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25 July 2015, Volume 2015 Issue 4 Previous Issue    Next Issue

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Study on layout of hydrologic network in the Changjiang estuary GU Sheng-hua,LI Qi 2015, 2015 (4):  1-6.  doi: 10.3969/j.issn.1000—5641.2015.04.001 Abstract ( 910 )   PDF (1891KB) ( 1580 )   Save The layout of hydrologic network in the Changjiang estuary, based on analysis monitoring requirements of seven hydrological factors including tidal level, discharge, wave, salinity, sediment, water quality, wind speed and direction, was formulated with hydrological stations which controlled the critical regions or in the key nodes in this paper. The construction thought of hydrologic network is “ highlight the main factor, multifactor monitoring, integrated monitoring and retrench the network”. The basic construction principles are “emphasizing focal point, holding overall consideration, integrating the old and the new stations, substantiating and improving the network, considering every station and the network simultaneously, combining flow measurement in fixed satation and the moving gauging.”  References | Related Articles | Metrics

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Analysis of salinity observational stations distribution in the Changjiang estuary QIU Cheng,GU Sheng-hua,LI Qi 2015, 2015 (4):  7-16.  doi: 10.3969/j.issn.1000-5641.2015.04.002 Abstract ( 1083 )   PDF (4083KB) ( 1452 )   Save Salinity observation is one of the major basic works for freshwater resource management and security of domestic water usage in the Changjiang estuary. The gained data can provide theory evidence for works as water intake in reservoirs and water conservancy projects. The observational stations and buoys that are set in estuarine region are the main longtime data sources of salinity in the Changjiang estuary. The longtime series measurement data has important scientific significance and application value for study on saltwater transport processes and reservoir operation. According to the comparison between numerical simulation results and observed data, the temporal and spatial variations of salinity distribution are analyzed. Meanwhile, the requirements of observation system and monitoring elements are discussed. In this paper, the designing method of salinity monitoring stations in the Changjiang River Estuary is presented, and the scheme of spatial unity and equilibrium of site locations as well as layout in the key research area are shown. References | Related Articles | Metrics

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Statistical analysis of the wind at the Chongming eastern beach DAI Ran,ZHU Jian-rong 2015, 2015 (4):  17-25.  doi: 10.3969/j.issn.1000-5641.2015.04.003 Abstract ( 982 )   PDF (2076KB) ( 1293 )   Save The wind plays an important role in circulation, mixing, saltwater intrusion and sediment transport in the Changjiang estuary. Based on the observed wind speed and direction by the weather station at the Chongming eastern beach from December 2007 to February 2014，the wind rose diagrams and seasonal wind variations are presented and analyzed. From January to December, the mean wind speeds in each month are 4.2, 4.6, 4.9, 4.9, 4.7, 4.4, 4.9, 4.9, 4.5, 4.0, 4.1 and 4.3 m/s, mean wind directions in each month are N, NE, NE, SE, SE, SE, S, SE, NE, NE, N and N, respectively. Wind direction, frequency and averaged wind speed of the wind with the first, second wind direction frequency, the maximum average wind speed direction, strong wind direction domain and strong wind speed domain in each month are presented statistically. In overall, the wind at the Chongming eastern shoal has the feature of subtropical zone monsoon, prevailing southeasterly wind in spring and summer, and northerly wind in autumn and winter. The strong wind has an obvious seasonal variation, its frequencies in March, April and July, August are distinct higher than in other months. The strong wind frequencies in July and August is higher than in March and April, reaches to 0.8% and 1.52% with mean wind speed of 11.5 and 12.4 m/s. The wind at the Changjiang mouth is the basic dynamic factor in the study of dynamics process and material transport there. References | Related Articles | Metrics

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Statistical forecasting of storm surge under single stationobservations in Zhoushan island terrain KANG Xing,ZHANG Bei,DU Pan-jun,XU Ting-ting,ZHANG Hui 2015, 2015 (4):  26-33.  doi: 10.3969/j.issn.1000-5641.2015.04.004 Abstract ( 810 )   PDF (1372KB) ( 1815 )   Save According to Zhoushan tidal observations including Dinghai, Daishan, Shengshan, and CMA STI tropical cyclone best tracking data from 1982 to 2011, we found two kinds of typical typhoon path caused the heaviest and most frequently storm surge. One is landing in southern Zhejiang, and the other is northward moving and near shore turning.Based on the above two kinds of typhoon data, we analyzed the relationship between characteristics of the typhoon(such as strength, moving speed, distance factor etc.) and tide and the storm surge intensity and type.Using the multivariate nonlinear regression analysis, we choose the most relevant factors to create a statistical model for storm surge forecasting. It showed the good results through the actual cases appling such as matsa， muifa and tembin. References | Related Articles | Metrics

