Activity evolution of landslides and debris flows after the Wenchuan earthquake in the Qipan catchme

来源 :山地科学学报(英文版) | 被引量 : 0次 | 上传用户:levychan
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
The Wenchuan earthquake that occurred on 12 May 2008 induced numerous landslides.Loose landslide materials were deposited on hillslopes,and deep channels were easily remobilized and transformed into debris flows by extreme rainstorms.Twelve years after the Wenchuan earthquake,debris flows were still active in the Qipangou Ravine in the quake-hit area.In this paper,we continuously tracked the spatiotemporal evolution of the landslides and vegetation restoration and evaluated the evolution of debris flow activity in the Qipan catchment with the aid of a GIS platform and field investigations from 2008 to 2019.We observed that the area with active landslides increased sharply immediately following the earthquake,and then decreased with time;however,the total area of landslides continued to increase from 6.93 km2 in 2008 to 10.55 km2 in 2019.The active landslides shifted towards lower angles and higher elevations after 2013.Since 2009,the vegetation coverage has been gradually increasing and approaching the coverage present before the earthquake as of 2019.The landslide activity was high and the vegetation recovery rates were rapidly rising during the first five years after the earthquake;the recovery rates then slowed over time.Therefore,we divided the evolution that occurred during the post landslide period into an active period (2008-2013),a self-adjustment period (2013-2026) and a stable period (after 2026).We then proposed a quantitative model to determine the trends of landslide activity rates and NDVI values in the catchment,which indicated that the landslide activities and postseismic vegetation restoration rates in this catchment will return to preseismic levels within approximately two decades.We also analysed the runout volumes of the debris flows after the earthquakes (Diexi and Wenchuan) and the standard deviation of the vegetation coverage and predicted that the debris flow activities will last for an additional 50 years or more.
其他文献
结构化数据和非结构化文本被视为两种不同的模态。数据到文本生成是自然语言生成领域中一个重要的跨模态任务,该任务的目标是对于给定的结构化数据,生成一段文本用以描述结构化数据中包含的关键信息。近年的研究工作通常关注于描述性文本的生成,虽然取得了一定的研究进展,但仅能做到信息的传递而不能带来任何增益。为解决这一问题,本研究数据到分析性文本的生成,并针对该任务提出一个基于主题感知的跨模态序列到序列模型。该模型在编码器-解码器结构的基础上,引入数据表的主题信息以保证生成文本与数据表之间的主题一致性,提高生成文本的质量
为了研究汽车操纵稳定性的影响机理,基于MATLAB/Simulink软件,建立了横摆角速度和质心侧偏角的频率响应模型,对模型进行稳定性、动态响应和准确性分析。基于横摆角速度和质心侧偏角的频率响应函数,对操纵稳定性的影响因素进行仿真分析。仿真结果表明:随着纵向车速和载荷的减小,操纵稳定性有所提高;在低频段较高的前轮侧偏刚度和较低的后轮侧偏刚度,在中高频段较低的前轮侧偏刚度和较高的后轮侧偏刚度,有利于改善汽车的操纵稳定性。探究各种因素对操纵稳定性的影响,为汽车的开发和设计提供参考。
在水下盾构掘进过程中出现带压开舱检修情况时,如何在高渗透性地层形成质量较好的泥膜从而保证开挖面稳定,是保障工程安全与进度的重要前提。以青岛地铁跨海段隧道掘进工程为依托,自主设计试验装置开展咸水泥浆配比及渗透成膜试验,并设置淡水泥浆作为对照组。采用控制变量法和析因分析法研究膨润土、羧甲基纤维素(CMC)、碳酸钠等不同制浆材料引起的泥浆相对密度和黏度变化对泥浆滤水量的影响。试验结果表明:在咸水泥浆中,随着膨润土含量的增加,泥浆相对密度变大,可以显著降低泥膜的滤水量,增加CMC含量可以提高泥浆黏度从而更易成膜,
Climate change will affect the geographic distribution and richness of species at different spatial and temporal scales.We applied Maximum entropy(MaxEnt) model
为了消除传统机器学习中分类方法的限制,提出一种基于主题模型与迁移学习的文本分类方法。将文本集合成由共同主题和特定主题所联合起来的混合模型;然后,通过这两类主题相关性推断出不同领域之间主题的映射关系;最后,融合共同主题以及映射后的特定主题形成一个新的特征空间,并在此特征空间中完成文本的分类。实验结果表明,相较于其他分类方法,本方法在国外的20newsgroups数据以及自建的中国专利数据集上能更加高效准确地预测未标记文本的类别,为文本挖掘领域相关方向的研究提供新的视角。
Forest cover change in the mountainous region is driven by a variety of anthropogenic and natural factors.The Hindu Kush-Himalayan Mountains has experienced a c
To quantify the impacts of native vegetation on the spatial and temporal variations in hydraulic properties of bank gully concentrated flows,a series of in situ
定量降水预报是无缝隙精细化网格预报中最具挑战的部分,目前存在需要长时间序列的训练样本、大多基于单模式订正及局地偏差特征反应不足等问题.本文提出基于相似网格点的多源
Ethnic mountain settlements are living heritage of varied vernacular cultures.The preservation of both the built form and the intangible socio-cultural associations with them are global concern in process of urbanization,and in the notion of sustainable d
Accurate assessment of soil erosion is an important prerequisite for controlling soil erosion.The engineering-control(E)and tillage(T)factors are the keys for C