In recent 10 years, actual water flow in the mainstream of the Yellow River have been decreasing, ranging from 20% to 65% compared with the previous average inflow. THe cut-off of the lower Yellow River in successive years in the 1990s has attracted the world's attention. According to the previous studies and observational data, this paper analysed quantitatively actual water flow reduction and its root causes in the mainstream of the Yellow River based on the characteristics in climate change (eg. precipitation variation), impact of human activities (eg. constant increase in water use for national economy), and eco-environmental water demand. Results showed that actual water flow reduction was mainly caused by climate change (75%) in the upper Yellow River while it was affected by human activities (57%) in the middle reaches (Hekouzhen-Huayuankou section) especially since the late 1970s.
Based on meteorological and hydrological data in the Yellow River Basin covering 1981-2000, Advection-Aridity model, CRAE model and Granger model were validated at different temporal scales and in different climatic conditions by means of remote sensing and digital elevation model. Different climatic factors' effects on performance of models and variation characteristics of empirical parameters were analysed. Results show that with the exception of several extreme arid years, annual errors of Advection-Aridity model, CRAE model and Granger model were less than 10%. Monthly evapotranspirations from Advection- Aridity model were rational. However, CRAE model and Granger model overestimates monthly evapotranspirations during the winter. Spatial distribution of water balance closure errors for Advection-Aridity model is similar to that of Granger model. The closure errors for Advection-Aridity model and Granger model are less than that of CRAE model. In arid and humid climates or under more and less available energy conditions, Advection-Aridity model, CRAE model and Granger model did not perform very well.
With an aid of the geographical information system of the hydrological, meteorological, soil and land use data, the Digital Elevation Model and NOAA-AVHRR remote sensing information, a distributed eco-hydrological model based on soil-vegetation-atmosphere transfer theory is developed to simulate the spatial and temporal variation of water balance components over the Wuding River Basin, the Loess Plateau, China from 1982 to 1991. It is found over the ten years, the maximum Normal Difference Vegetation Index (NDVI) changes year by year while the annually averaged NDVI is stable. There is not an obvious linear relationship between the annually averaged NDVI and annual precipitation, indicating that the variation of vegetation is not fully controlled by precipitation in this basin. The simulated evapotranspiration values over the Wuding River Basin and one of its sub-basins (Chabagou) agree well with the observed, the difference between the annual precipitation and runoff, with the relative errors being less than 5%. Over the simulated periods, the annual precipitation (372±53 mm yr-1) is consumed mostly by evapotranspiration (334±33 mm yr-1), of which about one third is transpiration (130±21 mm yr-1). Compared with the high yearly variation of precipitation and evapotranspiration, that of runoff is relatively stable. The seasonal variation pattern of evapotranspiration is similar to that of precipitation and net radiation with peaks in August, while that of runoff is unique with the high peak in March, indicating that freezing proCess should be further included in the model development. By increasing gradually from the northwestern part of the basin where the NDVI is low, the precipitation and evapotranspiration reaches the highest in the southeastern part of the basin where the NDVI is high. The spatial pattern of runoff shows the highest values in the middle part of the basin. Replacing the vegetation patterns in 1991 with each single vegetation type covering the whole of the Chabagou basin, canopy transpiration and soil evapotranspiration all change dramatically, whereas the changes of total evapotranspiration and runoff are small.
Zoning of water resources management of river basin is very important for making policies of water resources management. Based on 30 indexes divided into environmental, food, water resources and soCioeconomic groups, the paper uses Cluster Analysis and GIS to analyze clustering proCesses, and to make the project for zoning by means of management experiences. According to analytical results, the Haihe River Basin is divided into 7 zones: Taihang and Yanshan mountainous zone, piedmont diluvial/alluvial zone, Beijing-Tianjin-Tangshan region (zone), piedmont plain zone, middle and eastern plain zone, Tianjin downtown area (zone), and Tuhai Majia River plain. This result accords with water resources management in the Haihe River Basin. Because of different problems, it is imperative to make water resources management policies for different zones.
Many factors can impact RH, but up to now most of the researches only consider the climatic factors such as temperature and soil moisture or precipitation. The impacts of soil properties on RH have been ignored, so the models' effect is not as good in large area where soil properties vary greatly as in small area where soil properties vary less. The coefficient of soil heterotrophic respiration reflected the influence of soil properties on RH. Based on carbon balance equations of ecosystems, the 1-km resolution's soil heterotrophic respiration coefficient (aij) in China has been calculated by using net primary production (NPP) of ecosystems and observed climate data. The results show that the value of aij as a whole, is larger in Southeast and Northeast China than that in Northwest China. Compared with the NPP's distribution throughout the country, the value of aij in most parts of Southeast China is not large, but it is large in vast area of Northeast and East China, which indicates that the soil heterotrophic respiration has great increase potential in these regions if climate becomes favorable. And then, the authors simulate the carbon flux change between terrestrial ecosystem and atmosphere on the hypothesis of climate change, the average temperature is 1.5oC higher and average precipitation is 5% more. The results show that both fluxes from atmosphere to terrestrial and from terrestrial to atmosphere increase. The rate of average increase of NPP and soil heterotrophic respiration is about 6.2% and 5.5% respectively. The most powerful natural ecosystem which could accumulate carbon is needle-leaved deciduous forest, and the most powerful agricultural ecosystem which could accumulate carbon is one crop per year. On the contrary, the double cropping rice followed by a cool-loving crop per year and the double cropping rice followed by a thermophilous crop per year are potential carbon sources.
