Monitoring and Recognition of Debris Flow Infrasonic Signals

Low frequency infrasonic waves are emitted during the formation and movement of debris flows, which are detectable in a radius of several kilometers, thereby to serve as the precondition for their remote monitoring.However, false message often arises from the simple mechanics of alarms under the ambient noise interference.To improve the accuracy of infrasound monitoring for early-warning against debris flows, it is necessary to analyze the monitor information to identify in them the infrasonic signals characteristic of debris flows.Therefore, a large amount of debris flow infrasound and ambient noises have been collected from different sources for analysis to sum up their frequency spectra, sound pressures, waveforms, time duration and other correlated characteristics so as to specify the key characteristic parameters for different sound sources in completing the development of the recognition system of debris flow infrasonic signals for identifying their possible existence in the monitor signals.The recognition performance of the system has been verified by simulating tests and long-term in-situ monitoring of debris flows in Jiangjia Gully,Dongchuan, China to be of high accuracy and applicability.The recognition system can provide the local government and residents with accurate precautionary information about debris flows in preparation for disaster mitigation and minimizing the loss of life and property.     

Debris-flow of Zelongnong Ravine in Tibet

Zelongnong Ravine, a branch ravine of Brahmaputra, is an old large glacier debris-flow ravine. Debris-flows with medium and/or small scales occur almost every year; multiple super debris-flows have also broken out in history, and have caused destructive disaster to local residents at the mouth of ravine and blocked Brahmaputra. The huge altitude difference and the steep slope of the Zelongnong Ravine provide predominant energy conditions for the debris-flow. The drainage basin is located in the fast uplifted area, where the complicated geologic structure, the cracked rock, and the frequent earthquake make the rocks experience strong weathering, thus plenty of granular materials are available for the formation of debris-flows. Although this region is located in the rain shadow area, the precipitation is concentrated and most is with high intensity. Also, the strong glacier activity provides water source for debris-flow. According to literature reviews, most debris-flows in the ravine are induced by rainstorms, and their scales are relatively small. However, when the melted water is overlaid, the large scale debris-flows may occur. Parametric calculation such as the flow velocity and the runoff is conducted according to the monitoring data. The result shows that large debris-flows can be aroused when the rainstorm and the melted water are combined well, but the possibility of blocking off Brahmaputra is rare. The occurrence of the super debris-flows is closely related to the intense glacier activity (e.g., glacier surge). They often result in destructive disasters and are hard to be prevented and cured by engineering measures, due to the oversized scales. The hazard mitigation measures such as monitoring and prediction are proposed.     

Outlining a stepwise,multi-parameter debris flow monitoring and warning system: an example of application in Aizi Valley,China

In recent years, the increasing frequency of debris flow demands enhanced effectiveness and efficiency of warning systems. Effective warning systems are essential not only from an economic point of view but are also considered as a frontline approach to alleviate hazards. Currently, the key issues are the imbalance between the limited lifespan of equipment, the relatively long period between the recurrences of such hazards, and the wide range of critical rainfall that trigger these disasters. This paper attempts to provide a stepwise multi-parameter debris flow warning system after taking into account the shortcomings observed in other warning systems. The whole system is divided into five stages. Different warning levels can be issued based on the critical rainfall thresholds. Monitoring starts when early warning is issued and it continues with debris flow near warning, triggering warning, movement warning and hazard warning stages. For early warning, historical archives of earthquake and drought are used to choose a debris flow-susceptible site for further monitoring. Secondly, weather forecasts provide an alert of possible near warning. Hazardous precipitation, model calculation and debris flow initiation tests, pore pressure sensors and water content sensors are combined to check the critical rainfall and to publically announce a triggering warning. In the final two stages, equipment such as rainfall gauges, flow stage sensors, vibration sensors, low sound sensors and infrasound meters are used to assess movement processes and issue hazard warnings. In addition to these warnings, community-based knowledge and information is also obtained and discussed in detail. The proposed stepwise, multi-parameter debris flow monitoring and warning system has been applied in Aizi valley China which continuously monitors the debris flow activities.     

