Risk assessment of secondary geological disasters induced by the Yushu earthquake     

Quanfu Niu  Weiming Cheng  Yong Liu  Yaowen Xie  Hengxing Lan  Yanrong Cao 《山地科学学报》2012,9(2):232-242

The Yushu Ms 7.1 earthquake occurred on April 14,2010 in Qinghai Province,China.It induced a mass of secondary geological disasters,such as collapses,landslides,and debris flows.Risk assessment maps are important for geological disaster prevention and mitigation,and also can serve as a guide for post-earthquake reconstruction.Firstly,a hazard assessment index system of secondary geological disasters in the earthquake region was built in this paper,which was based on detailed analysis of environmental and triggering factors closely related to geological disasters in the study area.GIS technology was utilized to extract and analyze the assessment index.Hazard assessment maps of secondary geological disasters were obtained by spatial modeling and overlaying analysis.Secondly,an analysis of the vulnerability of hazard bearing bodies in the area was conducted,important information,such as, population density,percentage of arable land, industrial and agricultural outputs per unit area were regarded as assessment indices to evaluate socioeconomic vulnerability.Thirdly,the risk level of secondary geological disasters of the area was obtained by the formula:Risk=Hazard×Vulnerability. Risk assessment maps were categorized into four levels,including"low","moderate","high"and"very high".These results show that some urban areas are at very high risk,including Jiegu,Chengwen,Xiaxiula and Sahuteng towns.This research can provide some references and suggestions to improve decisionmaking support for emergency relief and post- earthquake reconstruction in the study area.  相似文献   

Topographic correction-based retrieval of leaf area index in mountain areas   总被引：1，自引：0，他引：1  

Wei Chen  Chunxiang Cao 《山地科学学报》2012,9(2):166-174

Leaf Area Index(LAI)is a key parameter in vegetation analysis and management,especially for mountain areas.The accurate retrieval of LAI based on remote sensing data is very necessary.In a study at the Dayekou forest center in Heihe watershed of Gansu Province,we determined the LAI based on topographic corrections of a SPOT-5.The large variation in the mountain terrain required preprocessing of the SPOT-5 image,except when orthorectification, radiation calibration and atmospheric correction were used.These required acquisition of surface reflectance and several vegetation indexes and linkage to field measured LAI values.Statistical regression models were used to link LAI and vegetation indexes.The quadratic polynomial model between LAI and SAVI (L=0.35)was determined as the optimal model considering the R and R2 value.A second group of LAI data were reserved to validate the retrieval result.The model was applied to create a distribution map of LAI in the area.Comparison with an uncorrected SPOT-5 image showed that topographic correction is necessary for determination of LAI in mountain areas.  相似文献   

泰安市煤炭资源开采老区开展资源挖潜的途径和对策          下载免费PDF全文

李文孟  李庆广  滕祥雷  聂廷才  苗元欣  李彬 《山东国土资源》2012,28(10):60-63

介绍了泰安市煤炭资源的赋存特征和开发现状,分析了煤炭开发老矿区面临的形势,总结了老矿区开展煤炭资源挖潜,延长矿井服务年限的途径和做法,提出了进一步搞好老矿区挖潜的对策和措施,具有重要的现实作用和长远意义。  相似文献   

洪湖湿地演替的影响因素与生态恢复对策   总被引：2，自引：0，他引：2  

刘章勇  何浩 《湿地科学与管理》2008,4(2):37-41

在自然因素（地质构造发育、气候、水文等）及人为因素（农业政策、人口压力、水利工程、环境污染等）对洪湖湿地共同作用下,洪湖湿地的自然演替发生了改变。自然因素影响下洪湖湿地生态系统有向逆演化方向演替的趋势,而不合理的人为影响因素加速了正演化过程。在系统地分析两种影响因素对洪湖湿地演替影响的基础匕,针对人为影响因素产生的不良影响,初步提出了洪湖湿地生态恢复的一些对策,包括加强立法及管理、加强污染控制、扩大湖泊面积、加强水利工程和湿地自然保护区的建设和管理、开展湿地保护教育,提高公众保护意识以及加强监测等。通过湖北省各级政府及部门的努力,有望恢复洪湖湿地良好的生态环境。  相似文献   

