2006 Vol. 16, No. 3
Display Method:
2006, 16(3): 193-198.
Abstract:
Regional core cities are the growth poles for regional economic development, thus the issue about efficient urbanization pattern has always become a hot spot among researchers and policy makers. The Spatial Economy can be employed to improve it. Nevertheless, there actually exists an obvious gap between its theoretical models and the em-pirical simulation. To do so, this paper modifies the measurement of initial geographical advantages Stelder gave, and implements the empirical analyses of urban distribution in Zhejiang during the period of 1980–1990 by means of computer simulations in GIS environment. There are several interesting results achieved in this process. Firstly, given the values of parameters (transport cost is τ, substitution elasticity of manufacturing sector ρ, and income share of spending on manufacture δ), initial geographical advantages have the different impacts on urban systems, namely, urban locations, numbers and sizes over time across space. Secondly, the cities were distributed without any overlay in geo- graphical space, which makes the patterns of urbanization generate the largest possible economic efficiencies. Thirdly, the urban systems—the location, number and size of cities—from the simulation of the study area are suitable for the actual social and economic situations in the real world during the testing periods. Such results may have substantial implications for the policy how to choose the way of urbanization in a region.
Regional core cities are the growth poles for regional economic development, thus the issue about efficient urbanization pattern has always become a hot spot among researchers and policy makers. The Spatial Economy can be employed to improve it. Nevertheless, there actually exists an obvious gap between its theoretical models and the em-pirical simulation. To do so, this paper modifies the measurement of initial geographical advantages Stelder gave, and implements the empirical analyses of urban distribution in Zhejiang during the period of 1980–1990 by means of computer simulations in GIS environment. There are several interesting results achieved in this process. Firstly, given the values of parameters (transport cost is τ, substitution elasticity of manufacturing sector ρ, and income share of spending on manufacture δ), initial geographical advantages have the different impacts on urban systems, namely, urban locations, numbers and sizes over time across space. Secondly, the cities were distributed without any overlay in geo- graphical space, which makes the patterns of urbanization generate the largest possible economic efficiencies. Thirdly, the urban systems—the location, number and size of cities—from the simulation of the study area are suitable for the actual social and economic situations in the real world during the testing periods. Such results may have substantial implications for the policy how to choose the way of urbanization in a region.
2006, 16(3): 199-202.
Abstract:
China's success in reform and opening up policy for twenty years is regarded as China's miracles in the world, whereas the income differential widening phenomenon has been the focus of the policymakers and researchers. This article researches 1994–2003 China's rural regions income differential and its decomposition. The method this paper used to measure the disparity is Gini Index. There are many ways to compute it, so the easiest way to decompose Gini Index—Matrix method is adopted. And based on it, farmer's income could be divided into wage income, farming income, transfer income and property income according to its composition. The conclusion is that all of the indexes are between 0.2 and 0.3, at the comparatively average level. From the fluctuation trend, it increased from 1994 to 1995, while reduced from 1995 to 1996, fluctuated in 1997, and then diminished again. In general, farmer's regions income differential stays at comparatively average level, but it has the widening trend with time. Through decomposing Gini Index, wage income is the most important increasing factor, while farming income is the reducing factor.
China's success in reform and opening up policy for twenty years is regarded as China's miracles in the world, whereas the income differential widening phenomenon has been the focus of the policymakers and researchers. This article researches 1994–2003 China's rural regions income differential and its decomposition. The method this paper used to measure the disparity is Gini Index. There are many ways to compute it, so the easiest way to decompose Gini Index—Matrix method is adopted. And based on it, farmer's income could be divided into wage income, farming income, transfer income and property income according to its composition. The conclusion is that all of the indexes are between 0.2 and 0.3, at the comparatively average level. From the fluctuation trend, it increased from 1994 to 1995, while reduced from 1995 to 1996, fluctuated in 1997, and then diminished again. In general, farmer's regions income differential stays at comparatively average level, but it has the widening trend with time. Through decomposing Gini Index, wage income is the most important increasing factor, while farming income is the reducing factor.
2006, 16(3): 203-210.
