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  • Orginal Article
    ZHAO Zhujun,JI Genlin
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    Spatial-temporal trajectory classification aims at predicting the category of a spatial-temporal trajectory. The classification of spatial-temporal trajectories plays an important role in urban planning, personalized user recommendation and so on. The process of trajectory classification includes three stages: trajectory preprocessing, feature extraction and classification. This paper reviews the recent research progress on trajectory classification. Firstly, we introduce the process of trajectory classification. Then, the trajectory classification algorithms are classified into three categories according to the method of feature extraction, including the trajectory classification algorithm based on motion feature, the trajectory classification algorithm based on classification rule and the trajectory classification algorithm based on image signal analysis. We also discuss the basic ideas, advantages and disadvantages of these algorithms. Thirdly, we compare the existing classification algorithms according to the sensors, feature extraction and classifiers used in these algorithms. Finally, we introduce the challenges of the existing trajectory classification algorithms.

  • Orginal Article
    LI Mengyuan,LI Anbo,ZHOU Wei,JIANG Wei
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    Secret classification marking is hidden information used to mark the security level of information products and is the basis and precondition for classification management, control and application of information. Since vector geographic data is the main organization format of classified geographic information products, it is of great significance to study secret classification marking method for vector geographic data. When suffered from geometry attack, the spatial relationship among elements of vector geographic data is invariable and secret classification marking method requires good imperceptibility and high robustness. In order to realize classification management and protection of vector geographic data, this paper presents a secret classification marking method for vector geographic data based on distance ratio modulating. In essence, using the digital watermark technology, the method embeds secret classification marking as watermarking information into vector geographic data, which has important application value for security protection of vector geographic data. The main ideas related to the study are as follows: Firstly, the method is based on distance ratio modulating and it can deal with geometry attack very well. Secondly, the method effectively improves the robustness against editing attack by repeatedly embedding secret classification marking within each line and area. Lastly, through embedding secret classification marking into feature points which are extracted by using Douglas-Pecker algorithm, the method can also effectively resist data compression attack. The experimental results show that the proposed method has good imperceptibility. In addition, when vector geographic data is suffered from the attacks, such as geometric transformation, data editing and data compression, the extraction ratio of its secret classification marking can reach almost more than 80%, indicating the robustness of this method.

  • Orginal Article
    ZHANG Dequn,XIE Chuanjie,PEI Tao
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    With the development of indoor positioning technique, more and more position data of indoor moving objects are recorded by sensors. As the basic work of moving objects database, index technique has become a research hot-spot. Majority of existing moving objects index are for outdoor moving objects which are not suitable for indoor environment. Also, they only build index on geography coordinates of moving objects, lack of supporting of semantic information which can offer effective support for management and analysis of indoor moving objects. There will be a performance bottleneck when massive data are ingested and frequent querying are asked when implemented on traditional relational database. In this paper, we built a grid of indoor floor environment and create a map relation from grid to semantic cell. Then, we utilized this map to semanticize indoor moving objects’ location if it was contained in a semantic cell. After this work, we built an index called SCoII (Semantic Cell Oriented Indoor moving objects Index). SCoII can answer not only semantic spatio-temporal range query but also indoor moving object’s semantic trajectory query, which can support for semantic-based analysis of indoor moving objects. SCoII is implemented on HBase, so it also avoided the performance degradation of traditional relational database when encounting massive data and have good performance of updating and querying without bottleneck. Experimental results also showed that it can be adapt to big data. Supporting for semantic information of indoor moving object is the most important feature of SCoII. More data mining jobs can be done on indoor moving object’s semantic location and semantic trajectory such as the simple example given out at the end. Management and analysis based on semantic of indoor moving objects will be convenient on SCoII, which lays a foundation of analysis work in the future.

