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    15 January 1999, Volume 54 Issue 1 Previous Issue    Next Issue
    COMMETNS ON GEOGRAPHIC ENVIRONMENTS ANDGLACIAL STUDIES: CONGRATULATIONS TO ACADEMICIANSHI YAFENG FOR HIS 80th BIRTHDAY
    1999, 54 (1):  1-8.  doi: 10.11821/xb199901001
    Abstract ( 604 )   PDF (239KB) ( 443 )   Save
    Professor Shi Yafeng has been studying geographic sciences, especially in geomorphology, glaciology and Quaternary geology for more than five decades, and has been recognized as one of the organizers and leading scientists in interdisciplinary geosciences. In early 1950s, he organizing the studies on geomorphologic regionalization in China. He and his colleagues firstly proposed that three mega regions, i.e. the eastern fluvial landform region, the north western eolian and arid landform region and the Qinghsi Xizang Plateau glacial and cryogenic landform region, and 29 sub regions can be distincted. Since 1958, he had organized the glacier resource expeditions in Qilian and Tianshan mountainous areas. “Report of Expeditions on Modern Glaciers in Qilian Mountains” and “Glaciol and Hydrological Invention in the Urumuqi River, Tianshan” were published under his editorship, which was actually a formal proclamation of the staring of the studies in modern glaciology in China. In 1960s, he entended the glacier expedition into the highest mountains in the the world Himalaya. He firstly gave the systematical explanation about the characteristics of alpine glaciers in low latitudes, and the impacts of rapid uplifting of Himalaya on glacier history. These pioneering works were presented in two books edited by him namely “Scientific Expedition Report of the Oomolungma Peak Area: Modern glaciers and Geomorphology” and “Scientific Expedition Report of the Xixiabangma Peak”. In 1970s, he led a group to study on Batura Glacier in Pakistan and developed the method so called “Fluctuating ice discharge balance” in the prediction of the glacier termination change and sub stantially improved the accuracy of prediction. This was a key challenge for selecting a reasonable rehabilitation scheme for the International Karakorum Highway. In early 1980s, he collaborated with others questioned the long debated “Quaternary Glaciation Hypotheses in Eastern China” and provided extensive and reliable evidence to deny it. These works were reflected in the book “Problems on Quaternary Glacitions and Environments in Eastern China” chiefly edited by Professor Shi Yafeng. This book Marked the breathtaking progress and diversification of glaciology studies of China in late 1980s. Professor Shi also advocated and organized virginal studies in permafrost researches in the Qinghai Xizang Plateau, the debris flow in southwestern China, and hydrology in arid regions in northwestern China in 1960s. These studies contributed remarkably to regional development in China. During 1980s~1990s, Professor Shi Yafeng gained an insight into global change and enthusiastically promoted the research activities in China. He edited and published “Climate and Environments in China during the Holocene Megathermal Period” in which he suggested that precipitation from northern China to central Asia during mid Holocene was more plentiful than that at present due to the enhancement of summer monsoon. These viewpoints have been widely accepted in China. In recent years, Prof. Shi Yafent actively promoted and contributed to the studies on the hazards caused by the sea level reise and urged for more studies to seek countermeasures for the related problems.
