This paper constructs a special data structure model for montane altitudinal belts (MABs) and thereby realizes their digitalization and visualization. A three-level hierarchy is drawn for MABs classification: the first level is "spectra series" with the same base belt. A total of 31 basic spectra series can be generalized for China; the second level is "spectra group" with the same characteristic belts; the third level is "spectrum type" with the same structure of MABs. Seven models are identified for the spatial variation of MABs: (1) identical structure model; (2) structure-thinning model; (3) mutation model; (4) latitudinal descending model; (5) longitudinal thinning-rising model; (6) step-ascending model; and (7) superimposed model. Five ecological types of MABs are also distinguished as follows: (1) climax MABs related with regional climate; (2) standard MABs related with main mountains; (3) special/transitional MABs related with special geoecological phenomenon; (4) disturbed MABs related with human disturbances; and (5) secondary mabs related with intensive human activities. Digital comparison and analysis of mabs could reveal more geographical information than ever before.
Based on the units of 26 prefectures and 66 counties, 9 typical mountainous areas, including Da-Xiao Hinggan Mountains, Yanshan Mountains, Taihang Mountains, Yimeng Mountains, Qilian Mountains, Hengduan Mountains, Karst Mountains, Wuling Mountains and Dongnan Mountains, were selected to analyze the state of off-farm income. After comparison with plains as well as developed regions, the results show that the average agricultural output per capita in plain and mountainous areas is both lower than 2000 yuan RMB without much difference, but the difference is much bigger in output value of off-farm industries between plain and mountainous areas. The output value of off-farm industries accounts for about 90% of GDP in plain areas, but in mountainous areas it is 70% of GDP. The authors therefore conclude that the "poverty" in mountainous areas or the gap between mountainous areas and plain areas lies in the underdevelopment of off-farm industries in mountainous areas. Also, this study indicates that agricultural growth trend in China is strongly correlated with growth of off-farm industries--the curve of net income from off-farm industries reflects the general characteristics of net income of households. That is to say that increase of net income of farm households is chiefly from off-farm industries, more than from agriculture.
Based on the biomass investigation, soil respiration and plant photosynthesis measurement of dominant trees in Hailuogou valley of Mt. Gongga, Southwest China, the carbon(C) storage, absorption and release for several typical woodland in sub-alpine zones have been discussed. For Abies fabri forest of 3000 m above sea level, the C storage amount is 177.4 t/hm2 for plant above ground surface and 143.2 t/hm2 for soil. The annual gross C fixed by vegetation photosynthesis is 20-24 t/hm2. The C release by canopy respiration is 3.0-5.5 t/hm2 for arbors and 10-19 t/hm2 for soil and roots. The total annual net C fixed in forest ecosystems is about 6.0-7.1 t/hm2. At lower position, the woodland released C amount is higher than that of woods at higher place. The C fixed capacity of renewed forest with middle-aged trees is higher than that of mature forest.
Based on the data from field survey in subalpine meadow on Mt. Xiaowutai, Hebei Province, α diversity and β diversity of the meadow were analyzed through Shannon-Weaver index and S?rensen index analysis in this paper. The results are as follows: 1) Both diversity indexes change obviously with elevation, and α diversity and β diversity change dramatically at the elevations of around 2300 m and 2700 m. 2) The order of α diversity index, from high to low, is Eastern > Western > Southern > Northern. β diversity reflected by S?rensen index increases when slope exposure changes. 3) Higher α diversity, but lower β diversity is observed on the mid-slope or the mid-bottom slope. The value of β diversity depends mostly on the range of elevation, normally between 2300 m and 2750 m, the β value reaches the highest.