  • Orginal Article
    YANG Cancan,JIANG Ling,CHEN Xin,WANG Chun,ZHAO Mingwei
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    Topographic features are defined as point, polyline and polygon elements which control surface topography of the earth. Its reasonable classification can provide the data foundation for the simulation of urban topography. There are already many industrial standards for topographic map classification. However, the existed feature classification and coding methods are mainly focused on surveying, mapping, editing, updating, and data storage of topographic map. These methods cannot be used for urban DEM construction directly. After parsing the characteristics of urban terrain and analyzing the deficiencies of classification method in urban terrain modeling based on large scale topographic map, a classification and expression method of urban topographic features is put forward in this paper. According to the principle of urban space is divided by road and land parcel, the topographic features of urban terrain are classified and expressed with mathematical equations based on object-oriented thought by taking the 1:500 topographic maps as fundamental data. To test and verify the effectiveness and feasibility of the classification and expression method, this paper made a registration between classification results and remote sensing images, constructed the DEM and extracted the slope. Meanwhile, this paper performed a comprehensive evaluation for classification results from geometric and semantic perspectives. Also, it analyzed modeling effects at global and local scale, respectively. The experiment results showed that the classification results can be well matched with remote sensing images, the proposed classification and expression method of topographic features can express the geometric and semantic information of complex urban terrain effectively at both global and local scale. The classification and expression method of topographic features for urban DEM construction can not only provide basis for analysis and application of terrain factors, but also provide technical support for the application of topographic features, such as urban terrain modeling, construction planning and decision-making.

  • Orginal Article
    YAO Mengmeng,LI Anbo,CHEN Ying,WU Chunying
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    It has been generally accepted that the geological boundary feature is essential and fundamental feature in the process of building the spatial database of geologic map. Owing to the largest numbers of graphic elements in geological boundary layer, its digitization and quality inspection become more onerous. The traditional method commonly starts with the drawing of geological boundary layer, then designs the geological body layer by the way of line to arc on the foundation of the geological boundary layer. According to the traditional way, we can learn that geological boundary layer and geological body layer share the same spatial data. It is consistent with the digital geological map database standards of China Geological Survey. When we have the existed geological body layer and the geological boundary layer is missing, the quick method which making the best use of the same spatial data to produce the geological boundary layer will be considered as fully remarkable and reliable. It not only puts forward an automatic method for creating the geological boundary layer, but also automatically tests the attribute data quality of the geological boundary layer. The method is implemented as a three-step process. First of all, the geological body adjacency relation graph is constructed briefly which is aimed at extracting the geological boundary efficiently and accurately based on the geological body layer. Secondly, the recognition rules of stratum contact relationship is summed up, and is applied to recognize the basic stratum contact relationship and the fault contact relationship automatically on the basis of occurrence data and fault data. Finally, according to the situation that the recognition results among the multi-segment boundaries of two adjacent stratums are not unique, principles of the "parallel unconformity first" and the "length first" are given to make a reasonable integrated judgment. This test is based on 1: 50,000 scale of Lushan geological map and created the geological boundary layer automatically. It demonstrated that this method was efficient, fast and accurate. This method has the certain advantages of a faster way to create the geological boundary layer in the process of constructing the geologic map spatial database and at the same time it is an effective tool to inspect the quality of the geological boundary layer.