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    UPLIFT OF THE QINGHAI—XIZANG (TIBETAN) PLATEAU AND EAST ASIA ENVIRONMENTAL CHANGE DURING LATE CENOZOIC
    Shi Yafeng, Li Jijun, Li Bingyuan, Yao Tandong, Wang Suming, Li Shijie, Cui Zhijiu, Wang Fubao, Pan Baotian, Fang Xiaomin, Zhang Qingsong
    1999, 54 (1):  10-20.  doi: 10.11821/xb199901002
    Abstract ( 1166 )   PDF (333KB) ( 1697 )   Save
    Pressed by the northward movement of the Indian Plate, The crust in the Qinghai Xizang (Tibetan) area was uplifted during the Late Cenozoic, which exerts a great influence on East Asian environment. The Qinghai Xizang area was subject to two cycles of uplift and plantation in the Tertiary. The Plateau had raised up to about 2 000 m above sea level during 25 Ma BP~17 Ma BP. This, coupled with favorable continent ocean configuration at that time, may have triggered Asia monsoon, which replaced previously dominated planetary wind system and led to a big environmental shift in China in the Middle-Tertiary because of global cooling and plantation in Xizang. Monsoon decreasing resulted in intensification of the Asian dry climate after 8 Ma BP. The rapid uplift of the Qinghai Xizang Plateau in the Last 3 4 Ma had enhanced in a great deal again the summer monsoon, leading to moistening of the northern Plateau and even North China. On the other hand, the intensification of winter monsoon resulted in deposition of Loess at 2 5 Ma BP in North China. The subsequent tectonic movement of Mid-Pleistocene (0 8 Ma BP~0 5 Ma BP) might raise the Plateau up to about 3 000 m~3 500 m above sea level. This coupled with temperature drop by periodicity shift in the earth orbit, and led the Plateau to enter the iceosphere and form the maximum glaciating with ice cover of over 500 000 km2. Because of strengthen of winter monsoon, desert in the northwest China was enlarged and Loess sediment expanded far to the lower reaches of the Yangtze River. Intense tectonic uplift happening in the last 150 ka, led to significant change of many local drainage system in the plateau. Based on 150 ka high resolution climatic records from the Guliya ice core, lake cores at Tianshuihai and Zoige, and loess profile at Linxia, it is found that the climate in MIS 5e was especially warm. The ice core record indicated temperature at 125 ka BP was 5℃ higher than that of today and climate was unstable in MIS 5e in the plateau, which was revealed also by loess and lake core records. The deglaciation since 15 ka BP was characterized by a clear identification of the Younger Dry as event at ac.. 12 ka BP followed by largely fluctuation rising of temperature with its warmest peak at 7 ka BP, corresponded with increase of precipitation, expansion of lakes. After 5 ka BP, temperature decreased again in fluctuation, accompanied with environmental deterioration. Repeated leveling indicates that the Plateau is still in rapid rising at an average rate of 5 8 mm/a in present time.
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    CHANGES IN THE FREQUENCIES OF TROPICAL CYCLONES AND THEIR RELATIONSHIPS TO SEA SURFACE TEMPERATURE IN THE NORTHWESTERN PACIFIC
    Yang Guishan, Shi Yafeng
    1999, 54 (1):  22-29.  doi: 10.11821/xb199901003
    Abstract ( 438 )   PDF (515KB) ( 697 )   Save
    Tropical cyclones are the most devastating natural disasters causing severe losses of lives and property. One question that merits analysis is whether the frequency, intensity and location of tropical cyclones will change with future global warming. Based on data for 1949~1994 on the frequencies, locations of formation of the tropical cyclones and the monthly average sea surface temperatures ( SST ) in the latitudinal and longitudinal zone of 5°×5° that occurred in the northwestern Pacific, this paper focuses on the temporal and spatial changes of the cyclones and the relationship of cyclone frequency and the SST . The study shows that the frequency of the storms increased unsteadily from the mid 1950s to the late 1960s and again from the mid 1970s to the 1980s. The frequency decreased unsteadily from the late 1960s to the mid 1970s and again in the early and the mid 1980s and the early 1990s. Such changes corresponded roughly with the changes of SST in the waters of 10°N~30°N, 125°E~170°E. Since the 1970s, high SST corresponded with high storm frequency and low SST corresponded with low cyclone frequency. Before the 1970s, the changes were inconsistent which could have been due to the incomplete statistics of storm frequency because of the lack of weather satellite coverage. Spatially, high SST corresponded roughly with high storm frequency in the waters north from of 20°N and west from 140°E, and with low storm frequency in the waters south from 10(N and east from 140°E since the 1970s. Additional correlation calculations indicate that the relationship between SST and cyclone frequencies was nonlinear ( P =aeb(SST-26)) for the 25 year period 1970~1994 in the waters of 10°N~30°N, 125°E~170°E, and the correlativity of long term change of 5 year running average SST and the frequencies is better than that of their annual change. The relationship between long term change in SST and cyclone frequencies is the best when the change in cyclone frequencies lags behind that of SST for about one year, the calculated parameters being a =10.89,b =0.88 and the correlation coefficient exceeding 0.76. This means that once the SST of northwestern Pacific rises with global warming, the frequency of tropical cyclones will also increase, and the trend of increase will be more obvious in the waters north from 20°N and west from 140°E.
