Use of targets to track 3D displacements in highly vegetated areas affected by landslides

Monitoring landslides with terrestrial laser scanning (TLS) is currently a well-known technique. One problem often encountered is the vegetation that produces shadow areas on the scans. Indeed, the points behind a given obstacle are hidden and thus occluded on the point cloud. Thereby, locations monitored with terrestrial laser scanner are mostly rock instabilities and few vegetated landslides, being difficult or even impossible to survey vegetated slopes using this method with its classical non-full wave form. The Peney landslide (Geneva, Switzerland) is partially vegetated by bushes and trees, and in order to monitor its displacements during the drawdown of the Verbois reservoir located at its base, an alternative solution has been found. We combined LiDAR technique with 14 targets made of polystyrene placed at different locations inside and outside the landslide area. The obtained displacements were compared with classical measurement methods (total station and extensometer), showing good resemblance of results, indicating that the use of targets in highly vegetated areas could be an efficient alternative for mass movements monitoring.     

我国海岛管理信息化建设问题与对策研究

海岛管理信息化建设是《中华人民共和国海岛保护法》赋予海洋行政主管部门的主要职责之一。文章分析研究我国海岛管理信息化建设的背景和现状,指出面临的一系列问题,从总体规划、数据应用、完善机制、统筹管理、加强配套、保障安全等方面提出相应对策,为我国海岛管理信息化建设提供参考。     

南海某导管架海洋平台倒塌分析

针对在役老龄导管架平台进行倒塌计算分析,确定极限承载力进而评估老龄导管架的安全裕度。采用非线性有限元方法,考虑平台的波流载荷及桩-土的非线性相互作用,利用SACS软件建立导管架整体三维有限元计算分析模型,并用逐步加载的方式,对南海某导管架平台进行了全过程非线性倒塌分析。计算分析表明,该导管架平台极限强度很高,具有较大的安全裕度;导管架倒塌过程呈逐步破坏形式,先是撑杆屈服,造成局部结构破坏,然后是钢桩发生屈服,降低结构承载力,最后节点逐步失效,造成结构倒塌。揭示了导管架平台结构失效倒塌的机理,给出了倒塌分析的可行方法和步骤。     

五硼酸铷溶液的物化性质及物种分布

碳酸铷、硼酸化学计量比混合,蒸发溶液,直至五硼酸铷RbB5O8·4H2O晶体析出。经粉末X射线衍射（XRD）、拉曼光谱（Raman spectroscopy）、热重/微商热重/差示扫描量热（TG/DTG/DSC）、原子吸收光谱等实验方法,确定其化学组成及结构。298.15、333.15K时测量溶液的物理化学性质（密度、电导、pH）,并与经验方程进行拟合,研究五硼酸铷溶液的物化性质随浓度、温度的变化规律。根据文献报道的平衡常数,实验测量的pH数据,采用牛顿迭代法进一步研究五硼酸铷溶液中主要存在的硼酸根离子对类型、含量以及物种的形成。     

Spatio-temporal evolution of urban innovation structure based on zip code geodatabase: An empirical study from Shanghai and Beijing

In today’s world, the innovation of science and technology has become the key support for improving comprehensive national strength and changing the mode of social production and lifestyle. The country that possesses world-class scientific and technological innovation cities maximizes the attraction of global innovation factors and wins a strategic initiative in international competition. Based on the urban zip code geodatabase, an evaluation system of urban innovation with the perspective of innovation outputs, and the spatial evolutionary mode, concerning the structure of innovation space of Shanghai and Beijing from 1991 to 2014, was developed. The results of the research indicated that the zip code geodatabase provided a new perspective for studying the evolving spatial structure of urban innovation. The resulting evaluation of the spatial structure of urban innovation using the urban zip code geodatabase established by connecting random edge points, was relatively effective. The study illustrates the value of this methodology. During the study period, the spatial structure of innovation of Shanghai and Beijing demonstrated many common features: with the increase in urban space units participating in innovation year by year, the overall gap of regional innovation outputs has narrowed, and the trend towards spatial agglomeration has strengthened. The evolving spatial structure of innovation of Shanghai and Beijing demonstrated differences between the common features during the 25 years as well: in the trend towards the suburbanization of innovation resources, the spatial structure of innovation of Shanghai evolved from a single-core to a multi-core structure. A radiation effect related to traffic arteries as spatial diffusion corridors was prominent. Accordingly, a spatial correlation effect of its innovation outputs also indicated a hollowness in the city center; the spatial structure of innovation of Beijing had a single-core oriented structure all the way. Together with the tendency for innovation resources to be agglomerated in the city center, the spatial correlation effect of innovation outputs reflected the characteristics of the evolutionary feature where “rural area encircles cities”. The innovation spatial structure of Shanghai and Beijing have intrinsic consistency with the spatial structure of their respective regions (Yangtze River Delta urban agglomeration and Beijing-Tianjin-Hebei metropolitan region), which suggested that the principle of proportional and disproportional distribution of a city-scale pattern of technological and innovational activities is closely related to its regional innovation pattern.     