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Morphological evolution and human activities impacts at the mouth area of the North Branch, Yangtze estuary, during the recent three decades WANG Ru-sheng,YANG Shi-lun,LUO Xiang-xin,LU Ye-feng,MIAO Li-min 2015, 2015 (4):  34-41.  doi: 10.3969/j.issn.1000-5641.2015.04.005 Abstract ( 1273 )   PDF (2549KB) ( 1268 )   Save In order to enrich the knowledge of landocean interaction, this paper examined the recent accretion and erosion at the mouth area of the North Branch, the Yangtze Estuary, based on bathymetric and remote sensing data and using ArcGIS techniques. The results show that: (1) from 1981 to 1997, 13 km2 of intertidal area was reclaimed; an average accretion rate of 1.4 cm/yr was observed in the subtidal area. (2) from 1997 to 2012, 163 km2 of intertidal zone was embanked, and an average erosion rate of -7.1 cm/a was found in the subtidal area. (3) Between 1981 and 2012, an average accretion rate of 0.77 cm/a was found in the inner portion, and an average erosion rate of -1.97 cm/a occurred in the outer portion. We concluded that the morphological evolution in the study area was controlled by three factors—the silting trend of the North Branch, the intertidal accretionpromoting projects, and dam construction within the Yangtze watersheds. During the recent 15 years, human activities were the dominant factor. References | Related Articles | Metrics

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Analysis of the coastal erosion and accretion in Haikou Bay by remote sensing ZHANG Xiao-dong,SHEN Si-min,ZHU Shou-xian, ZHANG Wen-jing,HUANG Ji-wen 2015, 2015 (4):  42-53.  doi: 10.3969/j.issn.1000-5641.2015.04.006 Abstract ( 932 )   PDF (3438KB) ( 1440 )   Save The analysis of coastal erosion and accretion, based on the remote sensing water line, is better than that using field observations because of its convenience, quickness and more data. However, this method hasn’t been applied to Haikou Bay. Four types of water index for extracting waterline from Landsat sensing image are checked by observations in Haikou Bay, in which the water index of NDWI is proved to be the best. The waterlines of 15 Landsat sensing images in 1994—2013 are extracted by NDWI, with which the evolution of the beach slope between high tidal level and low tidal level is analyzed. And the results show that the beach slope is basically stable with the value of 3.7~4.2°. Then the coastal erosion and accretion are analyzed using the extracted waterlines and the beach slope. The character of erosion and accretion isn’t uniform in the beach. Xixiu Beach and Jiari Beach have been eroded, and the eroded depth is 0.36 m near the high tidal level and 0.30 m near the low tidal level, the eroded speed is 1.9 cm/a near the high tidal level and 1.8 cm/a near the low tidal level. References | Related Articles | Metrics

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Responses of river discharge and sea level rise to climate change and human activity in the Changjiang River Estuary embodied in a numerical model ZHU Jian-rong, Qiu Cheng 2015, 2015 (4):  54-64.  Abstract ( 897 )   PDF (683KB) ( 1299 )   Save Climate change and human activity result in the variations in river discharge and sea level rise, both of which are very important for setting the boundary conditions of a numerical model.Thus, to obtain proper boundary conditions, this study presents projected variations in the amounts of Changjiang river discharge and sea level rise caused by climate change and human activity in 2030, 2050, and 2100. Considering the Three Gorges Dam closure in 2003 and utilizing the historical river discharge data at Datong Station from 1865 to 2002, the river discharge variations resulting from the extrapolation of historic data and climate models are almost identical. The mean river discharge in January and February will reach 12\,348, 12\,683, and 13\,522 m$^{3}\cdot$s$^{-1}$ in 2030, 2050, and 2100, respectively, due to climate change. In the past 20 years, the rate of absolute sea level rise was approximately 2.5\;mm$\cdot$a$^{-1}$ in the Changjiang River Estuary. In accordance with the observed tidal data that based on the sea level change over time analysis-based forecasting model, the absolute sea level rise will be 49.1, 148.1, and 395.6 mm in 2030, 2050, and 2100, respectively, compared to the 2012 levels. The saltwater intrusion simulation numerical model for the Changjiang River Estuary must consider the impacts of the Three Gorges Reservoir and South-to-North Water Diversion on the river discharge. The earth crust and land subsidence should also be considered for an accurate determination of the relative sea level rise. These values are presented in this paper for each prediction period Related Articles | Metrics

