Lessons learned from protective measures associated with the 2010 Zhouqu debris flow disaster in China

Natural Hazards - On August 7 and 8, 2010, a catastrophic debris flow disaster occurred in Zhouqu County in northwestern China’s Gansu Province. The large-scale debris flow event destroyed...     

甘肃舟曲特大泥石流灾害形成机制及减灾对策

2010年8月7日晚23：00左右,甘肃省甘南藏族自治州舟曲县罗家峪、三眼峪流域突然降强暴雨,在三眼峪支流和罗家峪上游形成洪流,降雨持续40min后,在两泥石流沟谷中形成特大泥石流灾害。由于其特有的峰尖谷深地形、坡体表面丰富的松散物质本质条件,在多雨季节降强暴雨诱发了本次泥石流的产生。本文从泥石流形成的潜在性、泥石流降雨诱发因素、城建开发不合理三方面分析了此次泥石流灾难的形成原因。作为泥石流频发区,可采取监测预报,加强管理以遏制人类活动,实施工程治理的综合方法减少和避免灾情的发生。     

甘肃舟曲县牙豁口滑坡发育特征与成因分析

2019年7月16日,位于舟曲—化马深大活动断裂带的舟曲县牙豁口发生滑坡,滑坡长1 920 m,宽50~190 m,体积212×10⁴ m³,为典型的推移式大型长条状断层破碎带堆积层滑坡。滑坡自上而下沿原老滑道分级分块逐步发育形成,滑动历时近50天,最大滑距500 m,滑坡破坏X414县道、养鸡场等,并使岷江呈半堵塞状态,影响汛期行洪安全。通过现场调查、监测、无人机测量、岩土试验和收集历史滑坡资料,对牙豁口滑坡形成的地质环境、滑坡发育历史、滑坡分级分块特征、滑动过程和成因进行了系统研究。牙豁口滑坡分为上、下相对独立的两级滑坡。上级滑坡又可分为南支滑块和北支滑块两部分,在老滑坡的基础上长期孕育发展,上级滑坡北支滑块在2013年前就已活动,2019年7月16日上级滑坡南支滑块开始剧烈滑动,并推挤北支滑块前部一同复活滑动。上级滑坡约10×10⁴ m³滑体下滑加载于下级滑坡,下级滑坡于7月24日由上向下逐步扩展变形和滑动,下级滑坡又可分为上、中、下三段滑体,滑坡前缘于8月10日达到岷江边,使岷江呈半堵状态。牙豁口滑坡总体具有孕育历史悠久、滑动历时长、滑动速度较低、分级分块差异性滑动的特点。长期活动的深大断裂带及凹槽状地形、软弱易滑的灰黑色风化破碎炭质板岩、地下水和大气降水的强烈作用、两侧崩滑体的堆积加载是滑坡发生的主要原因。     

Catastrophic debris flows triggered by a 4 July 2013 rainfall in Shimian,SW China: formation mechanism,disaster characteristics and the lessons learned

On 4 July 2013, three catastrophic debris flows occurred in the Hougou, Majingzi, and Xiongjia gullies in Shimian county and produced debris dams and river blockages, resulting in serious casualties and huge economic loss. Though debris flows have been identified prior to the catastrophic events, their magnitudes and destructive power were far beyond early recognition and hazard assessment. Our primary objective for this study was to explore the formation mechanism and typical characteristics and to summarize the lessons learned from these disastrous events in order to avoid the repeat of such disasters in the future. Based on field investigation and imagery interpretation of remote sensing carried out following the catastrophic events, four conclusions were drawn: (1) The catastrophic debris flows were initiated from surface-water runoff, and the triggering factor was attributed to the local intensive rainfall with an hourly intensity of more than 46.7 mm. (2) Entrainment was the most important sediment-supplying method for the debris flow occurrence, and the source materials transported by debris flows from the three gullies were estimated to be about 97?×?10⁴ m³ in volume altogether. (3) As surface-water runoff eroded and entrained hillslope and channel materials persistently, debris flows were characterized by intensive incision at upper or middle reaches and significant magnification effect in flow discharge and volume downstream. Corresponding peak discharge surveyed at the outlets of the Hougou, Majingzi, and Xiongjia gullies was estimated up to 751.0 m³/s, 870.1 m³/s, and 758.7 m³/s, respectively. (4) Debris flows that occurred from the three gullies all belonged to viscous ones and the bulk densities were calculated more than 1.80 g/cm³, indicating a huge carrying capacity and destructive impacting power. In addition, the lessons learned from the catastrophic events were summarized, including recognition and assessment on debris flow hazard and utilization of deposition fan. In this paper, prevention suggestions on debris flow prone valleys with high-vegetation coverage and low occurrence frequency were also put forward. The results of this study contribute to a better understanding on the initiation mechanism, dynamic characteristics, and disaster mitigation of debris flows initiated from intense rainfall and surface-water runoff in mountainous areas.     