Development of community-based landslide early warning system in the earthquake-affected areas of Nepal Himalaya

In the central Nepal Himalaya, landslides form the major natural hazards annually resulting in many casualties and damage. Structural as well as non-structural measures are in place to minimize the risk of landslide hazard. To reduce the landslide risk,a Landslide Early Warning System(LEWS) as a nonstructural measure has been piloted at Sundrawati village(Kalinchowk rural municipality, Dolakha district) to identify its effectiveness. Intensive discussions with stakeholders, aided by landslide susceptibility map, resulted in a better understanding of surface dynamics and the relationship between rainfall and surface movement. This led to the development of a LEWS comprised of extensometers,soil moisture sensors, rain gauge stations, and solar panels as an energy source that blows siren receiving signals via a micro-controller and interfacing circuit.The data generated through the system is transmitted via a Global System for Mobile Communications(GSM) network to responsible organizations in realtime to circulate the warning to local residents. This LEWS is user-friendly and can be easily operated by a community. The successful pilot early warning system has saved 495 people from 117 households in August 2018.However,landslide monitoring and dissemination of warning information remains a complex process where technical and communications skill should work closely together.     

Debris flows introduced in landslide deposits under rainfall conditions: The case of Wenjiagou gully

Debris flows often occur in landslide deposits during heavy rainstorms. Debris flows are initiated by surface water runoff and unsaturated seepage under rainfall conditions. A physical model based on an infinitely long, uniform and void-rich sediment layer was applied to analyze the triggering of debris-flow introduced in landslide deposits. To determine the initiation condition for rainfall-induced debris flows, we conducted a surface water runoff and saturated-unsaturated seepage numerical program to model rainfall infiltration and runoff on a slope. This program was combined with physical modeling and stability analysis to make certain the initiation condition for rainfall-introduced debris flows. Taking the landslide deposits at Wenjiagou gully as an example, the initiation conditions for debris flow were computed. The results show that increase height of surface-water runoff and the decrease of saturated sediment shear strength of are the main reasons for triggering debris-flows under heavy rainfall conditions. The debris-flow triggering is affected by the depth of surface-water runoff, the slope saturation and shear strength of the sediment.     

Distributed fiber optic monitoring and stability analysis of a model slope under surcharge loading

In the discipline of geotechnical engineering, fiber optic sensor based distributed monitoring has played an increasingly important role over the past few decades. Compared with conventional sensors, fiber optic sensors have a variety of exclusive advantages, such as smaller size, higher precision, and better corrosion resistance. These innovative monitoring technologies have been successfully applied for performance monitoring of geo-structures and early warning of potential geo- hazards around the world. In order to investigate their ability to monitor slope stability problems, a medium-sized model of soil nailed slope has been constructed in laboratory. The fully distributed Brillouin optical time-domain analysis （BOTDA） sensing technology was employed to measure the horizontal strain distributions inside the model slope. During model construction, a specially designed strain sensing fiber was buried in the soil mass. Afterward, the surcharge loading was applied on the slope crest in stages using hydraulic jacks and a reaction frame. During testing, an NBX-6o5o BOTDA sensing interrogator was used to collect the fiber optic sensing data. The test results have been analyzed in detail, which shows that the fiber optic sensors can capture the progressive deformation and failure pattern of the model slope. The limit equilibrium analyses were also conducted to obtain the factors ofsafety of the slope under different surface loadings. It is found that the characteristic maximum strains can reflect the stability of the model slope and an empirical relationship was obtained, This study verified the effectiveness of the distributed BOTDA sensing technology in performance monitoring of slope.     