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Saltwater intrusion sources at the water intake of Qingcaosha reservoir in different tidal pattern and wind case WANG Shao-xiang,ZHU Jian-rong 2015, 2015 (4):  65-76.  doi: 10.3969/j.issn.1000-5641.2015.04.008 Abstract ( 954 )   PDF (4204KB) ( 979 )   Save The measured salinity and numerical simulated current speed and direction in December 2013 and February 2014 were used to analyze the source of saltwater intrusion at the water intake of Qingcaosha reservoir. Under the general river discharge and wind case in dry season December 2013, the saltwater sources at the water intake during spring tide, medium tide after spring tide, early neap tide came from the upstream saltwaterspillover from the North Branch into the South Branch, whereas during late neap tide and medium tide after neap tide came from the downstream open sea, i.e., through the saltwater intrusion in the North Channel. It was found that the saltwater intrusion in the Changjiang Estuary in February 2014 was very severe and had never been happened in recent decades, which resulted in the not suitable take water days of the reservoir reach to 23 days, and serious threat of safety water supply in Shanghai. Under the general river discharge and long continue strong northerlies lasting 15 days in February 2014, the saltwater sources at the water intake of Qingcaosha reservoir during the all four tidal patterns came from the downstream open sea saltwater intrusion through the North Channel. References | Related Articles | Metrics

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Impacts of the reclamation project of Nanhui tidal flat on the currents and saltwater intrusion in the Changjiang estuary LI Lin-jiang,ZHU Jian-rong 2015, 2015 (4):  77-86.  doi: 10.3969/j.issn.1000-5641.2015.04.009 Abstract ( 917 )   PDF (6153KB) ( 1304 )   Save Considering the averaged river discharge and wind in dry season, the impacts of reclamation project of Nanhui tidal flat on the currents and saltwater intrusion were numerically calculated and dynamically analyzed. The funnel shape was reduced, flood current and tidal prism in the South Passage were changed after the reclamation project. The reclamation project resulted in tidal prism in the South Passage reducing 13% in spring tide and 16% in neap tide, and the flood currents spilling over the dikes of the deep water channel decreased; The northward salt fluxes spilling over the dykes from the South Passage were weakened which made the seaward salt flux in the North Passage reduced, the landward salt flux decreased the upper and middle reaches of the South Passage and on the southeast side of the project, whereas was increased at the mouth of the South Passage. After the reclamation project, the salinity front in the South Passage was weakened, the salinity in spring tide increases with exceeding 1.0 in the area near the mouth of the South passage and on the southeast side of the project; the salinity decreased with greater than 0.5 at the upper and middle reaches of the South Passage, in the North Passage and in the Hengsha eastern beach due to the decreases of the tidal prism, current spilling over the dikes and landward salt flux. The salinity in neap tide decreased in the whole South passage with greater than 1.5 because of the decreases of the flood current and salt flux at the mouth caused by the weaker tide. The net water diversion ratios were reduced slightly in spring and neap tide in the North Channel, increased 1.57% in spring tide and 1.50% in neap tide in the South Passage because the salinity front in the South Passage was weakened after the reclamation project, which weakened the block effect of the river water into the South Channel.  References | Related Articles | Metrics

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Numerical simulation on the major river plumes in China seas YAN Qi，WU Hui，ZHU Jian-rong 2015, 2015 (4):  87-96.  doi: 10.3969/j.issn.1000-5641.2015.04.010 Abstract ( 982 )   PDF (6707KB) ( 1494 )   Save A large domain model has been developed to simulate the major river plumes in the China seas, which takes into account the multiple dynamic factors. The results shows that different sea area responses differently to the river plumes. In Bohai Sea, due to its semienclosed topography that restricts the water mass exchange with outer area, the sea salinity keeps low,  though the received runoffs are generally small. The Yellow Sea is also semienclosed, plus a large amount of the Changjiang River freshwater extends into the sea, the salinity there is also low in most times. The salinity in East China Sea varies seasonally along with the extension of the Changjiang River plume. In the Northern South China Sea, the Pearl River plume dominates the sea salinity variation in the east of the Qiongzhou Strait. As the offshore extension of the Pearl River is limited, the low salinity area is smaller than that in other seas. In the west of the Qiongzhou Strait, the Red River plume controls sea salinity variation. References | Related Articles | Metrics

