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  • 2014 Volume 69 Issue 3
    Published: 20 March 2014
      
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  • Temperature variability and its possible causes in the typical basins of the arid Central Asia in recent 130 years
    YAO Junqiang, LIU Zhihui, YANG Qing, LIU Yang, LI Chengzhi, HU Wenfeng
    2014, 69(3): 291-302. https://doi.org/10.11821/dlxb201403001
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    Basin-scale is of the special significance to the climate change research in arid areas. In this study, data from five typical basins of the arid Central Asia are analyzed to investigate changes in annual temperature during the period of 1881-2011. The nonparametric Mann- Kendall test, wavelet analysis and the correlation analysis are used to identify trend, multiple time scale feature and their possible causes in the annual temperature. The results show that the average annual temperature had an increasing trend in the main basins (except Amu Darya Basin) of the arid Central Asia in the past 130 years. The rising rate is consistent with that of the northern hemisphere, much higher than that of the global average and surrounding region, suggesting that the arid Central Asia is more sensitive to climate change than other regions. Abrupt change point in annual temperature occurred around the year of 1986, and showed significant multi-time scale periodic oscillation, which is mainly due to the physical external force and internal climate-control system. The Central Asian vortexes' activity has a significant effect on annual temperature of the typical basins, followed by the northern annual mode cycle variation and the Tibetan Plateau, while the greenhouse effect caused by CO2 gas emissions in the arid Central Asia can not be ignored. Temperatures show an aperiodic cycle which is related to the BC, PDO and TBO, and we can confirm that temperature in the arid Central Asia is closely related to the atmospheric circulation, sea surface temperature and solar activity.
  • Variation of starting date of pre-summer rainy season in South China from 1736 to 2010
    DING Lingling, GE Quansheng, ZHENG Jingyun, HAO Zhixin
    2014, 69(3): 303-311. https://doi.org/10.11821/dlxb201403002
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    Based on the documented characteristics of Yu (rainfall)-Xue (snowfall)-Fen (Chinese length unit, 0.32 cm approximately)-Cun (10-Fens) archive in the Qing Dynasty, together with the features of precipitation in pre-summer rainy season in South China, the methods to reconstruct the starting date of pre-summer rainy season in South China was designed. Using the Yu-Xue-Fen-Cun archive, the series of starting date of pre-summer rainy season in Fuzhou and Guangzhou were reconstructed from 1736 to 1911. And the series of starting date of pre-summer rainy season during the instrumental period were identified by daily precipitation records in Fuzhou during 1953-2010 and Guangzhou during 1952-2010. The inter-annual and inter-decadal changes of the starting date for pre-summer rainy season in South China over the past 300 years were analyzed. The results show that the mean of starting date of pre-summer rainy season in South China was the first pentad of May; however there existed obvious inter-annual and inter-decadal variabilities in the starting date of pre-summer rainy season over South China, with quasi-cycles of 2~3 years, 10 years and 40 years during 1736-1911 and those of 2~3 years, 10 years and 22 years during the instrumental periods. The starting date in the earliest year was the fourth pentad of April, while the starting date in the latest year was the sixth pentad of May in Fuzhou and the first pentad of June in Guangzhou during 1736 to 1911; while the starting date in the earliest year and the latest year was the fourth pentad of April and the first pentad of June in Fuzhou during 1953-2010 and Guangzhou during 1952-2010. The maximum magnitude between the adjacent decades was 2.2 pentads in Fuzhou and 1.6 pentads in Guangzhou during the reconstructed periods; while it was 2.5 pentads and 2.4 pentads during the instrumental periods.