Effectiveness analysis of the prediction of regional debris flow susceptibility in post-earthquake and drought site

Debris-flow disasters occurred frequently after the Mw 8.0 Wenchuan earthquake on 12 May 2008 in Sichuan Province, China. Based on historical accounts of debris-flow disaster events, it found that debris flow occurrence is closely related to the impact of earthquakes and droughts, because earthquakedrought activities can increase the loose solid materials, which can transform into debris flows under the effect of rainstorms. Based on the analysis of historical earthquake activity(frequency, magnitude and location), drought indexes and the trend of climate change(amount of rainfall), a prediction method was established, and the regional debris flow susceptibility was predicted. Furthermore, in a debris flow-susceptible site, effective warning and monitoring are essential not only from an economicpoint of view but are also considered as a frontline approach to alleviate hazards. The advantages of the prediction and early monitoring include(1) the acquired results being sent to the central government for policy making;(2) lives and property in mountainous areas can be protected, such as the 570 residents in the Aizi valley, who evacuated successfully before debris flows in 2012;(3) guiding the government to identify the areas of disasters and the preparation for disaster prevention and mitigation, such as predicting disasters in high-risk areas in the period 2012-2017, helping the government to recognize the development trend of disasters;(4) the quantitative prediction of regional debris-flow susceptibility, such as after the Wenchuan earthquake, can promote scientific and sustainable development and socioeconomic planning in earthquake-struck areas.     

地下水分布式多参数实时监测系统

地下水分布式多参数监测系统是基于分布式总线技术,利用各种监测传感器和多路复用器,实现了对地下水多种参数的远程集中实时监测,解决了地下水多种参数监测问题。     

A Real-time Monitoring and Early Warning System for Landslides in Southwest China

Landslides not only cause property losses,but also kill and injure large numbers of people every year in the mountainous areas. These losses and casualties may be avoided to some extent by early warning systems for landslides. In this paper, a realtime monitoring network and a computer-aided automatic early warning system(EWS) are presented with details of their design and an example of application in the Longjingwan landslide, Kaiyang County, Guizhou Province. Then, according to principle simple method of landslide prediction, the setting of alarm levels and the design of appropriate counter-measures are presented. A four-level early warning system(Zero, Outlook, Attention and Warning) has been adopted, and the velocity threshold was selected as the main warning threshold for the landslide occurrence, but expert judgment is included in the EWS to avoid false alarms. A case study shows the applicability and reliability for landslide risk management, and recommendations are presented for other similar projects.     

Control System Design and Implementation at Flexible,Distributed Offshore Sensor Test Sites in the Yangtze Estuary Area

Marine in situ testing is a necessary step for stereotyping newly developed marine sensors. The use of test sites in the Yangtze Estuary area, which has high turbidity and abundant nutrients, can effectively reduce the needed testing time owing to its harsh conditions. Five test stations were established, and a floating buoy and fixed test equipment were designed. A control system, including a sensor connection, data processor, video remote transmission, and corresponding control algorithm, was developed. The control system enabled the nondestructive monitoring of biological attachments and bidirectional, real-time communication between an upper server on land and the control system at the test sites. The dissolved oxygen(DO), temperature, and pH data of DOS600 and DPS600 sensors were compared with those of AP2000 sensors. Temperature recording using the DOS600 sensor was performed nearly as well as that of the AP2000 sensor. The mean DO values(standard deviations) were 8.414 mg L-1(2.068) and 6.896 mg L-1(1.235) for the DOS600 and AP2000 sensors, respectively, indicating that the DOS600 performance was unsatisfactory. The pH recording of the DPS600 was slightly worse than that of the AP2000 sensor. Experimental results showed that the DO value was more easily affected by the buoy movement of waves compared to the pH and temperature. Moreover, data fluctuations showed that the DO and pH parameters were more vulnerable to biofouling than temperature. Waves and biofouling create a harsh test environment, and the performance difference between the developed sensors and a standard sensor can be obtained in a short time period.     

Characteristic rainfall for warning of debris flows

A characteristic rainfall is introduced to overcome the difficulties encountered in determining a critical rainfall value for triggering debris flow.The characteristic value is defined as the rainfall at which debris-flow occurrence probability shows a rapid increase,and can be used as a warning rainfall threshold for debris flows.Investigation of recorded debris flows and 24-hour rainfall data at Jiangjia basin,Yunnan Province,in southwestern China,demonstrates the existence of such a characteristic rainfa...     

