2006年 第16卷 第2期
2006, 16(2): 95-101.
摘要:
In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route. Canals should be dug so as to make up the lack of north-south river. Tongji Grand Canal, dug in the first year of Daye (605 A.D.) in the Sui Dynasty, was the important component of north-south system of Grand Canals in China. It promoted economic and social development of the Sui, Tang and Song dynasties (605 A.D.-1279 A.D.). As Tongji Canal (i.e. Tongji Grand Canal) flowed across the Huaibei Plain, which is aggraded by abundant mud and sand deposit resulted from the Huanghe (Yellow) River flooding, many traces (such as old channel) and human culture heritages were buried under mud-sand. Tongji Canal was silted up, and disappeared in the Jin Dynasty (1115 A.D.-1234 A.D.). From then on, there were many different stories about the flowing route of the canal in historical literature. Based on space-bone and air-bone remote sensing imagery, we attempt to search the old channel of Tongji Canal, and supplement historical record. The paper discusses transformation process of Tongji Canal's traffic function, and resumptively summarizes the reasons of the transformation, which results from synthetic function of physical geographical, political, economic, and social conditions.
In China, most directions of river flowing are from west to east. During historic period, since the water traffic played an important role, it was very important to form a cross-horizontal net of water carriage route. Canals should be dug so as to make up the lack of north-south river. Tongji Grand Canal, dug in the first year of Daye (605 A.D.) in the Sui Dynasty, was the important component of north-south system of Grand Canals in China. It promoted economic and social development of the Sui, Tang and Song dynasties (605 A.D.-1279 A.D.). As Tongji Canal (i.e. Tongji Grand Canal) flowed across the Huaibei Plain, which is aggraded by abundant mud and sand deposit resulted from the Huanghe (Yellow) River flooding, many traces (such as old channel) and human culture heritages were buried under mud-sand. Tongji Canal was silted up, and disappeared in the Jin Dynasty (1115 A.D.-1234 A.D.). From then on, there were many different stories about the flowing route of the canal in historical literature. Based on space-bone and air-bone remote sensing imagery, we attempt to search the old channel of Tongji Canal, and supplement historical record. The paper discusses transformation process of Tongji Canal's traffic function, and resumptively summarizes the reasons of the transformation, which results from synthetic function of physical geographical, political, economic, and social conditions.
2006, 16(2): 102-108.
摘要:
Urbanization can affect the physical process of river growth, modify stream structure and further influence the functions of river system. Shanghai is one of the largest cities in the world, which is located in Changjiang (Yangtze) River Delta in China. Since the 1970s, the whole river system in Shanghai has been planned and managed by the Shanghai Water Authority. The primary management objectives in the last 30 years have been to enhance irrigation and flood-control. By using Horton-Strahler classification and Horton laws as a reference, a novel method of stream classification, in conjunction with the traditional and specially designed indicators, was applied to understanding the structure and functions of the river system in Shanghai. Correlation analysis was used to identify the interrelations among indicators. It was found that the impact of urbanization on the river system was significant although natural laws and physical characteristics marked a super-developed river system. There was an obvious correlation between the degree of urbanization and the abnormal values of some indicators. Urbanization impacts on river system such as branches engineered out, riverbank concreting and low diversity of river style were widely observed. Each indicator had distinct sensibility to urbanization so they could be used to describe different characteristics of urban river system. The function indicators were significantly related to structure indicators. Stream structure, described by fractal dimension and complexity of river system, was as important as water area ratio for maintaining river's multi-function.
