Identifying drivers of urban landuse changes in the Wenchuan earthquake- affected area by using night-time light data

To learn the process of urban land evolution before and after an earthquake is vital to formulate the urban reconstruction control policies and recovery measures in the earthquake-stricken areas.However,spatiotemporal evolution and its driving factors of urban land in earthquake-prone areas remains limited due to the scarcity of ground observation data.This research,leveraging night-time light remote sensing imagery and land cover data,conducted a comprehensive analysis of the long-term evolution characteristics of urban land in earthquake-prone areas.It introduced methodologies for assessing the socio-economic impact and the primary natural environmental factors driving urban land evolution in these regions.To validate the proposed methods,the 2008 Wenchuan earthquake-affected area in China was selected as a representative study area.The results indicated that the average Digital Number(DN)values in socio-economically impacted areas showed a trend of rising,falling,and then rising again after the earthquake.DN values in three types of damaged areas including Type Ⅱ,Type Ⅲ,and Type Ⅳ exceeded pre-earthquake levels.The analysis of determinative factors influencing urban land evolution revealed that slope and elevation were key elements in controlling urban land expansion before the earthquake,whereas factors such as slope,elevation,lithology,and faults had a stronger influence on urban land expansion after the earthquake.It can be seen that,in view of the differences in the natural conditions of regions for post-disaster reconstruction,the local government need to actively adjust and adapt to urban spatial planning,so as to leverage the scale effect of large-scale inputs of funds,facilities,human resources and other factors after the disaster,thus enhancing resilience and recovery efficiency in response to disaster impacts.

Analysis of debris flow control effect and hazard assessment in Xinqiao Gully,Wenchuan M_(s)8.0 earthquake area based on numerical simulation

Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events.

Geo-engineering Lessons Learned from the 2008 Wenchuan Earthquake in Sichuan and Their Significance to Reconstruction

The 2008 Wenchuan earthquake in Sichuan of China was the result of quake-triggering along an active several hundred-kilometer-long fault. The subsequent landslides and debris flow geohazards are dominating factors in planning post-disaster recovery and rebuilding. This paper presents recommendations for coping with large-scale geohazards and disasters. It is essential to establish a national emergency management system for huge scale catastrophe and earthquake precursor identification. Town construction must be kept away from active faults, especially to improve town safety in areas with high risk of seismic and geological hazards, and it is important to improve geohazard investigation and remediation for mountain areas that have become loosened by earthquake activity. Geological factors must be better understood to reduce direct and secondary risks and effects of earthquakes. Site selections for public relocation require clear and informed analysis of geological and social risk reduction, so that relocation, infrastructure reconstruction, and commemorative relic-sites can be protected.

Preventing and Limiting Exposure to Geo-Hazards:Some Lessons from Two Mountain Villages Destroyed by the Wenchuan Earthquake

This paper examines the experiences of two mountain communities- Yinchanggou and Donghekou in the Wenchuan earthquake of May 12, 2008, where Yinchanggou's tourism economy and natural park system was destroyed and Donghekou was buried by a landslide. We conducted research surveys on both the communities, interviewing survivors and local officials, and observed the destruction/reconstruction, geological, and living conditions. We suggest that protracted educational processes be put into place so that mountain communities possess a knowledge base to consider long-term disaster prevention when building the economy in the fragile and geo-hazardous conditions of the Longmenshan. The Donghekou Earthquake Ruins Park is an exemplar of turning disaster into sustainable, safe development for small mountain villages.

Dynamic analysis of the Wenchuan Earthquake disaster and reconstruction with 3-year remote sensing data

Earth observation is an effective technique that plays an important role in earthquake damage reduction and reconstruction.This paper introduces the results of dynamic analysis on monitoring and assessing heavily impacted areas affected by the Wenchuan Earthquake using remote sensing data acquired in the past 3 years from 2008 to 2010.Immediately after the disaster on 12 May 2008,the Chinese Academy of Sciences launched a project entitled‘Wenchuan Earthquake Disasters Monitoring and Assessment Using Remote Sensing Technology.’More than 400 images from 17 satellites and 20.2TB airborne remote sensing data were acquired to facilitate quick monitoring and evaluation of severely damaged areas in 14 counties.Results of the image analyses were forwarded on a timely basis to assist with consultative service and decisionmaking support.In subsequent years,in order to monitor the process of environmental restoration and reconstruction,airborne optical remote sensing images covering most of the severely damaged areas were again acquired in May 2009 and April 2010.These images were analyzed and compared along with images from 2008.Results were useful in support of further work on environmental protection and reconstruction in earthquake-damaged areas.Three typical areas were selected for illustrative purposes including Tangjiashan Barrier Lake,Beichuan County,and counties of Yingxiu and the new Beichuan.These results well demonstrate the importance and effectiveness of the utility of earth observation for disaster mitigation and reconstruction.

