The dynamic simulation and scenario analyses on the spatio-temporal patterns of land use change, as a hotspot in the research field of land use and land cover change(LUCC), is involved with many driving factors. This paper reclassified the driving factors into three categories (stable controlling factors, seasonal changing factors and socio-economic factors) and revealed the influencing direction and intensity of different factors on land use change by logistic analyses between land use change and its driving factors. Furthermore, regarding CLUE-S model as the modeling framework, this paper designed a dynamic simulation model on the spatio-temporal patterns of land use change in Taibus County. In terms of the running results of the System Dynamic Model of Land Use Change and the change of social and economic factors, this paper realized the dynamic simulation of land use change as well as the scenario analyses of baseline, ecologically-oriented and economically-oriented models in Taibus County. The comparisons of the simulated results of baseline, ecologically-oriented and economically-oriented scenarios disclose the competitions and successions in spatial and temporal scales affected by the integrated effects from all kinds of driving factors. the findings show that the northeastern and northwestern sections covered by unused land at present will become the most sensitive belts for land use change, which further reveal the necessity of macro planning for land use in those areas. In this sense, the research results will serve the decision making on land use planning, the rational exploitation of land resources and the implementation of sustainable development strategy of Taibus County.
Based on detailed survey data of land use from early 1991 to late 2001, using models such as synthetic dynamic degree model,conversion rate model, new increase rate model, synthetic index model and synthetic index change model of land use, this paper analyzed great changes in land use in Shaanxi Province during this period of time.Figures indicated that 119.40×10 4hm 2 of farmland, 2.21×10 4hm 2of garden land,7.64×10 4hm 2 of forest land,21.02×10 4hm 2 of grassland,1.52×10 4hm 2 of rural residential land and city and town land,0.13×10 4hm 2 of traffic land,1.07×10 4hm 2 of waters and 14.85×10 4hm 2 of unused land changed to other types of land. Meanwhile, 10.44×10 4hm 2 of farmland, 45.47×10 4hm 2 of garden land, 59.79×10 4hm 2 of forest land, 29.28×10 4hm 2 of grassland, 9.65×10 4hm 2 of rural residential land and city and town land, 2.66×10 4hm 2 of traffic land, 2.36×10 4hm 2 of waters,and 8.19×10 4hm 2 of unused land were converted from other types of land. The synthetic dynamic degree of land use in Shaanxi is 0.726%·a -1. The covertsion rate of farmland is 1.885%·a -1, the biggest number among conversion rates of other land use types.Synthetic index of land use degree in Shaanxi is 2.301 in 1991, and 2.282 in 2001. The conclusions are drawn as follows: (1)Land use changed greatly in Shaanxi Province from 1991 through to 2001. Garden land changed most greatly, with cultivated land, traffic land, residential and urban land, and grassland also witnessing greater changes. (2)Land use in Yangling was most active and in Hanzhong was least active. The overall relative change rate of land use in Yan'an was high, because Yan'an emphasized the adjustment of industrial structure, put the policy of returning cultivated land to forest and grass into effect, and improved the infrastructure construction such as traffic conditions during the last 11 years. (3)Urban, rural residential and traffic land uses increased quickly, which indicates that under the situation of the West China development, the traffic conditions were improved and the urbanization steps quickened constantly in Shaanxi. (4)The land use degree in Yangling was the biggest. The one in Shangluo was the least. The land use degree in Weinan, Xi'an and Yangling increased during the last 11 years, and the land use degree in other regions decreased. (5) The cultivated land returning to forest and grass mainly happened in south and north of Shaanxi and agricultural structure adjustment mainly in the middle of Shaanxi.(6) The driving factors of land use change in Shaanxi are natural factor, policy factor, economic adjustment and population factors.