Urbanization can affect the physical process of river growth, modify stream structure and further influence the functions of river system. Shanghai is one of the largest cities in the world, which is located in Changjiang (Yangtze) River Delta in China. Since the 1970s, the whole river system in Shanghai has been planned and managed by the Shanghai Water Authority. The primary management objectives in the last 30 years have been to enhance irrigation and flood-control. By using Horton-Strahler classification and Horton laws as a reference, a novel method of stream classification, in conjunction with the traditional and specially designed indicators, was applied to understanding the structure and functions of the river system in Shanghai. Correlation analysis was used to identify the interrelations among indicators. It was found that the impact of urbanization on the river system was significant although natural laws and physical characteristics marked a super-developed river system. There was an obvious correlation between the degree of urbanization and the abnormal values of some indicators. Urbanization impacts on river system such as branches engineered out, riverbank concreting and low diversity of river style were widely observed. Each indicator had distinct sensibility to urbanization so they could be used to describe different characteristics of urban river system. The function indicators were significantly related to structure indicators. Stream structure, described by fractal dimension and complexity of river system, was as important as water area ratio for maintaining river's multi-function.
2006, 16(2): 109-115.
摘要:
Soil and water loss is now a major environmental problem in many areas of China, especially in the area of the Dabie Mountain, Anhui Province, which results in environmental degradation and does harm to the people's life and production there. Based on the observational records from the Dasha River, the authors analyze the character of the variation in flow and sediment in different flood and dry seasons from 1970 to 2000. The result shows that human activities had significantly reduced the sediment discharge and sediment module, and increased the runoff in low-water seasons since the 1980s. The average contribution rate of human activities to decreasing sediment was 65.67%, and at the same period the contribution rate of runoff and rainfall was about 34.33%. Therefore, it is necessary to take the biological and engineering measures to solve the problem of soil and water loss in the Dasha River watershed.
Soil and water loss is now a major environmental problem in many areas of China, especially in the area of the Dabie Mountain, Anhui Province, which results in environmental degradation and does harm to the people's life and production there. Based on the observational records from the Dasha River, the authors analyze the character of the variation in flow and sediment in different flood and dry seasons from 1970 to 2000. The result shows that human activities had significantly reduced the sediment discharge and sediment module, and increased the runoff in low-water seasons since the 1980s. The average contribution rate of human activities to decreasing sediment was 65.67%, and at the same period the contribution rate of runoff and rainfall was about 34.33%. Therefore, it is necessary to take the biological and engineering measures to solve the problem of soil and water loss in the Dasha River watershed.
2006, 16(2): 116-121.
摘要:
In this paper, Geostationary Meteorological Satellite (GMS) infrared black-body temperature (Tbb) data from June to August 1998 are used to automatically track the activity of Mesoscale Convective System (MCS) over the Tibetan Plateau in China. Consequently, the features of MCS, such as area, intensity, life cycle, activity region and shape, are obtained. High Resolution Limited Area Analysis and Forecasting System (HLAFS) values provided by China National Meteorological Center are used to study the relationships between the MCS trajectories and their environmental physical field values, based on the distribution and trajectories of MCSs over the Tibetan Plateau. Favorable environmental physical field charts of influencing MCS movement out of the Tibetan Plateau in different UTC (Universal Time Coordinate) are developed by using spatial data mining techniques at levels of 400hPa and 500hPa, respectively.
In this paper, Geostationary Meteorological Satellite (GMS) infrared black-body temperature (Tbb) data from June to August 1998 are used to automatically track the activity of Mesoscale Convective System (MCS) over the Tibetan Plateau in China. Consequently, the features of MCS, such as area, intensity, life cycle, activity region and shape, are obtained. High Resolution Limited Area Analysis and Forecasting System (HLAFS) values provided by China National Meteorological Center are used to study the relationships between the MCS trajectories and their environmental physical field values, based on the distribution and trajectories of MCSs over the Tibetan Plateau. Favorable environmental physical field charts of influencing MCS movement out of the Tibetan Plateau in different UTC (Universal Time Coordinate) are developed by using spatial data mining techniques at levels of 400hPa and 500hPa, respectively.
2006, 16(2): 122-126.