The Bhuj, India, earthquake: lessons learned for earthquake safety of dams on alluvium

The Bhuj, India, earthquake of 26 January 2001, M_s 7.9, caused dams built on alluvium to sustain damage ranging from cosmetic to severe. Major damage was caused almost entirely by soil liquefaction in the alluvium. The critical factor was the level of earthquake ground motion.

The Bhuj earthquake showed that peak horizontal accelerations (PHAs)≤0.2 g were generally safe. PHAs>0.2 g were hazardous, when unconsolidated granular foundation soils were water saturated. N values of <20 are indicative of susceptibility to soil liquefaction. The Bhuj experience showed that alluvial foundation soils, subject to a PHA>0.2 g, must be evaluated over the full area beneath a new dam and all soils deemed susceptible to liquefaction must be either removed or treated. For remediating an old dam, reliable options are removal and replacement of liquefiable alluvium beneath upstream and downstream portions of the dam, combined with building berms designed to provide stability for the dam should there be a strength loss in soils beneath the dam.     

Communicating uncertainty: lessons learned and suggestions for climate change assessment

Assessments of climate change face the task of making information about uncertainty accessible and useful to decision-makers. The literature in behavior economics provides many examples of how people make decisions under conditions of uncertainty relying on inappropriate heuristics, leading to inconsistent and counterproductive choices. Modern risk communication practices recommend a number of methods to overcome these hurdles, which have been recommended for the Intergovernmental Panel on Climate Change (IPCC) assessment reports. This paper evaluates the success of the most recent IPCC approach to uncertainty communication, based on a controlled survey of climate change experts. Evaluating the results from the survey, and from a similar survey recently conducted among university students, the paper suggests that the most recent IPCC approach leaves open the possibility for biased and inconsistent responses to the information. The paper concludes by suggesting ways to improve the approach for future IPCC assessment reports. To cite this article: A. Patt, S. Dessai, C. R. Geoscience 337 (2005).     

贵州纳雍崩塌式滑坡成灾特征及其避灾警示作用

纳雍滑坡是一个典型的崩塌式滑坡,灾害由灰岩陡崖上的崩塌引起,崩塌体滑落推动陡崖下的斜坡坡积层土体产生滑动,将下部的18户村民住房掩埋,死亡44人,财产损失一百万元以上。纳雍滑坡发生在石灰岩与煤系地层互层的地区,坡体呈上硬下软的地质结构,形成山顶为高陡的危崖,下部为斜坡,坡脚平缓的地貌特征。纳雍滑坡发生前有着明显的前兆现象,因此,加强山地灾害防灾避灾的基本知识教育,对山地灾害多发地区灾害发生的可能性进行预测和危险程度区划,是防止类似灾害发生的最有效方法。     

