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  • 2011 Volume 31 Issue 6
    Published: 20 June 2011
      
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  • Hydrological Characteristics and Its Responses to Climate Change for Typical River Basin in Northeastern China
    WANG Guo-qing, WANG Xing-ze, ZHANG Jian-yun, JIN Jun-liang, LIU Cui-shan, YAN Xiao-lin
    2011, 31(6): 641-646. https://doi.org/10.13249/j.cnki.sgs.2011.06.641
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    Global warming caused by increasing concentration of carbon dioxide and other trace gases in atmosphere has become evident. It has concluded that the earth surface air temperature increased by about 0.74℃ during 1905-2005. Surface air temperature change in China keeps well agreement with that of globe, which has risen by about 0.5-0.8℃ during the last 100 years, particularly, rising rate in the latest 50 years slightly exceeds the corresponding value of globe. Water resource in China is scarce, especially in the northeastern part of China, where is the main food source area of China as well. With the rapid development of agriculture and industry, as well as population growth, China has been undergoing increasingly stress of water resources. During the last two decades, recorded runoffs in the major rivers, which are located in the northern China, have been dramatically decreasing. As a result, conflict between water supply and demand in these areas has been becoming more significant, which has attracted great attention from both the relevant authorities and the general public. Global warming is likely to change precipitation patterns and raise the frequency of extreme events; in further, will affect many sectors of natural environment and human endeavor. Water is considered to be the most critical sector associated with climate change impacts. Climate change is estimated to alter timing and magnitude of runoff, consequently, which has significant implication for the existing water resources system as well as for future water resources planning and management. Climate change may bring adverse effect on food security of China through aggravating the severe situation of shortage in water resources of the northeastern China. Quantitative estimates for hydrological effects of climate change are essential. Taking Taizihe River basin as a case, which is main water source of Liaohe River, its variation characteristics of runoff and precipitation in the past 50 years were analyzed. Based on naturalization of runoff adopting a snowmelt-based water balance model (SWBM model), hydrological responses to climate change were studied. The results indicate that recorded runoff at Xiaolinzi hydrometric station has been decreasing during 1954-2005. Since the 1980s, climate-induced runoff reduction presents increase trend. The increase in precipitation could exert higher effect on stream flow than decrease in precipitation does, while soil moisture is more sensitive to rainfall reduction. Climatic aridification will extremely be not conducive to sustainable utilization of water resources and agricultural production for the northeastern China.
  • Digital Extraction of Artificial Micro-geomorphology in Plain Areas Based on DEM
    XIAO Fei, DU Yun, Parrot J F, WANG Xue-lei, YAN Yi
    2011, 31(6): 647-653. https://doi.org/10.13249/j.cnki.sgs.2011.06.647
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    This paper presented a numerical methodology for recognition and extraction of artificial micro-geomorphology in the Jianghan Plain. In the different spatial scales of geomorphologic types, micro-geomorphology is the smallest spatial pattern and thus is more easily influenced by human activities. In this sense, artificial micro-geomorphology would show more potential in understanding the interactions between natural environment and human activities. Due to the continuous land utilization and rearrangement from historical period in the Jianghan Plain, a kind of artificial micro-geomorphology characterized by enclosed embankments on the low-lying land was formed. For decades, it played a very important role in the spatial distributions of some disasters such as flood and waterlogging. Compared with the automated extraction of drainage network and catchments boundaries from nature valleys, automated recognition of artificial micro-geomorphology skeleton lines has distinctive difficulties because of its tiny size, greater susceptibility to data error, and the different spatial structures with nature geomorphology. Despite of the progress in the automatic extraction of terrain skeleton lines, there is no auto-extracting method of artificial micro-geomorphology availablility yet, and it still dependes on the manual way to extract the skeleton lines of artificial geomorphology from the remotely sensed images and topographic maps. In this paper, a digital method for extracting the skeleton line of artificial micro-geomorphology was developed through the combination of the local topography analysis and the overland flow simulation. According to the specific artificial geomorphology features in the Jianghan Plain, a method was brought forward to identify the potential positions of the topographic skeleton lines, which is based on the evaluation of difference between the local elevations and the average elevations within moving windows. Then, an algorithm of watershed-merging based on flow simulation was developed to extract the potential skeleton lines of enclosed embankments. The algorithm can reduce the influence of the spurious pits in DEM, and generate the possible skeleton lines in a continuous way. Afterwards, based on the calculation results from the local topography analysis and the flow simulation, a new method was proposed to extract the skeleton lines of artificial micro-geomorphology by using the GIS techniques of spatial analysis and geo-statistics. The potential skeleton lines extracted from watershed-merging process were divided into segments by intersection points, and then transformed to raster format. Afterwards, raster segments of skeleton lines belonging to the proper skeleton lines of artificial micro-geomorphology were judged and fixed by using the position information calculated from local topography analysis according to their superposition degree. For the disconnected places of the extracted skeleton lines, a method was designed which could automatically extend and join the arcs on direction of the catchments borderlines through a kind of path determination algorithm. At last, the complete and closed borderlines of all the artificial geomorphologic patterns were formed through the above steps. The result shows that the aforementioned methodology is an effective attempt for the digital extraction of artificial micro-geomorphology structures, and would be helpful for the estimation of the interactions among spatial patterns of disaster, human activities and natural environment.