摘要:
The channel at the estuary of the Weihe River to the Huanghe (Yellow) River has changed markedly since the 1970s. The Huanghe River has swung westwards about 5km and there was retrogressive deposition along the Weihe River. The mechanism and effect of channel evolution at the entrance of the Weihe River to the Huanghe River was analyzed with the survey data, historical statistic data and Landsat TM images of 1987 and 2002. Following conclusions were reached: 1) Physiognomy factors at the entrance, irrigation project and integrated environment evolvement in the Weihe River basin are the main factors for channel evolution at the entrance of the Weihe River to the Huanghe River. 2) The channel evolution not only reduces the ability of controling flood in the lower reaches of the Weihe River due to shrinking of the riverbed, but also increases the flood threat in the lower reaches of the Weihe River because the Huanghe River water inversely flows into the Weihe River. And there is a complexion of small flux, high water level and big disaster, which leads to the expansion of the alkali-saline cropland in the conflux area of the two rivers. 3) The regionalism and local protection must be broken to implement the integrated planning of the watershed and to decline the height of Tongguan to stabilize the physiognomy at the estuary.
The channel at the estuary of the Weihe River to the Huanghe (Yellow) River has changed markedly since the 1970s. The Huanghe River has swung westwards about 5km and there was retrogressive deposition along the Weihe River. The mechanism and effect of channel evolution at the entrance of the Weihe River to the Huanghe River was analyzed with the survey data, historical statistic data and Landsat TM images of 1987 and 2002. Following conclusions were reached: 1) Physiognomy factors at the entrance, irrigation project and integrated environment evolvement in the Weihe River basin are the main factors for channel evolution at the entrance of the Weihe River to the Huanghe River. 2) The channel evolution not only reduces the ability of controling flood in the lower reaches of the Weihe River due to shrinking of the riverbed, but also increases the flood threat in the lower reaches of the Weihe River because the Huanghe River water inversely flows into the Weihe River. And there is a complexion of small flux, high water level and big disaster, which leads to the expansion of the alkali-saline cropland in the conflux area of the two rivers. 3) The regionalism and local protection must be broken to implement the integrated planning of the watershed and to decline the height of Tongguan to stabilize the physiognomy at the estuary.
2006, 16(2): 127-132.
摘要:
The horizontal and vertical distribution characteristics of Pb in urban soil of Shenyang City, China were investigated in this study. The range of Pb concentration in the soil was 22.02-2910.60mg/kg. The standard deviation was 443.07mg/kg, and coefficient of variation was 1.64. Tiexi District was seriously contaminated by lead. In general, Pb concentration in the soil decreased with distance from pollution source. Lead concentration varied in different functional areas with the order of industrial area>commercial area>residential area>suburb>reference area. Pb concentration decreased with the depth of soil profile. Both geo-accumulation index and ecological risk index were used to estimate the potential risk of soil Pb pollution in Shenyang City. The results showed that the high potential risk area included Tiexi District and traffic roads.
The horizontal and vertical distribution characteristics of Pb in urban soil of Shenyang City, China were investigated in this study. The range of Pb concentration in the soil was 22.02-2910.60mg/kg. The standard deviation was 443.07mg/kg, and coefficient of variation was 1.64. Tiexi District was seriously contaminated by lead. In general, Pb concentration in the soil decreased with distance from pollution source. Lead concentration varied in different functional areas with the order of industrial area>commercial area>residential area>suburb>reference area. Pb concentration decreased with the depth of soil profile. Both geo-accumulation index and ecological risk index were used to estimate the potential risk of soil Pb pollution in Shenyang City. The results showed that the high potential risk area included Tiexi District and traffic roads.
2006, 16(2): 133-140.