Probabilistic landslide risk analysis considering direct costs in the area north of Lisbon (Portugal)   总被引：7，自引：1，他引：6  

J.L. Zêzere  R.A.C. Garcia  S.C. Oliveira  E. Reis 《Geomorphology》2008,94(3-4):467

The purpose of the present study is the analysis of landslide risk for roads and buildings in a small test site (20 km²) in the area north of Lisbon (Portugal). For this purpose, an evaluation is performed integrating into a GIS information obtained from multiple sources: (i) landslide hazard; (ii) elements at risk; and (iii) vulnerability. Landslide hazard is assessed on a probabilistic basis for three different types of slope movement (shallow translational slides, translational slides and rotational slides), based on some assumptions such as: (i) the likelihood of future landslide occurrence can be measured through statistical relationships between past landslide distribution and specified spatial data sets considered as landslide predisposing factors; and (ii) the rainfall combination (amount–duration) responsible for past slope instability within the test site will produce the same effects (i.e. same type of landslides and similar total affected area), each time they occur in the future. When the return period of rainfall triggering events is known, different scenarios can be modelled, each one ascribed to a specific return period. Therefore, landslide hazard is quantitatively assessed on a raster basis, and is expressed as the probability for each pixel (25 m²) to be affected by a future landslide, considering a rainfall triggering scenario with a specific return period. Elements at risk within the test site include 2561 buildings and roads amounting to 169 km. Values attributed to elements at risk were defined considering reconstruction costs, following the guidelines of the Portuguese Insurance Institute. Vulnerability is considered as the degree of loss to a given element resulting from the occurrence of a landslide of a given magnitude. Vulnerability depends not only on structural properties of exposed elements, but also on the type of process, and its magnitude; i.e., vulnerability cannot be defined in absolute terms, but only with respect to a specific process (e.g. vulnerability to shallow translational slides). Therefore, vulnerability was classified for the three landslide groups considered on hazard assessment, taking into account: (i) landslide magnitude (mean depth, volume, velocity); (ii) damage levels produced by past landslide events in the study area; and (iii) literature. Finally, a landslide risk analysis considering direct costs was made in an automatic way crossing the following three layers: (i) Probabilistic hazard map for a landslide type Z, considering a particular rainfall triggering scenario whose return period is known; (ii) Vulnerability map (values from 0 to 1) of the exposed elements to landslide type Z; and (iii) Value map of the exposed elements, considering reconstruction costs.  相似文献   

Nature rehabilitation by floodplain excavation: The hydraulic effect of 16 years of sedimentation and vegetation succession along the Waal River, NL   总被引：1，自引：0，他引：1  

G.W. Geerling  E. Kater  C. van den Brink  M.J. Baptist  A.M.J. Ragas  A.J.M. Smits   《Geomorphology》2008,99(1-4):317-328

The “Ewijkse Plaat” is a floodplain along the Waal River, NL. In 1988, the floodplain was excavated as part of a program for enlargement of the discharge capacity and was assigned as a nature rehabilitation area. This paper describes the combined geomorphological and vegetation evolution of the floodplain until 16 years after the initial excavation using elevation data and data on vegetation structure derived from detailed aerial stereographic imagery. The impact of these processes on flow velocity and water surface elevation was evaluated by using a hydraulic model. Within 16 years, the excavated amount of sediment was redeposited in the area. The dominant geomorphological process after excavation was vertical accretion of the floodplain which resulted in the formation of natural levees. The amount of sedimentation was correlated to the across-floodplain flow (R² = 0.89). In the research period, 41% of the sedimentation took place during two single major flood events. The creation of pioneer stages by excavation promoted softwood forest establishment, which influenced the sedimentation pattern significantly. The landscape evolved toward structure-rich vegetation. Nine years after excavation the initial hydraulic gain was lost by the combined effect of sedimentation and vegetation succession. Implications for river and nature management are discussed.  相似文献   