  • Response of Dongting Lake’s System Function Under Changed Water and Silt Process
    OU Chao-min, Li Jing-bao, Yu Guo, Yang Yan, Deng Chu-xiong, Zhang Lei
    2011, 31(6): 654-660. https://doi.org/10.13249/j.cnki.sgs.2011.06.654
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    Response of Dongting lake system function was discussed under water and silt process change and the following viewpoints were derived. First of all, Dongting Lake is a macro-system composed of morphological system, ecological system and service system. Secondly, water and silt changes resulted in several responses phenomenon such as the deformation of lake basin framework, shrinkage of lake area and volumes, instability of biodiversity, shorter shipping mileage, decrescence of water environment purification capability, weakening of microtus fortis and Oncomelania, and decreasing in fishing output and water resource. Finally, there existed a coupling relationship between the change of water and silk process and various lake system functions at different levels and in different space (the whole and the parts) and time (short-term and long-term). Some characteristics about hierarchy relevance, spatio-temporal difference, corresponding causality and mutual interdependency were shown.
  • Straw-burning Fire Detection Using HJ-1B IRS Data
    WANG Ling, TIAN Qing-jiu, BAO Ying
    2011, 31(6): 661-667. https://doi.org/10.13249/j.cnki.sgs.2011.06.661
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    Gas and particulate matter which resulted from straw burning can seriously pollute the atmospheric environment and threaten human health and traffic safety. Based on the HJ-1B IRS data acquired in the non-harvest period and the harvest period, a straw-burning fire detection mode has been established. All types of fire spots during the harvest period were identified using a modified classic fire-detection algorithm and the IRS channel 3 and channel 4 measurements, and then a straw field identification criteria were established based on the channel 2 and channel 1 DN difference (B2-B1) using the two IRS data, in order to identify the straw-burning fires from the fires of all types. On the basis of the two HJ-1B IRS images acquired on Oct. 6 and Oct. 21, 2009, a straw-burning detection experiment in Jiangsu Province on Oct. 21, 2009, when the crops have entered into the harvest period, was carried out here. Finally, the straw-burning fires detected by IRS were compared with that detected by MODIS, we found that their correlation coefficient R2 is 0.685 2, which validated the rationality and feasibility of the method in this study.
  • Hydrochemistry of Geothermal Water in Tianshui and Its Northern-southern Area
    WEN Yu-hua, WANG Nai-ang, ZHU Xi-fen, ZHANG Hua-an, MA Hong-wei, CHEN Li
    2011, 31(6): 668-673. https://doi.org/10.13249/j.cnki.sgs.2011.06.668
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    A geochemical study of geothermal water has been carried out in the Tianshui and its northern-southern area. Geothermal water of Wushan and Tianshui is bicarbonate water of low salinity characterized by pH in 7.94-9.06 and low total dissolved solids (TDS) (226-255 mg/L), which were probably formed by water-rock interaction between meteoric rain, biotite plagioclase gneiss rock and carbonate sediment in reservior. While geothermal water of Tongwei and Qingshui is sulfate water with characteristics of pH in 7.1-8.07 and high total dissolved solids (TDS) (915-1 793 mg/L), which may arised from water-rock interaction between meteoric rain, variscan granite and sinian amphogneiss. The isotopic data show that the origin of thermal water is meteoric water and not severely affected by water-rock isotope exchange. Assessments of various chemical geothermometer applied on the geothermal waters suggested the probable existence of a deep geothermal reservoir of middle-low enthalpy (70-111癈) in the Tianshui and its northern- southern area. The sustainable utilization of the thermal water will be maintained if the total withdrawal rate is relatively small, and an alternative pumping and non-pumping pattern is used in Tianshui and its northern-southern area with mean yearly rainfall of near 500 mm.
