Based on the temperature changes series of Winter-Half-Year in eastern China for the last 2000 years, the situation of the 20th century warming within a context of the past 2000 years is analyzed from the three aspects of changing amplitude, rate, and historical analogue. The results are summarized as follows: (1) Although it has been critically warm, the temperature of the 20th century in eastern China is still within the threshold of the variability of the last 2000 years. Substantially the 20th century warming is prominent and rapid from the cool epoch (i.e., the Little Ice Age) with a high rate of 1.1 oC/100a. (2) On a century scale, the temperature anomaly of the 20th century is lower than that of the 1200s-1310s, 570s-770s, and 930s-1100s, which are the late warm stage of Mediaeval Warm Period (MWP), the Sui and Tang dynasties warm period, and the early warm stage of MWP, respectively. (3) Analysis suggests that the most possible analogue type of the 20th century warming is that of the Sui and Tang dynasties warm period (570s-770s) instead of that of MWP. Additionally, the temperature of the 20th century has been rising dramatically since the 1980s, which is possibly influenced by the increasing green-house-effect induced by human activities.
Complex adaptive system theory is a new and important embranchment of system science, which provides a new thought to research water resources allocation system. Based on the analysis of complexity and complex adaptive mechanism of water resources allocation system, a fairly-new analysis model is presented in this paper. With the description of dynamical mechanism of system, behavior characters of agents and the evaluation method of system status, an integrated research system is built to analyse the evolvement rule of water resources allocation system. And a brief research of the impact of water resources allocation on beneficial regions of the Water Transfer Project from South China to North China is conducted.
Based on data from over 200 flood events covering a wide range of sediment concentration of the lower Yellow River from 1950 to 1985 and recent experimental data, this paper reveals the complex response of channel transverse adjustment at the wandering-braided reaches of the lower Yellow River to flood events with different sediment concentrations. The results show that the flood events can induce large extent of channel transverse deformation. And flood events with different sediment concentrations have different behaviors of fill-scour and ways of channel adjustment. The variations of the channel cross-section are firmly related to and exhibit complex relationships with the variations of sediment concentrations of flood events. When the sediment concentration of the flood events is low, the width to depth ratio of the channel will increase with it and when it increases to a certain degree to the range of hyper-concentrated flow, the width to depth ratio will decrease with the increase of sediment concentration. The channel metamorphosis controlled by channel fill and scour behavior is largely affected by the situations whether flood overflows floodplain or not. The over floodplain floods often carry heavy sediment load and cause the flow scouring in main channel and the sediment depositing on floodplain in large quantities, and as a result, the shallow and deep channel is formed. From the above results, the qualitative prediction relationships of river metamorphosis of Schumm's could be modified.
Based on the annual mean precipitation and evaporation data of 295 stations covering 1951-1999, the aridity index is calculated in this paper. The climatic regions in China are classified into three types, namely, arid region, semi-arid region and humid region. The number 0.20 (D) is the boundary between arid and semi-arid regions and 0.50 (D) is the boundary between semi-arid and humid climate regions. Dry and wet climate in China fluctuates markedly and differentiates greatly in each region in recent 50 years. The fluctuation amplitude is 20-400 km in Northeast China, 40-400 km in North China, 30-350 km in the eastern part of Northwest China and 40-370 km in Southwest China in recent 40 years. Before the 1980s (including 1980), climatic trend was dry in Northeast and North China, wet in the eastern part of the Northwest and very wet in the Southwest. In the 1990s dry signs appeared in the Southwest, the eastern part of Northwest China and North China. During the 1960s and 1970s dry and wet climates in China had single mutation changing wetness into drought. Moreover, drought shows an increasing trend. Dryly and wetly climatic boundary shows the fluctuation characteristics of the whole movement and the different fluctuations in East, West, South and North directions. The fluctuation of climatic boundary and the dry and wet variations of climate have 10 distinctive inter-annual features. It was drier in the 1950s, 1970s and 1990s in Southwest China, the eastern part of Northwest China (except Hexi region) and the first region in North China. It was wetter in the 1960s and 1980s.