临沂市地质灾害防治现状及监测预警体系构想

介绍了临沂市地质灾害及隐患点的发育情况,总结了临沂市在地质灾害防治方面一些好的做法,对临沂市地质灾害监测预警体系的发展方向进行了研究,提出了建立一套集远程自动测量和预警预报于一体的地质灾害监测预警系统的构想,对提高临沂市地质灾害监测自动化水平和预警预报效果有重要意义。     

区域人群状态的实时感知监控

 公众聚集场所人群高度聚集,流动性大,隐藏着巨大的安全隐患,时常发生群死群伤的拥挤踩踏等突发公共事件。针对现有以视频监控的人群分析,无法从空间视角掌握区域人群状态的时空格局,本文提出了面向人群分析的视频GIS框架,将视频数据映射至地理空间,在GIS环境下提取人群密度、人群运动矢量场等人群特征。通过分析人群运动矢量场可得到人群运动模式及各方向人群主体运动速率。最后,将视频监控系统与GIS进行有机集成,设计并实现了以视频与GIS协同的区域人群状态实时感知监控系统。实验结果表明,本系统可为大型集会活动的突发事件预防、人群疏导等提供决策依据。     

Disaster reduction stick equipment: A method for monitoring and early warning of pipeline-landslide hazards

Oil and gas pipelines are of great importance in China, and pipeline security problems pose a serious threat to society and the environment.Pipeline safety has therefore become an integral part of the entire national economy. Landslides are the most harmful type of pipeline accident, and have directed increasing public attention to safety issues.Although some useful results have been obtained in the investigation and prevention of pipeline-landslide hazards, there remains a need for effective monitoring and early warning methods, especially when the complexity of pipeline-landslides is considered.Because oil and gas pipeline-landslides typically occur in the superficial soil layers, monitoring instruments must be easy to install and must cause minimal disturbance to the surrounding soil and pipeline. To address the particular characteristics of pipelinelandslides, we developed a multi-parameter integrated monitoring system called disaster reduction stick equipment. In this paper, we detail this monitoring and early warning system for pipeline-landslide hazards based on an on-site monitoring network and early warning algorithms.The functionality of our system was verified by its successful application to the Chongqing Loujiazhuang pipeline-landslide in China. The results presented here provide guidelines for the monitoring, early warning, and prevention of pipeline geological hazards.     

基于Web GIS的广西雷电实时监测系统

以Web GIS技术为依托,将基础地理信息数据与闪电定位数据、雷达回波图相结合,建立了具有存储、应用、开发、分析及各种图形处理的INTERNET雷电定位实时监测系统,实现对闪电定位数据、雷达回波图的网络发布.系统可以对雷电天气发生发展进行实时监测、定位、跟踪并确定强雷电天气的落区,为各级气象台站预报员准确分析、判断、预报雷雨系统的移动及强度变化提供了较科学、直观的分析工具.     

Field observations of debris-flow initiation processes on sediment deposits in a previous deep-seated landslide site

Although information regarding the initiation processes of debris flows is important for the development of mitigation measures,field data regarding these processes are scarce.We conducted field observations of debris-flow initiation processes in the upper Ichinosawa catchment of the Ohya landslide,central Japan.On 19 June 2012,our videocamera monitoring systems recorded the moment of debris-flow initiation on channel deposits(nine surges) and talus slopes(eight surges).The initiation mechanisms of these surges were classified into three types by analyzing the video images: erosion by the surface flow,movement of deposits as a mass,and upward development of the fluid area.The first type was associated with the progress of surface flow from the upper stream on unsaturated channel deposits.The second type was likely caused by an increase in the pore water pressure associated with the rising in the groundwater level in channel deposits;a continuous water supply from the upper stream by the surface flow might have induced this saturation.The third type was associated with changes in the downstream topography caused by erosion.The flow velocity of most surges was less than 3 m s~(-1) and they usually stopped within 100 m from the initiation point.Surges with abundant pore fluid had a higher flow velocity(about 3- 5 m s~(-1)) and could travel for alonger duration.Our observations indicate that the surface flow plays an important role in the initiation of debris flows on channel deposits and talus slopes.     