Abstract:
Globalization, which is characterized by the escalating mobility of capital, people, ideas and information on a universal scale, has become a sweeping theme in the contemporary world. Tourism and its associated economic activities are evidently not immune to such a wider context of the world economy. In the past one or two decades, a stable increase has been witnessed in international tourist flows, inter-regional and inter-organizational alliances, and foreign direct investment. These trends are especially prevalent in the developing world, largely because of their pristine nature, diverse culture, inexpensive goods and services, cheap labours, and other resources. However, it has been cautioned by some scholars, especially those from the Third World countries, that tourism is an industry run by and for the rich, more powerful nations and their corresponding multinational corporations. This article, from the perspective of political economy, supplemented with views from development studies, made a normative analysis on the impacts of the globalization of tourism on the Third World destination countries. Specifically, these impacts have been detailed in terms of economic, sociocultural, and ecological domains. It was demonstrated that without appropriate planning and management, the costs of Third World tourism development may accrue to the extent that its benefits are burned out. To avoid this happening, some suggestions have been made.
Globalization, which is characterized by the escalating mobility of capital, people, ideas and information on a universal scale, has become a sweeping theme in the contemporary world. Tourism and its associated economic activities are evidently not immune to such a wider context of the world economy. In the past one or two decades, a stable increase has been witnessed in international tourist flows, inter-regional and inter-organizational alliances, and foreign direct investment. These trends are especially prevalent in the developing world, largely because of their pristine nature, diverse culture, inexpensive goods and services, cheap labours, and other resources. However, it has been cautioned by some scholars, especially those from the Third World countries, that tourism is an industry run by and for the rich, more powerful nations and their corresponding multinational corporations. This article, from the perspective of political economy, supplemented with views from development studies, made a normative analysis on the impacts of the globalization of tourism on the Third World destination countries. Specifically, these impacts have been detailed in terms of economic, sociocultural, and ecological domains. It was demonstrated that without appropriate planning and management, the costs of Third World tourism development may accrue to the extent that its benefits are burned out. To avoid this happening, some suggestions have been made.
2006, 16(3): 211-216.
Abstract:
Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.
Considerable changes have taken place in commercial passenger air transport since the enactment of the 1978 Airline Deregulation Act in the US and the deregulation of airline networks that has occurred elsewhere. The commercial and operational freedoms have led most of the larger carriers to develop hub-and-spoke networks, within which certain cities or metropolitan areas emerge as key nodes possessing tremendous advantages over other locations in the air transport system. This paper examines the nature of hub-and-spoke operations in air transportation services, and the benefits that accrue to a city or geographical region that is host to an airline hub. In particular, it looks into linkages between the air service hub and local economic development. Four potential types of impact of airports on the regional economy are defined and discussed. As an example, the assessment of the economic impacts of Cincinnati-Northern Kentucky International Airport (CVG), a major Delta Airlines hub, is introduced.
2006, 16(3): 217-222.
Abstract:
Character of population distribution is one of the focuses studied by urban geography. Using the fifth national census data as basic data and using areal interpolation method, this paper analyzes character of urban population distribution of Shenyang City, Northeast China, in terms of three aspects of statistical character, spatial auto-correlation and spatial structure. Furthermore, this research analyzes the factors affecting the population distribution of the city. The main conclusions include: 1) There is an obvious structure character of population distribution in the grid with a grain of 300m, which is appropriate scale when researching population distribution in Shenyang City. 2) Urban population distribution has the character of assembling while population density distribution takes on variability in Shenyang City. 3) Population density distribution shows spatial auto-correlation within 7.36km. Spatial heterogeneity of population density is low. 4) Urban center, population distribution barycenter and population density maximum points separate each other. Population density distribution has multi-cores character. 5) Layout of governments, primary schools, middle schools, colleges, hospitals and marketplaces affects population distribution directly. With the increase of distance to these factors, population density decreases as logarithm.