Research of runoff generation and routing mechanism is the foundation of hydrological simulations. Further analysis based on hydrological data is an effective means. Lushi basin (4623km 2) located above Luohe in the middle Yellow River is a typical tor-forest area. Its runoff generation and routing characteristics are different from the others’. To further research the asymmetry of precipitation spatial distribution, the following three indexes can be used: dispersion coefficient of basin precipitation (C V), asymmetry coefficient of basin precipitation (η),and ratio of the maximum and the minimum precipitation in basin area (α).To separate runoff components and show changes of air temperature, evaporation, precipitation,runoff and rainfall-runoff coefficient, a hydrograph recession curve displacement method and mass departure method were respectively used. The analysis of the selected 43 rainfall-runoff data from 1971 to 2000 revealed that the region's rainfall spatial distribution is very asymmetric with the existence of a distinctive a storm center; its mean dispersion coefficient of basin precipitation (C V) is 0.51, mean asymmetry coefficient of basin precipitation (η) 0.53 and mean ratio of the maximum and the minimum precipitation in basin area (α) 16.06. Its routing mechanism and modes are very complicated, including over-infiltration and over-fall patterns.The annual direct flow accounts for 74.7% of the total, routing time is 18.0h and lag time 13.7h. An in-depth analysis of routing characteristics on the variational conditions resulted in important conclusions : changes of annual runoff yield and rainfall-runoff coefficient were resulted from rainfall characteristics; changes of underlying surface and human activities did not cause prominent effect on the relation of rainfall-runoff; while to flood, biological protection and water and soil conservation measures increased the cover degree of vegetation and forest, improved interception and soil fixation abiligy, reduced runoff generation capacity and improved the correlation of flood-runoff in the study area, to a certain extent.
Flow routing model (FRM) plays important roles in the distributed hydrological modeling. Whether a simple or complex FRM is chosen depends on the relative relationship between the time resolution and the lagging time of routing. Generally, the FRM of a distributed hydrological model(DHM) consists of three components: the first is subdivision method of the basin; the second is the routing path; and the last is the routing method based on the routing path. In order to decrease the runtime of model, an efficient routing method, the so-called Ranked-Grid-based Kinematic Wave Routing model (RGKWR), is developed in this paper. This model applies the kinematic wave method to successive routing on ranked raster grids. Raster grids can be divided into different ranks due to each grid's flow direction computed by the single direction algorithm. We define the basin's outlet grids as the first rank, and the grids from which water flows into the first ranked grids as the second rank, the rest can be deduced by analogy, so the most upstream grids are defined as the highest rank. Flow routing is undertaken from those grids having higher rank onto the grids having lower rank.This paper puts forward the classifying method for raster grids, discusses the kinematic wave model and its numerical solutions, and carries out a case study on Chaobaihe River Basin in North China. The basin, with a drainage area of 13,846 km 2, has two outlets to Miyun Reservoir: one is Xiahui hydrologic station on Chaohe River, the other is Zhangjiafen station on Baihe River. The whole basin is divided into 55,444 grid elements at a 500-m resolution, with the Chaohe River basin partitioned into 298 ranks, and Baihe River basin 398 ranks. The application shows RGKWR based on GIS/DEM is reasonable and efficient.
A relationship between mean annual temperature, mean annual precipitation and mean annual runoff was derived with the contemporary data for 30 small catchments in northern China. With the relationship between magnetic susceptibility and climatological variables and between oxygen isotopic compositions and climatological variables established by other investigators, the past annual-temperature and annual-precipitation of the early and middle Holocene were inferred for Quzhou area situated in the southern Hebei Plain from the previously measured magnetic susceptibility and carbonate oxygen isotopic composition of sediments sampled in an inter-channel depression in this area. With the derived relationship between mean annual temperature, mean annual precipitation and mean annual runoff, the corresponding past annual-runoff of the early and middle Holocene was inferred for this area from the so inferred annual-temperature and annual-precipitation. During >10,210-10,000 yr BP, the annual runoff was abundant and apparently more than nowadays. It was relatively spare, being probably less than, roughly the same to or still more than during the contemporary time in 10,000-8,500 yr BP. In 8,500-8,000 yr BP, the annual runoff was again remarkably more than that in the modern time. It was relatively rare again during 8,000-7,200 yr BP. From 7,200 yr BP onwards, the annual runoff tended to increase and was extremely abundant at ～6,700 or 6,500 yr BP when it might be 2.4, 3.4, 4.1 or even 5.0 times more than today. After ～6,000 yr BP, it began to gradually decrease. The general trend of variations in annual runoff inferred for Quzhou area is generally similar to those inferred by other investigators for other parts of the Hebei Plain. However, the comparison of our estimates with those of other investigators indicates that the surface water was much more abundant in Quzhou area than in other parts of the Hebei Plain during the mid-Holocene (7500-5500 yr BP).
