分析,与2010年现代洪水滞流沉积物进行对比,结合其宏观特征确认其为汉江洪水悬移质沉积物,粒度成分分类为细沙质粉沙。它们记录了汉江上游特大古洪水事件。通过地层学对比分析和OSL测年断代,确定其发生在全新世中期–晚期转折阶段,即3 200~2 800 a B.P.。利用沉积学和古水文学原理恢复古洪水洪峰水位,采用比降法计算出两次古洪水洪峰流量为40 180 m3/s和49 170 m3/s。该结果大大延长了洪水水文数据序列,从而能够建立汉江上游万年尺度洪水流量–频率关系,对于揭示汉江上游水文过程对于全球变化的响应规律具有重要的科学意义,对于防洪减灾和水资源水能源工程建设具有重要的现实意义。
Palaeoflood hydrological studies were carried out in the upper reaches of the Hanjiang River. Palaeoflood slackwater deposit was found at the JJTZ site in the Baihe reach in the bedrock gorges. Analysis of the grain-size distribution indicates that these SWD consist of sandy silt, sourced from the suspended sediment load of the floodwater. Stratigraphic correlation with the chronological framework established in the Weihe River basin OSL dating show that these extreme floods occurred at the turn from middle to late Holocene, about 3200-2800 a B.P. at the end of the mid-Holocene Climatic Optimum. The reconstructed peak discharges of the palaeoflood range from 40 180 m3/s to 49 170 m3/s, which are much larger than the gauged largest floods. These results were further tested and proved to be reliable with reconstruction of the modern floods at the same reach with the same method. This research is of great importance in hydrological engineering and flood mitigation. And it is also very important in establishment of the relationships between extreme flood events and global climate change.
以中国科学院天山积雪雪崩研究站为研究区,在2009~2010年冬季观测期利用体视显微镜(XTZ-E)及拍照设备和雪特性分析仪(Snow Fork),对3种遮挡条件的开阔地(0遮挡)、树缘(50 %遮挡)和树下(90 %遮挡)的积雪深霜进行连续观测,比较和分析西北季节性积雪区不同遮挡条件下的深霜发育特征。研究表明：1) 深霜发育主要受温度制约,其次是温度梯度。由不同遮挡条件引起积雪累积和太阳辐射差异而导致雪深不同,从而形成的温度环境差异,是深霜发育差异的根本原因。2) 深霜发育厚度与雪深呈正相关关系,有开阔地(0遮挡)>树缘(50 %遮挡)>树下(90 %遮挡),融雪期深霜的消减速率为树下>开阔地>树缘。3) 深霜冰晶粒径呈先减小(稳定累积期-过渡期)再增大(-融雪期)的变化,积雪稳定累积期后,深霜粒径开阔地>树缘>树下。4)2009~2010年冬季雪深大,因而圆角深霜(DHxr)和圆角刻面冰晶(FCxr)在深霜中发育最多,二者共占70 %~80 %。开阔地易发育杯型深霜(DHcp),树缘和树下则易发育柱状条纹深霜(DHla)、棱柱状深霜(DHpr)和刻面冰晶(FCso)。深霜中胶结态冰晶约占10%~30 %,其比例在开阔地深霜中递减,而在树缘和树下处递增。
Depth hoar (DH) under different shading conditions in seasonal snow cover was studied in Tianshan Station Snow Cover and Avalanche Research Station in the winter of 2009-2010. Optical stereo microscope and the portable equipment Snow Fork were used to observe the grain size and shapes as well as water content and density of DH in the open ground (0 % shaded), canopy edge (50 % shaded) and canopied zone(90 % shaded). Results showed that: 1) DH growth primarily depends on temperature, and secondarily on temperature gradient. Temperature condition, caused by snow thickness depends on the snow accumulation and solar radiation, is the fundamental reason of DH’s differences under different shading conditions. 2) Both the snow depth and DH thickness indicate a diminishing sequence of open ground>canopy edge>canopied zone. In the snowmelt period, the decreasing rate of DH thickness shows canopied zone>open ground>canopy edge. 3) The DH grain size shows a decreasing trend at first stage (stable accumulation period - transition period) and then increase at the following stage (-snowmelt period). The rank of grain size keeps in the order of open ground>canopy edge> canopied zone after the stable accumulation period. 4) Due to the large snow thickness in the winter of 2009-2010, rounding depth hoar(DHxr) and rounding faceted particles(FCxr) are the two predominant grain shapes in DH, which accounted for 70%-80%. Hollow cups (DHcp) prefer to develop at open ground, while large striated crystals(DHla), hollow prisms(DHpr) and faceted particles (FCso) incline to grow at canopy edge and canopied zone. There are approximately 10%-30% congregate crystals in DH. The ratio declines at open ground and rises at canopy edge and canopied zone along time scale.