By analysing published papers on the Yangtze (Changjiang) estuary and hydrological and sedimentary data of Yangshan Harbor sea area, many similarities between Yangshan Harbor sea area and the Yangtze estuary are identified. These similarities indicate that: 1) Turbidity Maximums and mouth bars in estuaries are mainly caused by the hydraulic balance in the stagnating flow area of estuaries; 2) the accumulating area of sands caused by stagnating flow area is often located on the narrower side of the stagnating flow area; and 3) the location of fine sediments area caused by stagnating flow area is well identical with the location of the stagnating flow area. Both Yangshan Harbor area and the Yangtze estuary are the high developmental areas in the future. In-depth studies on these similarities between Yangshan harbor area and the Yangtze estuary will have theoretical and practical significance.
DEM is the main data source which is used in watershed analysis. There are many mature algorithms in watershed analysis and they can be used to delineate the drainage networks. Applications of the methods based on DEM make significant innovation in hydrological simulations. Topographic parameters which are used in hydrological models can be automatically calculated from DEM. The article introduces the main process to determine watershed geometry, drainage network and other map-type information for hydrological models. Lushi basin, located in the upper Luohe river which is a tributary of the middle Yellow River, was selected as the study region with an area of 4,623 km2. WMS6.1, a GIS hydrological tool, which is introduced to China recently, was used to develop the digital rainfall-runoff model, and other GIS tools such as ARC/Info, Arcview were also used to deal with the data. The drainage network was derived from 1:250,000 DEM, and the region was divided into seven sub-basins. HEC-1 model, a part of hydrological models in WMS, was selected to simulate the rainfall-runoff process. Curve Numbers (CNs) and other parameters were automatically calculated to input to models directly. Five historical flood events were simulated. The results demonstrate that the method was more efficient than trade method. Although it is very easy and quick to input and output data for the models, it does not mean that the hydrological model itself has high quality, so it is necessary to develop hydrological models which can be adapted to the region.
Vegetation cover is a major feature for ecological system. The change of vegetation cover in large area is mainly caused by climate and human activities. The Yellow River, the second largest river in China with a basin of 752,443 km2, includes semi-arid and arid environment. Therefore, it is necessary to study the change of vegetation cover in the Yellow River Basin, which will help us understand climate influences and impacts of human activities. In order to understand the change of vegetation cover in the Yellow River Basin and its influencing factors, we use the data of AVHRR-NDVI and the information of 76 meteorological stations in the Yellow River Basin covering 1982-1999 to analyze their spatial distribution and dynamic change in spring, summer and autumn. On the basis of calculating the NDVI mean deviation and Moisture Index (MI) mean deviation, we study the feature of MI mean deviation, the speed of NDVI mean deviation and the correlation between them. Finally, some conclusions are drawn. Firstly, the climate was relatively humid from 1982 to 1992 and relatively dry since 1993. The environment in the Yellow River Basin tended to be desiccated, but the vegetation cover is increasing. Secondly, the correlation between NDVI mean deviation and MI mean deviation demonstrates that the humid climate was helpful for vegetation cover. Thirdly, the average speed of vegetation cover increase was 0.58%. The speed of vegetation cover increase in the loess region and catchment area is 0-3.8%, which shows the achievement of ecological measurements in China. The vegetation cover in desert and riverhead region is decreasing, the speed of which is 0-3.0%, a reflection of the climate change.
Based on GIS and RS with the source information of hydrological data of 46 hydrological monitoring stations during the 52 years and the digital imageries of Landsat TM in 1986, 1996 and 2000, the landscape patterns, precipitation and runoff in the East Liaohe River Basin were analyzed. With the result of the above analysis, the spatial and temporal changes of the ecological water demand (EWD) in the slope systems of the East Liaohe River Basin were derived. Landscapes in the East Liaohe River Basin have great dominance and the standard form, however, the distribution of the landscape in that basin is disperse and strongly disturbed by human activities. The hydrological regime has distinct spatial variations. The annual average EWD of the slope system in the East Liaohe River Basin over years is 504.72 mm (between 324.08 mm and 618.89 mm), and that in the growing period (between May and September) is 88.29% of that of the whole year with the lower reaches of the basin facing crisis of the EWD. The ultimate satisfaction of the EWD of the slope system is 90%. The areas lacking of the EWD in the whole year and in the growing period are 60.47% and 74.01% of the whole basin, respectively. The trend of area lacking of the EWD is particularly serious with respect of the quantity and area lacking of the EWD.