Statistical interpolation of the temperature for the missing points is one of the most popular approaches for generating high spatial resolution data sets. However, many interpolation methods used by previous studies are purely mathematic ways, without geographical significance being considered. In the present study the authors interpolate the monthly and annual mean temperature climatologies using 726-station observations in China, utilizing improved methods by taking into account geographical factors such as latitude, longitude, altitude. In addition, a smart distance-searching technique is adopted, which helps select the optimum stations on which the guess values at missing points are generated. Results show that the methods used here have evident advantages over the previous approaches. The mean absolute err of ordinary inverse-distance-squared (IDS) technique is in the range of 1.44-1.63oC, on average 1.51oC. The smart distance searching technique yield a MAE of 0.53-0.92oC, on average 0.69oC. Errors have been reduced as much as 50%.
Using the data of monthly rainfall and rainy days from 1971 to 2000 in Tibet, the linear trends of the annual and seasonal rainfall and rainy days are analyzed. The results show that, the annual rainfall trend in most parts of Tibet increased, rainfall trend was 1.4-66.6 mm/10a, and the change trend of rainfall decreased in Ngari district. A decline trend of rainy days (R≥0.1) was found over Ngari and eastern Nyingchi districts, the increase of rainy days was obvious in middle-western Nagqu and northern Qamdo districts. In the 1970s, the precipitation positive anomaly occurred in western Tibet, and negative anomaly in eastern Tibet. The precipitation anomaly is negative in most parts of Tibet in the 1980s. For precipitation anomaly in the 1990s, the positive appeared in eastern Tibet and the negative in western Tibet. It was also found that change trend of mean annual and seasonal rainfall of Tibet increased during the 30 years, and annual rainfall trend indicated an increase of 19.9 mm/10a, especially in the 1990s. After 1992, the rainfall increased during spring and summer.
Based on the high temperature data covering June-August during summer of 1961-2000 in northern China, climatic characteristics of high temperature weather in Beijing, Jinan, Shijiazuang, Tianjin and Taiyuan are analyzed. Variable features of the subtropical high and denaturalization high are discussed. The results show that the subtropical high and denaturalization high over the high temperature weather in northern China are closely related with humidity. The subtropical high and denaturalization high in eastern China are the most important system. With an assessment model established, some computing cases show that the assessment experiment of the method has reference value to the assessment of the muggy high temperature weather in most cities of northern China.
The characteristics of wetland landscape structure in watershed in the Naoli River the Sanjiang Plain are exhibited in three aspects. The first one is wetland landscape gradient characteristic in the longitudinal landscape structure of the watershed from the sources area of rivers to the lower reaches, which shows that wetland landscape types were differently distributed according to the topographic gradient and hydrological gradient and formed a wide riparian landscape corridor in the watershed; the second is wetland landscape gradient characteristic in the transverse structure of watershed with perpendicularity rivers in the watershed, which also shows that wetland landscape types are differently distributed in a topographic gradient and hydrological gradient and formed an extensively distributed wetland area in watershed's flood plain; the third is wetland landscape internal structure, which shows that many small mosaics or patches were distributed in the microscopic geomorphic units in the extensive wetland landscapes. The driving forces leading to substantial changes of wetland landscape structure in the watershed were identified as: 1) land reclamation has led to more than 75% of wetlands loss in historical periods and 98% of the lost wetlands direct conversion to agricultural lands in the watershed, which is the major reason for watershed wetland landscape structure changes; 2) drainage ditches construction for agricultural development and dikes construction for flooding prevention after the 1980s has led to wetland loss and fragmentation and landscape structure changes in the watershed; 3) changes in wetland hydrological condition due to agricultural development have led to wetland ecosystem degradation, as a result, almost all the remaining marsh wetlands in the plain were degraded to meadow wetland at present state.