The section of Yangtze River in Jiangsu Province was selected as the research reach. Seven cross-sections of paleo-valley depositional sequences were established with 285 bore datum and 8 documents from the references, which were the NO.3, NO.1, NO.4 Nanjing Yangtze River Bridges, the Runyang Yangtze River Bridge, the Yangzhong Yangtze River Bridge, the Jiangyin Yangtze River Bridge and the Sutong Yangtze River Bridge. 8 age results of 14C and 1 age results of ESR were obtained through analysis of seven drilling cores samples near the Nanjing NO.4 Bridge and the Yangzhong Bridge. The results indicate that, in the Last Glacial Maximum (LGM), the incised-valley was cut down into bedrocks at the upper reach of Zhenjiang Province, and the paleo-channel of Yangtze River flows through old riverbed sedimentary facies at the down reach of Zhenjiang Province , and the paleo-valley formed partly deep cut in the Xiaguan-Qixia Mountain. The deep incised-valley at the depth of -63 m to -94 m was the Yangtze River valley during the LGM, the deep incised-valley channel was narrow and the river flowed swiftly at Nanjing reach. The width to depth ratio (BH )at Nanjing reach was small than that at Zhenjiang reach, which gradually increased along downstream. The bifurcation paleo-valley system of the Yangtze River were formed below Yangzhong. It is also found that the sediments of the paleo-valley in Jiangsu reach consist of an obvious rhythm from graver and coarse sand to fine sand from bottom to top and the sedimentation was gradually fined along downstream.
Settlement archaeology is a composit subject about spatial location and geographical distribution of settlement and relic and vestige. Conforming to some society organization principle, the prehistoric settlements congregated to kinds of settlement groups closely in space, which not only was a token of general life style of prehistoric person, but also provided a viewport and a platform for revealing and researching on the historical evolution in prehistoric society. The Luoyang area (mainly Luoyang basin) of the core of Central Plains was taken as a typical example and representative for studying the grouping pattern of prehistoric settlements and society evolution, and the research emphasized on the Era of the Yangshao and Longshan. Based on GIS , the data processing was done (including the digitalization and registration and database design and so on) firstly, and then the number ,scope , spatial distribution and space relationship of the discovered prehistoric settlements in the area were visualized with kinds of graphics and tables. And thirdly the spatial relationship of the settlements with topography and physiognomy were analyzed combined with some historical events and environment of the time. To be concrete, there were three results: More than 80% settlements located the area that gradient was lower than 3°,which showed the historical person were inclined to reside in the smooth area.More than 50% settlements located in the area less than 1 km far from the closest watershed and more than 90% settlements located in the area less than 4 km far from the closest watershed, which showed the prehistorical person were inclined to select the area where was moderate distance far from the closest watershed. The area of almost more than 60% settlements were 1~10 km2 moderately and the number and the area of the front 4 eras were balanced comparatively but that decreased in the Shang Era and increased largely in the West Zhou and East Zhou Dynasty, which were supposed to relate to some historical events. In this article, the space and attribute information were mined enough to reveal the modality characters of settlement group and union of settlement groups. Three factors were considered to assist and analyze the settlement modality: space distance between settlements, their scopes and some natural barriers (such as great river, jebel etc.). Based on the above analysis the settlements were plot out 24 settlement groups (in a group the distance among the settlements were generally short, and significantly greater than the mutual distance between the internal settlement ruins of the settlement group) and 5 unions of settlement groups (the Yi River, Luo River and Yiluo River were chiefly the partition boundaries ) on the Yangshao Era, which was a reflex of the society structure and class of the time.
