Thermo-hydro-poro-mechanical responses of a reservoir-induced landslide tracked by high-resolution fiber optic sensing nerves

Thermo-poro-mechanical responses along sliding zone/surface have been extensively studied.However,it has not been recognized that the potential contribution of other crucial engineering geological interfaces beyond the slip surface to progressive failure.Here,we aim to investigate the subsurface multiphysics of reservoir landslides under two extreme hydrologic conditions(i.e.wet and dry),particularly within sliding masses.Based on ultra-weak fiber Bragg grating(UWFBG)technology,we employ specialpurpose fiber optic sensing cables that can be implanted into boreholes as“nerves of the Earth”to collect data on soil temperature,water content,pore water pressure,and strain.The Xinpu landslide in the middle reach of the Three Gorges Reservoir Area in China was selected as a case study to establish a paradigm for in situ thermo-hydro-poro-mechanical monitoring.These UWFBG-based sensing cables were vertically buried in a 31 m-deep borehole at the foot of the landslide,with a resolution of 1 m except for the pressure sensor.We reported field measurements covering the period 2021 and 2022 and produced the spatiotemporal profiles throughout the borehole.Results show that wet years are more likely to motivate landslide motions than dry years.The annual thermally active layer of the landslide has a critical depth of roughly 9 m and might move downward in warmer years.The dynamic groundwater table is located at depths of 9e15 m,where the peaked strain undergoes a periodical response of leap and withdrawal to annual hydrometeorological cycles.These interface behaviors may support the interpretation of the contribution of reservoir regulation to slope stability,allowing us to correlate them to local damage events and potential global destabilization.This paper also offers a natural framework for interpreting thermo-hydro-poro-mechanical signatures from creeping reservoir bank slopes,which may form the basis for a landslide monitoring and early warning system.

DICE:An open-source MATLAB application for quantification and parametrization of digital outcrop model-based fracture datasets

An open-source MATLAB application(app)named Discontinuity Intensity Calculator and Estimator(DICE)was developed in order to quantitatively characterize the fractures,or in more general,discontinuities within a rocky outcrop in three-dimensional(3D)digital data,such as digital outcrop model(DOM).The workflow proposed for the parametrization of the discontinuities consists of the following steps:(1)Analysis and mapping of the fractures detected within the 3D DOMs;(2)Calculation of the orientation,position and dimensions of discontinuities that are represented by best-fit circular planes;(3)Determining the discontinuity parameters(dimension,distribution,spacing and intensity)by the DICE algorithm using different 3D oriented sampling techniques(3D oriented scanline,3D oriented circular scan window and spherical scan volume).Different sampling methods were bench tested with a synthetic,as well as a natural case study,and compared in order to understand the advantages and limitations of each technique.The 3D oriented circular scan window appears to be the most effective method for fracture intensity estimation with high accuracy(error 0.4%)and stability with variations in scan radius.

Mitigation measures of debris flow and landslide risk carried out in two mountain areas of North-Eastern Italy

The design of remediation works for the mitigation and prevention of the associated risk is needed where these geological hazards affect anthropized areas. Remedial measures for landslides commonly include slope reshaping, plumbing, drainage, retaining structures and internal slope reinforcement, while debris flow control works consist in open or closed control structures. The effectiveness of the remedial works implemented must be assessed by evaluating the reduction of the risk over time. The choice of the most appropriate and cost-effective intervention must consider the type of hazard and environmental issues, and selects, wherever possible, naturalistic engineering operations that are consequently implemented according to the environmental regulations or the design and specification standards imposed by the competent public administrations. The mitigation procedures consist of five basic steps:(a) acquisition of the knowledge of the hazard process;(b) risk assessment with identification of possible disaster scenarios;(c) planning and designing of specific remedial measures to reduce and/or eliminate the potential risk;(d) slope monitoring after application of remedial measures,(e) transfer of knowledge to the stakeholders. This paper presents two case studies describing the practice for the design of the mitigation measures adopted for debris flow and active landslide sites in North-Eastern Italy. The first case study is a debris flow site, for which, based on observation of past events and numerical simulations using the software FLOW-2D, the most suitable mitigation measures were found to be the construction of a debris basin, barriers and breakers. The second case study deals with an active landslide threatening a village. Based on the landslide kinematics and the results of numerical simulations performed with the code FLAC, hard engineering remedial works were planned to reduce the driving forces with benching and by increasing the available resisting forces using jet grout piles and deep drainage.