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    WORLD DELTAS AND THEIR EVOLUTION
    H.Jesse Walker, Warren E.Grabau
    1999, 54 (1):  30-41.  doi: 10.11821/xb199901004
    Abstract ( 408 )   PDF (447KB) ( 322 )   Save
    In August 1998, an international symposium on the world deltas was held in New Orleans, Louisiana, USA. This symposium attracted discussion about more than 25 deltas from around the world with emphasis placed on those that are most densely populated and impacted by humans. Keynote papers printed details about the physical, biological, engineering and socioeconomic aspects of six deltas including the Mississippi, Nile, Ganges Brahmaputra, Rhine Meuse, Changjiang and Po. The main purpose of this symposium was to inform scientists, engineers and decision makers about information that is currently available and to provide them a basis for working in such environments.
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    A SIMULATION OF THE DYNAMICS OF SOIL EROSION IN THE LOESS HILLS OF SHAANXI AND SHANXI PROVINCES
    Zhang Hanxiong, Shao Mingan
    1999, 54 (1):  42-50.  doi: 10.11821/xb199901005
    Abstract ( 432 )   PDF (495KB) ( 676 )   Save
    Soil erosion in the loess hills of Shaanxi and Shanxi Provinces is extremely serious, caused mainly by unreasonable land use. This study is the first attempt to use system dynamics theory to simulate the changes of land use and soil erosion in a large region. The system dynamic model used in this study contains 35 flow level equations, 70 flow rate equations, 185 subsidiary equations, 45 table functions and 196 parameters. The model consists of six sub models, each interacting with the others. Through the feedback loop they are connected with all variables and parameters. The functioning of the model depends on feedback mechanisms. The model was run on a PC computer with the software of PD (Professional DYNAMO) Plus. The period of simulation is from 1980 to 2040. The results were tested using collected data for 1980~1990. The efficiency of the model is 91 5%. The model was used to simulate the dynamic changes in soil erosion in three different types of land use management programs through 2040: intensified management, traditional management, and steady development management. The simulation results of the three types of programs were analyzed by a comprehensive evaluation method using fuzzy and multi objective targets. The main conclusions of the study are: First, in the loess hills, land use for farming, forestry and animal husbandry changes in a nonlinear dynamic fashion and they affect one another. Thus the adjustment for land use structure should be made gradually to maintain dynamic balance. Different types of land use should be balanced. Second, land use pattern is the key factor affecting soil erosion. Reasonable land use and effective management can reduce erosion to a minimum. Otherwise soil erosion will intensify and the overall land use benefits will decline. Third, the levels of soil erosion in the region vary from slight, moderate to severe, and the rate of erosion is related to land use pattern and the intensity of land use management. There has been an increase in slight and moderate erosion in the recently developed land due to intensified human activities in the contemporary period. Soil erosion can be reduced to a minimum but it can never been stopped completely. Fourth, intensified management is the best approach for a balanced development of farming, forestry and animal husbandry and for sound ecological equilibrium in the region.