利用地理信息系统和地统计分析技术分析了松嫩平原湖泊群湖泊底泥重金属的空间变异特征,并绘制了6种重金属的空间分异图,利用地累积指数法和潜在生态危害指数法对湖泊底泥重金属的污染现状和潜在生态风险进行了评价。结果表明,松嫩平原湖泊群底泥重金属含量除Mn低于土壤背景值外,其他元素均高于背景值2~4倍,并且重金属含量在空间上呈东北向西南方向逐渐降低,表现出较强的相关性;污染现状评价表明,Zn已处于中等以上的污染程度,其他重金属污染程度较低,而Mn无污染,污染程度的顺序为Zn > Cu > Ni > Pb > Sr > Mn;潜在生态风险评价表明,评价的重金属均处于低生态风险程度,单项重金属的风险程度顺序为Pb>Cu>Ni> Zn;综合污染评价与风险评价,Zn的污染程度虽然较大,但仍处于低风险程度。
Geostatistics is useful for characterizing and mapping spatial variability of heavy metal. The geostatistics method combined with geographic information system (GIS) was applied to the spatial variability of heavy metal in lake sediments in the Songnen Plain, then drawing the map of heavy metals by Kriging method. The geo-accumulation index (Igeo) and the potential ecological risk index were applied for assessing the status of sediment heavy metal pollution and the extent of potential ecological risk. The results indicated that the content of Mn(30.4-468 mg/kg) was lower than soil environmental background values of the Songnen Plain(484.96 mg/kg), but other five heavy metals were higher than the background values. The mean contents of Cu, Zn, Ni, Pb and Sr in lake sediments were 29.09 mg/kg (soil environmental background value was 17.78 mg/kg), 189.79 mg/kg (52.02 mg/kg), 35.07 mg/kg (23.65 mg/kg), 25.57 mg/kg (20.23 mg/kg)and 134.97 mg/kg (113.76 mg/kg). The spatial distribution map of heavy metal demonstrated that the distribution pattern of heavy mental in lake sediments was that the northeast region was hyper the southwest in the Songnen Plain, the contents of heavy mentals in the city of Daqing, Zhaoyuan, Anda, Qigihar, Dorbod and Nong’an were higher than others areas. Igeo indicated that the pollution extent of heavy metals followed the order that Zn>Cu>Ni>Pb>Sr>Mn, Mn was non-pollution and the pollution of Zn had been above mid-level(1<Igeo≤2), but others were at low-level pollution (Igeo≤1). The single potential ecological risk of heavy metals indicated all elements were in low- level risk(Eri<40), the order was Pb>Cu>Ni>Zn. Combined the geo-accumulation index with the potential ecological risk index , Zn was in mid-level pollution, but in low-level potential ecological risk. The results showed that the Songnen Plain was affected by human activities.
自20世纪70年代以来,渤海湾西北岸陆续实施了大量填海工程,形成了目前中国最大的人工填海造陆区,有必要对其进行精确和连续的监测与分析。以1974~2010年逐年MSS/TM/ETM影像为主要数据源,利用RS/GIS技术,分析了研究区填海造陆的动态空间分布和数量变化特性。36 a间,研究区共填海901.7 km2,主要在滩涂和近海进行,海岸线长度从1974年的224.9 km增长到2010年的536.7 km,填海区的重心总体上从东北向西南方向迁移了26.3 km。将研究期细分为5个阶段进行深入分析发现：研究区海岸线长度增量与填海造陆规模呈正相关关系;填海利用方式经历了盐田为主→盐田和水产养殖相结合→港口和临港工业为主的发展历程;以天津港和曹妃甸港及各自的临港工业区为填海造陆中心和副中心的格局已经形成。
From 1970s, many projects of land reclamation from the sea were implemented in the northwest coast of Bohai Bay successively. Therefore this region becomes the biggest zone of artificial land reclamation from the sea in China at present. It is necessary to monitor and analyze these changes accurately and continuously. Using the annual MSS/TM/ETM images from 1974 to 2010 and based on comprehensive analysis of GIS and RS, the spatial variance and quantitative changes of land reclamation from the sea in the study area were obtained. During the past 36 years, the main land increased 901.7 km2 which mainly reclaimed from tidal flat and offshore. The coastline increased from 224.9 km in 1974 to 536.7 km in 2010 and the barycenter of total reclamation area transferred 26.3 km from northeast to southwest continuously. Then, 5 phases were divided based on the annual change of land reclamation and some results could be concluded as follow. 1) the increment of coastline length was positively correlated with annual reclamation area. 2) the aim of land reclamation from the sea experienced several development courses: “saltern-oriented” →“combining saltern and aquaculture”→“combining port and port-vicinity industry”. 3) Tianjin Port with its port-vicinity industry zones and Caofeidian Port with its port-vicinity industry zones became the center and sub-center of land reclamation from the sea respectively.