甘肃舟曲垭豁口滑坡复活机理及成因探讨

2019年7月19日18时许,甘肃舟曲县垭豁口滑坡复活,约3.92×106 m3的滑体顺坡而下,迅速流入岷江,堵塞河道,造成河道水位上升,江边公路中断,滑坡变形持续至8月中旬。基于野外勘察、遥感解译、钻孔勘探等方法获取了滑坡变形的基本特征,并开展了滑坡监测工作,并结合气象资料,探讨了该滑坡复活原因及启动机制。初步研究认为,该滑坡为降雨诱发。通过对滑坡变形历史进行梳理,结合滑带证据,滑坡复活机理可概括为:首先上部块体缓慢蠕变,降雨后发生塑性流滑;其次,因上部滑体堆积在滑坡中部,造成中部平台堆载,引发中部滑体变形;最终一滑而下,刮产连带下部滑体坠入河道。滑坡的上中下三部分滑体逐步被激活,最初缓慢变形,随后加速启动。滑坡变形模式为蠕滑—拉裂—流滑。对滑坡变形过程和机理的初步判断为滑坡灾害应急处置提供了科学依据。     

Industrial accidents triggered by earthquakes,floods and lightning: lessons learned from a database analysis

Natural hazards and disasters can cause major accidents in chemical and process installations. These so-called Natech accidents can result in hazardous-materials releases due to damage to process and storage units, or pipes. In order to understand the dynamics of Natech events, accidents triggered by earthquakes, floods and lightning recorded in industrial accident databases were analysed. This allowed the identification of the most vulnerable equipment types, their modes of failure due to natural-event impact and the final accident scenarios. Moreover, lessons learned for future accident prevention and mitigation were derived. The analysis showed that pipes and storage tanks are the most vulnerable equipment for earthquakes, floods and lightning, calling for more research of equipment behaviour under natural-event loading. The damage modes and states are strongly dependent on the characteristics of the impacting natural event. Toxic dispersion, fires and explosions were observed as a consequence of all three types of analysed natural events. In the case of floods, two additional scenarios were identified. These are water contamination and the formation of toxic and/or flammable vapours upon reaction of the released chemicals with the floodwaters. The overall number of recorded Natech accidents was found to range from 2 to 5% of all reported accidents in the analysed databases.     

Environmental hazard in Shanghai,China: lessons learned from Huangpu River dead pigs incident

Natural Hazards - This paper expounds facts related to the Huangpu River dead pigs incident on March 20, 2013, in Shanghai, China. The causes of the incident were discussed. The suggestions for...     

舟曲县三眼峪沟特大型泥石流的形成和运动特征

2010年8月8日凌晨,舟曲县城北侧三眼峪沟和罗家峪沟暴发了自1949年以来强度最大的特大山洪泥石流灾害。本文基于现场调查,对三眼峪沟泥石流的运动特征进行了分析。该流域泥石流的特征显示,三眼峪沟"8.8"泥石流在流域中游已基本形成,但是,由于沟谷不同地段沟谷形态及固体物质的特征不同,泥石流在冲淤和流量方面差异显著。三眼峪沟的两个支沟汇合后,泥石流流量迅速增大,但其最大峰值流量未形成叠加,主沟出山口处最大峰值流量达1833.18m3/s。     

When hazard avoidance is not an option: lessons learned from monitoring the postdisaster Oso landslide,USA

On 22 March 2014, a massive, catastrophic landslide occurred near Oso, Washington, USA, sweeping more than 1 km across the adjacent valley flats and killing 43 people. For the following 5 weeks, hundreds of workers engaged in an exhaustive search, rescue, and recovery effort directly in the landslide runout path. These workers could not avoid the risks posed by additional large-scale slope collapses. In an effort to ensure worker safety, multiple agencies cooperated to swiftly deploy a monitoring and alerting system consisting of sensors, automated data processing and web-based display, along with defined communication protocols and clear calls to action for emergency management and search personnel. Guided by the principle that an accelerating landslide poses a greater threat than a steadily moving or stationary mass, the system was designed to detect ground motion and vibration using complementary monitoring techniques. Near real-time information was provided by continuous GPS, seismometers/geophones, and extensometers. This information was augmented by repeat-assessment techniques such as terrestrial and aerial laser scanning and time-lapse photography. Fortunately, no major additional landsliding occurred. However, we did detect small headscarp failures as well as slow movement of the remaining landslide mass with the monitoring system. This was an exceptional response situation and the lessons learned are applicable to other landslide disaster crises. They underscore the need for cogent landslide expertise and ready-to-deploy monitoring equipment, the value of using redundant monitoring techniques with distinct goals, the benefit of clearly defined communication protocols, and the importance of continued research into forecasting landslide behavior to allow timely warning.