Character of population distribution is one of the focuses studied by urban geography. Using the fifth national census data as basic data and using areal interpolation method, this paper analyzes character of urban population distribution of Shenyang City, Northeast China, in terms of three aspects of statistical character, spatial auto-correlation and spatial structure. Furthermore, this research analyzes the factors affecting the population distribution of the city. The main conclusions include: 1) There is an obvious structure character of population distribution in the grid with a grain of 300m, which is appropriate scale when researching population distribution in Shenyang City. 2) Urban population distribution has the character of assembling while population density distribution takes on variability in Shenyang City. 3) Population density distribution shows spatial auto-correlation within 7.36km. Spatial heterogeneity of population density is low. 4) Urban center, population distribution barycenter and population density maximum points separate each other. Population density distribution has multi-cores character. 5) Layout of governments, primary schools, middle schools, colleges, hospitals and marketplaces affects population distribution directly. With the increase of distance to these factors, population density decreases as logarithm.
2006, 16(3): 223-228.
Abstract:
Taking TM images, ETM images, SPOT images, aerial photos and other remote sensing data as fundamental sources, this research makes a thorough investigation on landslides and debris flows in Sichuan Province, China, using the method of manual interpretation and taking topography maps as references after the processes of terrain correction, spectral matching, and image mosaic. And then, the spatial characteristics of landslides and debris flows in the year of 2005 are assessed and made into figures. The environmental factors which induce landslides and debris flows such as slope, vegetation coverage, lithology, rainfall and so on are obtained by GIS spatial analysis method. Finally, the relationships of landslides or debris flows with some environmental factors are analyzed based on the grade of each environmental factor. The results indicate: 1) The landslides and debris flows are mainly in the eastern and southern area of Sichuan Province, however, there are few landslides and debris flows in the western particularly the northwestern Sichuan. 2) The landslides and debris flows of Sichuan Province are mostly located in the regions with small slope degree. The occurring rate of debris flow reduces with the increase of the vegetation coverage degree, but the vegetation coverage degree has little to do with the occurrence of landslide. The more rainfall a place has, the easier the landslides and debris flows take place.
Taking TM images, ETM images, SPOT images, aerial photos and other remote sensing data as fundamental sources, this research makes a thorough investigation on landslides and debris flows in Sichuan Province, China, using the method of manual interpretation and taking topography maps as references after the processes of terrain correction, spectral matching, and image mosaic. And then, the spatial characteristics of landslides and debris flows in the year of 2005 are assessed and made into figures. The environmental factors which induce landslides and debris flows such as slope, vegetation coverage, lithology, rainfall and so on are obtained by GIS spatial analysis method. Finally, the relationships of landslides or debris flows with some environmental factors are analyzed based on the grade of each environmental factor. The results indicate: 1) The landslides and debris flows are mainly in the eastern and southern area of Sichuan Province, however, there are few landslides and debris flows in the western particularly the northwestern Sichuan. 2) The landslides and debris flows of Sichuan Province are mostly located in the regions with small slope degree. The occurring rate of debris flow reduces with the increase of the vegetation coverage degree, but the vegetation coverage degree has little to do with the occurrence of landslide. The more rainfall a place has, the easier the landslides and debris flows take place.
2006, 16(3): 229-235.
Abstract:
The impact of land-use on distributed groundwater recharge and discharge in the western Jilin (WJ) was analyzed in this study. WJ is a transitional, semi-arid zone with a fragile, hydrological closed ecosystem in the Songhua River Basin (SRB). The research tool includes a seamlessly linked MODFLOW, WetSpass, the Seepage packages, and ArcGIS. The model calibration showed good agreement between simulated water table elevation and measured water table depths, while predicted groundwater discharge zones showed strong correlations with field occurrences of drainage systems and wetlands. Simulated averages for distributed recharge, water table elevation and groundwater drawdown were 377.42mm/yr, 194.43m, and 0.18m respectively. Forest vegetation showed the highest recharge, followed by ag- ricultural farmlands, while open-water and other drainage systems constituted groundwater exit zones. When present land-use conditions were compared with the hypothetical natural pre-development scenario, an overall loss of ground-water recharge (24.09mm/yr) was observed, which for the project area is 18.05×108m3. Groundwater abstraction seemed to be the cause of water table drawdown, especially in the immediate vicinities of the supply wells. An important issue of the findings was the ability of the hypothetical forest vegetation to protect, and hence sustain aquifer reserves and dependent ecosystems. The profound data capture capability of ArcGIS makes it particularly useful in spa- tio-temporal hydroecological modeling.