The measure of friction angles for different types of granular material

The aim of this research is to deepen the knowledge of the role of friction on the dynamics of granular media; in particular the friction angle is taken into consideration as the physical parameter that drives stability, motion and deposition of a set of grains of any nature and size. The idea behind this work is a question: is the friction angle really that fundamental and obvious physical parameter which rules stability and motion of granular media as it seems from most works which deal with particle dynamics? The experimental study tries to answer this question with a series of laboratory tests, in which different natural and artificial granular materials have been investigated in dry condition by means of a tilting flume. The characteristic friction angles, both in deposition(repose) and stability limit(critical) conditions, were measured and checked against size, shape, density and roughness of the considered granular material. The flume tests have been preferred to "classical" geotechnical apparatuses(e.g. shear box) since the flume experimental conditions appear closer to the natural ones of many situations of slope stability interest(e.g. a scree slope). The results reveal that characteristic friction angles depend on size and shape of grains while mixtures of granules of different size show some sorting mechanism with less clear behaviour.

Disaster risk reduction in mountain areas: an initial overview on seeking pathways to global sustainability

As disasters cripple the world’s prospects for sustainable development, protecting the most vulnerable groups exposed to hazards is one of the main challenges facing humanity. Owing to the systemic nature of risk and the interactions and interdependencies between upland and lowland systems, healthy and productive mountain households and livelihoods are essential to global sustainability. This paper argues that, building on existing international frameworks, and integrated knowledge and praxis, the development of a global policy agenda should be established to build sustainable peace, sustainable security, and development.

Disaster risk reduction in mountain areas: a research overview

This paper gives an account of the diverse dimensions of research on disaster risk reduction in mountain regions derived from an open call of the Journal of Mountain Science that brought 21 contributions.This special issue includes topics as diverse as landslide dynamics and mechanisms,landslide inventories and landslide susceptibility models,insights to landslide hazards and disasters and mitigation measures,disaster response and disaster risk reduction.The overall structure of the paper takes the form of three sections.The first part begins by laying out the significance of disaster risk reduction in mountain areas,whereas the second one looks at the research insights on disaster risk reduction in mountains provided by the contributions comprised in the special volume.The final section identifies areas for further research.

Environmental Data Acquisition, Elaboration and Integration： Preliminary Application to a Vulnerable Mountain Landscape and Village （Novalesa, NW Italy）

Climate conditions play a crucial role in the survival of mountain communities, whose survival already critically depends on socioeconomic factors. In the case of montane areas that are prone to natural haz-ards, such as alpine slope failure and debris flows, climatic factors exert a major influence that should be considered when creating appropriate sustainable scenarios. In fact, it has been shown that climate change alters the availability of ecosystem services （ES）, thus increasing the risks of declining soil fertility and reduced water availability, as well as the loss of grassland, potential shifts in regulatory services （e.g., protection from natural hazards）, and cultural services. This study offers a preliminary discussion on a case study of a region in the Italian Alps that is experiencing increased extreme precipitation and erosion, and where an isolated and historically resilient community directly depends on a natural resource econ- omy. Preliminary results show that economic factors have influenced past population trends of the Novalesa community in the Piemonte Region in northwest Italy. However, the increasing number of rock fall and debris flow events, which are triggered by meteo-climatic factors, may further influence the livelihood and weflbeing of this community, and of other similar communities around the world, Therefore, environmental monitoring and data analysis will be important means of detecting trends in landscape and climate change and choosing appropriate planning options. Such analysis, in turn, would ensure the survival of about 10% of the global population, and would also represent a possibility for future economic development in critical areas prone to poverty conditions.