The dust events in China have been studied using the data of dust storms, wind-blown sand and floating dust from 338 observation stations selected in China from 1954 to 2000. The results are as follows: (1) In China, there are two high frequent areas of dust events, one is located in the area centered around Minfeng and Hotan in the South Xinjiang Basin, the other is situated in the area centered around Minqin and Jilantai in the Hexi Region. (2) The affected areas of dust storms can be divided into seven sub-regions, that is, North Xinjiang Region, South Xinjiang Region, Hexi Region, Qaidam Basin Region, Hetao Region, Northeastern China Region and Qinghai-Xizang Region. The area of the most frequent occurrence of dust storms and floating-dust is in South Xinjiang Region, and of wind-blown sand in the Hexi Region. The annual occurrence days of wind-blown sand in four representative regions have been increasing since 1998, but that of floating dust does not evidently reveal this phenomenon.
This paper gives an overall summary on recent progress in the control of sand drift damages in the Taklimakan Desert highway. The following theoretical research results and practical aspects in the prevention of sand drift encroachment on the cross-desert highway have been undertaken: (1) With start-up wind speed and sand-moving power as physical parameters to describe sand drift damages, a function relation between sand transport rate (Q) and threshold wind velocity for sand movement (V) has been established. (2) Sand dune migration rate varies between 3.33 and 10.87 ma-1 and shows a linear relation with height (H), base area (S) and volume (V) of sand dune, where D = a-bH, D = a-bS, D = a+bV-c and D = a-bS-cV. (3) Sand drift damages exhibit a horizontal and vertical differentiation law, from this the calculating formula of sand damage intensity and five different damage sections are identitied. (4) Wind tunnel experiments on the sand control mechanism and effect of three kinds of film-covered sand bag barriers with a penetrating coefficients of β = 10%, β = 20% and β = 40% and three kinds of upright reed fences of 2.5 × 2.5 m, 5 × 5 m and 10 × 10 m show that there exist a retarded circumfluence zone, a lift-accelerating zone and a back flow zone around the sand bodies protected by film-covered sand bag barriers; wind velocity at the front edge of upright grids gradually increases and becomes stable at a distance of 15-20 m from the fence; nylon net fence has sand diversion function, with an optimal porosity of 40-50%. (5) The burial rate of sand control system mainly depends on landform types and sites where the system lies, start-up wind speed and intersection angle of the fence etc.
China witnesses serious disasters of tropical cyclones every year. There were 459 tropical cyclones landing along the coast of China in 1951-2000, of which 15 tropical cyclones are in the maximum year, 4 tropical cyclones in the minimum year, and 9.2 tropical cyclones in the average year. According to the relationship analysis between tropical cyclones landing in China and El Nino years and La Nina years, some results are obtained as follows: (1) There are less frequencies of tropical cyclones landing in China in El Nino years; (2) the greater the intensity of El Nino event, the less the frequencies of tropical cyclones landing in China; (3) if the finish time of El Nino event appears after May 1, there are less frequencies of tropical cyclones landing in China in the following year; (4) the years of extremely high frequencies of tropical cyclones landing in China are mainly in La Nina years; (5) there are less frequencies of tropical cyclones landing in China in the following year of La Nina years; (6) the greater the intensity of tropical cyclones landing in China, the less the arising possibility in El Nino years; and (7) there are later tropical cyclones first-landing in China, and earlier tropical cyclones last-landing in China in El Nino years. The knowledge can be regarded as the formula of statistical forecast of frequencies of tropical cyclones landing in China, which is of the forecasting significance. It is demonstrated by analysis that there is the comparatively close relationship between tropical cyclones landing in China and sea surface temperature in the Pacific. In fact El Nino and La Nina events are one of the main physical factors affecting tropical cyclones landing in China via the sea-air function. Rising and maintaining of tropical cyclones needs the huge energy, and ocean surface of high temperature is its huge energy warehouse. When El Nino event appears, the energy supply decreases in the main source area of tropical cyclones, the inter-tropical convergence zone becomes weaker, and the activity of cumulus convection is affected because sea surface temperature in the tropical western Pacific reduces. Therefore there is an environmental field that tropical cyclones disadvantageously rise and develop. In this way there are less tropical cyclones landing in China. When La Nina event appears, there is quite the opposite situation.