This paper takes Zhexi hydraulic region in Taihu Basin as the study area. Using hydraulic analysis function of Arcgis8.3, the drainages were delineated by selecting the monitoring points and discharge stations as outlets. The landuse map was finished by denoting the TM/ETM image. The precipitation map was finished by spatial interpolation using the rainfall monitoring records. Overlaying the drainage boundary, landuse map and precipitation map, the rainfall, areas of different landuse types, and runoff pollution concentration and runoff were calculated. Based on these data in different drainages, by Origion7.0 regression tool, an equation is found to predict runoff using the relationship between runoff, precipitation depth and percentage of land use in each of the drainages. Selecting the sub-watershed which is mainly composed of forest landuse type, the mean runoff concentration (MRC) from sub-watershed has been estimated. The mean runoff concentration of farmland has been estimated by the same methods after removing the contribution of forest landuse type. The result is: for the forest landuse type, the mean runoff concentrations of COD, BOD, Total N and Total P are 2.95 mg/l, 1.080 mg/l, 0.715 mg/l, and 0.039 mg/l; for the farmland, the mean runoff concentrations of COD, BOD, Total N and Total P are 5.721 mg/l, 3.097 mg/l 2.092 mg/l, and 0.166 mg/l. Using these results, the agricultural non-point pollution loads have been assessed. The loads of COD, BOD, Total N and Total P in Zhexi region are 14631.69 t/a, 6401.93 t/a, 4281.753 t/a and 287.67 t/a respectively.
Based on GIS techniques and land-use data of Xinjiang in 1990 and 2000, which were interpreted by Landsat TM remote sensing images, the grassland changes were studied carefully. First, the vector format data of the two phases were overlaid and areas of land-use changes were summarized. Then, land-use dynamic degree and transition matrix of the land-use change were calculated, and the grassland quantity changes, i.e. changes between grassland and the other land-use types, as well as its quality changes, i.e. changes among dense-grass, moderate-grass and sparse-grass, were detected clearly. Next, the ARC/INFO-Grid format data set of grassland change was built on the basis of the integrated grassland change information. This data set has perfectly supported the spatial pattern analysis of grassland dynamic change. It was proved that, in the past decade, conversion between grassland and unused land was in equilibrium. However, the total amount of grassland was greatly reduced due to cultivation, afforestation etc. At the same time, a great deal of moderate-grass and sparse-grass changed into dense-grass, which alleviated the impacts caused by the grassland total amount reduction.
The tempo-spatial processes of the construction land, which includes urban area, town area and unattached industrial land area in Changshu city are analyzed in detail. The Landsat TM/ETM satellite images, which were respectively acquired in August 1984, October 1988, June 1994, May 2000 and July 2002, are used to digitize the area of the needed land use type with the help of GIS, which is also the main tool for analyzing the town and construction land growth data. The results are as follows: (1) the growth intensity of the common towns is less than one of the administrative towns, but the area of the common towns is not reduced. (2) The growth speed of the construction land is being accelerated, but spatial pattern of growth is not balanced and is dispersive. (3) The industrial strip and the uninterrupted zone of town is being engendered, the kernel of which is the city area and sub-kernel is Xingang town. (4) The growth of construction land is transforming from the city proper and its surrounding area to the towns along the Yangtze River. (5) The economic growth with high speed has always been one of the most important factors affecting land growth, and the correlative policies directing the economic growth run through the town land growth from beginning to end.
This paper analyzes the current commercial status quo in the tourist historic towns of Zhouzhuang and Lijiang in China by using first-hand data. It examines the present use of historical buildings in the two towns in order to investigate the relationship between tourism and the use of buildings. In 2002, 682 building units in Lijiang, accounting for nearly 70% of all units in the main streets, were used for commercial purposes catering tourists; while 10.42% of the buildings catered local residents. These findings suggest that Lijiang has become a tourism-oriented town and its traditional culture is being threatened by tourism. This applies to Zhouzhuang, which attracted 1.5 million tourists in 2000, when 67.02% of building units in the main streets were used to cater tourists, while only 7.28% of them served local residents.A comparison with the use of historic buildings in 2000 and 2002 in Lijiang reveals that commercial units have been increasing rapidly. Tourism plays a key role in this process. As a result, tourism commercialization has taken place in Lijiang. The same case is also true for Zhouzhuang.
Based on the statistical data, this paper makes an analysis on the change of spatial differentiation of urban development in China during the 1990s. The spatial units in this study are the 30 provincial level districts, including provinces, municipalities and autonomous regions. Principal component analysis and cluster analysis are two main methods in the research. Firstly, the characteristics of urban development in China since 1990 are sketched out. Results indicate that the level of urbanization increased greatly and the process of urbanization has stepped into an accelerating period; the metropolises developed so rapidly that the regionalization has become more popular; the quantity of compact urban districts has increased and the landscape of regional urbanization has emerged; and the outward property of the urban system has been enhanced, and the relationship between cities and regions has been changed greatly. Secondly, three main factors, namely aggregative-oriented factor, innovative-oriented factor and outward-oriented factor, are chosen by factor analysis to describe the spatial variation of the urban development properties, and ten city-clusters are obtained. Thirdly, through the comparison of the spatial disparity of 2000 to that of 1990, the change of spatial disparity of urban development since 1990 is analyzed from three perspectives, namely the level of urban development, the property of urban development and the speed of urban development.