Analysis of the population capacity in the reconstruction areas of 2008 Wenchuan Earthquake

Assessment of population carrying capacity is a key task in the reconstruction planning of areas struck by disasters, in which the precision of estimation is required. This study developed a decision-making model for estimating the population capacity of the involved townships and cities in the 2008 Wenchuan Earthquake based on the assessment of the suitability for reconstruction of the areas. Through analysis, arable land resources were argued to be the critical constraint of population capacity in these areas. Then, the spatial differentiations of the post-quake development conditions across different regions were analyzed with respect to their natural environments, socio-economic development and quake damages. The expected levels of urbanization, family incomes and income structures, output levels of land, and the reliance of agricultural population on arable land were estimated by different regions. With these parameters, the population capacities of the involved townships and cities in three scenarios were estimated. The total population capacity of the entire areas is abundant compared with the actual post-quake population; however, the status of over-population substantially varies across space. It was suggested to put the emphasis of post-quake resettlement policy on those counties where earthquake had been the main causes of over-population. In the Full Recovery Scenario, three mountain counties were identified including Wenchuan, Beichuan and Maoxian, with a total over-population of about 100,000 people.

Post-earthquake economic resilience and recovery efficiency in the border areas of the Tibetan Plateau: A case study of areas affected by the Wenchuan Ms 8.0 Earthquake in Sichuan, China in 2008

The border areas of the Tibetan Plateau and the neighboring mountainous areas have a high incidence of earthquakes with a magnitude greater than Ms 5.0, as well as having a dense distribution of geological disasters such as collapses, landslides, and debris flows. Revealing the post-disaster economic development and recovery process is very important for enhancing disaster prevention and response capacity in order to formulate control policies and recovery methods for post-disaster economic reconstruction based on economic resilience. Using long-term socioeconomic data and the autoregressive integrated moving average (ARIMA) model, this paper calculated the economic resilience index of the areas most severely affected by the Wenchuan Earthquake of 2008 and adopted the improved variable returns to scale (VRS) date envelopment analysis (DEA) model and the Malmquist productivity index to analyze the efficiency and effect of annual post-disaster recovery. The results show that: (1) the economic resilience index of the areas most severely affected by the Wenchuan Earthquake was 0.877. The earthquake resulted in a short-term economic recession in the affected areas, but the economy returned to pre-quake levels within two years. In addition, the industrial economy was less resilient than agriculture and the service industry. (2) The comprehensive economic recovery efficiency of the disaster-stricken area in the year following the disaster was 0.603. The comprehensive efficiency, the pure technical efficiency, and the scale efficiency of the plain and hilly areas were significantly greater than those of the plateau and mountain areas. (3) The annual fluctuation in total factor productivity (TFP) following the disaster was considerable, and the economic recovery efficiency decreased significantly, resulting in a short-term economic recession. The TFP index returned to steady state following decreases of 33.7% and 15.2%, respectively, in the two years following the disaster. (4) The significant decrease in the post-disaster recovery efficiency was caused mainly by technological changes, and the renewal of the production system was the leading factor in determining the economic resilience following the disaster. With the decline in the scale of economic recovery following the earthquake, long-term economic recovery in the disaster-stricken areas depended mainly on pure technical efficiency, and the improvement in the latter was the driving force for maintaining the long-term growth of the post-disaster economy. Therefore, according to the local characteristics of natural environment and economic system, the disaster-stricken areas need to actively change and readjust their economic structures. At the same time, attention should be paid to updating the production system to enhance the level of technological progress and give full play to the scale effects of large-scale capital, new facilities, human resources, and other investment factors following the disaster so as to enhance the impact of economic resilience and recovery efficiency in response to the disaster.

现代竹结构在汶川地震灾后重建中的应用

竹结构安置房经济合理,安全舒适,符合环保要求。现代竹结构本身也是一种新型的绿色可持续建筑技术。采用竹结构抗震安置房可以利用包括四川灾区的丰富竹资源,因地制宜抗震救灾,恢复灾区的生活。文章提出试制经济、安全和实用的竹木住宅用于灾后重建家园。

汶川大地震灾害与灾区重建的岩土工程问题

2008年5月12日14:28四川省西部龙门山山区发生Ms=8.0级强震。地震是由龙门山中央断裂逆冲兼走滑产生的,沿300 km长的断裂带造成大量的山体崩塌、滑坡,城镇与村庄房屋坍塌不计其数,厂矿与交通设施严重毁损,并造成大量的人员伤亡。截至7月11日12时,地震已造成69 197人遇难、18 341人失踪、374 176人受伤。基于震后灾区的第一手调查资料,在简介龙门山地质条件与断裂构造格局的基础上,从工程角度对地震产生的震害类型和分布,及其与断裂构造的关系等进行初步的总结和归纳,提出灾区重建工作中面临的主要岩土工程问题,以期为灾后重建和相关科研工作提供参考。