  • An approach of spatially-explicit reconstruction of historical forest in China：A case study in Northeast China
    LI Shicheng, HE Fanneng, ZHANG Xuezhen
    2014, 69(3): 312-322. https://doi.org/10.11821/dlxb201403003
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    To research the climatic and ecological effects of historical land cover change, it is necessary to create historical land cover datasets with explicit spatial information. Using potential vegetation and satellite-based land use data, we determined the possible distribution extent of forest cover before reclamation. Then, some factors affecting land reclamation were selected to evaluate land suitability value of China for cultivation and then they were integrated into a model. Furthermore, historical forest gridding reconstruction model (the size of grid cell is 10 km by 10 km) was developed according to the land suitability value. As a case study, we reconstructed spatially explicit forest cover of 1780 and 1940 in Northeast China using this approach. The results demonstrated that the forest gridding reconstruction model we created can transform provincial forest area into spatially explicit data well. To test the model's rationality, we compared satellite-based forest cover and reconstructed forest cover of 2000. And the one sample t-test of the absolute error of them showed that the two-tailed significance was 0.12, larger than the significant level 0.05, suggesting that there was no significant difference between them and the gridding reconstruction method we designed was rational. The relative errors at county scale of forest cover reconstruction in 1780 of Northeast China were calculated. And the number of counties, whose relative error ranged from -30% ~ 30%, is 99, accounting for 74.44% of the totals (data missing counties are discharged).
  • Assessment of the spatiotemporal variations of diffuse photosynthetic active radiation in China from 1981 to 2010
    REN Xiaoli, HE Honglin, ZHANG Li, YU Guirui
    2014, 69(3): 323-333. https://doi.org/10.11821/dlxb201403004
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    Photosynthetically active radiation is the energy source of plant photosynthesis, and the diffuse component can enhance canopy light use efficiency, thereby increasing the carbon uptake. Therefore, diffuse PAR is an important driving factor of ecosystem productivity models. In this study, we estimated the diffuse PAR of over 700 meteorological sites in China from 1981 to 2010 using an empirical model based on observational data from Chinese Ecosystem Research Network (CERN) and China Meteorological Administration. Then we derived the spatial data set of 10 km monthly diffuse PAR using ANUSPLIN software, and analyzed the spatiotemporal variation of diffuse PAR through GIS and trend analysis. The results showed that: (1) the spatial patterns of annual average diffuse PAR during 1981-2010 are heterogeneous across China, lower in the northeast and higher in the west and south. The nationwide average value for the 30 years ranges from 6.66 mol m-2 d-1 to 15.27 mol m-2 d-1, and the value in summer is the biggest while the value in winter is the smallest. (2) There is an evident increasing trend of annual diffuse PAR during recent 30 years, with increasing amplitude at 0.03 mol m-2 d-1/10a. But a significant declining trend is observed in the first 10 years, and obvious anomalies can be seen in 1982, 1983, 1991 and 1992. And there is a downward trend in spring and an upward one in all other seasons. (3) The spatial distribution of temporal variation rates of diffuse PAR is inhomogeneous across the whole country, generally decreasing in the north and increasing in the south.
  • The relationship between forest ecosystem emergy and forest ecosystem service value in China
    WU Shuang, YAN Xiaodong, ZHANG Lijuan
    2014, 69(3): 334-342. https://doi.org/10.11821/dlxb201403005
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    In this study, with the help of emergy value theory and ecosystem service value theory, we established the function relationship between forest emergy value and ecosystem service value in China using the global temperature and precipitation data during 1901-2009 and 1266 sample forest data of major vegetation types in China. Results indicate that: there was a high consistency of the spatial distribution of the Chinese forest ecosystem service value in 1994 between the simulated results by the established function relationship and the evaluation results from Costanza. In particular, the raster number of forest areas in China increased by about 14.02% from 1990 to 2009, and the mean forest ecosystem service value density increased by about 54.46 USD/hm2. In addition, the mean forest ecosystem service value density for Beijing, Shanghai, Jiangsu, Tianjin, Hebei decreased by about 86.87%, 85.45%, 81.99%, 46.48% and 23.07%, respectively, and the mean ecosystem service value density for Henan, Hunan, Jilin, Jiangxi, Heilongjiang and Zhejiang decreased by about 71.35%, 58.65%, 52.70%, 34.56%, 23.36% and 22.03%, respectively. There was also a severe forest destruction in Guangxi, Tibet, Gansu, Inner Mongolia, Sichuan, Yunnan, and Ningxia, and the mean forest ecosystem service value density of those provinces decreased by about 2.89%-22.36%. According to the fourth and seventh National forest survey reports, the forest areas have continually increased in recent years. However, the reports show that the forest ecosystem service value density in several provinces have decreased, and indicate that the forest ecosystem has not been fully recovered. Generally speaking, the forest ecosystem service value is lower than the global average level, suggesting that the forest eco-environment is not good enough in China, and human activities have a tremendous negative impact on the ecosystem.