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    ADJUSTING THE CROPPING SYSTEM IN THE FLOOD DIVERSION REGION IN THE MIDDLE REACHES OF THE HUAI RIVER
    Zhang Yifeng
    1999, 54 (1):  51-58.  doi: 10.11821/xb199901006
    Abstract ( 436 )   PDF (237KB) ( 340 )   Save
    In the flood prevention system of the Huaihe River basin, the areas of flood diversion region play an important role. They protect the vast regions in the middle reaches of the Huaihe River, reduce the threat of flooding, and divert the effects of flood peak in the lowed part. The gradient of the river channel in the middle reach is very small, averaging 0 5‰, which can cause flooding that frequently threat urbane and villages on the two sides of the Huaihe River. The flood diversion region are economically backward and poor, and in some placer farming is possible only once in 1~2 years. Thus such area are a major problem in the Huaihe River basin. At present, there are 4 flood water retaining areas and 18 flood water transportation areas in the middle reaches of the river, which are total area of 3080 hm2, and a population of 148 million. These 22 areas occupy a transition zone between two types of monsoon climates, classified by abrupt changes of the cold and warm seasons and my alternation occurrences of drought and waterlogging. In these areas, about 60% of the farmland are low yielding producing only 3 700 kg/a·hm2~4 500 kg/a·hm2 of grain. Farming has suffered from prolonged backward wheat soybean rotation, insects, weeds, and waterlogging, to improve gain yield, a system of wheat rice multicropping is proposed to reach the target of more than 6 700 kg/a·hm2. The wheat selected for cultivation is Bie-Nong No.6. This strain is characterized by high yield, short stacks, early ripening and disease resistance. The yield of it can be as high as 8 000 kg/a·hm2, the rice seed selected is No.180, an early ripening and xerophilous strain can be planted directly in the wheat stubble and it does not require frequent irrigation. It is also a high quality, with average yield of 6 000 kg/a·hm2 and a maximum yield of 7 500 kg/a·hm2. For the dry regions of the Huaihe Rivers where water saving farming is essential, the introduction of this rice strain is indeed an innovation.
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    THE QUANTITY AND INTENSITY OF REGIONAL AEOLIAN SAND EROSION AND DEPOSITION: THE CASE OF SHANXI SHAANXI NEI MONGGOL REGION
    Liu Lianyou
    1999, 54 (1):  59-68.  doi: 10.11821/xb199901007
    Abstract ( 505 )   PDF (418KB) ( 618 )   Save
    Wind erosion, aeolian sand transportation and deposition are complex and closely linked aeolian processes. An aeolian region can be looked upon as an open system that exchanges aeolian sand with its surrounding regions. A region’s aeolian erosion and deposition play decisive roles in the development of the region’s aeolian landform. More specifically, the relationship between importing and exporting aeolian sand, or the balance between boundary mass input and output of sand, determines the resultant aeolian landform. The rate of regional erosion and deposition or the intensity of erosion can be expressed as: Re=We/S, where We is the balance between boundary mass input and output during a certain period of time and S is the areal size of the region. Field observation was conducted in the Shanxi-Shaanxi-Nei Monggol border area and different formulas between wind velocity and the transport rate of sand drift on different types of land surface were established. The rate of transport increases rapidly with increasing surface sand mobility and wind velocity. Three specific factors that have decisive effects on sand transportation are identified as wind velocity ( V ), blowing time ( T ) and wind direction. An analysis of the data on erosive wind collected by local weather stations determined the total annual quantity of sand transport flux on different types of surface. Vector analysis and charting ascertained that the prevailing direction of sand transport flux is mainly from the northwest to the southeast, with varying azimuth angles of between 288 7° to 303 6°, revealing clearly that the basic direction of aeolian sand movement and encroachment in the region is southeastward. Based on the interpretation of boundary land surface types from TM imagery, the boundary balance, quantity and intensity of aeolian erosion and deposition in different counties in the study area are calculated. The results show that the entire study area, which lies in the transitional belt between sand desert and loess plateau, is an aeolian erosion region. The region’s annual quantity of aeolian sand erosion is 109 million tons and the average intensity of sand erosion is about 160 t/a·km2. Erosion increases from the sandy loessial region in the southeast to the desert region in the northwest as rainfall decreases, wind velocity increases, and vegetation cover declines. Thus the quantity of regional aeolian erosion increases with increasing interaction between the erosive agents of wind and water.
