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  • 2013 Volume 68 Issue 9
    Published: 05 September 2013
      
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  • Prospects on future developments of quantitative remote sensing
    LI Xiaowen, WANG Yiting
    2013, 68(9): 1163-1169. https://doi.org/10.11821/dlxb201309001
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    With regard to the national needs and basic research, several critical issues should be addressed in quantitative remote sensing: inefficient use of mass remote sensing data, inadequate universality and systematicness of quantitative remote sensing research, and limits in remote sensing applications. Therefore, Remote Sensing Science (RSS) research subjects need to be integrated with other disciplines in order to advance our understanding of RSS. In the authors' opinion, due to the heterogeneity of the geo-surface, generalization and modeling on the basis of experimental data, as opposed to individual interpretation of a specific location, could be the key for the future research. Combining "a top-down deduction method" with "a bottom-up induction method" in integrative physical geography in China, we want to build a methodological framework to resolve the central issues of RSS, for instance, the "scale effect", and to create several open platforms (such as data, inversion and computer simulation), and to bring together experts from different disciplines.
  • A review of the research on red beds and Danxia landform
    PENG Hua, PAN Zhixin, YAN Luobin, Scott SIMONSON
    2013, 68(9): 1170-1181. https://doi.org/10.11821/dlxb201309002
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    In the context that China Danxia landform went into the world and began the research of a new phase, it is necessary to make a review on the research progress of red beds and Danxia landform in and outside China. It is revealed that the domestic study was focused on the characteristics of red beds, engineering geology, features of Danxia landform and the basic problems of development. In general, in China there were no integrated studies of red beds concerning the field of geology and geomorphology, and the differences between lithologic characteristics of red beds and their related geomorphic development processes under the influence of exogenetic force were not well understood. However, research outside China were limited in the field of geology, and relevant studies of red beds and Danxia landform were conducted in the field of sandstone landform, with a microscopic, quantitative and experimental analysis. This paper suggests that most of the existing studies on red beds and Danxia landform were focused on single factor, and lack of subject system, and the integration of related subjects was also insufficient. Then, a new agenda for the future research was put forward, in which a clear discipline classification of red beds and Danxia landform and further basic research should be made, and the integration of related subjects, international communication and the global comparative research should also be strengthened.
  • Medium-to long-term morphodynamic modelling in estuaries and coasts: Principles and applications
    GUO Leicheng, HE Qing, Dano ROELVINK, Zhengbing WANG, Mick VAN DER WEGEN
    2013, 68(9): 1182-1196. https://doi.org/10.11821/dlxb201309003
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    The interplay between hydrodynamics, sediment transports and geometrical constraints govern the evolution of large scale estuarine and coastal morphological features. On a long time scale (> decades) sea level rise, and changing regimes in river discharge and sediment supply may influence morphological evolution as well. Spatial gradients in tide residual sediment transport cause the morphodynamic development. Relevant mechanisms are the Stokes' drift, tidal asymmetry, wave skewness, settling and scour lag, estuarine gravitational circulation, and residual transport driven by river discharge or wind. Morphodynamic models consider these physical processes and include a feedback between hydrodynamics and morphological development. Process-based morphodynamic models may deploy process and input reduction techniques to accelerate developments focusing on major processes. An example is the morphological acceleration factor to account for the different time scales of morphodynamic evolution and hydrodynamic processes. Process-based numerical models are able to reproduce realistic morphology, such as channel-shoal patterns and delta distributary channel formation. These models are also able to hindcast historical estuarine and coastal morphodynamic evolutions and to predict morphological response to sea level rise in future. So far, limited attention has been paid to muddy systems and river flow impact thus requiring further research effort.