  • Determination of 137Cs reference inventory in the large scale region：A case study in the central and eastern Inner Mongolia Plateau
    HU Yunfeng, LIU Jiyuan, Batunacun, ZHEN Lin
    2014, 69(3): 343-352. https://doi.org/10.11821/dlxb201403006
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    In isotope 137Cs tracing studies, it is a basic premise to select a suitable 137Cs reference inventory (CRI) sample plot and to determine an accurate CRI value. However, there are many difficulties and uncertainties in practical studies due to the heterogeneous spatial distributions of 137Cs deposition and different artificial operations in sampling and testing. In a large scale region or a long-distance field exploration, such difficulties and uncertainties become more obvious and annoying, which seriously impedes the developments of 137Cs tracing technology applied in wind eroded regions, such as the Mongolia Plateau and Northeast China Plain. In this paper, studies releted to the traditional CRI acquiring process were summarized at first, and then a systematic framework to get the CRI in large scale areas or long distance investigations was proposed. The framework covers 7 sub-processes and the core steps include: building sub-regions in a large area supported by geographical backgrounds and long time-serial remote sensing information, calculating the potential range of CRI according to the theoretic model which was developed by Walling D E, analyzing erosion/deposition processes based on 137Cs soil profile distribution patterns, and determining the final CRI plots and CRI values. Taking the central-eastern part of Inner Mongolia Plateau as the case study region, the above steps were implemented and depicted in detail. The CRI in dark chestnut soil zone located in the east and south of Xing'an was 2447 Bq·m-2, the CRI in aeolian sandy soil zone stood in the south and center of Tongliao and central Chifeng was 2430 Bq·m-2, the CRI in sandy chernozem soil zone situated in the northwestern Chifeng was 2384 Bq·m-2, and the CRI in chestnut soil zone located in the southern Xilingol was 2368 Bq· m-2. Compared with the relevant consequences in the adjacent areas, the above results were believed to be reliable and accurate. The CRI determination framework and key steps offered an important basis for the future 137Cs tracing studies, especially in the large scale regions and long distance excursions.
  • Spatiotemporal changes of maize sown area and yield in Northeast China between 1980 and 2010 using spatial production allocation model
    TAN Jieyang, LI Zhengguo, YANG Peng, LIU Zhenhuan, LI Zhipeng, ZHANG Li, WU Wenbin, YOU Liangzhi, TANG Huajun
    2014, 69(3): 353-364. https://doi.org/10.11821/dlxb201403007
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    Understanding crop patterns and their changes on a large scale is a critical requirement for projecting agro-ecosystem dynamics. However, tools and methods for analyzing crop sown area and yield on spatiotemporal variations are still insufficient currently. By the use of cross-entropy method, a Spatial Production Allocation Model (SPAM) was developed. Combined with geographic spatiotemporal analysis methods, a case study was further presented to analyze the spatial characteristics of maize sown area and yield in Northeast China during 1980-2010 within 5' × 5' grid cells. The results indicated the following: (1) Maize sown area mainly expanded northwards during 1980-2000 (located at 44° N-48° N) and then concentrated at central and southern in Northeast China on latitudinal variations in the following years. Also it moved eastwards (located at 123°E to 127°E) and lower elevation (below 100m) as well as higher elevation (mainly from 200 m to 350 m) region on longitudinal and altitudinal variations, respectively. (2) Maize yield which has been improved largely mainly located at 42°N to 48°N and concentrated at the region below the altitude of 350 m on latitudinal and altitudinal variations, respectively, while its increase is relatively homogeneous on longitudinal variations. (3) Additionally, dominant maize proportion on a pixel scale has developed to middle-high proportion gradually during 1980-2010, and maize yield located at the pixel of middle-high proportion seems higher, which reflected the trends of agglomeration and large-scale development of maize cultivation driven by market economy.