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    A PRELIMINARY STUDY OF THE SOCIAL GEOGRAPHYOF BEIJING DURING THE LATE QING ANDTHE EARLY REPUBLICAN PERIOD
    Wang Jun, Zhu Gongwu
    1999, 54 (1):  69-76.  doi: 10.11821/xb199901008
    Abstract ( 559 )   PDF (369KB) ( 981 )   Save
    Unlike the imperial rule before 1840 and the socialist period after 1949, Beijing during the first 30 years of the twentieth century experienced colonialism and internal social change which caused a corresponding change in the city’s social areas. Based on the city’s population data and several social surveys conducted after 1906 and using notions of classic urban ecological theory and the preindustrial city, this paper examines the internal spatial structure of Beijing during the late Qing and the early Republican period. With the erosion of the Qing authority, the decline of the Manchu noblemen, and the rise of modern citizenship and new professionals in the commercializing society, dramatic social transformation taking place in Beijing caused major changes in the city’s traditional internal spatial structure. Three types of social spatial patterns emerged that bear some resemblance to the characteristics of the preindustrial city and the urban structure in Latin America. First, social spatial differentiation took place. While the elite were concentrated in the central zone where they enjoyed spacious housing and good urban facilities, the urban poor were compelled by rents to move to the periphery where the living conditions were much inferior. Second, family size and family economic condition were positively correlated, with the city center having more large families and the periphery more small families. Relatives, concubines and servants living in the same household were all counted as members of the same household. Third, in terms of ethnic distribution, the declining Manchu nobles and numerous Bannermen had to sell their houses to make a living and to leave their comfortable princely estates and the Inner City for the fringe areas, especially in the northern part of the city. The Hui had a lowly social status who were clustered in the Ox Street and the Flower Market areas, both in the urban fringe. Since the Qing established its capital in Beijing, the Inner City was known as the Tartar City because it was occupied by the Bannermen. Since the downfall of the Qing, social segregation and residential integration appeared, the patterns of which were determined mainly by the residents’ economic status. In addition, international forces further complicated the patterns of social spatial differentiation. Typical examples include the emergence of the new commercial center at Wangfujing, the formation of the high-class residential area in Dongdan, the appearance of a banking district in Xijiaominxiang, and the presence of the Legation Quarter in the adjacent Dongjiaominxiang area.
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    A HISTORICAL STUDY ON THE BACK FLOWS OF WATER FROM THE CHANGJIANG RIVER TOTHE POYANG LAKE AT HUKOU, JIANGXI
    Hu Chunhua
    1999, 54 (1):  77-82.  doi: 10.11821/xb199901009
    Abstract ( 613 )   PDF (344KB) ( 864 )   Save
    The bottom of Poyang Lake, China’s largest fresh water lake, slopes northward toward the Changjiang (Yangzi) River into which the lake drains. The lake’s outlet is located at the lake’s northern end at Hukou, Jiangxi. In earlier times, the river had been further north but it shifted its course southward, eventually reaching Hukou. This caused the river water to flow to the lake basin, forming natural levees and sand bars which obstructed the lake’s discharge into the river and affected the lake’s later development. However, it is not clear when did the river swing southward to reach Hukou, when did the river water begin to flow to the lake and what was the intensity of the lake’s back flow. This preliminary study is concerned with these questions which thus far have escaped the attention of researchers. High resolution data are obtained from Hole ZK 2, which is located at the outlet and which sometimes submerges during the dry season. The maximum water level at the site reaches 14 m during the flood season. The data indicate that lacustrine facies has dominated the modern sedimentary