There are many dams constructed in the Huaihe River basin which are drastically altering the natural hydrologic regimes of the river. In order to demonstrate the influence on the natural hydrologic regimes of the river by such intensive dams, the Bengbu Sluice which lies on the mainstream of the Huaihe River as a typical control node was selected to study the influence of the Bengbu Sluice and all its upstream dams on the hydrologic regime. Using Indicators of Hydrologic Alteration and Range of Variability Approach methods, hydrologic alteration at the streamgauge site was assessed to demonstrate the influence of dams on ecohydrological conditions in the Huaihe River basin. The results show that dams profoundly affect the Huaihe River hydrology, primarily through changes in the timing, magnitude, and frequency of high and low flows, ultimately producing a hydrologic regime that differs significantly from the pre-impoundment natural flow regime. They reduce annual peak discharges, decrease the ratio of annual maximum/mean flow, decrease the range of daily discharges, increase the number of reversals in discharge, reduce the daily rates of ramping, alter the timing of high and low flows, and change the timing of the yearly maximum and minimum flows. Dams in the Huaihe River basin have more drastic impact on low-flow events. In the post-dam period, large-scale cease-to-flow events began to occur and last for long periods of time in the basin, which is seriously destructive to the riverine ecosystem. The elimination of floods following impoundment has extirpated native riparian forest communities, subsequently reducing biodiversity and causing major changes in river food webs. It has significantly disrupted aquatic life cycles and contributed to adjustments in the riparian community structure, ultimately promoting the dominance of invasive exotics. Other components of the hydrograph and flow duration curve also have corresponding ecological responses, especially those associated with changes in the timing and duration of flows and in the rates of change and frequency of hydrograph rises and falls. The river ecohydrological targets for the Bengbu section defined by this study can support ecosystem management and restoration plans, and provide ecological operations for the Bengbu Sluice.
玉米是吉林省西部的主要农作物,通过在吉林省西部开展玉米大田试验,探讨在相同的土壤及农田管理条件下,不同试验年份玉米生产需水及水分来源的变化规律,通过比较分析玉米生产水足迹的动态变化,实现水资源的合理利用,保护生态环境,促进农业的可持续发展。3 a大田试验的研究结果表明,玉米生产水足迹以绿水足迹为主,占80%以上,蓝水足迹不足1%,灰水足迹介于10%~20%之间。而在绿水足迹中,降水较充足的年份,有效降水足迹占70%以上,一般干旱年份有效降水足迹占一半,极端干旱年份有效降水足迹则只占30%,这将对土壤水分平衡带来不利影响。3a中,单位质量玉米蓝水量约0.005~0.006 m3/kg,占单位质量玉米需水量的比例低于1%;单位质量玉米绿水量为0.559 ~0.839 m3/kg,占单位质量玉米需水量的99%以上;单位质量玉米灰水量为0.099~0.122 m3/kg。通过对玉米生产水足迹的研究,明确了绿水在吉林省西部雨养农业粮食安全中的重要地位。
Maize is the main crop in the west of Jilin Province. According to the field experiments in the west of Jilin Province, this paper discusses the water requirement of maize growth and the changes of water source in different years based on the same soil and farm management conditions, namely, comparatively analyzes the dynamic change of maize production water footprint. It is useful for the rational utilization of water resources, the protection of ecological environment and the agricultural sustainable development. The results of the 3 years field experiments (2005,2006 and 2007)indicate that the major portion of maize production water footprint is green water with more than 80%. The blue water footprint is less than 1% and the gray water footprint is between 10%-20%. In the green water footprint, the effective precipitation footprint is more than 70% in the abundant rainfall year. By contrast, in the drought year it accounts for 50%, while in the extreme drought year, it only accounts for 30%. They will bring about an adverse effect on the soil moisture balance. During the 3 years, the blue water per unit weight of maize is about 0.005-0.006 m3/kg, which is lower than 1% of the maize water requirement per unit weight. The green water per unit weight of maize is 0.559-0.839 m3/kg, accounting for more than 99% of maize water requirement per unit weight. The gray water per unit weight of maize is 0.099-0.122 m3/kg. According to the study of water footprint of maize production, it clearly shows that green water occupies an important position in rain-fed agriculture and food security in the west of Jilin Province.
In order to better implement student-centered teaching philosophy in the field practice teaching of physical geography, this article proposed to develop probing platform systems for physical geography field practice by using GIS technology. The system changes the traditional proof-theory and cognitive-based practice model, improves the autonomy and initiative of students practice. The paper analyzed the needs of probing platform system for physical geography field practice, and according to the needs, designed frame and functions of platform system, and made in-depth study for the core technology of the system developed. Finally, Lushan physical geography field practice was taken for an example to verify the platform system. The results show that: 1) The system fully mobilized the enthusiasm of student practice, provided a set of mechanism for students to participate the entire practice process, so that students can actively explore the geography problem, really make student play a leading role in entire practice process. 2) The independent practice function of the platform is a strong complement for the traditional practice mode, it provides a platform for the ability for developing students ability and quality of innovation. In a specific practice process, it can flexibly allocate different independent practice program based on the basis and interest of students, and can achieve the principle of teaching students in accordance with their aptitude. 3) In the development process, the system improves scalability by using plug-in framework model, improves reusability by using object-oriented design methods, and builds the system application model by using GIS. 4) The platform system can improve the quality of practice, and enhances the learning autonomy for student, and has important application value.