The impact of land-use on distributed groundwater recharge and discharge in the western Jilin (WJ) was analyzed in this study. WJ is a transitional, semi-arid zone with a fragile, hydrological closed ecosystem in the Songhua River Basin (SRB). The research tool includes a seamlessly linked MODFLOW, WetSpass, the Seepage packages, and ArcGIS. The model calibration showed good agreement between simulated water table elevation and measured water table depths, while predicted groundwater discharge zones showed strong correlations with field occurrences of drainage systems and wetlands. Simulated averages for distributed recharge, water table elevation and groundwater drawdown were 377.42mm/yr, 194.43m, and 0.18m respectively. Forest vegetation showed the highest recharge, followed by ag- ricultural farmlands, while open-water and other drainage systems constituted groundwater exit zones. When present land-use conditions were compared with the hypothetical natural pre-development scenario, an overall loss of ground-water recharge (24.09mm/yr) was observed, which for the project area is 18.05×108m3. Groundwater abstraction seemed to be the cause of water table drawdown, especially in the immediate vicinities of the supply wells. An important issue of the findings was the ability of the hypothetical forest vegetation to protect, and hence sustain aquifer reserves and dependent ecosystems. The profound data capture capability of ArcGIS makes it particularly useful in spa- tio-temporal hydroecological modeling.
2006, 16(3): 236-242.
Abstract:
Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.
Under the guide of system theory, taking the oasis in the Sangong River watershed as a case study, this paper analyzes the oasis structure and function from 4 aspects including oasis spatial structure, water resources structure, vegetation structure, economic structure and their corresponding functions. The results indicate that as a typical small-scale watershed, Sangong River watershed has the relatively complete mountain-basin structure, and ecological and productive function. Because of human drastic activity the utilization rate of water resources was as high as 98.7%, and the utilization of groundwater was not reasonable, which resulted in an average annual decline of 0.353m in the water table of alluvial-diluvial-fan oasis, and an average annual increase of 0.047m in the alluvial-plain. The layout of crop and shelter forest benefits to the utilization of water and land resources. The development of oasis economy is at low level, and its eco-economic function is weak.
2006, 16(3): 243-248.
Abstract:
Based on the experiments conducted in an irrigated intercropping field in Zhangye Oasis in the middle reaches of Heihe River basin in 2004, the characteristics of radiation budget are analyzed. Furthermore, energy balance is calculated by using Bowen-Ratio Energy Balance (BREB) method. The results show that the ratio of the absorbed radiation to the incoming short radiation in intercropping crop canopy-soil system is increasing with growing stages, from 0.81 in the initial growing stage (IGS) to 0.86 in the late growing stage (LGS). The net radiation, which is smaller in IGS, increases rapidly in the first period of the middle growing stage (MGS) and reaches the maximum value in the second period of MGS. It then somewhat decreases in LGS. The ratio of net radiation to total radiation has a similar trend with the net radiation. In the whole growing stages, latent heat flux, which takes up 70% or so of the net radiation, is the dominant item in energy balance. Sensible heat flux shares 20% of the net radiation and soil heat flux has a percentage of 10%. The characteristics of heat balance vary distinctly in different growing stages. In IGS, the ratios of latent heat flux, sensible heat flux and soil heat flux to net radiation are 44.5%, 23.8% and 31.7% respectively. In MGS, with the increasing of latent heat flux and the decreasing of sensible heat flux and soil heat flux, the ratios turn into 84.4%, 6.3% and 9.3%. In LGS, the soil heat flux maintains 0W/m2 or so, and latent heat flux and sensible heat flux take up 61.4% and 38.6% respectively. The energy balance also shows an obvious daily variation characteristic.