With rapid development of tourism, the environmental degradation in Wulingyuan Scenic Spot, especially the degradation of the air and water quality, has attracted some scholarly and governmental attention. To quantitatively evaluate the environmental quality, this paper developed an evaluation model based on the field work and a Delphi methodology. The main findings show that although there exist advantageous ecological environment and tourism resources, the rapid development of tourism has laid more pressure on the environment capacity which further leads to a series of environmental problems. In this sense, this paper brought about some suggestions on the tourism resources exploitation, optimum determination of the tourism planning and tourism environmental management and suggested that the local government should strength the monitoring of environmental quality, promote the assessment programs of environmental impacts, strengthen the systematic reforms to internalize the external effects of environment and develop the industries of environmental resources to guarantee the rational exploitation of environmental resources.
The features of pollen assemblages are dealt with in this paper using the methods of DCA and correlation analysis. Altogether 23 samples taken from topsoils at 8 sites in the east of Qaidam Basin are studied. In this study area, pollen taxa are mainly shrubs and herbs, whose total percentage is 92.77%～100%. Pteridophyta pollen is found in 5 samples, but the percentage is quite low, only less than 0.38%. This pollen assemblage clearly shows the characteristics of obvious desert and steppe desert area without trees. In the pollens of shrubs and herbs, Artemisia and Chenopodiaceae dominate in desert area, being respectively about 40% and 70% in general and 66.38% and 74.54% at maximum. Comparatively, Ephedra is also commonly seen, whose percentage is usually less than 5%, but in 6 samples the percentage is more than 10% and 49.27% at maximum. Gramineae and Compositae also occupy a certain percentage, the maximum may reach 10.6% and 6.82%. Results of DCA and correlation analysis appear that the features of topsoil pollens in different vegetations are not the same. Different assemblages of pollens can be distinguished and are in accordance with corresponding vegetations and environments. According to the aridity, the vegetation communities are divided into four groups: severe drought group, moderate drought group, slight drought group and slight-drought-and-slight-wetness group and it is found that A/C (Artemisia/ Chenopodiaceae) in the desert can indicate the aridity. A/C value is less 0.2 in the severe drought group, 0.2～0.5 in the moderate drought group, 1.63 in the slight drought group and 5.72 in the slight-drought-and-slight-wetness group with aridities being 8.96, 3.00, 2.98 and 2.82 respectively.