     

Natural and industrial analogues for leakage of CO2 from storage reservoirs: identification of features, events, and processes and lessons learned

Instances of gas leakage from naturally occurring CO₂ reservoirs and natural gas storage sites serve as analogues for the potential release of CO₂ from geologic storage sites. This paper summarizes and compares the features, events, and processes that can be identified from these analogues, which include both naturally occurring releases and those associated with industrial processes. The following conclusions are drawn: (1) carbon dioxide can accumulate beneath, and be released from, primary and secondary shallower reservoirs with capping units located at a wide range of depths; (2) many natural releases of CO₂ are correlated with a specific event that triggered the release; (3) unsealed fault and fracture zones may act as conduits for CO₂ flow from depth to the surface; (4) improperly constructed or abandoned wells can rapidly release large quantities of CO₂; (5) the types of CO₂ release at the surface vary widely between and within different leakage sites; (6) the hazard to human health was small in most cases, possibly because of implementation of post-leakage public education and monitoring programs; (7) while changes in groundwater chemistry were related to CO₂ leakage, waters often remained potable. Lessons learned for risk assessment associated with geologic carbon sequestration are discussed. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Mountain hazards and the resilience of social–ecological systems: lessons learned in India and Canada

Mountain regions are subject to a variety of hazardous processes. Earthquakes, landslides, snow avalanches, floods, debris flows, epidemics and fires, among other processes, have caused injury, death, damage and destruction. They also face challenges from increased populations, and expansion and intensification of␣activities, land uses and infrastructure. The combination of a dynamic bio- geophysical environment and intensified human use has increased the vulnerability of mountain social–ecological systems to risk from hazards. The ability of social–ecological systems to build resilience in the context of hazards is an important factor in their long-term sustainability. The role of resilience building in understanding the impact of hazards in mountain areas is examined and illustrated, in part, through examples from Canada and India. Resilient social–ecological systems have the ability to learn and adjust, use all forms of knowledge, to self-organize and to develop positive institutional linkages with other social–ecological systems in the face of hazards. The analysis suggests that traditional social–ecological systems built resilience through avoidance, which was effective for localized hazards. The more recent development and implementation of cross-scale institutional linkages is shown to be a particularly effective means of resilience building in mountain social–ecological systems in the face of all hazards.     

Managing for sustainability in an arid climate: lessons learned from 20 years of groundwater management in Arizona,USA

Substantial progress has been made within central Arizona in moving towards a more sustainable water future, particularly in transitioning the urban demand from a primarily nonrenewable groundwater-based supply to increasing dependence on the Colorado River, Salt River and effluent. Management efforts include a wide range of regulatory and voluntary programs which have had mixed success. The Department of Water Resources has learned a number of key lessons throughout the years, and this paper attempts to establish the water management context and identify those lessons for the benefit of others who may want to evaluate alternative approaches to groundwater management. Themes to be discussed include evaluating water management approaches in a public policy context, the effectiveness of alternative management approaches and the relative merits of regulatory vs. nonregulatory efforts, and the importance of high-quality data in making management decisions.