Based on the experiments conducted in an irrigated intercropping field in Zhangye Oasis in the middle reaches of Heihe River basin in 2004, the characteristics of radiation budget are analyzed. Furthermore, energy balance is calculated by using Bowen-Ratio Energy Balance (BREB) method. The results show that the ratio of the absorbed radiation to the incoming short radiation in intercropping crop canopy-soil system is increasing with growing stages, from 0.81 in the initial growing stage (IGS) to 0.86 in the late growing stage (LGS). The net radiation, which is smaller in IGS, increases rapidly in the first period of the middle growing stage (MGS) and reaches the maximum value in the second period of MGS. It then somewhat decreases in LGS. The ratio of net radiation to total radiation has a similar trend with the net radiation. In the whole growing stages, latent heat flux, which takes up 70% or so of the net radiation, is the dominant item in energy balance. Sensible heat flux shares 20% of the net radiation and soil heat flux has a percentage of 10%. The characteristics of heat balance vary distinctly in different growing stages. In IGS, the ratios of latent heat flux, sensible heat flux and soil heat flux to net radiation are 44.5%, 23.8% and 31.7% respectively. In MGS, with the increasing of latent heat flux and the decreasing of sensible heat flux and soil heat flux, the ratios turn into 84.4%, 6.3% and 9.3%. In LGS, the soil heat flux maintains 0W/m2 or so, and latent heat flux and sensible heat flux take up 61.4% and 38.6% respectively. The energy balance also shows an obvious daily variation characteristic.
2006, 16(3): 249-254.
Abstract:
Through denoting each expert as an agent and viewing a multiple criteria decision-making as a synthesis problem of aggregating experts' ratings, a multi-agent blind model (MABM) is developed for regional eco-environmental quality assessment. In this model, the ratings of the evaluated object under an index, given by expert group, are first utilized to construct a series of blind numbers. In general, each index will correspond to different blind numbers. On the basis of aggregating index weights, the rank score in the form of a blind number is obtained for the evaluated object. Then, by means of calculating expected value of the above blind number, its rank score is further converted into a crisp value. By way of comparing the expected value with classification standards, eco-environmental quality of the evaluated sample could be identified successfully in the end. As a case, the MABM is used to evaluate the eco-environmental quality of Chaohu Lake basin. Study result shows that the MABM is a useful model for regional eco-environmental quality assessment.
Through denoting each expert as an agent and viewing a multiple criteria decision-making as a synthesis problem of aggregating experts' ratings, a multi-agent blind model (MABM) is developed for regional eco-environmental quality assessment. In this model, the ratings of the evaluated object under an index, given by expert group, are first utilized to construct a series of blind numbers. In general, each index will correspond to different blind numbers. On the basis of aggregating index weights, the rank score in the form of a blind number is obtained for the evaluated object. Then, by means of calculating expected value of the above blind number, its rank score is further converted into a crisp value. By way of comparing the expected value with classification standards, eco-environmental quality of the evaluated sample could be identified successfully in the end. As a case, the MABM is used to evaluate the eco-environmental quality of Chaohu Lake basin. Study result shows that the MABM is a useful model for regional eco-environmental quality assessment.
2006, 16(3): 255-259.
Abstract:
Virtual Reality provides a new approach for geographical research. In this paper, a framework of the Virtual Huanghe (Yellow) River System was first presented from the view of technology, which included five main modules—data sources, 3D simulation terrain database, 3D simulation model database, 3D simulation implementation and application system. Then the key technologies of constructing Virtual Huanghe River System were discussed in detail: 1) OpenGL technology, the 3D graphics developing instrument, was employed in Virtual Huanghe River System to realize the function of dynamic real-time navigation. 2) MO and OpenGL technologies were used to make the mutual response between 3D scene and 2D electronic map available, which made use of the advantages of both 3D scene and 2D electronic map, with the macroscopic view, integrality and conciseness of 2D electronic map combined with the locality, reality and visualization of 3D scene. At the same time the disadvantages of abstract and ambiguity of 2D electronic map and the direction losing of virtual navigation in 3D scene were overcome.