  • Climate and Phenology Variations in Sichuan and Chongqing
    WANG Bing-yun, FAN Guang-zhou, DONG Yi-ping, HUA Wei, ZHOU Ding-wen, ZHU Li-hua, ZHANG Qi
    2011, 31(6): 674-681. https://doi.org/10.13249/j.cnki.sgs.2011.06.674
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    According to the daily temperature and precipitation data of 44 stations in 1961-2007 and part of the woody plant data of Beibei observation stations and Renshou observation stations in 1963-1988, the Chinese Academy of phenological observation network in Sichuan-Chongqing, temperature, precipitation, season, woody plant phenology variation were analyzed. The results showed that mean annual temperature of the last 10 years were 0.68 ℃ higher than the previous 37 years, and mean annual precipitation basically unchanged. Low temperature is mainly distributed in the western Sichuan Plateau, and the number of low temperature days and accumulated low temperature decreased. Mean daily maximum temperature in the southern region of the western Sichuan Plateau tended to decrease, while that in other regions increased. Mean daily minimum temperature was confirmed to have warming trends, and that in the southwestern Sichuan and the northern Sichuan Plateau grew faster. Precipitation in the central and southern of Sichuan Basin declined, southwest of Chongqing and western Sichuan plateau tended to increase. Precipitation days in the western Sichuan Plateau demonstrated an increasing trend, that in other regions tended to decrease, especially, those decreased rapidly in the east of Sichuan and Chongqing. According to Zhang Baokun Designate Temperature Method to define seasons, spring starting time delayed in Renshou, advanced in Beibei, and autumn starting time delayed in those two stations. In the leaf expansion phase, apricot and black locust of Renshou, and black locust, Metasequoia, Bauhinia, Indus of Beibei delayed, wisteria, peaches of Beibei advanced. In the leaf defoliation stage, black locust of Renshou advanced, but all plants of Beibei delayed.
  • Correlation Analysis for Fractal Dimension Between TM Image and Terrain of Broadleaved Forest in Tianmu Mountain
    SHAN Yong-bing, YU Fa-zhan, LI Xian-hua
    2011, 31(6): 682-687. https://doi.org/10.13249/j.cnki.sgs.2011.06.682
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    Broadleaved forest spatial distribution map in Tianmu Mountain has been obtained by classifying TM image on 11 October, 2000 ,with combining supervised and unsupervised technique method in the paper. A digital elevation model (DEM) was established from the vector contours in ArcGIS environment, which was derived slope and aspect. This paper describes quantitatively fractal dimensions of both TM images and terrain of broadleaved forest using the triangular prism surface area method (TPSAM), explores the distribution of fractal dimensions of them, and makes a correlate analysis between them using ArcGIS spatial analysis and statistic function of SPSS. The results indicate that: (1) The distribution of TM image fractal dimension of broadleaved forest is orderly. Fractal dimension of TM image shows an increasing trend with the increase of elevation and slope gradient. Fractal dimension of TM image on sunny, half-shady and half-sunny slope is larger than that on the shady slope. The distribution of TM image fractal dimension is closely related with the slope gradient. (2) The distribution of terrain fractal dimension is orderly on elevation and aspect. There is a decreasing trend of fractal dimension as elevation increases. Fractal dimension of shady slope is larger than that on sunny, half-sunny and half-shady slope, while the distribution of terrain fractal dimension on the slope is disorderly. The distribution of terrain fractal dimension is closely related with the elevation. (3) The study further shows that there is a positive correlation between the fractal dimension of TM image and terrain of broadleaved forest, and the distribution was physically explained.