2010年“8.8”舟曲特大山洪泥石流灾害形成的气候特征及地质地理环境分析

利用舟曲气象和地质资料,分析了2010年8月8日发生的"8.8"舟曲特大山洪泥石流灾害形成的气候特征和地质地理环境.这次泥石流是在舟曲特殊的地质地貌和地理环境下,由于前期干旱,突遇强降水而发生的一次特大地质灾害.崩塌、滑坡、地震和人为因素,特别是"5.12"汶川地震,较大程度上破坏了舟曲地质,为泥石流提供了丰富的物质来源;前期干旱在一定程度上加剧了这次灾害;超历史极值的强降水是触发泥石流的直接因素.通过对舟曲气候研究表明,7、8月降雨频繁,而且过程雨量大,尤其8月上旬大雨发生频率最高,应密切关注可能引发的地质灾害.加强对地质地貌的保护,研究历史气候及月季气候特征对泥石流发生的影响,确定在不同地形和地质地貌背景下的泥石流降水量阈值,对泥石流灾害发生的预报有着十分重要的意义.     

Landslide-dammed lake at Tangjiashan,Sichuan province,China (triggered by the Wenchuan Earthquake,May 12, 2008): risk assessment,mitigation strategy,and lessons learned

Landslides and rock avalanches triggered by the 2008 Wenchuan Earthquake produced 257 landslide dams, mainly situated along the eastern boundary of the Qinghai-Tibet Plateau where rivers descend approximately 3,000 m into the Sichuan Basin. The largest of these dams blocked the Tongkou River (a tributary of the Fujiang River) at Tangjiashan. The blockage, consisting of 2.04 × 10⁷ m³ of landslide debris, impounded a lake with a projected maximum volume of 3.15 × 10⁸ m³, potentially inundating 8.92 km² of terrain. Its creation during the rainy season and the possibility of an uncontrolled release posed a serious, impending threat to at least 1.3 million people downstream that could add substantially to the total of 69,200 individuals directly killed by the earthquake. Risk assessment of the blockage indicated that it was unlikely to collapse suddenly, and that eventual overtopping could be mitigated by notching the structure in order to create an engineered breach and achieve safe drainage of the lake. In addition to the installation of monitoring and warning instrumentation, for emergency planning we estimated several outburst scenarios equivalent to 20, 25, 33, and 50% of the dam failing suddenly, creating, respectively, 3.35, 3.84, 4.22, and 4.65 km² of flooded area, and overbank water depths of 4.6, 5.1, 5.7, and 6.2 m, respectively, in Mianyang, the second largest city in Sichuan Province, 48 km downstream from the blockage. Based on these scenarios, recommendations and plans for excavating a sluiceway, draining the lake, and downstream evacuation were proposed and later were implemented successfully, with the blockage breached by overtopping on June 10, less than a month after dam emplacement. The peak discharge of the release only slightly exceeded the flood of record at Mianyang City. No lives were lost, and significant property damage was avoided. Post-breaching evaluation reveals how future similar mitigation can be improved. Although initial breach erosion was slow, later erosion was judged uncontrollably rapid; increased slope of the engineered channel and adoption of a compound, trapezoid–triangular cross-section can be considered, as can other measures to control the rate of breach incision. Evacuees from Mianyang City spent an unnecessarily long time (12 days) in temporary settlements; more precise risk management planning can reduce this time in the future.     

Re-specifying disaster risk: concepts,methods, and models

The discussion on the social-ecological dimensions of hazards is constantly evolving. This paper explores the trajectory of research relating to hazards and their impact on vulnerable human populations. Interpretations of disaster risk have included estimating losses in terms of human life and property, and analyzing the social mechanisms in place that exacerbate or mitigate a population’s sensitivity to hazard events. In keeping with recent trends in research relating to disaster risk, the paper focuses on the social dimension of vulnerability and the contribution of social structures and relationships in building community resilience. Institutional frameworks and policies in particular determine the quantity and quality of resources and services available to people that contribute to resilience over time. The hazard-risk-location-model (HRLM) is proposed that is based on re-specifying disaster risk in terms of exposure and coping ability to capture the focus on social vulnerability and resilience. The framework of the HRLM incorporates the following components: (1) linkages within existing social capital; (2) spatial variation in social and institutional frameworks; (3) positive and negative feedbacks; and (4) characteristics of the hazard event. The model contributes to the range of place-based assessments designed to address the human-environmental impacts of hazards and disasters.