基于旅游动机的旅游业灾后恢复重建研究——以“5·12”汶川地震后的九寨沟为例

旅游业灾后恢复重建是灾区经济社会恢复重建的重要"突破口",尤其在旅游业作为主导产业或支柱产业的地区;而理解灾区游客旅游动机有利于旅游业灾后恢复重建管理战略的制定。该研究以遭受"5.12"汶川地震影响的九寨沟为例,运用结构方程模型,引入"灾害事件引发的旅游动机",对灾区国内游客的多种旅游动机交互作用关系进行分析,证实了灾区旅游业恢复重建管理中:①恢复重建的关键内容是"核心旅游吸引物与安全";②恢复重建的重点区域是灾区内已有高知名度的旅游地或在灾害事件中成为全球关注焦点的地区;③对目的地优质旅游接待服务意象的修复或构建能够恢复和提升灾区的旅游市场竞争力;④灾后旅游业市场营销需要重新区分客源市场并进行定位;⑤国民对灾区的爱国情怀可能会为目的地带来更多的国内旅游流,但需要营造"到灾区旅游是对灾区恢复重建最大援助"的社会氛围。

汶川地震对岷江上游水电工程的影响分析

2008年5月12日四川汶川发生8.0级地震,导致岷江上游河段山体垮塌,大中型水电站机组停运,交通中断,但挡水大坝无一溃决,整体稳定;其他主要建筑物的直接震损有限,部分建筑设施受地震滑坡影响突出。通过工程震损调查,在简述岷江水电工程基本特征以及流域地震地质环境的基础上,对紫坪铺和沙牌两座高坝电站的震损情况,以及各闸坝引水式电站的地震灾害作了重点分析;并根据震损情况,就工程防震抗震设计与建设,提出了的几点初步认识。

汶川地震灾后重建地区的人口容量分析

结合国家汶川地震灾区资源环境承载力评估的工作任务,对区域人口容量分析的方法和技术流程进行了研究。依据区域人口和城镇化发展的基本理论和汶川地震灾区的实际情况,提出以耕地总量为基本约束的人口容量测算思路,并对影响区域人口承载能力的各种区域经济发展条件进行了预测和分析,由此确定了测算人口容量的政策参数。在上述分析的基础上,构建了人口容量分析的计算机辅助决策模型,对灾区各县市的合理人口容量、人口超载情况及人口超载的不同类型,灾后人口调整方案进行了分析和测算,并提出了具体的政策建议。分析表明,汶川大地震灾后重建区的51个县市区的灾后实际人口为2025.91万人,而整个区域未来可以承受的总人口在2970万人左右,整个区域的人口容量尚有较大富余。为了避免跨县跨区域人口迁移的后续难题,应该重点解决由于地震而引起的部分县市的人口超载问题。在51个县市区当中,这样的县包括汶川、北川和茂县,三县的超载总人口为10万人左右。3县目前在外打工的人口较少,仅靠打工所在地省市对于这一部分人口进行就地安置不足以解决10万人口的超载问题。为此,有必要采取更加直接的中长期人口对策,包括实施跨县人口转移,提高耕地的复垦率、通过政策扶持的手段提高城镇化率、降低农村居民对于耕地的依赖度等。

汶川地震与唐山地震损失与救助之对比

1976年发生的唐山7.8级地震与2008年发生的汶川8.0级地震,是近年来破坏程度深、影响范围广的两次特大地震灾害,造成的人员伤亡与经济损失都是惨重与巨大的。但是,不同时代背景下,参数相近的两次地震在灾后救援与救助方面却相差甚远,表现在军队人数调动、受伤人口抢救、恢复重建资金投入、国内外援助、保险再保险分担等方面。着重对比了以上几方面后得出结论:在各项应急预案颁布并实施后,我国灾害救援工作更加有序,提高了救援效率;同时,保险与再保险的参与也减轻了政府负担,为灾民自主开展家园的恢复重建提供了便捷与保障。

利用成像测井资料分析汶川地震断裂带科学钻探3号孔(WFSD-3)裂缝特征

WFSD-3孔是汶川地震断裂带科学钻探主要钻孔之一,全井段(终孔深度1 502.30 m)实施了连续取心(累计取心进尺1 548.44 m)和测井作业。采集到的成像测井资料包含丰富的原位地质特征信息,对裂缝、破碎带识别和构造应力场分析具有重要作用。利用该钻孔的电阻率成像测井和超声成像测井资料,结合岩心资料进行了裂缝特征分析。结果表明,WFSD-3孔岩层高角度斜交缝最为发育,其次是低角度斜交缝,垂直缝和水平缝极少;25～200 m和900～1 000 m深度范围内裂缝尤为发育;不同深度的裂缝倾向存在明显差异:410 m之上主要分布于260°～290°,410～730m集中于330°～360°,730～960 m主要分布于210°～240°,960～1 185 m与410 m之上基本一致,1 410～1 450 m与前述各深度段不同,集中于180°～200°;裂缝与破碎带、层理密切相关,宏观分布受构造控制。