Virtual Reality provides a new approach for geographical research. In this paper, a framework of the Virtual Huanghe (Yellow) River System was first presented from the view of technology, which included five main modules—data sources, 3D simulation terrain database, 3D simulation model database, 3D simulation implementation and application system. Then the key technologies of constructing Virtual Huanghe River System were discussed in detail: 1) OpenGL technology, the 3D graphics developing instrument, was employed in Virtual Huanghe River System to realize the function of dynamic real-time navigation. 2) MO and OpenGL technologies were used to make the mutual response between 3D scene and 2D electronic map available, which made use of the advantages of both 3D scene and 2D electronic map, with the macroscopic view, integrality and conciseness of 2D electronic map combined with the locality, reality and visualization of 3D scene. At the same time the disadvantages of abstract and ambiguity of 2D electronic map and the direction losing of virtual navigation in 3D scene were overcome.
2006, 16(3): 260-264.
Abstract:
Forest fire is a serious disaster all over the world. The Fire Weather Index (FWI) System can be used in ap- plied forestry as a tool to investigate and manage all types of fire. Relative humidity (RH) is a very important parameter to calculate FWI. However, RH interpolated from meteorological data may not be able to provide precise and confident values for areas between far separated stations. The principal objective of this study is to provide high-resolution RH for FWI using MODIS data. The precipitable water vapor (PW) can be retrieved from MODIS using split window techniques. Four-year-time-series (2000-2003) of 8-day mean PW and specific humidity (Q) of Peninsular Malaysia were analyzed and the statistic expression between PW and Q was developed. The root-mean-square-error (RMSE) of Q estimated by PW is generally less than 0.0004 and the correlation coefficient is 0.90. Based on the experiential formula between PW and Q, surface RH can be computed with combination of auxiliary data such as DEM and air temperature (Ta). The mean absolute errors of the estimated RH in Peninsular Malaysia are less than 5% compared to the measured RH and the correlation coefficient is 0.8219. It is proven to be a simple and feasible model to compute high-resolution RH using remote sensing data.
Forest fire is a serious disaster all over the world. The Fire Weather Index (FWI) System can be used in ap- plied forestry as a tool to investigate and manage all types of fire. Relative humidity (RH) is a very important parameter to calculate FWI. However, RH interpolated from meteorological data may not be able to provide precise and confident values for areas between far separated stations. The principal objective of this study is to provide high-resolution RH for FWI using MODIS data. The precipitable water vapor (PW) can be retrieved from MODIS using split window techniques. Four-year-time-series (2000-2003) of 8-day mean PW and specific humidity (Q) of Peninsular Malaysia were analyzed and the statistic expression between PW and Q was developed. The root-mean-square-error (RMSE) of Q estimated by PW is generally less than 0.0004 and the correlation coefficient is 0.90. Based on the experiential formula between PW and Q, surface RH can be computed with combination of auxiliary data such as DEM and air temperature (Ta). The mean absolute errors of the estimated RH in Peninsular Malaysia are less than 5% compared to the measured RH and the correlation coefficient is 0.8219. It is proven to be a simple and feasible model to compute high-resolution RH using remote sensing data.
2006, 16(3): 265-269.
Abstract:
Evapotranspiration (ET) process of plants is controlled by several factors. Besides the physiological factors of plants, height, density, LAI (leaf area index), etc., the change of meteorological factors, such as radiation, temperature, wind and precipitation, can influence ET process evidently, thus remodeling the spatial and temporal distribution of ET. In order to illuminate the effects of meteorological factors on wetland ET, the ET of Zhalong Wetland was calculated from 1961 to 2000, the statistical relationships (models) between ET and maximum temperature (Tmax), minimum temperature (Tmin), precipitation (P) and wind speed at 2m height (U2) were established, and the sensitivity analysis of the variables in the model was performed. The results show that Tmax and Tmin are two dominating factors that influence ET markedly, and the difference of rising rate between Tmax and Tmin determines the change trend of ET. With the climatic scenarios of four General Circulation Models (GCMs), the ET from 2001 to 2060 was predicted by the statistical model. Compared to the period of 1961-2000, the water consumption by ET will increase greatly in the future. According to the scenarios, the rise of Tmax (about 1.5℃ to 3.3℃) and Tmin (about 1.7℃ to 3.5℃) will cause an additional water con- sumption of 14.0%-17.8% for reed swamp. The ecological water demand in Zhalong Wetland will become more severe.