By using large-scale underwater contour map, the paper investigated waterfront resources of the mainstream in the middle and lower reaches of the Yangtze River, assessed respectively the stability and depth conditions of the waterfront. And then, by selecting depth and stability conditions of waterfront, extends waterfront to water area and to land area, the natural conditions of waterfront for building ports were assessed. The basic characteristics of the waterfront resources in the middle and lower reaches of the mainstream of the Yangtze River were concluded. First, the total amount of the waterfront resources is rich, but high level waterfront combined with favorite conditions is limited. The total length of the waterfront of the mainstream in the middle and lower reaches of the Yangtze River is 3,523.2 km. The left-bank is 1,804.6 km and the right-bank is 1,718.6 km. Second, there is distinct quality discrepancy in waterfront's spatial distribution in the Yangtze River. The right-bank is better than the left-bank in terms of both depth and stability of waterfront. Third, the depth of and stability of waterfront are the most important natural factors affecting waterfront quality. Of the two factors, C-level and D-level waterfronts occupy 63.6% and 62.7% of the whole waterfront. Fourth, ports, warehouse and industries are the most essential use modes of waterfront in the Yangtze River. Fifth, there are high waterfront use rates in some important cities, especially in case of high quality waterfronts.
The paper analyzed the influencing factors in the industrial GDP growth of each province in China. The results showed that the TFP due to both technological progress and resource optimization increasingly becomes the main power of regional economic growth. Conclusions are drawn as follows: (1) In the 1990s, the TFP is becoming the main reason to influence regional disparity, and it is the main force to promote economic growth. (2) The capital is the main force to promote regional economic growth in China, but, the labor force affect is not distinct. (3) In the 1990s, each province witnessed the increase of TFP as a consequence of economic growth in scale and labor productivity, however, the contribution of resource allocation and capital-output ratio for economic growth is very low.
Based on the numerable and standardized data collected from historical documents, we reckoned the areas of urban land use for 18 provinces in the Qing Dynasty, analyzed the changing situation, regional differentiation, and contrasted them with those of the contemporary age. The results are shown in the following: (1) The method, by which the areas of urban land use in the Qing Dynasty are reckoned in light with at the administrative division levels, the number of towns and city wall perimeters, was provided with rationality to a certain degree. (2) The results showed that the area of urban land use was 1,987.44 km2 in 18 provinces of the Qing Dynasty, merely 0.05% of the total land area in the region. Among which the scopes of Zhili and Jiangsu provinces were the greatest, being 316.34 km2 and 185.77 km2, respectively 0.097% and 0.188% of the jurisdiction area, and Guangxi and Guizhou provinces were the smallest, 27.92 km2 and 32.78 km2, respectively (only 0.012% and 0.033% of the jurisdiction area). (3) There were obvious spatial differences in urban land use in the region. For the scale of urban land use, the northern provinces were greater than the southern provinces, the eastern provinces were greater than the western provinces, and southwest provinces were the smallest in all the provinces. The provinces of Zhili, Shaanxi, Sichuan, Jiangsu and Zhejiang were obviously greater than the other provinces.