  • Study on Distribution Characteristics of Spatial Thermal Environment of Yutian Oasis Based on RS Image
    ZHANG Fei, TASHPOLAT稵iyip, TIAN Yuan, DING Jian-Li, MAMATSAWUT
    2011, 31(6): 688-694. https://doi.org/10.13249/j.cnki.sgs.2011.06.688
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    Oasis is a unique geographical system in the arid area, which is stricted by the material and energy flow of the Mountain-Oasis-Desertification system. So, it should focus on the study of the interaction process between the Mountain-Oasis-Desertification system, including the flow of energy among the oasis, desert and the mountains. This paper takes Yutian Oasis as an example, using Landsat TM/ETM+ as the data source and the temperature as an index to study the interaction process of the Mountain-Oasis-Desertification system. The article analyzed the oasis average temperature distribution, and the result showed that the surface temperature is determined obviously by underlying surface type and surface land type distribution influences the overall distribution of land temperature. Through the different temperature chart, it is found that the distribution of temperature is impacted by the spatial distribution of different land use types. The temperature trend analysis on Keriya River downstream obtained the result that in the north-south direction, there is no temperature change, and in east-west direction, the temperature changes obviously. Meanwhile, the influence range to both channel of Keriya River is limited.
  • Dune Evolution in Horqin Dunefield of China Since Late Glacical Period Inferred from Luminescence Dating and Pollen
    YANG Lin-hai, LAI Zhong-ping, ZHOU Jie, LONG Hao, ZHANG Jing-ran
    2011, 31(6): 695-701. https://doi.org/10.13249/j.cnki.sgs.2011.06.695
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    The Horqin dunefield is located in the northern frontier of East Asian Monsoon (EAM) zone, and its activation and stabilization is sensitive to the ebb and flow of the EAM. However, the activity of dunes in the Horqin dunefield is still poorly understood due to the limited numerical dating. The purpose of the present study is to explore the dune evolution using luminescence dating and pollen analysis in order to understand the relative role of climate and human activity. In the present study, 21 samples collected from seven sections in the Horqin dunefield were dated using quartz optically stimulated luminescence (OSL) dating method. Combined with the stratigraphy, pollen materials and the OSL chronology, the dune avolution in the Horqin dunefield since the late glacial period can be summarized that before 16-10 ka B.P., aeolian sand dunes were mobilized; during 10-3 ka B.P., dunes were stabilized, with dark sandy soil development; at around 3 ka B.P., dunes were mobilized again abruptly; since 3 ka B.P., there were multiple phases of dune stabilization/mobilization. Between 4 and 2 ka B.P., the vegetation of Horqin dunefield degenerated gradually from the meadow steppe to steppe. Dune activity was dominated by climate before 3 ka B.P. However, since 3 ka B.P., both climate variability and human impact have influenced dune evolution in the Horqin dunefield.
  • Pollen-based and Quantitative Reconstruction of Holocene Palaeovegetation of Surface Soil of Xinjiang
    FENG Xiao-hua, YAN Shun, NI Jian
    2011, 31(6): 702-707. https://doi.org/10.13249/j.cnki.sgs.2011.06.702
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    A total of 200 pollen samples of surface soil and 685 pollen records were used to reconstruct vegetation patterns in Xinjiang, based on a new global classification system of plant functional types (PFTs) and a standard numerical technique for biome assignment (Biomisation). The work processes include the establishment of pollen database, the design of plant function types, the design of biomes, reconstruction of modern vegetation and palaeovegetation patterns using the Biomisation method and the palaeovegetation mapping. It has got better uniformity between the reconstructed biome using the pollen sample of surface soil and the modern natural vegetation in the vertical distribution, and it is also ideal in the horizontal distribution. It proved this model can use in reconstructing the palaeobiome during the geologic history and can do some dynamic and quota analyses in Xinjiang.
  • Perception of Local Climate Change of Rural Residents in Huining County and Southwestern Shandong Province
    CHANG Gen-ying, LI Man, HUANG Fu-peng
    2011, 31(6): 708-714. https://doi.org/10.13249/j.cnki.sgs.2011.06.708
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    Based on questionnaire survey, climate data and agricultural disaster data, this paper concerned about how the rural residents in Huining County of Gansu Province and in Shanxian of Shandong Province perceived local climate change in the past 20 years and which factors influenced their perceptions. It is found that at the most cases, the majority of respondents could perceive the trend of local climate change correctly. It is argued that perception of respondents of local climate change is decided basically by the trend of climate changes and its effects on their production and daily life, but other factors, such as obvious climate change occurred recently and extreme weather conditions, play a decisive role in some cases as well.