  • Spatial and temporal variability in the net primary production (NPP) of alpine grassland on Tibetan Plateau from 1982 to 2009
    ZHANG Yili, QI Wei, ZHOU Caiping, DING Mingjun, LIU Linshan, GAO Jungang, BAI Wanqi, WANG Zhaofeng, ZHENG Du
    2013, 68(9): 1197-1211. https://doi.org/10.11821/dlxb201309004
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    Using NOAA AVHRR NDVI data (8 km spatial resolution) from 1982-2000, as well as SPOT VGT data (1 km spatial resolution) and observation data from 1998-2009, the CASA model was applied to analyze the spatial-temporal characteristics of alpine grassland NPP change on the Tibetan Plateau (TP). This study will help to evaluate the health status of the alpine grassland ecosystem and is of great importance to studies on sustainable development of pasture on the plateau, as well as to research on the national ecological security shelter function of the Tibetan Plateau. Spatial statistical analysis is carried out based on physio-geographical zonality (natural zone, altitude, latitude and longitude), river basin, and administrative areas at a county level. Data processing was completed on an ENVI 4.8 platform while spatial analysis and mapping were completed on an ArcGIS 9.3 and ANUSPLINE platform. The analysis of the spatial-temporal pattern and change in characteristics of alpine grassland NPP showed that: (1) the alpine grassland NPP gradually decreased from southeast to northwest on the TP, which corresponded with the gradients of precipitation and temperature. The average annual total NPP in alpine grassland on the TP is 177.2×1012 gC·yr-1, and the average annual NPP is 120.8 gC·m-2yr-1, from 1982 to 2009. (2) The annual alpine grassland NPP on the TP has a fluctuating and increasing tendency, ranging from 114.7 gC·m-2yr-1 in 1982, to 129.9 gC·m-2yr-1 in 2009, with a 13.3% increase; the alpine grassland showing a significantly increasing tendency of NPP is above 32% of the total, while the alpine grassland that shows a remarkably decreased tendency of NPP is 5.55%. (3) A notable change of annual NPP existed in alpine grassland: (a) NPP increased in most of the natural zones on the TP, and showed a slightly decreasing trend, except for the Ngari montane desert-steppe and desert zone, where the increasing tendency of NPP was stronger in a high-cold shrub-meadow zone, high-cold meadow steppe zone and high-cold steppe zone, than that in the high-cold desert zone; (b) The vertical variations in annual NPP are significantly different, including an "increasing-steady-decreasing" trend in area percentage with a significant increase and a "decreasing-steady-increasing" trend with a significant decrease, as altitude rises; (c) The variations of annual NPP in latitude and longitude have a relationship with the vegetation distribution. The variations in annual NPP in basins present a growing tendency, with the Yellow River Basin being the most remarkable. The relationship between NPP and vegetation coverage suggests that there was a benign trend in the quality of alpine meadow ecosystem and significant regional differences on the TP.
  • Spatial distribution of forest vegetation carbon stock in China based on HASM
    ZHAO Mingwei, YUE Tianxiang, ZHAO Na, SUN Xiaofang
    2013, 68(9): 1212-1224. https://doi.org/10.11821/dlxb201309005
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    As the forests are the main carbon stock reservoir of the terrestrial ecosystem, it is of great importance to estimate its carbon stock and spatial distribution accurately in regional scale. However, the current estimation of forest carbon stock in regional scale primarily depends on the forest inventory data, and the whole process of it consumes labor, money and time, and influences the update of the forest carbon storage at the same time. With the purpose of solving these problems, this paper puts forward a forest vegetation carbon storage simulation method based on HASM. This new method takes the output of LPJ-GUESS model as initial values of HASM and uses the inventory data as sample points of HASM to simulate the distribution of forest carbon storage in China. The research takes the 7th forest resources statistics of China as the data source to produce sample points, and it also serves as the simulation accuracy test. The HASM simulation makes it clear that the total forest carbon storage of China is 9.2405 Pg, and the calculated value based on forest resources statistics is 7.8115 Pg. As regards that the forest resources statistics is taken based on a forest canopy closure, the result of HASM is much more suitable to the real forest carbon storage. The simulation result also demonstrates that the southwestern mountainous and the northeastern forests are the dominating forest carbon reservoirs in China, and they account for 39.82% and 20.46% respectively. Compared with the former value (1975-1995), the carbon storage of the two regions did increase apparently. The results of this research indicate that the large reforestation in the last decades in China attains a significant carbon sink.
  • Optimized decision-making of water resources supply and demand system in Changsha-Zhuzhou-Xiangtan urban agglomeration based on the analog simulation
    XIONG Ying, LI Jingzhi, JIANG Dingling
    2013, 68(9): 1225-1239. https://doi.org/10.11821/dlxb201309006
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    Using the theory and method of system analysis, a water resources supply and demand system dynamic model was built to simulate the changing trends of the balance of water resources supply and demand in Changsha-Zhuzhou-Xiangtan urban agglomeration from 2012 to 2030 under four scenarios (traditional development model, economic development model, water saving model and concerted development model). The simulation result suggested that: (1) the problem of water resources supply and demand is becoming increasingly conspicuous with growing population and rapidly developing economy; (2) by 2030, the water resources demand will be reaching a total of 105.1×108 m3, and the supply of water resources is 5.4 × 108 m3 over the demand, while water resources supply be basically meeting the growing demands of economic and social development, and generated great comprehensive benefits under concerted development model. So the concerted development model will be the best solution to develop and use water resources in Changsha-Zhuzhou-Xiangtan urban agglomeration; (3) in order to realize the expectation aim, we should accelerate the construction of water conservancy projects, strengthen the management on water conservation, optimize economic structure, enhance our awareness of protection of water resources, moreover quicken the recycling of waste water and environmental improvement. In addition, raising the utilization ratio and the support capabilities of water resources are also important to the balance of water resources supply and demand.