In this paper, the exploitation of water resources and the corresponding environmental problems in the Tarim River during the past five decades are mainly analyzed as follows: (1) Statistics show that in the 1990s, the annual volumes of runoff from the mountainous regions of the source stream areas increased obviously (by 10.9%), compared to that in the 1950s. The water volume supplied from the Aqsu, Yarkand, and Hetian rivers to the Tarim River reduced greatly (18.83%). (2) Increasing use of water in the source area resulted in problems of secondary soil salinization. Increasing consumption of water in the upper and middle reaches caused droughts in the lower reaches. The reduction amplitude of the inflow volume at the lower reaches was far higher than that at the Aral section in the upper reaches of the mainstream of Tarim River. (3) The ecosystems in the lower reaches of the Tarim River has damaged seriously. Due to the drying up of the watercourses, groundwater level along the lower reaches of the river basin dropped from 3-5 m to 8-12 m, and water quality became salinized. Vegetation survival depended on groundwater there has seriously degenerated: 68% of natural vegetation has been lost, 47% of Populus euphratica died. Biodiversity has been seriously damaged, and desertification process has been quickened, at a rate of 150-200 km2 every year.
100 fluvial transects were specifically selected along the Yangtze River channel extending from Wuhan to the river mouth. Three samples were taken at each transect, i.e., one from the main river channel and the other two from both flank shallow-water riverbeds. The present study examines the distribution of grain size throughout the river channel, in terms of along the river-channel transect and along the one perpendicular to the river channel. This is primarily on the basis of different river-channel patterns defined. Computing simulation of various grain-size parameters obtained from the laboratory helps recognize effectively the sediment characteristics of the river patterns. It is believed that the river flow and river morphology affected largely by the regional geology, climate setting, etc., are the determinant factors, which characterize the sedimentation of the middle and lower Yangtze river catchment. The paper demonstrates that the sedimentation of modern Yangtze River channel below Wuhan remains relatively stable, as evidenced by: 1) almost equivalent input and output of sediment budget in the upstream Hankou and downstream Datong hydrological stations; and 2) bed load movement rarely occurred in the river channel where fine and medium sand prevail. Four segments of the sediment distribution of the river channel recognized as "coarser-finer-coarser-finer" were differentiated.
Based on data from hydrometric stations and other documented sources about the hydro-engineering works downstream from Datong (the tidal limit from the East China Sea), this paper presents a preliminary study on water discharge changes between Datong and Xuliujing during the dry season. The natural hydrological processes and human factors that influence the changes of water discharge are analyzed with the help of the GIS technology. The investigations indicate that the water-extracting engineering projects downstream Datong had totaled to 64 in number by the end of 2000, with a water-extraction capacity up to 4626 m3/s averaged in a tidal cycle. The water abstractions from the Changjiang River downstream Datong have become the most important agent that may cause large and episodic drop in water discharge downstream Datong during dry season. The potential magnitude in water discharge changes under different climatic and hydrological conditions in dry season and its influence on the discharge into the sea are estimated based upon records of water extractions and parameters of engineering capacity. The results were calibrated with the actual data. The future trend of changes in water discharge to the sea during the dry season was discussed according to the historical data and the newly built engineering projects. The results show that the water extractions in dry season before 2000 downstream Datong had exerted remarkable impacts on discharges into the sea only during the extremely dry year like the period 1978-1979, when the monthly mean discharges all decreased over 490 m3/s. The decrease in January and February accounted for about 7% of the total discharge recorded at Datong. It is expected that the water extractions will continually increase in the coming decades, especially during dry years, and will have a far-reaching effect on the changes of water discharge from the Changjiang into the sea. The decrease in monthly mean water discharge is estimated to be over 1,000 m3/s.