  • Orginal Article
    WANG Chenzhi,ZHANG Zhao,ZHOU Maigeng,YIN Peng,TAO Fulu,JIN Yuexiong
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    Global warming has increased the frequency of meteorological disasters, especially extreme temperature events. Many previous studies have reported that human health risk is very sensitive to temperature and climate change was considered to be the most severe global health threat in the 21st century. Nowadays, the research on the impact of extreme temperature on public health has been a hotspot. Compared to those in developed countries, the related studies have started late in China. Moreover, there are three limitations in these studies. (1) Most of such studies focused only on one city or a few cities and the studies on the whole country are few.(2) The previous studies have not quantitatively identified the influence of temperature on health because the spatial scales were based on administrative regions, not on temperature zones. (3) Comparing with many studies on hot wave, relatively fewer are concerned with the influence of extreme low temperature. To overcome aforementioned problems, we collected the mortality dataset and meteorological variables of 127 communities in China during 2007 to 2012 from China Center for Disease Control and Prevention and pooled the community-specific cold risk in various latitude-effected temperature zones with the meta-analysis method. Then, we utilized the Distributed lag non-linear model (DLNM) at community level to investigate temperature-mortality relationship in different temperature zones and calculated the relative risk (RR) of extreme low temperature on mortality. The results showed that although temperature-mortality curves at the community level appeared huge differences, the pooled curves were generally U- or J- shaped in these five zones. Temperature-mortality curves in three zones (the sub-temperate region, warm temperate region and north subtropical region) were all U-shaped, indicating both low and high temperatures could increase significantly mortality risk. Moreover, the curves appeared J-shaped in other two zones (the middle subtropical region and south subtropical region). The most significant cold effect was observed in middle subtropical, with a RR of 1.93 (95% CI: 1.08-3.60); while the cold effect in north subtropical was not so obvious, with a RR of 1.27 (95% CI: 0.94-1.72). Based on this, an M-shaped curve of the cold risk was found across Chinese mainland. This means the risks of cold-related mortality are high in warm temperature and middle subtropical zone, moderate in sub-temperate and south subtropical zone, and low in north subtropical zone. Low temperature does show significant impact on temperature-mortality risk, but considering the M-shaped risk curve, we believe social-economic factors should also be taken into consideration. To explain this phenomenon, we collected the social-economic data including population and GDP and found that the highest per capita GDP matched with the lowest cold-related risk, while the related lower per capita GDP matched with the highest cold-related risk. Based on these findings, different characteristics of mortality of cold stress highlighted that not only ambient temperature but also social-economic condition can be a main factor controlling health risk. Our findings also suggest that more adaptive and effective measures especially increasing investment on public health are necessary, especially for the middle subtropical zone, to reduce health risks in China.

  • Orginal Article
    ZHANG Ningxu,LIAO Yilan,LIU Xiaochi,CHEN Huiyan
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    Emergent public health events have a wide range of effect and serious harm to public health. The Centers for Disease Control and Prevention (CDC) is an important institution of disease prevention and control and public health management and technical services in China. Its ability of responding to public health emergency will directly affect the effectiveness of emergency handling and a timely reaction can provide useful information for the public at the first time and reduce the panic caused by this incident to the largest extent. Therefore, it's important to scientifically evaluate the capability of CDC to deal with the public health emergencies. In this study, we took the “Shandong vaccine event” outbreak in March 18, 2016 as an example, collected the relevant information published on the CDC website and used the temporal-spatial analysis to evaluate the capability of CDC in China to deal with the public health emergencies. The data was from the CDC official website of each city which responded to this event. It shows that 73.2% of the total cities has established a CDC official website, of which 69% of the cities have responses. This analysis included the visualization analysis of the speed and the contents of responses and the spatial clustering analysis, using the spatial scan statistics method to detect the spatial cluster of the responded city. The results of this analysis showed that the spatial distribution of the information construction of CDC in China is inequality. Compared with the other regions of China, the CDC department's official websites of cities in southwestern region responded faster on public health emergency, and has a significant spatial clustering in this area. The CDC department of Shandong and Henan provinces which was the huge circulation province of the failing vaccine and the high-risk areas in this vaccine incident, didn't have a timely reaction and the capability of response to the public health emergency is weak.