摘要:
This paper studied the cumulative effects of different cultivating patterns on the properties of albic soils in the Sanjiang Plain using correlation analysis. The results showed that the physical and chemical properties of the albic soil changed greatly when it was cultivated as farmland. As for physical properties of the soil, bulk density and specific gravity increased gradually, the porosity and field capacity decreased gradually year by year, but they increased after being abandoned. As for chemical properties, pH increased, organic matter and other nutrients decreased with increasing of the cultivating years. For the albic soil cultivated with forage, the cumulative effects were apparently strengthened with the increase of cultivating years, especially for the bulk density, total porosity, capillary porosity and capillary moisture capacity. Moreover, fertilization also had great effects on the albic soil. Applying magnetism fertilizer improved the physical properties such as bulk density, soil moisture and porosity, raised the utilization rate of nitrogen and phosphorus fertilizer. Compared with nutrient fertilizer, utilization of the magnetism fertilizer made production increase by 5.9%-13.9%. At the same time, using organic material and loosing the albic layer could improve not only the physical, chemical and biological properties of the cultivating layer, but also the ill properties of the albic layer, thus making organic carbon and heavy fraction carbon contents increase, and biological activity increase obviously.
This paper studied the cumulative effects of different cultivating patterns on the properties of albic soils in the Sanjiang Plain using correlation analysis. The results showed that the physical and chemical properties of the albic soil changed greatly when it was cultivated as farmland. As for physical properties of the soil, bulk density and specific gravity increased gradually, the porosity and field capacity decreased gradually year by year, but they increased after being abandoned. As for chemical properties, pH increased, organic matter and other nutrients decreased with increasing of the cultivating years. For the albic soil cultivated with forage, the cumulative effects were apparently strengthened with the increase of cultivating years, especially for the bulk density, total porosity, capillary porosity and capillary moisture capacity. Moreover, fertilization also had great effects on the albic soil. Applying magnetism fertilizer improved the physical properties such as bulk density, soil moisture and porosity, raised the utilization rate of nitrogen and phosphorus fertilizer. Compared with nutrient fertilizer, utilization of the magnetism fertilizer made production increase by 5.9%-13.9%. At the same time, using organic material and loosing the albic layer could improve not only the physical, chemical and biological properties of the cultivating layer, but also the ill properties of the albic layer, thus making organic carbon and heavy fraction carbon contents increase, and biological activity increase obviously.
2006, 16(2): 141-147.
摘要:
The Quadrangle Economic Cooperation Zone in Great Mekong Region, where the Golden Triangle is located, is composed with the border areas of China,Laos, Thailand and Myanmar. The poorest and inaccessible remote Golden Triangle now faces the opportunity to develop and participate in the global economic system. Not only has the traditional border tourism between two countries in this region been growing rapidly and various tourism products cross the regions also have been developed. The article attempts to explore the multiplier effects of tourism on regional cooperation. These consequences of tourism cooperation take effect through the infrastructure improvement, facilitation of the free movement, improvement of communication and promotion of the alternative economy. The study also points out the unexpected negative consequences to limit its role as a regional cooperative engine due to the lack of consideration of the dual economic and social structure in tourism development. The special attention should be drawn to consider the limited benefits for the marginalized community, the high transaction of the social costs related with the drug tourism and sex tourism. The paper calls for more rigorous cooperative regional plans and policies to the complexity of tourism development in this region.
The Quadrangle Economic Cooperation Zone in Great Mekong Region, where the Golden Triangle is located, is composed with the border areas of China,Laos, Thailand and Myanmar. The poorest and inaccessible remote Golden Triangle now faces the opportunity to develop and participate in the global economic system. Not only has the traditional border tourism between two countries in this region been growing rapidly and various tourism products cross the regions also have been developed. The article attempts to explore the multiplier effects of tourism on regional cooperation. These consequences of tourism cooperation take effect through the infrastructure improvement, facilitation of the free movement, improvement of communication and promotion of the alternative economy. The study also points out the unexpected negative consequences to limit its role as a regional cooperative engine due to the lack of consideration of the dual economic and social structure in tourism development. The special attention should be drawn to consider the limited benefits for the marginalized community, the high transaction of the social costs related with the drug tourism and sex tourism. The paper calls for more rigorous cooperative regional plans and policies to the complexity of tourism development in this region.
2006, 16(2): 148-153.