Evapotranspiration (ET) process of plants is controlled by several factors. Besides the physiological factors of plants, height, density, LAI (leaf area index), etc., the change of meteorological factors, such as radiation, temperature, wind and precipitation, can influence ET process evidently, thus remodeling the spatial and temporal distribution of ET. In order to illuminate the effects of meteorological factors on wetland ET, the ET of Zhalong Wetland was calculated from 1961 to 2000, the statistical relationships (models) between ET and maximum temperature (Tmax), minimum temperature (Tmin), precipitation (P) and wind speed at 2m height (U2) were established, and the sensitivity analysis of the variables in the model was performed. The results show that Tmax and Tmin are two dominating factors that influence ET markedly, and the difference of rising rate between Tmax and Tmin determines the change trend of ET. With the climatic scenarios of four General Circulation Models (GCMs), the ET from 2001 to 2060 was predicted by the statistical model. Compared to the period of 1961-2000, the water consumption by ET will increase greatly in the future. According to the scenarios, the rise of Tmax (about 1.5℃ to 3.3℃) and Tmin (about 1.7℃ to 3.5℃) will cause an additional water con- sumption of 14.0%-17.8% for reed swamp. The ecological water demand in Zhalong Wetland will become more severe.
2006, 16(3): 270-275.
Abstract:
Nitrogen (4, 10, 20 and 40g/m2) and phosphorus (1.2, 4.8 and 9.6g/m2) were applied to tanks to evaluating the effects of N and P additions on plant tissue nutrition and the biomass of two freshwater wetland plants in the Sanjiang Plain of Northeast China, namely Carex lasiocarpa and Carex meyeriana. For C. lasiocarpa, the total N concentration (TN) of plant tissues under the treatment of 10g/m2 was lower compared with the other N treatments. Initially, C. lasiocarpa exhibited a significant increase of biomass as compared with the control value, reaching the maximum of 31.20±4.01g/tank under the treatment of 10g/m2, and then dropped to 18.02±1.53g/tank under the treatment of 40g/m2. For C. meyeriana, TN generally increased with increasing amount of N applied. High N applied produced more aboveground biomass than low N applied. C. meyeriana, as the accompanying species, can adapt itself to the wetland enriched by N, and it may replace C. lasiocarpa as the dominant species of wetland. The total P concentration (TP) in tissues of C. lasiocarpa increased with P addition. The aboveground biomass of C. lasiocarpa increased with P addition, and it changed from 18.77±3.29g/tank to 46.03±3.95g/tank. However, TP of tissue may accelerate the C. meyeriana development under the treatment of 1.2g/m2. P accumulation contributes to the dominance of C. lasiocarpa but limits the production of C. meyeriana, and the latter may disappear gradually from the wetland enriched by P. Increased input of N and P might have an influence on wetland plant community composition and structure, so the effects of nutrient inputs and accumulation should be considered to protect the freshwater wetland.
Nitrogen (4, 10, 20 and 40g/m2) and phosphorus (1.2, 4.8 and 9.6g/m2) were applied to tanks to evaluating the effects of N and P additions on plant tissue nutrition and the biomass of two freshwater wetland plants in the Sanjiang Plain of Northeast China, namely Carex lasiocarpa and Carex meyeriana. For C. lasiocarpa, the total N concentration (TN) of plant tissues under the treatment of 10g/m2 was lower compared with the other N treatments. Initially, C. lasiocarpa exhibited a significant increase of biomass as compared with the control value, reaching the maximum of 31.20±4.01g/tank under the treatment of 10g/m2, and then dropped to 18.02±1.53g/tank under the treatment of 40g/m2. For C. meyeriana, TN generally increased with increasing amount of N applied. High N applied produced more aboveground biomass than low N applied. C. meyeriana, as the accompanying species, can adapt itself to the wetland enriched by N, and it may replace C. lasiocarpa as the dominant species of wetland. The total P concentration (TP) in tissues of C. lasiocarpa increased with P addition. The aboveground biomass of C. lasiocarpa increased with P addition, and it changed from 18.77±3.29g/tank to 46.03±3.95g/tank. However, TP of tissue may accelerate the C. meyeriana development under the treatment of 1.2g/m2. P accumulation contributes to the dominance of C. lasiocarpa but limits the production of C. meyeriana, and the latter may disappear gradually from the wetland enriched by P. Increased input of N and P might have an influence on wetland plant community composition and structure, so the effects of nutrient inputs and accumulation should be considered to protect the freshwater wetland.