Advanced information and telecommunication technology has brought human being into a new information age, resulting in the emerging of an informational, global, and networked society. In the 1990s, the rapid growth of the Internet not only had strong impacts on the social and economic fields, but also restructured the organizations of global physical and virtual spaces. In recent years, the scholarly research on Internet has rapidly increased in many fields such as urban geography in the western developed countries. However, little research on the cities of developing countries exists in the Internet studies literature, and almost none addresses the topic of China, despite of their obvious implications for urban development in China. This paper seeks to fill this gap and understand the impact of Internet on the urban system in China. Based on the measurement of Internet backbone networks, it analyses the spatial structure of the Internet city network and ranks these cities in China. Beijing, Shanghai and Guangzhou and their linkages constitute the core level of long-distance telecommunication network. The investments in infrastructure are rewriting the map of competitive advantage of cities. An urban network of the information network cities is emerging in which the geographical factor plays an important role.
Based on the investigation and excavation, emphasis was placed on gaining an appreciation for post-depositional processes that form and shape site and examining the effects of natural processes on temporal and special patterns of archaeological sites at Guanting Basin. As to the distribution of archaeological sites, the following features are shown after investigation and excavation: (1) the sites transferred vertically on temporal and special patterns; (2) the earliest cultural layer deposited on the second terrace is Majiayao type of Majiayao Culture, suggesting that the ancient men moved to the second terrace at least during 3169-2882 a BC; (3) the number of sites increased abruptly during Qijia Culture period; (4) the human beings repeatedly occupied the second and third terraces during one culture period; and (5) the sites of Qiajia culture on the second terrace were not covered by the successive culture deposit, but were on the third terrace.
The classic channel slope-discharge relationship proposed by Leopold and Wolman (1957) for channel pattern discrimination has been tested by a large database including 4 types of rivers: gravel-bed meandering, gravel-bed braided, sand-bed meandering and sand-bed braided rivers. The result shows that the Leopold-Wolman relationship cannot discriminate channel patterns well when both gravel- and sand-bed rivers are considered. It is indicated that the Leopold-Wolman relationship reflects the difference between gravel- and sand-bed rivers more than the difference between meandering and braided channel patterns. The channel width-bankfull discharge relationship for discrimination channel patterns of sand-bed rivers in China is also tested in this stud. The result shows that the channel width-discharge relationship discriminates channel patterns better than the slope-discharge relationship. To improve the Leopold-Wolman relationship, a diagram based on the channel slope-bankfull width relationship is proposed. This diagram shows that the slope-width plane is divided by two straight-lines into 4 areas, with each type of river located in each area. Hence, the two straight lines can be regarded as the thresholds between the 4 types of rivers: gravel-bed meandering, gravel-bed braided, sand-bed meandering and the sand-bed braided patternes.
This paper shows the research and application level of geographical science, and reveals the present situation of researches, the characteristics and its system and regional distribution, based on the statistical analysis on the articles, authors and quotations published in Acta Geographica Sinica from 1984 to 2003. The law of the quotations followed by authors, the number and proportion of the core authors and their groups have been obtained. Some conclusions are put forward: (1) 1181 signed articles by 836 first authors were published, which are related to the various fields of geographical science. The authors are distributed all over the country and the core authors mainly in Beijing, Jiangsu and Shanghai. (2) The degree of the cooperation about authors is 2.4 and the average rate of co-authorship is 65.0%. The degree of cooperation and the rate of co-authorship increased year by year, which indicates the quality requirements for articles become increasingly higher. (3) The rate of the first prolific author groups is 9.8% with articles published being about 26.7% of the total. This indicates it is a very important task for geographic circles to train more and more leaders of the discipline and to enhance research of geographical science by creating good conditions. (4) The time of lag of publication of the articles was shortened since the year 2000, which is not only favorable for authors to publish high quality articles as soon as possible but also favorable for readers to obtain new information about geographical science. At the same time, it is propitious to bring into play the guiding role of the journal in theory and practice. (5) The amount of the average quotations is 12.6 for each article, which is more than the average quotation of the existing journals in China (8.86). The literature cited was mainly in Chinese and English. The number of the Chinese quotations was 9315, about 62.7%; that of the English quotations was 5470, about 36.8%; and other language quotations, only 62. The quotations of the Acta Geographica Sinica were mainly Chinese, but the number of English reference increased year by year. Finally, the paper also affirms the rationality of the Journal as one of the authorized key issues in natural science in China.