  • Orginal Article
    DU Guoming,SUN Xiaobing,LIU Yansui,ZHENG Huiyu,MA Ronghui
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    Ecological restoration is an important way to adjust the structure and function of ecosystem in order to cope with the excessive interference of land use. Scientific mastery of restoration pattern and farmland pattern evolution has a profound significance on the management of regional ecological environment and the conservation of vegetation in Loess Plateau. This study, taking Yan'an City in Loess Plateau as a typical area, explores the spatial differentiation characteristics of farmland variation and restoration status from the overall characteristics of ecological restoration, topographic factors and regional differences since ecological restoration. The results show that the arable land of Yan'an City decreased from 11752.80 km2 to 9149.93km2 due to the ecology restoration during 2000-2013. The returned farmland is 2756.85 km2, and the returned farmland index is 22.15%. The cultivated land was mostly converted to forest and grassland accounting for 95.29% of the total amount. Farmland and the returned farmland area was mainly distributed in slope (6~25°) and the altitude level of II(925~1115 m), III(1115~1275 m), IV(1275~1442 m), which accounted for more than 70% of the area. The degree of farmland returning increased gradually with the increase of slope, with the land reclamation rate decreased gradually with the increase of slope and elevation. The highest degree of ecological restoration is the altitude level of IV, and the least is altitude level of III. The ecological restoration rate of 2005-2013 was higher than that of 2000-2005. The area and extent of restoration in county decreased from north to south. The center of farmland returning and cultivated land is located in the boundary of Ansai county and Baota District which are in the north of Yan’an City. The center of ecological restoration was changing from northeast to southwest while the center of cultivated land was changing from north to south. This study may provide more scientific and reasonable reference for ecological conservation and construction of ecological civilization in Loess Plateau by the analysis of spatial-temporal differentiation characteristics of ecological restoration in Yan'an city.

  • Orginal Article
    CHEN Sujing,LI Lijuan,LI Jiuyi,LIU Jiaxu
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    Based on the monthly precipitation data from 30 meteorological stations in and surrounding the Lancang River basin, we analyzed the temporal and spatial characteristics of precipitation from 1960 to 2014 using the climate tendency rate, Mann Kendall trend test, Morlet wavelet analysis, interpolation co-Kriging, and gravity center model methods. The results showed that: (1) in the analysis period, the overall precipitation and regional precipitation in the northern and central regions showed a rising trend, but a decreasing trend on precipitation for the southern region occurred. The overall, northern, central and southern precipitations showed an increasing trend in spring, while in summer they showed a decreasing trend. In autumn, there was a decreasing trend of precipitation in the whole region and in the south. The northern and central parts of the region were having an increasing trend. The precipitation in the whole region, the middle and the southern parts showed a downward trend in winter with the exception of the northern part. (2) There were cycles in precipitation of 29 years, 22 years and 5 to 10 years within the region, including the northern, central and southern parts in the past 55 years. The performance of the three cycles in the analyzed period was very stable, indicating a domain-wide characteristic. There was also a significant cycle of around 13 years in precipitation for the whole, northern and southern regions. Before mid 1975 and after 1995, there was also a cycle of about 13 years in precipitation for the central area. In the northern area before 1975 and after 1995, there was a cycle of 7-10 years in precipitation. The first grade main cycle in precipitation was 29 years, and the second grade main cycle was 22 years. (3) The average annual precipitation decreased in the Lancang River Basin from the south to the north. The precipitation in the southern basin was the heaviest, with an average precipitation of more than 1200 mm. The average annual precipitation in the middle area was 800-1100 mm, while the average annual precipitation in the northern part was usually less than 800 mm, mostly in the range of 400-800 mm; the annual and monthly precipitation gravity centers of the Lancang River Basin were located in the central region. The precipitation gravity center of November had the largest migration distance, which migrated southeast by a distance of 131.82 km. From the seasonal point of view, the precipitation gravity centers in spring, summer and autumn had migrated toward the southeast, while in winter, it migrated toward the northwest. The precipitation gravity centers in the rainy seasons were relatively aggregated, while in the dry seasons they were relatively dispersed.