Based on the calibration of LISEM (Limburg Soil Erosion Model), five land use scenarios consisting of the previous in 1975 (LU75), present in 1998 (LU98) and future land use pattern were used to simulate the effects of the land use change on runoff and erosion at outlet of the Da Nangou catchment on the Loess Plateau, China. The future land-use maps were made based on three land-use scenarios in which cropland areas are restricted to slope gradients smaller than 25 (FA25), 20 (FA20) and 15 degrees (FA15). Two stages were recognized based on the comparison analysis on these five maps. In the first stage from LU75, LU98 to FA25, the area of the wood/shrub land increases while those of the wasteland, fallow land and cropland decrease, and the orchard/cash-tree land remains the same. During the second stage consisting of the FA25, FA20 and FA15, there is a gradual decrease in the cropland and fallow land and a gradual increase in the orchard/cash-tree land; the other land-use types remain the same. According to the simulation, the predicted peak-velocity, runoff and erosion at outlet decrease significantly if the slope cropland and fallow land are replaced by other types of land use. The peak-velocity, runoff and erosion show the same sequences for different land use patterns in the following order: land use in 1975 (LU75) > land use in 1998 > 25-degree-limit scenario > 20-degree-limit scenario > 15-degree-limit scenario. The runoff and erosion for LU75 and LU98 with much more cropland and fallow land is significantly greater than that for the three degree-limit scenarios with sharp increases in area of wood/shrub land. However, there is little difference in runoff and erosion among the three degree-limit scenarios since there is only a gradual decrease in the cropland and fallow land and a gradual increase in the orchard/cash-tree land. Based on the comparison with the land use in 1975, the predicted peak-velocity, runoff and erosion decrease by about 5-10% for land use in 1998, while the predicted decreases for the three slope-degree-limit scenarios are much larger, ranging between 40% and 50%.
Urbanization and city development in China have been unique. As a result, the concepts and theories developed in China related to the nature and structure of Chinese cities are quite different from those popular in urban geography that are based on Western experiences. The present paper is a historical review of these key concepts and theories regarding China's cities. It is divided chronologically into three parts: (1) feudal China; (2) China in 1949-1978; and (3) China after the implementation of the opening up and reform policy was started in 1978. The concepts and theories that have emerged in the three periods form an important foundation for understanding and guiding future urbanization and city development in China, and will contribute to comparative urban studies.
In this paper, data of monthly distribution of domestic tourist flows in recent years are applied to analyzing the seasonal characteristics of domestic tourist flows both in coastland resorts such as Sanya, Beihai, Mt. Putuo and mountain resorts such as Mt. Huangshan and Mt. Jiuhua. The seasonal distribution curves of tourist flows of Sanya and Mt. Jiuhua show the patterns of“3-peak-2-valley”and“2-peak-2-valley”respectively, while those of Beihai, Mt. Putuo and Mt. Huangshan all show a similar“3-peak-3-valley”pattern. As for the assembling index R of tourist flows, the highest one appears in Mt. Huangshan, with an average value of 5.7 in recent years; while that in Sanya is the lowest one, with an average value of 1.3. Besides, the R values of both Mt. Huangshan and Sanya vary slightly and maintain stability to a certain degree; while those of Beihai, Mt. Putuo and Mt. Jiuhua stay between the values of the above two sites, with a decreasing tendency in recent years in general. By analyzing the causes of seasonal variation of tourist flows in these tourist attractions, we conclude that they are affected by both natural seasonal factors and social seasonal factors. The former include mainly climate suitability, precipitation, etc., apart from which the temperature of seawater and impacts of tropical cyclone movement also play a very important role in coastland tourist resorts. The latter include mainly public holidays and residents' tour customs, besides which religious festivals also constitute an important factor affecting religious mountain resorts. Based on the above analyses, the authors have also further drawn some conclusions as follows: 1) Natural seasonal factors play the leading part in causing seasonal variation of tourist flows in natural attractions or natural-cultural attractions, while social seasonal factors only add some minor effects to the change on the basis of tourist seasonality caused by natural seasonal factors. 2) Among the five tourist attractions, the seasonal variations of those coastland resorts in southern China such as Sanya and Beihai vary slightly throughout the four seasons, act as a fairly strong tourism function as leisure resorts and thus still have a tendency to narrow the seasonal differences of tourist flows in the future; while those mountain resorts such as Mt. Huangshan retain a strong sightseeing function, which makes it much harder to alleviate the great variation in different seasons. 3) In a word, seasonal variation of tourist flows is an inherent characteristic in the development of tourist attractions. The great differences between peak period and off-season time can only be alleviated through series of effective countermeasures so as to enhance the economic, social and ecological benefits of tourist attractions.