Monitoring and warning of landslides and debris flows using an optical fiber sensor technology

Landslides and debris flows are typical geo-hazards which occur in hilly or mountainous regions. Debris flows may result from landslides. Geotechnical instrumentation plays an important role in monitoring and warning of landslides and resulted debris flows. Traditional technologies for monitoring landslides and debris flows have certain limitations. The new optical fiber sensors presented in this paper can overcome those limitations. This paper presents two new optical fiber sensor systems: one is the Fiber Bragg Grating (FBG)-based in-place inclinometer for monitoring landslides and the other is the FBG-based column-net system for monitoring debris flows. This paper presents the calibration results of FBG-based in-place inclinometers in laboratory. It is found that the calibration results are in good agreement with theoretical results. Both the FBG-based in-place inclinometers and the FBG-based column-net system have been installed at a site in Weijiagou valley, Beichuan County, Sichuan Province of China. Some preliminary results have been obtained and reported in the paper. The advantages of the FBG monitoring systems and their potential applications are also presented.     

PIR传感网数据的几何代数建模与行为分析

现有基于PIR（Passive InfraRed）传感器数据的人体行为研究主要局限于运动时空分布、聚类等,对行为轨迹的重建和语义特征的解析相对较少,亟需发展新的建模与行为分析方法。本文尝试利用室内区域PIR传感器监测数据进行时空轨迹重构及其所揭示的运动语义特征研究。本文引入几何代数理论方法,构建传感器场景网络,实现了几何代数空间下动态网络的表达与路径计算,分析了人体运动特征及语义特征,建立最小语义单元,实现了空间数据到语义特征的转化,并可对个人和群体运动的空间区域特征和拓扑特征分析提供支撑。论文将传统PIR传感器网络分析从以几何、统计等为主的信号提取,转变为基于几何代数系统中不同类型代数结构的生成与转化问题,为诸如PIR传感网数据分析一类的非确定问题的求解提供了新的思路和数学基础,可为物联网GIS的构建提供借鉴。     

Highly nonlinear internal solitary waves over the continental shelf of the northwestern South China Sea

Large amplitude internal solitary waves (ISWs) often exhibit highly nonlinear effects and may contribute significantly to mixing and energy transporting in the ocean. We observed highly nonlinear ISWs over the continental shelf of the northwestern South China Sea (19°35′N, 112°E) in May 2005 during the Wenchang Internal Wave Experiment using in-situ time series data from an array of temperature and salinity sensors, and an acoustic Doppler current profiler (ADCP). We summarized the characteristics of the ISWs and compared them with those of existing internal wave theories. Particular attention has been paid to characterizing solitons in terms of the relationship between shape and amplitude-width. Comparison between theoretical prediction and observation results shows that the high nonlinearity of these waves is better represented by the second-order extended Korteweg-de Vries (KdV) theory than the first-order KdV model. These results indicate that the northwestern South China Sea (SCS) is rich in highly nonlinear ISWs that are an indispensable part of the energy budget of the internal waves in the northern South China Sea.     

基于数据级任务分解的大范围地质灾害预警并行计算架构设计与应用

为实现大范围地质灾害预警实时分析计算,搭建了地质灾害预警并行计算架构。结合地质灾害隐患点的现状和监测设备的实际情况,以地质灾害隐患点为分析计算单元,采用数据级并行计算方式对地质灾害计算任务进行分解,实现了任务生成、分解、派发、计算等功能;采用MPI和Socket套接字相结合的方式,达到了并行计算与高效通信的目的;将该并行计算架构应用于某省2016年8月2~4日台风造成的大范围强降雨状况下的地质灾害预警计算实验验证。结果表明:在大范围地质灾害预警中,该并行计算架构随着执行进程数增加而获得一定的加速比,当执行进程达到16个时加速比可达5.652,明显缩短了传统串行计算所需要的时间,实现了地质灾害的实时预警。