Using the interpretation of remote sensing images and synthesis of the historical literature and maps, this paper deals with the river evolution of the Yellow River in the Houtao Plain, Inner Mongolia. The following results are obtained: It is deducted that the south alluvial fan whose acme is located near Ershiliuzi, south to Dengkou formed before the 2nd century BC. The Yellow River wandered with a converged pattern on the alluvial fan and then flowed northward until the southern foot of the Yinshan Mountains and then turned eastward. In the 2nd century BC, the development of the south alluvial fan was stopped at that time and the acme of the alluvial fan moved northward to nearby 8 km north to Bulongnao. The Yellow River wandered with a converged pattern on the new alluvial fan (the north alluvial fan), then northward till the southern foot of the Yinshan Mountains and along it eastward many courses converged. The Taiyangmiao depression between the south and the north alluvial fans became Tushenze Lake due to water collection. There are many paleochannels of the Yellow River in the eastern part of the Houtao Plain, most of which flowed from west to east. From the 6th century to the mid-17th century, the Yellow River in the Houtao Plain was divided into two branches, the South River and the North one.
Sedimentary method has been used to determine the historical sedimentation rate in this study, and historical literature has been studied to obtain information on climate change and human activities. Based on the data obtained in this way, the temporal variation in the sedimentation rate of the lower Yellow River in the past 2300 years has been studied in relation with climate change and human activities. The results indicate that the response of the sedimentation zone of the Yellow River system to the change in the erosion zone is sensible. The changes in vegetation and land use, both related to climate change and human activities, are two major controls for the acceleration of sedimentation rate. In addition, changes in strategies for the harnessing of the lower Yellow River are also responsible for such acceleration. During the process of accelerated sedimentation in the past 2300 years, the period of the 7th-10th centuries and the period since the mid-19th century have been identified as two periods with abrupt changes.
Socio-economic water cycle means water cycle driven by human activity and contrast with natural water cycle driven by natural factors. The backgrounds of putting forward the research of socio-economic water cycle are becoming more and more serious because of water scarcity and human impact on water cycle. The main domains of research of socio-economic water cycle include water security appraisement, sustainable and integrated management of water resource, socio-economic studies of water resources, human impact on water cycle, water environment and water-ecology interaction etc. This paper reviewed international research progress of socio-economic water cycle which had a focus on China. China has completed national water resources and medium to long term water supply planning. She has been engaging in study on water-deficient regions in North China and Northwest China for about half a century. For solving water shortage problem in northern China, she has put forward the famous South-to-North Water Transferring Project, which has been set as one of the four key national projects in the Tenth Five-Year Plan period although there are still debates. For promoting water use efficiency, China has been reforming her water management system, including water right system and water price system. There has already been a case of water right purchase. China has also conducted a lot of research on the interaction between human activity, water and ecosystem. For meeting the need of sustainability and coordinating water resources development and environmental protection, the study of ecological water requirement became very hot in recent years. There are three focuses of socio-economic water cycle study now in China: water transfer project from the south to the north, water resources management and ecological water requirement.
The probability of crane living in reedy wetlands can reach 100%, at the same time, the area of reed, the water level and adjacent water area are main factors which control the crane's habitat selection. We all know that all these factors are spatially heterogenous. For the sake of Xianghai wetland safety and of protecting the Xianghai wetland habitat of crane, this paper mainly has found a method to solve these problems. The wetland information is extracted from the TM images, which reflect the whole wetland landscape and are very important for both quantitative analysis of remote sensing observation of the earth system and positioning analysis in GIS database that is automatically extracted from DEM. The DEM for Xianghai characteristics of topography is created. On the basis of the GRID SUBMODULE, applying the GIS spatial overlay analysis, the relationship between the water level and the reed area below the water level and the rating distribution maps of reed area above water level is established. When the water level reaches the altitude of 16 m, the reed area, 981.2 hm2, is the maximum, i.e., the water level of 165 m is the optimal.