摘要:
Animal husbandry industry in Jilin Province is developing rapidly toward the one in large-scale, standardization and industrialization. It is upgrading to a higher level. This lays the foundation for the industry to practice ecological industry. Following the policies of Chinese Government, more and more enterprises are being engaged in seeking the effective ways of circular-economy. This paper does some researches on the projects of two major enterprises in this industry, redesigns the eco-industrial chains using principles of industrial ecology, and provides two models of circular-economy, namely vertical circulation and horizontal combination. After that, it analyzes the technological and economic effectiveness of the two designing plans. At the end, it summaries the traits of suitable circular-economy models adopted in the industry.
Animal husbandry industry in Jilin Province is developing rapidly toward the one in large-scale, standardization and industrialization. It is upgrading to a higher level. This lays the foundation for the industry to practice ecological industry. Following the policies of Chinese Government, more and more enterprises are being engaged in seeking the effective ways of circular-economy. This paper does some researches on the projects of two major enterprises in this industry, redesigns the eco-industrial chains using principles of industrial ecology, and provides two models of circular-economy, namely vertical circulation and horizontal combination. After that, it analyzes the technological and economic effectiveness of the two designing plans. At the end, it summaries the traits of suitable circular-economy models adopted in the industry.
2006, 16(2): 154-159.
摘要:
Urban agglomeration is made up of cities with different sizes to be linked by traffic network in a given area, and it is an inevitable result when urbanization reaches a certain level. Taking urban agglomeration in central Jilin (UACJ) as an example, this article analyzes the formation mechanism and spatial pattern of urban agglomeration in the less-developed area. First, the dynamics of UACJ has been analyzed from the aspects of geographical condition, economic foundation, policy background, and traffic condition. Then the development process is divided into three stages-single city, city group and city cluster. Secondly, the central cities are identified from the aspects of city cen-trality, and the development axes are classified based on economic communication capacity. Finally, the urban agglo-meration is divided into five urban economic regions in order to establish the reasonable distribution of industries.
Urban agglomeration is made up of cities with different sizes to be linked by traffic network in a given area, and it is an inevitable result when urbanization reaches a certain level. Taking urban agglomeration in central Jilin (UACJ) as an example, this article analyzes the formation mechanism and spatial pattern of urban agglomeration in the less-developed area. First, the dynamics of UACJ has been analyzed from the aspects of geographical condition, economic foundation, policy background, and traffic condition. Then the development process is divided into three stages-single city, city group and city cluster. Secondly, the central cities are identified from the aspects of city cen-trality, and the development axes are classified based on economic communication capacity. Finally, the urban agglo-meration is divided into five urban economic regions in order to establish the reasonable distribution of industries.
2006, 16(2): 160-164.
摘要:
This paper uses a spatial statistics method based on the calculation of spatial autocorrelation as a possible approach for modeling and quantifying the distribution of urban land price in Changzhou City, Jiangsu Province. GIS and spatial statistics provide a useful way for describing the distribution of urban land price both spatially and temporally, and have proved to be useful for understanding land price distribution pattern better. In this paper, we apply the statistical analysis method to 8379 urban land price samples collected from Changzhou Land Market, and it is turned out that the proposed approach can effectively identify the spatial clusters and local point patterns in dataset and forms a general method for conceptualizing the land price structure. The results show that land price structure in Changzhou City is very complex and that even where there is a high spatial autocorrelation, the land price is still relatively heterogeneous. Furthermore, lands for different uses have different degrees of spatial autocorrelation. Spatial autocorrelation of commercial lands is more intense than that of residential and industrial lands in regional central district. This means that treating land price as integration of homogeneous units can limit analysis of pattern, over-simplifying the structure of land price, but the methods, just as the autocorrelation approaches, are useful tools for quantifying the variables of land price.