Factors driving riverbed scouring and sedimentation in the Bayangaole to Toudaoguai reaches of the Upper Yellow River

The Inner Mongolia reaches of the Yellow River face problems of severe sedimentation caused by a variety of complex factors. The sedimentation process in those reaches has been characterized using the sediment balance method, and the key factors affecting the process have been analyzed using the correlation analysis method. The results show that during the period 1952–2012 the Bayangaole (Bayan Gol) to Toudaoguai reaches in Inner Mongolia have undergone successive processes of accumulative sedimentation, then relative balance, and then accumulative sedimentation once again. The total annual sedimentation is 12.0341×10⁸ m³, of which accumulations from July to October account for 95.1% and the reaches from Sanhuhekou to Toudaoguai account for 98.5%. The main factor affecting scouring and sedimentation of the Bayangaole to Sanhuhekou reaches is the combined water and sediment condition. The critical conditions for equilibrium are an incoming sediment coefficient < 0.007 kg·s·m^–6 and a flow discharge > 700 m³·s^–1. The main factor affecting scouring and sedimentation of the Sanhuhekou to Toudaoguai reaches is the incoming sediment from the tributaries on the south bank and the combined water and sediment condition of the main stream. The critical conditions of the main stream for maintaining equilibrium status are a flow discharge of the main stream exceeding 800 m³·s^–1 and a comprehensive incoming sediment coefficient < 0.005 kg·s·m^–6. The incoming sediment from the tributaries has little impact on the main stream when the annual sediment load is less than 0.1×10⁸ t. The incoming sediment coefficient of the main stream and the incoming sediment from the tributaries both play vital roles in the riverbed evolution of the Inner Mongolia reaches, but the latter contributes the most.     

Spatiotemporal distribution and historical evolution of polders in the Dongting Lake area,China

Dongting Lake is the largest lake in the middle reaches of the Yangtze River in China. For centuries, people inhabiting the Dongting Lake area have been reclaiming land and constructing dams for flood resistance, agricultural production, and rural settlement, forming geographical entities known as polders. In this study, the regional spatial distributions of polders in the Dongting Lake area in 1949, 1998, and 2013 were obtained using historical maps and modern remotely sensed data, revealing changes since the establishment of the People’s Republic of China. Nanxian County was then selected to demonstrate polder changes at the county level, because it has undergone the most dramatic changes in the area. Different polder change models for the Datonghu, Yule, and Renhe polders were analyzed for eight periods: 1644 (the early Qing Dynasty), 1911 (the late Qing Dynasty), 1930 (the Republic of China), 1949 (the People’s Republic of China), 1963, 1970, 1998, and 2013. Three resulting polder evolution models are: 1) reclaiming polders from lakes, 2) integrating polders by stream merging, and 3) abandoning polders for flood release. The polder evolution models demonstrate the wisdom of local people in using land resources according to the specific regional conditions. Throughout their long-term historical evolution, the spatial distribution of polders in the Dongting Lake area tended to be homogeneous, and the degree of human disturbance tended to be stable. However, a shift occurred, from pure polder area growth or removal to more comprehensive management and protection of the regional environment.     

Progress in China’s sustainable development research: Contribution of Chinese geographers

Sustainable development has always been a hotspot in Chinese geographical research. Herein, we conduct a systematic statistical analysis of the contribution of Chinese geographers to sustainable development research using bibliometric methods. Based on the review of a vast amount of literature, we identify the main research teams, research funding sources, journals, and key research fields. The findings are as follows: (1) the resources and environmental institutes of the Chinese Academy of Sciences have a significant influence on sustainable development research; (2) China’s central government foundations (the National Natural Science Foundation of China and National Social Sciences Fund) are the main research funding sources; (3) most of the highly cited articles are published in journals sponsored by the Geographical Society of China; and (4) sustainable development theory and its research areas are being constantly enriched and perfected. Based on the statistics of keywords, the theory, research methods, research regional scales, and key research areas are summarized and expounded.     

崇明岛东滩湿地芦苇光合作用对土壤水盐因子的响应

2015年3~10月,在崇明岛东滩湿地设置7块采样地,以不同水盐条件下生长的芦苇(Phragmites australis)为材料,应用便携式光合系统分析仪(Li-6400),对芦苇的光响应特征进行实地测定,探讨芦苇光合过程对干旱和盐胁迫的响应机理。结果表明:1各月采样日的水位与土壤电导率显著负相关(n=420,p0.01),适当增加土壤水位,有利于降低土壤电导率,从而缓解植物盐胁迫伤害;28月21日的芦苇叶片净光合速率、蒸腾速率和气孔导度与水位显著正相关(n=42,p0.01),而与土壤电导率显著负相关(n=42,p0.01);胞间CO2浓度与水位和土壤电导率不相关。当水位高于-50 cm,净光合速率随着水位下降而降低,非气孔因素可能是净光合速率下降的主要原因;当水位低于-50 cm时,土壤电导率高于10 m S/cm,叶片蒸腾速率快速降低,水分利用效率不断提高,芦苇叶片以较低的净光合速率来适应干旱胁迫和盐胁迫;芦苇叶片通过降低最大净光合速率、暗呼吸速率、光补偿点和光饱和点等光合生理特征来适应干旱胁迫和盐胁迫;芦苇叶片净光合速率和最大净光合速率对土壤水盐因子具有高度相关性,可以作为土壤水盐胁迫程度的反应指标。因此,在芦苇快速生长阶段,合理调控水位,对芦苇光合作用具有重要意义。