  • RS analysis of glaciers change in the Heihe River Basin in the last 50 years
    HUAI Baojuan, LI Zhongqin, SUN Meiping, ZHOU Ping, XIAO Yan
    2014, 69(3): 365-377. https://doi.org/10.11821/dlxb201403008
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    The Heihe River Basin is the second largest inland river basin in Northwest China and it is also a hotspot in arid hydrology, water resources and other aspects of researches in cold regions. In addition, the Heihe River Basin has complete landscape, moderate watershed size, and typical social ecological environmental problems. So far, there has been no detailed assessment of glaciers change information of the whole river basin. Therefore, it is urgent to conduct studies on the assessment of glacial change in this region. Landsat TM/ETM+ remote sensing images, digital elevation model data and 1:50,000 topographic map data were used in this research. Through integrated computer automatic interpretation and visual interpretation methods, the object-oriented image feature extraction method was applied to extract glacier information. Glaciers change data were derived from spatial analysis, and the glacier variation and its response to climate change in the period 1956/63-2007/11 were also analyzed. The results are shown in the following. (1) In the period 1956/63-2007/11, the Heihe River Basin's glaciers had an evident retreat trend, the total area of glaciers decreased from 361.69 km2 to 231.17 km2, at a rate of 36.08%, and average single glacier area decreased by 0.14 km2; the total number of glaciers decreased from 967 to 800. (2) Glaciers in this basin are mainly distributed at elevations of 4300-4400 m, 4400-4500 m and 4500-4600 m; there are significant differences in glacial distribution and glacial change. (3) Compared with other western mountain glaciers, glaciers retreat in the Heihe River Basin had a higher rate. (4) By analyzing the meteorological data at six weather stations from 1960 to 2010, it is found that the mean annual temperature increased significantly and the annual precipitation also showed an increasing trend. It is concluded that glacier shrinkage is closely related with temperature rising. Besides, glacier melting caused by rising temperatures is greater than glacier mass supply by increased precipitation to some extent.
  • Characteristics and formation mechanisms of the rhythmic morphology of salt-marsh edge cliffs
    ZHAO Yangyang, GAO Shu, WANG Dandan, XU Zhen, ZHU Dong, WANG Xiaofeng
    2014, 69(3): 378-390. https://doi.org/10.11821/dlxb201403009
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    Marsh-edge cliffs represent a unique geomorphological unit at the border of marsh vegetation and the intertidal mud flat. Research on the processes and mechanisms for the formation of salt-marsh marginal cliffs will improve our understanding of the influence of salt marshes on tidal flat growth and stability. Based on the results obtained from the measurements and analyses of morphological parameters of salt-marsh cliffs in the Yancheng Nature Reserve, central Jiangsu coasts, during December 2013, the development of the rhythmic morphology associated with the marsh cliff may be divided into three stages. These stages of long-term evolution present cyclical patterns and are related to seasonal changes in wave conditions. Furthermore, the formation of significantly rhythmic features of salt-marsh marginal cliffs may be explained partly by the theory of standing edge waves. In the future, numerical modeling can be applied to investigate the formation mechanisms of marsh-edge cliffs associated with such rhythmic features, in combination with in situ measurements for wave climates and sediment dynamics.