  • Trend and Spatial Features of Drought in Guangdong
    ZHENG Bin, LIN Ai-lan
    2011, 31(6): 715-720. https://doi.org/10.13249/j.cnki.sgs.2011.06.715
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    Although there is an annual mean precipitation about 1 700 mm in Guangdong Province, it greatly varies with season and region. Flood season (April-September) includes above 80% rainfall of a year, and meanwhile the rainfall has a significant intra-seasonal variability. On the other hand, large evaporation due to high average air temperature also balances some part of the great precipitation in Guangdong. An index to reflect the drought is defined using rainfall and temperature observations of 86 surface stations in Guangdong. The index distinguishes the dry and wet season in Guangdong and reflects the fact that there is a dryer climate in the south than elsewhere of Guangdong in spring and a wetter climate in the north in fall, which indicates the index is reasonable. The trend analyses give an understanding of the linear humidity change. For the whole province of Guangdong, the climates from February to March, from July to August and December tend to be wetter than before, and dryer from October to November and few changes in months else. The results show that the autumn drought would be more severe in the future and the winter-spring drought would be lighter. The spatial distribution of the linear trends has a great difference and its interannual variability is affected by air-sea and air-land interactions.
  • Spatio-temporal Variance of Annaul Runoff in Jinghe River Basin of Northwest China in Past 50 Years and Its Main Causes
    ZHANG Shu-lan, WANG Yan-hui, YU Peng-tao, ZHANG Hai-jun, LIU Ge-fei, TU Xin-wu
    2011, 31(6): 721-727. https://doi.org/10.13249/j.cnki.sgs.2011.06.721
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    The spatio-temporal variation of annual runoff in the Jinghe River Basin of Northwest China and its main driving forces were studied based on the meteorological and hydrological data over 50 years in this paper. It showed that the precipitation and runoff presented an obvious decreasing trend from south to north in the Jinghe River Basin, the high value areas of both precipitation and runoff existed in the upstream mountainous parts. While the averaged temperature in the basin increased significantly in last 50 years since the 1960s, the pan evaporation decreased slightly and the precipitation decreased insignificantly, the annual runoff of the whole Jinghe Basin decreased significantly from 50.1 mm in the 1960s to 22.3 mm at the beginning of the 21st century. However, the runoff reduction among subbasins differed significant, which manifested the highest runoff decrease in the west, southwest and southeast parts of Jinghe River Basin, with a reduction rate up to 17.5 mm/10a; while the runoff reduction in the north and northwest parts of Jinghe River Basin presented an unobvious runoff reduction, with a maximum reduction rate of 1.3 mm/10a. The change of annual precipitation is an important cause for the runoff reduction, but the change of soil surface characteristics due to human activities became more profound cause for the runoff reduction since the 1990s, including the increasing terrace field and forest/vegetation coverage resulted from a series of ecological restoration projects, such as grain for green and nature forest protection.
  • The Annual Runoff Variation Trends in the Three Headstreams of Tarim River
    LING Hong-bo, XU Hai-liang, ZHANG Qing-qing, SHI Wei
    2011, 31(6): 728-733. https://doi.org/10.13249/j.cnki.sgs.2011.06.728
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    Based on the observed annual runoff data of 5 hydrological stations in Tarim River headstreams areas from 1957 to 2008, the paper studied the annual trend, abrupt change, periodicity and the coming period trends by use of the nonparametric test, R/S analysis and wavelet analysis and so on. The results showed that: (1) Both Aksu river and Yarkand river of which the jump points happened at 1993 hold significant step change, but Hetian river expressed a slightly decreasing step trend and is not significant;(2)Aksu river holds a significant increasing trend but Yarkand river the trend is not, and based on the Hurst exponents(Aksu:0.777>0.5,Yarkand:0.485 7<0.5) of two the streams, the annual runoff of Aksu river will keep an increasing trend and Yarkand river will be in reverse in the coming period; Hetian river has a slightly decreasing trend and the Hurst exponent is 0.501 4, which equals 0.5 approximately and indicates that the annual runoff process is in chaos, then it can not be taken a long-term predict .(3) The primary periods of Aksu river and Hetian river are 6a, 18a, 22a and 9a, 17a respectively, otherwise, Yarkant river is at 3a,9a,13a and 17a.