Soil organic carbon is the main part of terrestrial carbon pool. It plays an important role in terrestrial carbon cycle and is one of the important components in the research of global change, so it is important for soil carbon cycle to ascertain soil organic carbon reserves and spatial distribution in soil carbon cycle research. This paper adopted the soil distribution areas, sampling data and soil organic contents from 84 samples and 50 profiles to estimate soil carbon pool in Xingguo county of Jiangxi province. The calculation results show that parent material has influence on contents of soil organic carbon, soil derived from lime rock has higher levels of organic carbon (17.92 g/kg) in surface layer(0-20 cm),soil derived from red sandstone has lower levels of organic carbon (6.11 g/kg); and contents of soil organic carbon increased in turn from red clay,red sandstone, granitic, phyllite to lime rock. The contents of soil organic carbon vary greatly under different vegetation types.Soil under pin (Pinus massonniana) has lower levels of organic carbon, but soil under fir(Cunninghamia lanceolata) or broad-leaved forest has higher levels of organic carbon. The total amount of soil organic carbon is about 559.38×10 4t and organic carbon density is about 2.47 kgC/m 2 in depth of 20cm, the total amount of soil organic carbon is about 1437.19 10 4t and organic carbon density is about 6.36 kgC/m2 in depth of 100cm. The distribution of soil organic carbon density is high in the northwest and northeast but low in the middle and southwest in Xingguo county. Soil organic carbon and topographic variables have correlations. In topsoil(0-20cm), the correlations of aspect and the content of soil organic carbon is positively significant while that of elevation and the content of soil organic carbon is highly significant. In profile(0-100cm), the correlation of elevation and the content of soil organic carbon is significant while the content of soil organic carbon and aspect and slope grade have no obvious correlations.
Based on an analysis of fieldwork data collected by the authors from 80 households in the Shapo Village of Shuicheng County in Guizhou Province, the phenomenon of differentiation between behaviors of households who own different resources has been found. The differentiation is adaptable to resources, environment and structure of society and economy up against households. The paper has revealed the main characteristics of employment structure, employment behaviors in both agricultural and nonagricultural sectors and has explained the causes. The results show that factors such as household registration system, low economic accumulation, limited knowledge and simple technology restrict the farmers to be employed by nonagricultural sectors; and household registration constitutes the greatest institutional barrier constraining the migration of rural workers. Because of the low input and output agricultural production mode, households have few accumulation generally, helping the households break out the greatest institutional barrier of registration system to migrate. But owing to the limited knowledge and simple technology, the farmers can not get stable job and incomes, which pull them back home, most of the farmers cannot but choose part time work in nonagricultural sectors. Part time work in nonagricultural sectors can improve the farmers' living standard to a certain degree, which however can contribute little to the optimization of the rural resources, as well as the rural social and economic development. Finally some feasible suggestions are put forwards, i.e.,control the amount of population and increase investment of education; to establish uniform system of social security; and to strengthen rural infrastructure construcion.
Using the data of 1,000 questionnaires, the authors try to analyze the behavior of intra-urban migration and residential suburbanization, the second house and seasonal suburbanization, and other correlative spatial behaviors including commuting, traveling and shopping of urban residents in the process of suburbanization in Beijing. The main findings include the following: To begin with, the moving ratio is higher in Beijing, comparing with that in other Chinese cities, and the moving ratio in the inner suburb of Beijing is the highest, comparing with that in the core and the outer suburb, showing the typical characteristics of inner suburbanization in Beijing. The fact that the temporal characteristics of intra-urban migration accord well with the process of development of real estate and renewal of the old city in Beijing reflects the development of residential suburbanization. In Beijing, investigation of intra-urban migration also shows that local urbanization and inner suburbanization are obvious, that the most important reasons of intra-urban migration include the allocation of housing by danwei (place of work), and housing rehabilitation, and that the separation between habitation and place of work has broken the traditional pattern of unity of habitation and job, causing the changes of urban residential spatial structure. Secondly, the authors think that there are 900 thousand second houses in Beijing. Then, why do urban residents have their second houses? Investigation shows that the most important reason is the allocation of housing by danwei, and the second one is that they need them when work. Most of the second houses are put out to lease,for other purpose and inhabitancy by parents or some relatives coming from hometown. In Beijing, second house has not reached the extent of centralization in large scale, although it manifested some characteristics of seasonal suburbanization. Thirdly, the behavior of commuting, traveling and shopping of Beijing's residents changed in the process of residential suburbanization. Migration improves the commuting of long period in Beijing. On weekdays, migration improves the traffic conditions of urban residents, with the decreasing of ratio of changing buses in the core and the increasing of ratio of private cars in the core and inner suburb, while on weekends, migration also changes the traffic ways of urban residents with the increasing of ratios of non-changing buses and private cars, inflecting the characteristics of change and renewal of urban traffic ways. The changes of choice of shopping place of Beijing's residents and the changes of frequency of going to shopping place of residents now and ten years ago are investigated and analyzed, indicating that urban residents in Beijing are decreasing their dependence on commercial facilities in the core, and that residential suburbanization is quickening its step.