  • A study on classification system and inventory of gobi
    FENG Yiming, WU Bo, YAO Aidong, CAO Xiaoyang, CONG Richun, YAO Bin, WANG Feng, LU Qi
    2014, 69(3): 391-398. https://doi.org/10.11821/dlxb201403010
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    Gobi is one of the main landscape types in the arid regions in northwest China. There is an area of about 661 thousand km2 in China, accounting for 6.9% of the total territory, and meanwhile, there are abundant natural resources, such as land resources, biology resources, solar energy resources, wind energy resources, and mineral resources in the gobi region. However, bad natural conditions and sparse population in this region lead to few field investigations, and thus few research documents related to the gobi can be obtained. Establishing a series of unified gobi classification standards and cataloging system are not only the theory basis for conducting further gobi studies, but also the precondition for developing the abundant natural resources in the gobi region reasonably. So far, there are few research documents related to the gobi status, gobi distribution and gobi type classification, and the research documents on the gobi cataloging are even more scarce. In combination with the existing study on the gobi classification system, the result analysis of science exploration for the gobi and the discussion results of expert panels, the gobi classification system with three levels is put forward to promote the standardization of gobi research according to the cause of gobi formation, the material composition of earth's surface and the vegetation characteristics. At the same time, the relevant characteristics of each gobi type at all levels are described in detail. Moreover, some ideas on the gobi cataloging are also presented so as to collect, collate and record the main characteristic data and the related information for each gobi type systematically. It is inferred that these results can promote the standardization of gobi research.
  • Lateral shift rate variation of the river banks in the Yinchuan Plain reach of the Yellow River and its causes
    WANG Suiji, LI Ling
    2014, 69(3): 399-408. https://doi.org/10.11821/dlxb201403011
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    It is important to examine the lateral shift rate variation of river banks in different periods. One of the challenges in this regard is how to obtain the shift rate of river banks, as gauging stations are deficient for the study of river reaches. The present study selected the Yinchuan Plain reach of the Yellow River with a length of 196 km as a case study, and searched each point of intersection of 153 cross-sections (interval between two adjacent cross-sections was 1.3 km) and river banks in 1975, 1990, 2010 and 2011, which were plotted according to remote sensing images in those years. Then the shift rates for the points of intersection during 1975-1990, 1990-2010 and 2010-2011 were calculated, as well as the average shift rates for different sections and different periods. The results show that the left bank of the river reach shifts mostly to the right, with the average shift rates being 36.5 m/a, 27.8 m/a and 61.5 m/a in the three periods, respectively. Contemporarily, the right bank shifts mostly to the right in the first period, while it shifts to the left in the second and third periods, with the average shift rates being 31.7 m/a, 23.1 m/a and 50.8 m/a in the three periods, respectively. The average shift rates for the left and right banks during the period 1975-2011 are 22.3 m/a and 14.8 m/a, respectively. The bank shift rates for sections A, B and C are different. The shift rate ratio of the left bank in the three sections is 1:7.6:4.6 for shift to the left and 1:1.7:3.8 for shift to the right, while that of the right bank is 1:1.8:1.2 for shift to the left and 1:5.6:17.7 for shift to the right during the period 1975-2011. Obviously, the average shift rate is the least in section A, while it reaches the maximum in section B for shift to the left and in section C for shift to the right. The temporal variation of the shift rate is influenced by human activities, while the spatial variation is controlled by the local difference in bank materials.