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Numerical simulation on the phytoplankton dynamics in Changjiang estuary and MinZhe coastal waters WANG Yi-he,WU Hui,ZHU Jian-rong,SHEN Jian 2015, 2015 (4):  97-109.  doi: 10.3969/j.issn.1000-5641.2015.04.011 Abstract ( 945 )   PDF (9009KB) ( 1088 )   Save This study was based on a highresolution, threedimensional, physicsbiogeochemistry coupling numerical model that considered multiple dynamics and biochemical factors to simulate the spatial and temporal distribution of the dinoflagellata and diatoms. The results showed that the algae bloomed in late spring, summer and early autumn in this area. The diatoms bloomed twice in spring and summer and dinflagellata bloomed only once in spring. The high phytoplankton mass concentrated around the area of 30 to 50 isobath, which was an frontal area between the high temperature and low turbidity shelf waters and the low temperature and rich nutrient Changjiang diluted water. This area satisfied the physical and biogeochemical requirements for the growth of the phytoplankton. Furthermore, we also analyzed the influences of the physical dynamics such as runoff and shelf circulation on the phytoplankton growth. References | Related Articles | Metrics

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Integrated carrying capacity assessment of Xiangshan bay ecosystem WENG Jun-chao,YUAN Lin,ZHANG Liquan,LI Hui 2015, 2015 (4):  110-122.  doi: 10.3969/j.issn.1000-5641.2015.04.012 Abstract ( 866 )   PDF (6318KB) ( 1275 )   Save Xiangshan bay is a typical longnarrow and semienclosed bay ecosystem in China. In recent years, human activities have caused degradation of resources, environment and service function in Xiangshan bay. In this study, taking Xiangshan bay ecosystem as a case study, based on the theory of ecological carrying capacity, an integrated carrying capacity indicator system was developed from resource supply capacity, environmental carrying capacity and human supporting capacity for the assessment of Xiangshan bay ecosystem carrying capacity. The results indicated that the environmental carrying capacity decreased in Xiangshan bay during 2003 to 2011. The proportion of overloaded area increased from 17.2% in 2003 to 41.8% in 2011. Water inorganic nitrogen and active phosphate were the main reasons caused environmental carrying capacity overloaded. Resource supply capacity had gradually decreased during 2003 to 2011 and showed a declined trend from the mouth to inwards of the bay. The proportion of loaded area decreased from 87.4% in 2003 to 0.1% in 2011 Human supporting capacity were loaded and improved slightly. The integrated carrying capacity decreased yearly from the mouth to inwards of bay and overloaded area increased yearly which was mainly caused by overload of environmental carrying capacity. The results of this study could objectively reveal the integrated carrying capacity of Xiangshan bay ecosystem. The assessment methods and model of integrated carrying capacity could be flexibly applied to other bay ecosystem and provide a feasible technical approach and demonstration cases for other comparable coastal zones in China. References | Related Articles | Metrics

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Type and seasonal difference of urban wetland’s temperature effect in Hangzhou ZHANG Wei ,JIANG Jin-gang,ZHU Yu-bi 2015, 2015 (4):  123-131.  doi: 10.3969/j.issn.1000-5641.2015.04.013 Abstract ( 1022 )   PDF (2704KB) ( 1747 )   Save This paper takes four typical urban wetlands of Hangzhou for example and discusses the influence of season and wetland type on the temperature effect of urban wetland by means of remote sensing and GIS spatial analysis. The results show that: (1) the seasonal difference of wetland’s temperature effect is very obvious. Seasonal factors have an important influence on the type, range, amplitude and gradient change of urban wetland’s temperature effect. (2) There are no direct relationships between traditional classification system for wetland types and urban wetland’s temperature effect. Wetland’s size and perimeter have an important influence on its temperature effect, while the influence of wetland’s shape on the temperature effect is not obvious. (3) Comparing the efficiency of different wetland’s temperature effects, we find that the efficiency of Grande Canal is the highest. The relationship between wetland size and temperature effect is most likely to be S curve model. References | Related Articles | Metrics

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Experimental study on hydrogeochemistry action in the process of freshwater displacing saltwater XING Liting1,WANG Liyan2,LI Changsuo3,XU Mintian1 2015, 2015 (4):  132-143.  doi: 10.3969/j.issn.1000-5641.2015.04.014 Abstract ( 988 )   PDF (4154KB) ( 1052 )   Save Based on test materials, including of silt, shallow salt groundwater and atmospheric precipitation which were got in northwestern Shandong geochemistry action in the process of freshwater displacing saltwater were studied. The results indicated that (1) When content of clay was high in aquifer medium, and specific conductivity of exudate was less than or equal to 0.83 ms/cm in the process of freshwater displacing saltwater, clay played a role of film effect in concentrating ion components. (2) Dolomite still kept precipitation with water, and halite still kept dissolution in the process of freshwater displacing saltwater. Calite precipitated when specific conductivity of exudate was more than 1.00 ms/cm; Gypsum balanced with water when specific conductivity of exudate was more than or equal to 6.22 ms/cm. Mg/CaNa exchange interaction was remarkable with critical ion strength being in 0.20～0.25 mol/L. Adsorption was remarkable while specific conductivity of exudate was more then 12.00 ms/cm. Displacement experiment showed that hydrogeochemistry actions were happened in the process of freshwater displacing saltwater with adsorption, exchange interaction, lixiviation, dolomitization and mixing action. References | Related Articles | Metrics