  • Orginal Article
    CHEN Xingren,HAN Yang,WANG Jiaqi,LU Zhen
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    In remote sensing images, mixed pixel is a common phenomenon. The inversion of component composition and proportion of mixed pixels has been a key and difficult point in remote sensing research. Besides, the study of the mixed pixel using polarization vegetable index has not been conducted in China, yet. This study analyzed the hyperspectral characteristics of polarized reflections of vegetation-soil mixed pixels in different area ratios and discussed the hyperspectral characteristics under different conditions. We used the polarized reflection ratios to calculate the polarization vegetation indices of 12 types of 0 degree polarization and constructed the mathematical model of vegetation area ratio related to spectral characteristic parameters and vegetation index. The results show that vegetation area ratio and polarization angle have certain influence on hyper-spectrum of polarization of mixed pixels. The correlation between polarized reflection ratio of 865nm and the proportion of the vegetation is the best. When the polynomial fitting is applied, the coefficient of determination is up to 0.99. It implies this method is suitable for the inversion of the proportion of vegetation in pixels. With the proportion of vegetation there is a good linear correlation of first order differential of the polarization spectrum on "red edge",R- square = 0.974. Spectral characteristic parameters and vegetation index have good correlations with vegetation area ratio with the P-DVI and spectral absorption index (SAI) showing the best fitting goodness of vegetation area ratio (the coefficients of determination are 0.99 and 0.94, respectively). It implies this method is suitable for the inversion of vegetation area in vegetation-soil mixed pixels.

  • Orginal Article
    LI Jialin,FAN Zide,DENG Min
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    With the rapid development of economy, air pollution becomes more and more serious in China. The quality of the interpolation results of air pollutant concentration is very significant for analyzing the spatial-temporal distribution of the air pollutant, estimating the exposure risk of people in different areas, and making precaution. However, there are some problems when applying the existing spatial interpolation methods directly to the interpolation of air pollutant concentration. One of the most important problems is that the existing spatial interpolation methods cannot fully consider the influence of wind direction and speed on the air pollutant diffusion. We proposed a method (Direction-Velocity IDW) of spatial interpolation of air pollutant concentration taking wind direction and speed into account. First, we constructed a wind-field surface based on the discrete wind direction and speed data and the diffusion distance is computed in the wind-field. Then, we used Dijkstra algorithm to obtain the shortest path in wind-field. Finally, we interpolated the attribute value using IDW by the shortest path distance instead of the Euclidean distance. In the experiment, we verified the effectiveness of the method we proposed by comparing DVIDW and the commonly used spatial interpolation methods. We concluded that the proposed method (DVIDW) can produce interpolation results with higher precision.

  • Orginal Article
    BAI Lin,XU Yongming,HE Miao,LI Ning
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    Near-surface air temperature is an important symbol of urban thermal environment, which is also an important factor affecting and changing the climate of the city. The data of near-surface air temperature is often in absence because the number of meteorological stations is few. In order to obtain spatial continuous near surface air temperature data, this study takes Beijing city as the research area, using Landsat5/TM data to retrieve land surface temperature, normalized difference vegetation index, modified normalized difference water index, albedo and impervious surface cover. These are combined with the meteorological station temperature and DEM as the input parameters into random forest regression model to retrieve near surface air temperature. In this study, land surface temperature was retrieved by single-channel algorithm which was proposed by Jiménez-Muoz in 2003. The imperious surface cover was calculated by the linear spectral unmixing method and Vegetation-Impervious surface-Soil (VIS) model. The random forest is one of the most effective methods of classification and it runs by constructing multiple decision tree while training and outputting the class. This study uses the R language which is a free software environment for statistical computing and graphics to achieve random forest. The results show that the random forest method has good applicability in the near surface temperature retrieval. The mean absolute error (MAE) and root mean square error (RMSE) of the random forest method are 0.80 and 1.07, respectively. Compared with the ordinary regression model, the MAE and (RMSE) accuracy increased by 0.06 and 0.09. Using R language to analyze the importance of variables, land surface temperature has the greatest influence on the results. The increase in Mean Square Error of land surface temperature is 14% and the increase in node purity of land surface temperature is 241.36%.