This paper uses a spatial statistics method based on the calculation of spatial autocorrelation as a possible approach for modeling and quantifying the distribution of urban land price in Changzhou City, Jiangsu Province. GIS and spatial statistics provide a useful way for describing the distribution of urban land price both spatially and temporally, and have proved to be useful for understanding land price distribution pattern better. In this paper, we apply the statistical analysis method to 8379 urban land price samples collected from Changzhou Land Market, and it is turned out that the proposed approach can effectively identify the spatial clusters and local point patterns in dataset and forms a general method for conceptualizing the land price structure. The results show that land price structure in Changzhou City is very complex and that even where there is a high spatial autocorrelation, the land price is still relatively heterogeneous. Furthermore, lands for different uses have different degrees of spatial autocorrelation. Spatial autocorrelation of commercial lands is more intense than that of residential and industrial lands in regional central district. This means that treating land price as integration of homogeneous units can limit analysis of pattern, over-simplifying the structure of land price, but the methods, just as the autocorrelation approaches, are useful tools for quantifying the variables of land price.
2006, 16(2): 165-170.
摘要:
With the construction of spatial data infrastructure, automated topographic map generalization becomes an indispensable component in the community of cartography and geographic information science. This paper describes a topographic map generalization system recently developed by the authors. The system has the following cha-racteristics: 1) taking advantage of three levels of automation, i.e. fully automated generalization, batch generalization, and interactive generalization, to undertake two types of processes, i.e. intelligent inference process and repetitive operation process in generalization; 2) making use of two kinds of sources for generalizing rule library, i.e. written specifications and cartographers' experiences, to define a six-element structure to describe the rules; 3) employing a hierarchical structure for map databases, logically and physically; 4) employing a grid indexing technique and undo/redo operation to improve database retrieval and object generalization efficiency. Two examples of topographic map generalization are given to demonstrate the system. It reveals that the system works well. In fact, this system has been used for a number of projects and it has been found that a great improvement in efficiency compared with traditional map generalization process can be achieved.
With the construction of spatial data infrastructure, automated topographic map generalization becomes an indispensable component in the community of cartography and geographic information science. This paper describes a topographic map generalization system recently developed by the authors. The system has the following cha-racteristics: 1) taking advantage of three levels of automation, i.e. fully automated generalization, batch generalization, and interactive generalization, to undertake two types of processes, i.e. intelligent inference process and repetitive operation process in generalization; 2) making use of two kinds of sources for generalizing rule library, i.e. written specifications and cartographers' experiences, to define a six-element structure to describe the rules; 3) employing a hierarchical structure for map databases, logically and physically; 4) employing a grid indexing technique and undo/redo operation to improve database retrieval and object generalization efficiency. Two examples of topographic map generalization are given to demonstrate the system. It reveals that the system works well. In fact, this system has been used for a number of projects and it has been found that a great improvement in efficiency compared with traditional map generalization process can be achieved.
2006, 16(2): 171-175.
摘要:
The snow-cover mapping in forest area is always one of the difficult points for optical satellite remote sensing. To investigate reflectance variability and to improve the mapping of snow in forest area, GeoSail model was used to simulate the reflectance of a snow-covered forest. Using this model, the effects of varying canopy density, solar illumination and view geometry on the performance of the MODIS (Moderate-resolution Imaging Spectroradiometer) snow-cover mapping algorithm were investigated. The relationship between NDSI (Normalized Difference Snow Index), NDVI (Normalized Difference Vegetation Index) and snow fraction was discussed in detail. Results indicated that the weak performance would be achieved if fixed criteria were used for different regions especially in the complicated land cover components. Finally, some suggestions to MODIS SNOWMAP algorithm were put forward to improve snow mapping precision in forest area based on the simulation, for example, new criteria should be used in coniferous forest, that is, NDSI greater than 0.3 and NDVI greater than zero. Otherwise, a threshold on view zenith angle may be used in the criteria such as 45°.