China has a long history of urban development and has numerous cities.Macroscopically the congnition of development law of China’s urban system provides an ideal source for enrichment of urban system theoretical research.Furthermore,China,as a developing country on the fast track,is experiencing rapid urban growth.A better understanding of China’s urban system development will be helpful for predicting the city scale(such as,urban land scale,urban population scale)and macro-planning of China’s urban growth. The urban rank-size and the fractal theories are the important bases for studying the urban system.The former can perfectly depict the distribution of urban size,and the latter can be employed to explain the characteristics of distribution of urban size.At the same time,the fractal dimension and the Zipf dimension are the basic parameters of the two theories.But when studying the urban rank-size rule and the fractal,some scholars theoretically believe there is the relationship between Zipf dimension and the fractal dimension of distribution of urban size,that is,their product equals 1.But,we think,if D and q are the results of OLS(Ordinary Least Square)estimation,then their product should be R2(R2,the coefficient of determination).Then,this paper deduces and proves this result. To study the relationship between Zipf dimension and the fractal dimension of distribution of urban size is helpful to understanding the rule of urban rank-size.Moreover,this study is also necessary for grasping urban development in the future characteristics of urban system evolution in the past and predicting in the urban development future because China is experiencing rapid urbanization process.
The sandy land of western Jilin Province is located in the ecotone of semi-humid and semi-arid area in the temperate zone of China, which is a sensitive region to eco-environmental changes.Sandy desertification is widely distributed in this area because of the vulnerable natural conditions and the unreasonable human activities.As a result, the precious land resources and the economic development in the area have been seriously threatened. In this paper, the spatial distribution change of the sandy desertification and its causes in western Jilin is analyzed in detail. The sandy land eco-environment geographical information system is established based on the multi-spectral, multi-temporal Landsat TM images and field investigation. The comprehensive indexes of sandy desertification extent assessment which include vegetation degradation, windy erosion extent and soil depth are presented to classify the sandy land in western Jilin into three levels-slight, moderate and severe sandy desertification with the support of GIS platform. The results demonstrate that the sandy desertification has been effectively controlled in the past twenty years, except some small sites. The sandy desertified area has reduced 86.4×10 3hm 2, especially in Tongyu and Fuyu counties where sandy desertification has been generally controlled, too. It is partially because that there is relatively ample rainfall and thermal conditions. Most of the rainfall turn into soil water and seldom passes by in the formation of running water, thus the sandy land in this area is more easily to rehabilitate comparing with the same latitude zone of China. On the other hand, the successful ecological engineering and landscape ecological engineering projects in typical sites have effectively facilitated the amelioration of sandy land. However, this doesn't necessarily mean that there is nothing for more concern. The two main causes of sandy desertification still exist, one is its natural factors, especially the physical and chemical characters of the Quarternary deposit and the dry climate; another is the immoderate economic activity of human being that has highly accelerated the sandy desertification process. The sandy desertified area has increased in several sites comparing with the 1980s, in particular in Taonan, Zhenlai and Changling counties. The three sandy belts are spreading to the southeast tardily under the influence of the prevailing wind, and their width tends to be larger.