  • Silting/scouring process responses of Dongting Lake basin to the operations of TGR and thresholds of water-sediment regulation
    ZHOU Yongqiang, LI Jingbao, ZHANG Yunlin, ZHANG Xinping, LI Xichun
    2014, 69(3): 409-421. https://doi.org/10.11821/dlxb201403012
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    Based on measured runoff and sediment discharge rate of major control stations in the Dongting Lake basin and the Jingjiang River section, Yangtze River, from 1951 to 2011, this paper analyzes silting/scouring process responses of the Dongting Lake basin to different impoundment phases and different dispatching modes of the Three Gorges Reservoir (TGR). Results are shown as follows: (1) Significant correlations were found between flow rate of the Zhicheng Station and flow rate of the Three (Four) Outlets of the Southern Jingjiang Rivers (r2=0.859, p<0.0001), flow rate and sediment deliver rate of the Three (Four) Outlets (r2=0.895, p<0.0001), indicating that flow rate and sediment deliver rate of the Three (Four) Outlets were strongly influenced by upstream Yangtze River flow rate. (2) Compared with period before operation of the TGR (1999-2002), sediment silting/scouring amount of the Dongting Lake basin during the TGR impoundment phases I, II and the TGR in comprehensive operation phase (2008.10-2011.12) dropped from +4796.4×104 t to +684.1×104 t, +449.8×104 t, -559.6×104 t, and sediment silting/scouring rate dropped from +70.25% to + 31.13%, +23.56%, -42.64% successively. The results present notably positive effects due to operation of the TGR. (3) During pre-discharge dispatch and water-storage dispatch period, the lake basin changed from silting to scouring mode. For flood-storage dispatch and water-supplement dispatch period, the Dongting Lake basin was mainly controlled by silting and scouring processes, respectively. (4) The calculated optimum thresholds of annual mean flow rate, sediment transport rate and sediment concentration of the Three Outlets were 970.81 m3/s, 466.82 kg/s and 0.481 kg/m3, respectively, while the Dongting Lake basin were under the state of neither silting nor scouring. The thresholds could provide practical references for operation regulation of the TGR.
  • Multi-scale variability of water discharge and sediment load in the Pearl River during 1954-2011
    WU Chuangshou, YANG Shilun, HUANG Shichang, WANG Shanshan
    2014, 69(3): 422-432. https://doi.org/10.11821/dlxb201403013
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    This paper is based on hydrological data gathered from Gaoyao (West River), Shijiao (North River) and Boluo (East River) stations in the Pearl River from 1954 to 2011, and the temporal and spatial variations in water discharge and sediment load are analyzed by Mann-Kendall trend test and wavelet analysis. The results are shown as follows. (1) There is no significant trend in water discharge, but a significant decreasing trend in sediment load during 1954-2011 due to impacts of climate change and human activities. Furthermore, there are different trends in different periods. From 1954 to 1983, both water discharge and sediment load show an increasing trend. The contribution rates of climate change and human activities are about 70% and 30%, respectively. From 1984 to 1993, there are undulating phases in water discharge and sediment load (1989 is the changing point), which is mainly resulted from climate change. From 1994 to 2011, both water discharge and sediment load show a decreased trend, and the contribution rates of climate change and human activity to sediment load are about 20% and 80%, respectively. (2) Compared with the data before 2006 when Longtan Dam started operation, the annual average water discharge from 2007 to 2011 decreases by 14%, meanwhile the annual average sediment load decreased by 70% . The contribution rates of reservoirs and soil and water conservation are about 90%. (3) There are apparent decadal cycle periods (DCPs) and annual cycle periods (ACPs) for water discharge and sediment load in different tributaries of the Pearl River, with cycle periods varying among different tributaries. For example in the West River the DCPs of water discharge were mainly 24 yr and 13 yr and ACPs were 4-7 yr, while for sediment loads the DCPs were ~16 yr and 10 yr, and the ACPs were 4-7 yr. In the North River, the significant DCPs of water discharge were about 12 yr, and the ACPs were 2 yr and 8 yr, but the significant DCPs of sediment load were about 13-16 yr, and the ACPs were 4-7 yr and 2-3 yr, respectively. In the East River, both the water discharge and sediment load had 12 yr of DCPs and 2 yr and 6 yr of ACPs. These periodic variations may be related with periodic variations of precipitation in the Pearl River Basin.