The snow-cover mapping in forest area is always one of the difficult points for optical satellite remote sensing. To investigate reflectance variability and to improve the mapping of snow in forest area, GeoSail model was used to simulate the reflectance of a snow-covered forest. Using this model, the effects of varying canopy density, solar illumination and view geometry on the performance of the MODIS (Moderate-resolution Imaging Spectroradiometer) snow-cover mapping algorithm were investigated. The relationship between NDSI (Normalized Difference Snow Index), NDVI (Normalized Difference Vegetation Index) and snow fraction was discussed in detail. Results indicated that the weak performance would be achieved if fixed criteria were used for different regions especially in the complicated land cover components. Finally, some suggestions to MODIS SNOWMAP algorithm were put forward to improve snow mapping precision in forest area based on the simulation, for example, new criteria should be used in coniferous forest, that is, NDSI greater than 0.3 and NDVI greater than zero. Otherwise, a threshold on view zenith angle may be used in the criteria such as 45°.
2006, 16(2): 176-182.
摘要:
The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people's understanding and cognition to driving forces of regional LUC. Biophysical driving forces are relatively stable, and have the cumulating effects. Human driving forces are relatively active, and are main driving forces of short-term regional LUC. Existing regional LUC models can answer the three main problems: which contribution (why), which location (where) and what rate (when). But, regional land use system is defined as the self-organized system, usually affected by the cri-tical value area and sudden change, and controlled by different stages. To reduce the impact of critical threshold and break on land use system, the studies of LUC driving forces will aim at following priority areas: data linkage between remote sensing and no-remote sensing data; underlying driving force identification; driving factor quantification; driving factor scale dependence; and driving process integration simulation.
The studies of driving forces of regional land use change (LUC) are to reveal the real motivation behind the LUC and its interacting mechanism, so as to simulate and predict the process of LUC. Presently, studies rooting from different natural and socio-economic backgrounds and from different scales have deepened the people's understanding and cognition to driving forces of regional LUC. Biophysical driving forces are relatively stable, and have the cumulating effects. Human driving forces are relatively active, and are main driving forces of short-term regional LUC. Existing regional LUC models can answer the three main problems: which contribution (why), which location (where) and what rate (when). But, regional land use system is defined as the self-organized system, usually affected by the cri-tical value area and sudden change, and controlled by different stages. To reduce the impact of critical threshold and break on land use system, the studies of LUC driving forces will aim at following priority areas: data linkage between remote sensing and no-remote sensing data; underlying driving force identification; driving factor quantification; driving factor scale dependence; and driving process integration simulation.
2006, 16(2): 183-191.
摘要:
Inorganic carbon, the great part of the riverine carbon exported to the ocean, plays an important role in the global carbon cycle and ultimately impacts the coupled carbon-climate system. An overview was made on both methods and results of the riverine inorganic carbon researches. In addition to routine in situ survey, measurement and calculation, the direct precipitation method and the gas evolution technique were commonly used to analyze dissolved inorganic carbon in natural water samples. Soil CO2, carbonate minerals and atmospheric CO2 incorporated into riverine inorganic carbon pool via different means, with bicarbonate ion being the dominant component. The concentration of inorganic carbon, the composition of carbon isotopes (δ13C and Δ14C), and their temporal or spatial variations in the streams were controlled by carbon input, output and changes of carbon biogeochemistry within the riverine system. More accurate flux estimation, better understanding of different influential processes, and quantitative determination of various inputs or outputs need to be well researched in future.
Inorganic carbon, the great part of the riverine carbon exported to the ocean, plays an important role in the global carbon cycle and ultimately impacts the coupled carbon-climate system. An overview was made on both methods and results of the riverine inorganic carbon researches. In addition to routine in situ survey, measurement and calculation, the direct precipitation method and the gas evolution technique were commonly used to analyze dissolved inorganic carbon in natural water samples. Soil CO2, carbonate minerals and atmospheric CO2 incorporated into riverine inorganic carbon pool via different means, with bicarbonate ion being the dominant component. The concentration of inorganic carbon, the composition of carbon isotopes (δ13C and Δ14C), and their temporal or spatial variations in the streams were controlled by carbon input, output and changes of carbon biogeochemistry within the riverine system. More accurate flux estimation, better understanding of different influential processes, and quantitative determination of various inputs or outputs need to be well researched in future.
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