北黄海前新生代残留盆地勘探潜力分析   总被引：3，自引：3，他引：0       下载免费PDF全文

陈洁 《地球物理学进展》2005,20(3):757-760

通过对北黄海及其邻区地质构造、石油地质条件的分析,认为北黄海盆地沉积地层基底为元古界,经历了五期构造演化,形成4套区域角度不整合界面,具有多套烃源岩及生储盖组合,具有良好的勘探前景.  相似文献   

Ocean temperature climate off North‐East New Zealand     

Philip J. H. Sutton  Dean Roemmich 《新西兰海洋与淡水研究杂志》2013,47(3):553-565

The ocean temperature field off the north‐east coast of New Zealand is studied to quantify the annual cycle and reveal the intra‐ and inter‐annual variability. The data used are repeat expendable bathythermograph (XBT) sections between Auckland and either Suva or Honolulu which have been collected quarterly since 1986. These sections give temperature measurements between the surface and 800 m and Auckland and 30°S from 1986 to August 1999. The mean and annual cycle are compared with those from the NOAA World Ocean Atlas (WOA98). The results are similar; however WOA98 lacks the horizontal resolution to fully discern the East Auckland Current and North Cape Eddy, while the XBT analysis lacks the temporal resolution to discern higher frequency intra‐annual signals. The temperature variability in the mixed layer is dominated by the annual cycle, which accounts for 80–90% of the variance. The amplitude of the annual cycle diminishes rapidly with depth, from 2.8°C at the surface, to c. 0.1°C at 180 m. The phase of the annual cycle is retarded with depth, with peak temperatures occurring in February at the surface and in June/July at 180 m. Removing the annual cycle from the time series reveals the more subtle inter‐ and intra‐annual variability. This variability is of the order of 1°C in the upper 50 m, decreasing to 0.3°C at 400–500 m. The surface layer was cold between 1991 and 1994 (c. 0.7°C cooler than average), and 0.7°C warmer than average in 1999. The deeper ocean shows a different signal, being up to 0.3°C cooler in 1990–92, 0.3°C warmer in 1998, and c. 0.2°C warmer than average in 1999. The inter‐annual mixed layer variability is highly correlated with the Southern Oscillation Index and also with inter‐annual terrestrial air temperature and wind measurements from northern New Zealand. In contrast, at higher intra‐annual frequencies, the mixed layer variability is not correlated with air and wind measurements. At these higher frequencies, the air temperature is better correlated with the sea surface temperature (SST) than with the bulk mixed layer temperature.  相似文献   

Planktonic stages of the teleost family carapidae in eastern New Zealand waters     

D. A. Robertson 《新西兰海洋与淡水研究杂志》2013,47(3):403-409

The occurrence of planktonic carapid eggs in Otago waters, of young stages of Echiodon rendahli off Castlepoint, and the possible presence of unrecorded members of the family Carapidae in New Zealand waters is discussed. Young E. rendahli possess a long spine which originates dorsally to a distinctive suspended gut.  相似文献   

Airborne Laser Sensing of Scottish Coastal Waters     

Grigorii Kokhanenko  Geoff Ludbrook  Ivan Penner  Vitalii Shamanaev 《Marine Geodesy》2013,36(4):195-207

An Nd:YAG-based airborne lidar system has been used to measure the optical properties of littoral waters off the northwest Scottish coast. The small-scale structure of subsurface scattering layers was also investigated. Methods of solving the Lidar Sensing Equation in the single scattering approximation are described and the values of the derived extinction indices presented. The extinction index averaged over a series of five flights to the northeast of the Gulf Stream was k = 0.224 m -1 with a standard deviation of 0.212 m -1 . Further, it was demonstrated that, in coastal waters, optical inhomogeneities with dimensions between 50 m and 200 km obey the power law Sp k ~ k -P with the parameter P close to two. In turbid or transparent areas, the water extinction index can change by several tenths of a percent with respect to the surrounding water mass. This suggests that the observed nonmonotonic behavior of the power spectra of the water extinction index fluctuations is caused by the outer scale of turbulence, in particular, by the bottom depth at the measurement site.  相似文献