  • Trends and causes of suspended sediment concentration variation in the turbidity maximum zone at the Yangtze River Estuary
    YANG Yunping, LI Yitian, SUN Zhaohua, FAN Yongyang
    2013, 68(9): 1240-1250. https://doi.org/10.11821/dlxb201309007
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    Based on the analysis of suspended sediment elements at estuaries, influences of human activities and estuarine regulation projects on the turbidity maximum zone are studied. Data comes from the measurement between 1959 and 2011. It is found that human activities had little effect on the seawards water and that the sharp decrease of sediment volume and concentration in runoff led to the sharp decrease in the estuary. The concentrations off the coast and at Hangzhou Bay did not change. The concentrations along the coast of northern Jiangsu decreased a little and had no influence on the turbidity maximum zone. Affected by the hydrodynamics of runoff and tide, the area of maximum turbidity zone is related to the volume of seawards sediments. Comparisons between 1959 and 1999 show that the concentrations in 2000-2009 decreased by about 24.73% and the range reduced along the river to the sea. The peak of concentration moved upstream in the estuary. The suspended sediment concentrations in North Passage are low in upstream and downstream reaches because of the decrease of seawards sediments, spilt ratio and coarsening of bed material. In the middle of the North Passage, the concentrations increased because of the influence of the sediments across the north jetty.
  • Eco-environmental change in the lower Tarim River under the influence of intermittent water transport
    HUANG Yue, BAO Anming, WANG Shifei, WANG Yongqin, DUAN Yuanbin
    2013, 68(9): 1251-1262. https://doi.org/10.11821/dlxb201309008
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    For the sake of improving the eco-environment, and preventing degradation of the vegetation, the water transport project in the lower Tarim River was carried out in April 2000. According to the water path, temporal and spatial distributions of water resources in this region were greatly changed in the past 10 years. As a result, the eco-environment condition has also changed obviously. In this paper, field surveys data and remote sensing data from 2001 to 2011 were used to analyze the variation of groundwater level and natural vegetation; and the vegetation response to the groundwater level variation in typical sections were also discussed. The results indicated that (1) the fluctuation of groundwater level in each section is closely related to the quantity and duration of the water transport, and shows a process from a significant rise to slow reduction, and to a slight rise during the 10 years; the correlation coefficient of groundwater depth variation and water transfer quantity is approximately 0.78, and the correlation coefficient of groundwater depth variation and water transport duration is 0.7. (2) The area of vegetation cover in this region showed an increasing trend from 2001 to 2011, and the biggest area change in natural vegetation occurred in shrub land; the fraction of vegetation coverage were increased obviously during 2001-2006, and changed slightly from 2006 to 2011. (3) The fraction of vegetation coverage was found to increase along with the rise of groundwater level. In vertical direction of the river, ground water level and vegetation coverage showed a similar spatial distribution: the more distance away from river the lower groundwater level is, the lower fraction vegetation coverage. In parallel direction of the river, the response intensity of the fraction of vegetation coverage to groundwater level showed a decreasing trend along the distance from Daxihaizi reservoir.
  • The changes of potential evaportranspiration over Yarlung Zangbo River Basin during 1961-2010
    YANG Zhigang, TANG Xiaoping, LU Hongya, MA Pengfei, HONG Jianchang
    2013, 68(9): 1263-1268. https://doi.org/10.11821/dlxb201309009
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    Based on the daily temperature and air pressure datasets recorded by 6 observation stations in the Yarlung Zangbo River Basin during the period 1961-2010, the monthly, seasonal and annual PE (potential evapotranspiration) at this basin was calculated by using Penman-Monteith method, and the changes of PE were analyzed in this paper. The main results were obtained as follows: in terms of annual, wet-seasonal and dry-seasonal variations, there was a weak increasing trend of PE at a rate of less than 3.00 mm/10a. The inter-decadal variation shows that annual PE experienced an increasing process from the 1960s to 1980s, followed by a decreasing trend. The abrupt change of PE was observed in 1981.