The new-born wetland in the Yellow River Delta (YRD) is located in the active river mouth in the east of the YRD, which is one of the separate parts of the Nature Reserve in YRD. From 1976 to 2000, as Yellow River water with high sediment content flowed over the flood plains, a progressing coastline and conspicuously changing land cover in this new-born wetland have occurred. Spatial and temporal landscape patterns resulting from interactions between natural conditions (e.g. vegetation, soil properties, and hydrology) and anthropogenic land use activities (e.g. agriculture, road construction and oil exploration) changed greatly during the last 20 years. Landscape is classified into 9 zones according to its different land covers in this region, i.e., sea in the study Bohai area, tidal flat, Seablite-Chinese tamarisk, Chinese aeluropus-Lalang grass, Common weed, Hankon willow and artificial forest, water bodies, agriculture area, and residence, road and oil field zone. They respectively stand for saline habitat, swamp habitat, neutral habitat and artificial habitat for different ecosystems. The archive of satellite data allows us to quantify land cover changes in the region over the past 20 years. Based on supervised classification by ERDAS with field survey and statistical data, fourtemporal land cover classifications were achieved by LandsatTM432,CBERS-1 CCD432 imager and vector data from atlas of the Yellow River Delta covering 1984, 1991, 1996 and 2000. Two ecological evolving series are concluded in those maps and intertwined with each other in the region, i.e., the wetland ecological evolvement and the saline ecological evolvement. Three evolving patterns of the zonal centroid of these 9 types of landscapes are summarized according to their different spatial distributions and temporal evolvement directions. One is the Land-evolving pattern, which is followed by tidal flats, common weed, water bodies, forested land, and Seablite. Another one is the Sea-backward pattern, which is followed by sea in the study area and Chinese aeluropus-Lalang grass. The third pattern is Human-resulting pattern, i.e., cultivated land and residence and industrial zone, which is mostly controlled by human beings in suitable living environment for productivities.
Starting from the three dimensions and virtual reality, the hot spots of ”digital Earth” and ”digital city” of GIS,this paper analyses the development status of 3D visualization GIS at home and abroad, and discourse upon the key technologies of 3D-GIS. In view of the specialty of surveying and mapping, the 3D cyber-landscape GIS in Tangcheng of Wuxi was realized based on 4D surveying and mapping data(DEM,DOM,DLG,DRG). In addition, some modifications on traditional 3D spatial data model of GIS were made.The authors think that the division of point object in 3D modeling of object-oriented is different from that of 2D GIS.The single tree of the generally defined point object is usually composed of bulk data storage and one of the difficult technologies of GIS modeling. At the same time, the authors think that the way of using oriented curves for modeling complicated geometric objects is simple and direct. Based on oriented curves the paper makes several descriptions for common geometric objects, and puts forward the mathematical way which constructs simple surface object and complex 3D objects. As a basic data stream, 4D of surveying and mapping data was modeled by automatic and manual ways through digital technology for editing textures of buildings and linking their attribute data, then the 3D landscape reappearance and virtual reality of Tangcheng scenic spot were completed.
This paper discusses about the extraction of urban green space from an IKONOS image using a hierarchical classification technique. Green space information was obtained based on the spectral characteristics of different objects with the help of available corresponding methods after the combination of IKONOS multi-spectral data. Due to high resolution of IKONOS imagery, large amount of data and heterogeneous nature of spectrum, the extraction of urban green space was carried out on segments after image segmentation. This would help much improving the accuracy of extraction of urban green space from the whole image. In test area of the image, the spectral characteristics of different features in all 4 bands are analyzed. The spectral characteristics of old urban area and asphalt road are similar to those of part of green space. Moreover, it is difficult to extract green space under the shadow. In order to extract information from the mixed green space with non-green space, through enhancing NDVI values of a green space under the shadow, parts of green space are extracted (NDVI > 0.18), then parts of non-green space are eliminated. The next step is to extract green space from mixed green space and non-green space based on spectral knowledge and unsupervised ISODATA clustering. Finally, green space information of test area is obtained by aggregating different levels of green space. The methodology is basically concerned with the object spectral features and noise due to the mixture of different land-use/land-cover categories is significantly avoided. To demonstrate the efficiency of proposed method, unsupervised ISODATA clustering method was used to extract green space from the test area,then both results were compared to show accuracy. The visual interpretation and ground truth checks of the test area have proved that the classification accuracy and productivity accuracy of the first method are higher than that of the latter.