  • Orginal Article
    LI Qiang,SU Fenzhen,WANG Wenyue
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    As one of the major equipment for offshore oil and gas exploration, the number and spatial distribution of oil and gas platform would reflect the situation of exploitation in a region. Nowadays, it is difficult to acquire data of oil and gas platform because the traditional field observation method is expensive and time-consuming. With the development of remote sensing technology, remote sensing images as an important data source are applied in the extraction of marine targets effectively. However, traditional optical images are easily influenced by cloud and the radar data are too expensive, which make oil and gas platform detection difficult. During the operation process, the oil and gas platform need lamplight, and gas combustion also generate strong light. Thus, the oil and gas platform extraction can be done by detecting light. VIIRS data has a strong ability of detecting light at night and it can be used for the data extraction of oil and gas platform. Considering the feature of VIIRS data, this paper proposed a convolution operation threshold algorithm to extract offshore oil and gas platform and chose Pearl River Mouth basin as a study area for experiment. Firstly, VIIRS data of different time phase were operated to enhance the pixel value and weaken the background pixels so that the suspected target and background can be distinguished. Then, we took the 0 value as the dividing point to extract suspected targets. Finally, we extracted oil and gas platform through the neighborhood analysis making use of the relatively static characteristic of oil and gas platform. The results showed that the accuracy of extracting oil and gas platforms was about 85.4% and the method could effectively reduce the impacts of empirical threshold. At last, this study analyzed the shortage and causes of using VIIRS data to extract oil and gas platforms.

  • Orginal Article
    SHI Tingting,XU Hanqiu,WANG Shuai,FANG Canying,LIN Zhongli,WANG Meiya,TANG Fei
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    As the starting point of China’s ancient Maritime Silk Road, Quanzhou Port has become a new starting point of “One Belt and One Road” in the 21st century. Quanzhou Port has a winding coastline running northward from Weitou Bay to Meizhou Bay. This paper studied the coastline dynamics of Quanzhou Port during 1990 to 2014. A total of six scenes of Landsat TM/OLI (1990, 1994, 2000, 1994, 2009 and 2014) were utilized for this study. The modified normalized difference water index (MNDWI) was used to enhance water information of the remote sensing images. The enhanced water images were then used to extract the coastlines from the images by setting a threshold. The extracted coastlines were later vectorized and integrated in ArcGIS to analyze their dynamics. The study of the coastline change in Quanhou Port was based on five aspects: coastline length, length changing rate, coastline fractal dimension, changed sea areas, and the use type of changed sea areas. Results showed that the coastline lengths of Quanzhou Port increased continually in the 24-study years, which was 418.19 km in 1990 and 455.97 km in 2014, an increase of 37.78 km during the period. The coastline shape of Quanzhou Port was generally stable. Nevertheless, intensive coastline changes do occur in some areas due to tide-land reclamation. This has locally led to the seaward advance of the shoreline and the simplification of the shoreline from winding to straight. The related sea area change due to the coastline modification was 68.02 km2, of which built-up land and port land occupied the largest proportion. However, the reclamation area is not highly used and more than half of the reclamation area has not yet been developed. This remote sensing based study has detected four large reclamation areas, which are located in Nanpu of western Meizhou Bay (7.33 km2 in area), Dongqiao of southwestern Meizhou Bay (34.85 km2 in area), western entrance of Quanzhou Bay (4.88 km2 in area), and eastern Jinjiang coast (5.17 km2 in area). Among them, only eastern Jinjiang coast is an enclosed tideland reclaimed for agriculture and fishery, whereas the other three are mainly the lands reclaimed for built-up land and port land. For example, the landfill in the western entrance of Quanzhou Bay is now the seat of Quanzhou Government. On the whole, the new town construction, nearshore industrial and agricultural fishery development led to the coastline changes of Quanzhou Port.