  • Hydrochemical Characteristics of Three Rivers Around Yulong Mountain in Rainy Season
    PU Tao, HE Yuan-qing, ZHU Guo-feng, XIN Hui-juan, DU Jian-kuo, WANG Shu-xin, WANG Shi-jin
    2011, 31(6): 734-740. https://doi.org/10.13249/j.cnki.sgs.2011.06.734
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    In order to study the characteristics of hydrochemical composition in rivers, water samples were collected in Baishui, Sanshu and Geji hydrological stations around Yulong Mountain. The results indicated that water of the three rivers is mildly alkaline with rich with Ca2+ and HCO3-. Obvious variations have been perceived during the rainy season. According to sources study of major ions, water of the three rivers were mainly influenced by precipitation and rock weathering function. The proportions of Na+, K+, Ca2+, Mg2+ and SO42- from precipitation in water are 23.44%, 9.66%, 3.10%, 17.81%, and 10.48%, respectively. In addition, the ion characteristics of river water were mainly influenced by carbonating weather. The human activities should not be ignored though its influence was little.
  • Seawater Quality Characteristic of Greenland Coastal Waters in Summer
    SONG Tian-ze
    2011, 31(6): 741-746. https://doi.org/10.13249/j.cnki.sgs.2011.06.741
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    Sampling of surface seawater, ice and runoff were carried out during the Arctic scientific expeditions in July in 2010, which was organized by Beijing Teenager Science and Technology Club. The study area was coastal waters of Greenland, Svalbard and Iceland. The water quality analysis results showed that F- and NO3- were not detected. Concentrations of macro-components in seawater were sequenced as Cl- > Na+ > SO42- > Mg2+ > K+ > Ca2+, which was accordant with general seawater. The ratio between concentration of all ions and chlorinity followed the Marcet-Dittmar Constant Ratios Law which testified that Greenland Sea was mainly recharged by precipitation and runoff from mainland. Ion concentrations in seawater of inshore were much lower compared with that of offshore because surface seawater was recharged by runoff resulted from glacier melting. Despite NO3- was detected in runoff at Svalbard, the coastal seawater samples were determined without NO3-, which indicated that the NO3- in runoff was sufficiently diluted under the effect of ocean current.
  • Cross Wavelet Analysis and R/S Analysis of Relationship Between Geomagnetic Ap Index and Sunspot Number
    WANG Ya-min, Zhang Bo, Guo Ling-xia, Dai Sheng-pei, Wang Xing-mei
    2011, 31(6): 747-752. https://doi.org/10.13249/j.cnki.sgs.2011.06.747
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    Two of the most widely used indices in geophysical research are the sunspot number as a measure of solar activity and the index Ap representing geomagnetic activity in the sub-auroral region. The sunspot number is a significant index of the solar activity because of its availability and reliability. Studies in solar terrestrial relationships have consistently shown the close and occasionally elusive link between the evolution of activity of the Sun and geomagnetic manifestations on the surface and in the magnetosphere. We use R/S assessing statistical singnificance and wavelet methods to assess statistical significance and confidence intervals of cross-wavelet phase and wavelet coherence. The Continuous Wavelet Transform is a common tool for analyzing localized intermittent oscillations in a time series. It is very often desirable to examine two time series together that may be expected to be linked in some ways. In particular, to examine whether regions in time-frequency space with large common power have a consistent phase relationship, causality between the time series is suggestive. Many geophysical time series are not normally distributed and we employed the Continuous Wavelet Transform. From two Continuous Wavelet Transforms we constructed the Cross Wavelet Transform which will expose their common power and relative phase in time-frequency space. We will further define a measure of Wavelet Coherence between two Continuous Wavelet Transform, which can find a significant coherence even though the common power is low, and show how confidence levels against red noise backgrounds are calculated. The rescaled range analysis (R/S) is proposed as a method to detect the correlations in pseudorandom number generators used in Monte Carlo simulations. In an extensive test, it is demonstrated that the R/S analysis provides a very sensitive method to reveal the hidden long-run and short-run correlations. Several widely used pseudorandom number generators are subjected to this test. In many generators, correlations are detected and quantified. In this paper, we used data of the Geomagnetic Ap index and the sunspot number from 1932 to 2009 to analyze the relationship between the Geomagnetic Ap index and the sunspot number by cross-wavelet method and the rescaled range analysis method. The results show that, 1) The Geomagnetic Ap index and the sunspot number have the similarity shape in the significant degree band with high frequency, and have a significant and steady oscillation period from 8.02 to 11.35 a; in the low frequency band, Geomagnetic Ap index and sunspot number have an uncontinuous oscillation period from 2 to 6 months, which is only a part of the year within the 95% of the red noise test. 2) There is significant in-phase resonance oscillation between the Geomagnetic Ap index and sunspot number in 8.02–11.35 a, in which the variation of the Geomagnetic Ap index occurs about 1.5 a after that of the sunspot number, and their phase relationship is steady. The Geomagnetic Ap index and the sunspot number also have relatively intermittent resonance periodicity from 4 to 6 months in the low frequency, but their phase relationship was not steady. 3) The Hurst index of the Geomagnetic Ap index and the sunspot number were 0.7923 and 0.8141, respectively. It indicated that the Geomagnetic Ap index and the sunspot number were continuous time series, and there existed a long persistence and chaoticity in the Geomagnetic Ap index and the sunspot number.