environment. The earliest date when the river reached Hukou was determined by searching for sediments that would provide clues to river lake interactions. At the depth of 7 48 m, the hole’s profile shows a boundary. Dated by 14 C to approximately 2 360 a BP, the sedimentary environment immediately above and below the boundary line was one of open lacustrine, but the clay minerals, heavy minerals, granularity, magnetic susceptibility and colors are all different, indicating different sources. The location of the hole suggests that the old sediment source was the ancient Ganjiang River (or the river system of the Poyang Basin), and sediment source changed only when the Changjiang water reached the site, bring different sediment. The age of the boundary is determined to be about 2 360 a BP when the Changjiang shifted southward and reached modern Hukou. This date is the date when the lake first experienced back flow from the Changjiang. In the fine sediment in the outlet waterway at Hukou, those from the ancient Ganjiang River have low Xlf while those from the Changjiang have high Xlf. When the back flow intensity is strong, the proportion of sediment from the Ganjiang becomes less while that from the Changjiang increases with higher Xlf, and vice versa. Moreover, the 20 year running average of the back flow for 1950~1984 matches perfectly with the Xlf curve, providing further evidence that Xlf may be used as a proxy indicator of the intensity of the back flow. The Xlf curve indicates that the history of the lake’s back flow can be divided into three stages. During 2 360 a BP~1 550 a BP, the intensity was weaker than that of today. From 1 550 a BP to 880 a BP, the intensity increased in a wavy pattern, with the greatest intensity occurring around 880 a BP. From 880 BP to the present, the intensity has fluctuated violently in six complete cycles, each lasting about 115 years.
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    EQUIVALENT SOLAR RADIATION AZIMUTH AND THE SELECTION OF THE DIRECTIONOF BUILDING EXPOSURE
    Sun Hanqun, Fu Baopu
    1999, 54 (1):  83-89.  doi: 10.11821/xb199901010
    Abstract ( 375 )   PDF (218KB) ( 556 )   Save
    The sunrise and sunset hour angles on a slope are determined by considering the sun’s horizontal hour angles and the non horizontal hour angles of the slope. Such coordinated relationship varies with latitude φ, slope angle α, slope azimuth β, and solar declination δ . When latitude φ and slope azimuth β meet the condition of |sin β |cos φ >sin23 45°, the coordination of sunrise and sunset hour angles has only one form for any solar declination δ . But when |sin β |cosφ≤sin 23 45°, the coordination will vary with slope azimuth β . For any given solar declination δ and latitude φ, there are two slope azimuths β1 and β2 (where | β1 |=arcsin(sin δ /cos φ ), | β2 |=π-| β1 |). Between β1 and β2 and beyond β1 and β2, the coordination relationships are different. This detailed study provides a way to determine the concrete form of coordination for any slope azimuth. Based on the coordination of sunrise and sunset hour angles on a slope, we deduce a series of formulas that are used to calculate the daily duration of sunshine and the daily extraterrestrial solar radiation on the wall surface. From the results of calculation, we obtain the distribution of daily duration of sunshine and daily extraterrestrial solar radiation with slope azimuth. We find that there is a pair of slope azimuths, where the daily duration of sunshine in summer half of the year is equal to that in the winter half when the absolute values of solar declination are equal. These slope azimuths are called “equivalent duration of sunshine azimuth (EDSA)”. There is also a pair of slope azimuths where the daily extraterrestrial solar radiation in the summer half is equal to that in the winter half at the same time. These slope azimuths are called “equivalent insulation azimuth (EIA)”. Together, EDSA and EIA are called “equivalent solar radiation azimuth (ESRA)”. ESRA is a function of latitude (only. The value of EDSA can be expressed as | β |=arccos(tg φ ). The value of EIA can be expressed as | β |=arctg(cos2φ /sin φ · Yφ ), where Yφ is a solution of the equation y +tg2 φ ·tg y =0.
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