汶川震区狭陡型泥石流典型特征与防治

汶川MS 8.0强震发生6年来,震区暴发了数量众多、类型多样的泥石流灾害,其中一类可总结为"狭陡型泥石流",其特征指标及防治对策与震前常规泥石流存在显著差异,给灾后重建和灾害防治技术提出了新的命题。在对(极)重灾区泥石流活跃的五大片区(汶川、都江堰、绵竹、北川、安县)进行大量现场调查和资料分析的基础上,提出了强震区狭陡型泥石流的概念并给出定义,提炼了其在形成、活动及危害等方面的典型特征;通过工程实践,分析了其独特的治理难点及相应的防治对策,介绍了几项极具适应性和有效性的防治新技术,可为强震扰动区泥石流治理研究和工程设计提供一类新的思路和借鉴。

地震地质灾害防治工程运行效果评价:以汶川震区平武县魏坝滑坡为例

2008年"5·12"汶川地震诱发了数以万计的崩塌、滑坡、泥石流等地质灾害,造成众多人员伤亡和财产损失。汶川地震后,地震灾区危害性大的滑坡多采用截排水沟、挡土墙、抗滑桩、坡面减载和坡脚反压等措施进行了治理,总体防治效果较好,但仍存在一些问题。通过现场调查,结合地震扰动区地质灾害特点,提出了地震地质灾害防治工程运行效果评价的指标体系,包括地质灾害本体因子、防治工程技术因子和社会影响因子3个一级评价指标和12个二级评价指标,并建议将防治效果(R)划分为4个等级:良好(R≥0.85)、较好(0.70≤R<0.85)、一般(0.6≤R<0.70)、差(过于保守或失败,R<0.6)。以汶川震区平武县魏坝滑坡为典型案例,采用层次分析法,建立了地震扰动区滑坡防治工程防治效果评价模型,计算获得魏坝滑坡防治效果R值为0.63,总体防治效果一般,与实际情况相符。

中日地震恢复重建对比研究

近年来,世界范围的巨震频发给人类的正常生产生活以及全球经济的快速发展造成了严重的影响。尤其是破坏性地震发生后,如何快速高效地进行受灾地区的恢复重建,已成为世界各国震后重建决策者和相关学者的研究热点。结合笔者2013年年初赴日参加"Pre-Recovery Planning From Natural Disasters"研修班中,对阪神地震以及"3.11"东日本地震海啸恢复重建的学习和考察内容,总结了两次地震恢复重建的特点以及现状,并对比了我国汶川地震恢复重建的相关数据和案例,分析了中日两国在地震恢复重建中的各自优点与不足,并针对未来我国可能面对的大震恢复重建工作,提出了一些新的思路和方法,对了解中日两国地震恢复重建工作的各自特点,以及未来如何完善现有恢复重建方案的设计和提高相关重建服务的效率,具有一定的理论和实际意义。

汶川8.0级地震人员伤亡及分布特征分析

在收集汶川8.0级地震造成人员伤亡统计数据的基础上,结合笔者在此次地震现场工作期间的调查结果,绘制出此次地震造成人员伤亡的分布图,并分析了此次地震造成人员伤亡重、分布范围广的原因,进而总结了经验和教训,为灾区的恢复重建提出意见和建议。

汶川地震四川重灾区地质安全综合评估

以四川12个地震重灾县为研究区,在详细收集分析地震前后相关资料的基础上,开展了研究区灾后恢复重建的地质安全综合评估。首先在综合分析历史最高洪水位、25°坡角、活动断裂、沟谷稳定性、地质灾害易发性5项因子的基础上,划分出不宜建区和相对宜建区;再对相对宜建区开展地质安全综合评估,利用GIS软件的空间分析叠加功能,在对相对宜建区进行多边性网格单元剖分的基础上,选取地形地貌、活动断裂及区域地壳稳定性、斜坡稳定性、地质灾害易发程度4项指标进行单独分级评价,然后按照取差原则综合上述各单因子评价结果,进行综合评价,划分出了相对安全区、次安全区、不安全区,为灾后恢复重建工作提供了地质安全依据。

加强震后生态评价,促进灾区生态修复

结合《科技导报》首期学术沙龙"汶川震区生态影响评价及灾后生态重建与修复"讨论的成果,对汶川地震灾区生态环境的特点,地震对灾区生态的影响,震后生态评价的地位及任务,灾区重建及生态修复的原则、内涵和方法等进行了综合评述,力图为汶川地震灾区重建及生态修复提供相关的理论依据和建议。