2006, 16(3): 276-281.
Abstract:
The paper presents a set of techniques of digital watermarking by which copyright and user rights messages are hidden into geo-spatial graphics data, as well as techniques of compressing and encrypting the watermarked geo-spatial graphics data. The technology aims at tracing and resisting the illegal distribution and duplication of the geo-spatial graphics data product, so as to effectively protect the data producer's rights as well as to facilitate the secure sharing of geo-spatial graphics data. So far in the GIS field throughout the world, few researches have been made on digital watermarking. The research is a novel exploration both in the field of security management of geo-spatial graphics data and in the applications of digital watermarking technique. An application software employing the pro- posed technology has been developed. A number of experimental tests on the 1:500,000 digital bathymetric chart of the South China Sea and 1:10,000 digital topographic map of Jiangsu Province have been conducted to verify the feasibility of the proposed technology.
The paper presents a set of techniques of digital watermarking by which copyright and user rights messages are hidden into geo-spatial graphics data, as well as techniques of compressing and encrypting the watermarked geo-spatial graphics data. The technology aims at tracing and resisting the illegal distribution and duplication of the geo-spatial graphics data product, so as to effectively protect the data producer's rights as well as to facilitate the secure sharing of geo-spatial graphics data. So far in the GIS field throughout the world, few researches have been made on digital watermarking. The research is a novel exploration both in the field of security management of geo-spatial graphics data and in the applications of digital watermarking technique. An application software employing the pro- posed technology has been developed. A number of experimental tests on the 1:500,000 digital bathymetric chart of the South China Sea and 1:10,000 digital topographic map of Jiangsu Province have been conducted to verify the feasibility of the proposed technology.
2006, 16(3): 282-288.
Abstract:
With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remotely sensed information classification pattern and a literature review of related research progress, this paper sums up 4 developing phases of object-oriented classification pattern during the past 20 years. Then, we discuss the three aspects of method- ology in detail, namely remotely sensed imagery segmentation, feature analysis and feature selection, and classification rule generation, through comparing them with remotely sensed information classification method based on per-pixel. At last, this paper presents several points that need to be paid attention to in the future studies on object-oriented RS in- formation classification pattern: 1) developing robust and highly effective image segmentation algorithm for multi-spectral RS imagery; 2) improving the feature-set including edge, spatial-adjacent and temporal characteristics; 3) discussing the classification rule generation classifier based on the decision tree; 4) presenting evaluation methods for classification result by object-oriented classification pattern.
With the wide use of high-resolution remotely sensed imagery, the object-oriented remotely sensed informa- tion classification pattern has been intensively studied. Starting with the definition of object-oriented remotely sensed information classification pattern and a literature review of related research progress, this paper sums up 4 developing phases of object-oriented classification pattern during the past 20 years. Then, we discuss the three aspects of method- ology in detail, namely remotely sensed imagery segmentation, feature analysis and feature selection, and classification rule generation, through comparing them with remotely sensed information classification method based on per-pixel. At last, this paper presents several points that need to be paid attention to in the future studies on object-oriented RS in- formation classification pattern: 1) developing robust and highly effective image segmentation algorithm for multi-spectral RS imagery; 2) improving the feature-set including edge, spatial-adjacent and temporal characteristics; 3) discussing the classification rule generation classifier based on the decision tree; 4) presenting evaluation methods for classification result by object-oriented classification pattern.
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