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Online testing of geographic location recognition using Google Earth WANG Xi-feng,ZHU Liang-feng 2015, 2015 (4):  144-153.  doi: 10.3969/j.issn.1000-5641.2015.04.015 Abstract ( 889 )   PDF (3122KB) ( 970 )   Save Geographic location recognition, or the ability to locate and name places on a map, is an essential indicator to assess individuals’ geographic literacy levels. Past research has concentrated on testing one’s geographic location recognition using twodimensional paper maps. Whereas the paper mapping method is flexible and easy to follow, it requires a fixed paper map with a series of predefined quizzes and is therefore difficult to reuse. Advances in geospatial information technologies, led by geographical information systems and digital earth systems, is providing educators with a convenient platform to cultivate and assess one’s geographic location recognition. In this paper, we present a general framework and corresponding implementation methods for the online testing of geographic location recognition using the Google Earth digital earth platform. The most significant feature of the proposed framework and corresponding implementation program is that they have abilities to improve the individuals’ geographic literacy while conducting the testing. References | Related Articles | Metrics

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Plant image classification and retrieval based on leaf margin features YAN Yi-zhen,ZHOU Jian-hua 2015, 2015 (4):  154-163.  doi: 10.3969/j.issn.1000-5641.2015.04.016 Abstract ( 776 )   PDF (2741KB) ( 1332 )   Save Leaf margin is one of the main characteristics to identify plant species. Compared to leaf shape features, leaf margin features are much more subtle, so they are often indispensable in multiscale recognition of plant species as either dependent features or supplements for others. The progresses include designing 7 new margin feature descriptors, taking hierarchical classification organized by some semantic dictionaries to reach a better classification accuracy, and finally deciding plant species of a leaf node member by similarity evaluation and retrieval. Our experiments have revealed that the descriptors, named as the ratio of residual convex to leaf area and the ratio of right edge to left edge, are efficient to distinguish between different nonlobedleaf species and different nonintegrifoliousleaf species; the mean value of residual convex etc., is of other examples of useful descriptors to the identification between different nonintegrifoliousleaf species. By using the hierarchical classification in the feature space of multi leaf margin descriptors, 30 nonlobedleaf species have been divided into several leaf nodes, and the mean overall accuracy is better than 81.21%. The test of assessing the similarity between the new assigned leaf node member and the known samples has further demonstrated that the framework of jointly using the hierarchical classification and the image retrieval is effective for the identification of plant species. References | Related Articles | Metrics

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Temporalspatial variations of carbon sink/source in Northeast China from 2000 to 2010 ZHANG Lu，WANG Jing，SHI Run-he 2015, 2015 (4):  164.  doi: 10.3969/j.issn.1000-5641.2015.04.017 Abstract ( 826 )   PDF (3938KB) ( 1226 )   Save Net Ecosystem Productivity (NEP) is an important parameter when estimating regional carbon source/sink. Based on EOS/MODIS data and meteorological data, NEP was calculated in Heilongjiang, Jilin and Liaoning from 2000 to 2010. The temporal characteristics of NEP were analyzed, the results showed that during 2000 to 2010 most areas in three provinces of Northeast China were carbon sinks, NEP was between 0~300 g C·m-2·a-1, carbon sources were in Northwestern Jinlin and Southwestern Heilongjiang; the mean NEP of forest(176.74 g C·m-2·a-1) was the highest, followed by shrub(175.02 g C·m-2·a-1), the carbon sequestration ability of farmland, wetland and grass decreased successively. In nearly 66.36% of the territory of the study area, NEP tended to decline, which meaned their carbon sequestration were weaker. Area with increased carbon sequestration were in Southeastern Changbai Mountain in Liaoning province and hills in western Liaoning, where the increasing slope was between 5~15. The correlation coefficient between NEP and precipitation was significant; NEP was sensitive to the extreme value of the temperature and precipitation, the trend of NEP was consistent with the fluctuation of precipitation. This paper conducted regional simulation of carbon sink/source, providing theoretical basis and methodological references for the usage of remote sensing data in the related study areas. References | Related Articles | Metrics