  • Variations of extreme air temperature events over Tibet from 1961 to 2010
    DU Jun, LU Hongya, JIAN Jun
    2013, 68(9): 1269-1280. https://doi.org/10.11821/dlxb201309010
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    Based on homogeneity-adjusted daily temperature (maximum, minimum and average) data of 18 stations, spatial and temporal changes of extreme temperature events over Tibet were analyzed for the period 1961-2010. The result shows that the number of frost days and ice days reduced significantly, with the most significant reduction in northern Tibet for ice days, but more extensively across the autonomous region for frost days. The length of growing season (GSL) presented a statistically significant increasing trend at a rate of 4.71 d/ 10a, especially in Lhasa and Zedang. The extra-maximum air temperature (TXx) and extra-minimum air temperature (TNn) generally increased. TXx significantly increased along the east section of the Yarlung Zangbo River and in Nagqu Prefecture, and decreased at the southern edge of Tibet, while TNn significantly increased across the region of Tibet, especially during 1981-2010 with a rate of 1.06oC/10a. Significant reduction at a rate of 9.38 d/10a (4.96 d/10a) occurred on cool nights (days), and significant increase at a rate of 10.99 d/ 10a (6.72 d/10 a) occurred for warm nights (TN90p) (days (TX90p)). There is a close correlation between the trends of most extreme temperature indices and altitude, i.e., positive correlations between altitude and TNn, negative correlations between altitude and TXx, TX90p, TN90p and GSL. In terms of decadal variations, TXx, TNn and other warm indices showed an increasing trend, while the cold indices and GSL decreased. It is also found that the abrupt change points of the TNn, warm (cool) nights and GSL were mainly observed before the mid-1990s, while frost days, ice days and warm (cool) days occurred in the early 2000s. In most cases, the linear trend magnitudes of extreme air temperature indices in Tibet were larger than those in the whole country, Tibetan Plateau and its surrounding areas (Qinghai Province, Hengduan Mountains), which show that the extreme air temperature indices response are more sensitive to the regional warming.
  • Zhou Tingru’s academic thoughts and achievements in physical geography
    LI Rongquan, QIU Weili
    2013, 68(9): 1281-1291. https://doi.org/10.11821/dlxb201309011
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    The academic thoughts and achievements of the pioneer scientists are valuable scientific wealth and educational resources. Professor Zhou Tingru is a famous geographer, educationalist and the founder of the Cenozoic geography in China. His academic ideas and achievements in developing a new branch of physical geography provide a representative example for the growth of the younger generation of innovative geographers. To seek for the answers of two regional physical geographic problems that why the subtropical region in China is humid instead of arid and why China has a unique pattern of physical geographic environment, Professor Zhou had immerged in extensive readings. After realizing that each physical geographic region has its own history, he, standing at the academic frontier of his time, put forward the thought that "the past is the key to the present and the future" and initiated Cenozoic geography, a new branch of physical geography, which deals with the origin, evolution, and development of regions. Thus, he started a new research branch and elevated the regional physical geographic research of China to a new stage and the front rank of the world. Professor Zhou clarified that the evolution of geographic environment is the core content of physical geography, and that the start point of geographical environment evolution is the early phase of the Cenozoic. The basic principles of the Cenozoic geographical evolution he expounded includes three essentials: 1) the regions of different levels are formed when the zonality is disintegrated or interrupted; 2) the evolution of geographic environment is controlled by the rule of dominant factor combination; 3) the driving force of evolution has both endogenic and exogenic sources of energy, but the endogenetic one dominates the processes. At the same time, he also summed up the research methods of analysis and synthesis. The main academic achievement Professor Zhou obtained is the conclusion that the disintegration or interruption of the original zonality in China took place at the end of the Palaeogene, the five physical geographic regions emerged in the Neogene and have evolved over the Neogene and Quaternary periods, and then, the modern pattern of physical geographic environment in China formed. Professor Zhou's works, especially the "Physical Geography of China: Palaeogeography of the Cenozoic Era" builds up a milestone for the regional physical geography of China. His idea that "the past is the key to the present and the future" has been accepted as a basic research guide now and in future for the study of physical geography and especially for the study of regional physical geography.
  • The discipline distribution characteristics of geography journals (English edition) in China
    FAN Guangbing
    2013, 68(9): 1292-1297. https://doi.org/10.11821/dlxb201309012
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    In order to explore the academic level of geography journals (English edition) in China, this paper selects 12 geography journals (English edition) as the object of search, based on the distribution status of main journal indexes such as Impact Factor announced by ISI in June, 2013. And further it makes a deeper data analysis of five kinds of comprehensive journals from the 12 geography journals (English edition). This paper shows the hotspot disciplines of the reports and the extent of disciplines concentration on publishing. The results of the paper offer more evidence to improve the quality for publishing of China's geography journals (English edition) and their international influence.