  • Orginal Article
    YANG Lijuan,XU Hanqiu,TANG Fei,FU Wei,WANG Meiya,SUN Feng-qin
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    As the natural intersection belt of land and ocean areas, coastline zone plays a key role in promoting regional economic development. Therefore, the evaluation of coastline utilization is of great importance for coastline resource management. This paper firstly created an index system for the evaluation of coastline resource. Then, for optimal allocation of coastline resource, an evaluation index system for intensive coastline utilization based on remote sensing data as well as socio-economic data was proposed. Through interpreting two SPOT remote sensing images and field survey, all the index values were obtained. Then, two multi-factor evaluation models, coastline resource evaluation model and intensive coastline utilization evaluation model, were established based on the analytical hierarchy process (AHP). Tianjin center harbor, China, was taken to validate the feasibility of the models. The interpretation and analysis of remote sensing data of the harbor between 2006 and 2015 indicated that: (1) Tianjin center harbor covers an area of 2639.16 hm2, of which 1451.46 hm2 is the land reclamation area, accounting for 55% of the total area; (2) the length of coastline surrounding the harbor was 2.46 km in 2006, but increased to 10.84 km in 2015 due to the land reclamation; and (3) the utilized land reclamation area is 527.76 hm2, accounting for a proportion of 36.36%.The application of the aforementioned evaluation models to Tianjin Center Harbor on the basis of the information extracted from the remote sensing images and in situ investigation data showed that (1) the coastline-occupation level of the harbor in 2006 can be classified as a third grade with a score of 3.004; (2)the intensive coastline utilization of the harbor reached a comprehensive value of 0.3271, of which the factor of coastline utilization status scored a relatively high value of 0.1611, accounting for 49.25%, while the factor of output-to-input ratio hit a lowest of 0.0565. The analysis results suggested that the two proposed models could work effectively in the evaluation of the coastline resource and intensive coastline utilization for the Tianjin center harbor.

  • Orginal Article
    LI Huawei,WAN Qing
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    Mountain torrents are one of the most dangerous weather-related natural disasters in the world. As the direct driving force and inducing factor of mountain torrent disasters, rainfall can be used as an indispensable index in the hazard analysis of flash flood. In different study areas, the rainfall with different return periods and durations may affect mountain torrent disasters differently and would be therefore selected disparately for the hazard analysis. However, there is little quantitative research on the principles of rainfall index selection in the previous literatures. Based on the small watershed map (1:50,000 scale), the rainstorm atlas and the spatial distribution of mountain torrent disasters, this paper focused on the small watersheds in Wuyuan County in Jangxi Province and used GIS (Geographic Information System), Correlational Analysis, Spatial Cluster and Geographical Detector to obtain the rainfall indices which had great impact on the mountain torrent disasters of the small watersheds. The selected rainfall indices will take part in the hazard analysis of mountain torrent disasters in the study area. The conclusion is drawn as follows: (1) Seven uncorrelated rainfall indices have been obtained from the original 24 rainfall indices by the correlational analysis method. This means that in order to avoid the information overlap, we need to analyze the correlation between pairs of the rainfall indices before the hazard analysis of mountain torrent disaster. (2) By using the Optimized Hot Spot Analysis tool based on Local Getis-Ord Gi* Algorithm to get the estimated hazard values of the mountain torrent disasters of small watersheds, the calculation results are in line with the spatial distribution of mountain torrent disasters in this study area. (3)It’s better to introduce geographical detector to quantify the relevance between rainfall indices and mountain torrent disasters of small watersheds. Through the comprehensive analysis, the final rainfall factors, which cause mountain torrent disasters of the small watersheds with a great probability, will be derived and will participate in the hazard analysis of flash flood. The finally selected rainfall factors of small watersheds in Wuyuan County are the maximum rainfall with 100-year return period and 6-hour duration and the maximum rainfall with 100-year return period and 24-hour duration. The technical method in this paper possesses an important reference value and guidance to the quantitative selection of rainfall indices in the hazard analysis of flash flood of small watersheds.