Based on the research of city centrality and economic core areas of China and the analysis of foreign trade freight flow, railway passenger flow, railway freight flow, transmigrant flow and letter flow, this paper summarizes the characteristics of domestic and foreign hinterlands of the economic core areas. (1) Beijing-Tianjin Area, the Yangtze River Delta and the Pearl River Delta have become more and more dominant in China's regional economy since the reform and opening up started in 1978. (2) The Central-and-Southern Liaoning Area has been dropped behind by the other three core areas in economic development. The North-East China has degraded from first-class into second-class UERs. (3) As China's economy being gradually integrated into the world, there is a huge steering effect on domestic economic linkages of China's. (4) The distributions of the three core areas' hinterlands in domestic and foreign linkages are different, which reflect their different functional divisions in economic linkages. (5) The foreign economic linkages of Shandong and Fujian provinces almost depend completely on their own foreign ports, including Qingdao, Xiamen and Fuzhou. (6) The foreign economic linkages of frontier provinces bordering foreign countries are playing an important role in their economic development through landway channel.
China has experienced a rapid urbanization process during the past two decades because of its fast-growing economy. In the near future, the urbanization process will be accelerated due to promotion of governments at different levels. As a major type of land use change, urban expansion, because of its potential impact on croplands, has become one of the top concerns in land planning, land management and food security of China. This paper analyzed changes in urban built-up area of 200 major cities in the 1990s, using the rank-size law, which is often employed in the study of city's population size distribution. Then, we explained the rank-size curves using theory of fractal and the results include the following several aspects. Firstly, the city size distribution in terms of urban built-up area perfectly accorded with rank-size rule, and the coefficient of determination (R2) were all more than 0.95. Secondly, according to the curve shape, we claimed that Chinese cities could be divided into three categories, i.e., large cities with an area of more than 200 km2, medium-sized cities with an area between 50 and 200 km2, and small cities, with an area of less than 50 km2. Thirdly, the China's city system in terms of built-up area is relatively well developed. and the rank-size distribution curve therefore moved in a parallel evolution manner from 1990 to 2000. Fourthly, the rank-size distribution curve revealed that the rate of urban land expansion was markedly different among these three groups of cities during the past decade. At last, this study suggested that the rank-size law could be a good tool to predict future urban expansion in China.
Based on the understanding that the city expansion is the result of the collective effects of exogenous constraints and internal expanding ability of urban pixel, a city expansion model in metropolitan area (CEM) based on CA and Tietenberg model is developed to understand the city development in metropolitan area in China and Beijing is selected as the case study city here. At first, the city development in Beijing from 1975 to 1997 was simulated. Then according to the simulation, the city expansion from 1998 to 2015 was predicted under the condition that the optimal amount and optimal location of the urban land use in the future should be both satisfied. The results suggested that the model can represent the characteristics and rules of the city development, especially the city expansion in the metropolitan area to a certain extent if the influencing factors are standardized strictly and the optimal weights are given by adaptive Monte Carlo method newly developed in the paper.
This article brings forward a set of comprehensive indicators aiming at the temporal process of land use change. Productivity, stability, restorability, equity, self-supporting ability and harmonizing capacity in a rather long period are used to measure the sustainability of land use, and applied in the case study of Laixi City, Shandong Province. Productivity is the growth process of yield per unit of land area. Stability is the coherence and consistency of the productivity and may be presented by variation coefficient V= σ/ā. Restorability is the ability of land use system withstanding outside impacts, such as natural hazard and policy or market changes, and resuming productivity. It can be shown by annual variation. Equity is the degree of justice of land use benefit allocation, and can be measured by the proportion of population at various levels of income. Self-supporting ability presents the extent of supply, improvement, organization and control of land use system itself and may be shown by the proportion of capital assert investment in the total financial income. Harmonizing capacity is the extent of balance between demand for land products and supply of land productivity. The result of the case study shows that land use in Laixi City is sustainable in general. It is evident in the case study that these comprehensive measurements representing processes are concise, effective, reasonable and operationable.
Based on 1:500,000 digital map of lithology distribution in Guizhou, spatial analysis of the maps of rock desertification and of lithology is conducted by GIS. Results indicate that there is obvious relativity between rock desertification and lithology. Intense rock desertification scatters maily in pure carbonate rock area, especially in pure limestone area whereas moderate rock desertification is more widely distributed in dolomite association than in limestone association and slight rock desertification is widely distributed in carbonate rock association layered with clastic rock.