  • Tillage Impacts on Soil Total Nitrogen and Alkali-hydrolyzed Nitrogen of the Purple Paddy Soil in Southeast China
    ZHU Tao, HAO Qing-ju, JIANG Chang-sheng, YUAN Xue
    2011, 31(6): 753-757. https://doi.org/10.13249/j.cnki.sgs.2011.06.753
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    Soil total nitrogen and alkali-hydrolyzed nitrogen based on a long-term experiment with various tillage systems were studied in a purple paddy soil at the farm of Southwest University, Chongqing, China. The experiment included five tillage treatments: conventional tillage with rice only system (DP), conventional tillage with rotation of rice and rape system (SH), no-till and ridge culture with rotation of rice and rape system (LM), no-till and plain culture with rotation of rice and rape system (XM), and tillage and ridge culture with rotation of rice and rape system (LF). The content of soil total nitrogen in the 0-60 cm soil layers under different tillage systems was LM (1.53 g/kg)>DP (1.50 g/kg)>XM (1.32 g/kg)>LF (1.31 g/kg)>SH (1.16 g/kg), the content of alkali-hydrolyzed nitrogen was DP (111.48 mg/kg)>LM (105.20 mg/kg)>SH (101.97 mg/kg)>LF (97.26 mg/kg)>XM (95.19 mg/kg). Long-term LM treatment significantly increased soil total nitrogen content. The C/N ratio was LM (14.94)>XM (10.49)>SH (10.38)>LF (10.20)>DP (10.18) which indicated that an easier nutrients release to soil during the process of organic matter decomposition under no-till systems.
  • The Relationship Between Pollen Assemblages in Topsoil and Modern Vegetation in the Typical Karst Rocky Desertification Area
    HAO Xiu-dong, OUYANG Xu-hong, XIE Shi-you, SHI Sheng-qiang, LI Lin-li, LUO Lun-de
    2011, 31(6): 758-763. https://doi.org/10.13249/j.cnki.sgs.2011.06.758
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    The pollen analysis of 25 topsoil and mosses samples under six typical types of vegetations in the Karst rocky desertification area showed that: (1) 47 pollen taxes are recorded totally, among which, herbs and ferns are dominate with 23.62%-76.47%,then the trees (mainly Pinus massoniana) with 17.73%-74.05%, and the shrub pollen is only about 0-12.50%, indicating the character of a serious degradation of local vegetation; (2) Pollen assemblages are obvious differentiation under different vegetations, which corresponding to the actual vegetation and reflecting the present conditions of the modern vegetation in the rocky desertification area, indicating pollen analysis can give a reference to the rehabilitation and reconstruction of natural environment in the study area.
  • Risk Assessment of Typhoon Disasters in China Coastal Area During Last 20 Years
    NIU Hai-yan, LIU Min, LU Min, QUAN Rui-song, ZHANG Li-jia, WANG Jing-jing
    2011, 31(6): 764-768. https://doi.org/10.13249/j.cnki.sgs.2011.06.764
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    The risk assessment method of typhoon disasters was proposed according to the nature disaster system theory and considering the characteristics of hazard factor and bearing body. And in the GIS environment the hazard, vulnerability and risk of typhoon disasters in China coastal area were assessed. The assessment result showed that the hazard of typhoon disaster is higher in Hainan Province, Shanghai and the coastal areas of Guangdong, Fujian, Zhejiang provinces. The vulnerability of bearing body is higher in Beijing, Tianjin, Shanghai, the most parts of Jiangsu, Shandong provinces, and the coastal areas of Guangdong, Fujian, Zhejiang, Hebei Provinces. The risk of typhoon disaster is higher in Hainan Province, Shanghai and the coastal areas of Guangdong, Fujian, Zhejiang provinces, while in Beijing, Tianjin and the the most parts of Hebei, Liaoning, Shandong provinces, it is lower the risk.