滑坡脆弱性标准：意大利中部翁布里亚区实例研究

世界上许多地区的居民及周围环境虽然频繁遭受滑坡危害，但滑坡脆弱性的问题却鲜为人知。滑坡脆弱性相关信息的缺乏限制了我们对滑坡风险的确定能力。本文提供了意大利中部翁布里亚区内滑坡对建筑物和公路造成的相关的危害信息。本文使用了对翁布里亚区90多个场地的建筑物和公路造成破坏的103个断层的滑坡和土崩-泥流的相关信息，确定滑坡区域与滑坡脆弱性之间的相关性，将得到的相关依据应用于意大利中部Collazzone市有利于进行滑坡填图的周边丘陵地带。利用滑坡编录手段和编制滑坡脆弱性曲线图，绘制滑坡脆弱性的地理分布图和填写计算出的预期损害统计表。本文探讨了脆弱性临界值和获得的脆弱评估值的可靠性和局限性。

基于COSMO SKYMED星座监测阿奎拉地震——以MORFEO项目的DInSAR结果为例

2009年4月6日意大利拉奎拉地区发生Mw6.4级地震。SAR系统已经被证明在分析地震影响以及震前位移方面具有很高的价值。由于形变速率缓慢,震后事件的研究需要多时相差分干涉处理。COSMO/SKYMED星座由4颗X波段合成孔径雷达卫星组成,同时提供民用数据,我们获得了该地区一系列升轨数据,通过两种多时相干涉处理方法(SPINUA法及SBAS法)得到了震后形变图。该项工作在MORFEO框架下进行,MORFEO项目致力于利用地球观测数据监测滑坡。文中对与震后活动有关的位移图进行了解译,结果清楚地展示了利用COSMO/SKYMED星座进行灾害监测的潜力。

Towards hydrometeorological thresholds of reservoir-induced landslide from subsurface strain observations

Synergistic multi-factor early warning of large-scale landslides is a crucial component of geohazard prevention and mitigation efforts in reservoir areas.Landslide forecasting and early warning based on surface displacements have been widely investigated.However,the lack of direct subsurface real-time observations limits our ability to predict critical hydrometeorological conditions that trigger landslide acceleration.In this paper,we leverage subsurface strain data measured by high-resolution fiber optic sensing nerves that were installed in a giant reservoir landslide in the Three Gorges Reservoir(TGR)region,China,spanning a whole hydrologic year since February 2021.The spatiotemporal strain profile has preliminarily identified the slip zones and potential drivers,indicating that high-intensity short-duration rainstorms controlled the landslide kinematics from an observation perspective.Considering the time lag effect,we reexamined and quantified potential controls of accelerated movements using a data-driven approach,which reveals immediate response of landslide deformation to extreme rainfall with a zero-day shift.To identify critical hydrometeorological rules in accelerated movements,accounting for the dual effect of rainfall and reservoir water level variations,we thus construct a landslide prediction model that relies upon the boosting decision tree(BDT)algorithm using a dataset comprising daily rainfall,rainfall intensity,reservoir water level,water level fluctuations,and slip zone strain time series.The results indicate that landslide acceleration is most likely to occur under the conditions of mid-low water levels(i.e.,<169.700 m)and large-amount and high-intensity rainfalls(i.e.,daily rainfall>57.9 mm and rainfall intensity>24.4 mm/h).Moreover,this prediction model allows us to update hydrometeorological thresholds by incorporating the latest monitoring dataset.Standing on the shoulder of this landslide case,our study informs a practical and reliable pathway for georisk early warning based on subsurface observations,particularly in the context of enhanced extreme weather events.

Adopting the margin of stability for space–time landslide prediction–A data-driven approach for generating spatial dynamic thresholds

Shallow landslide initiation typically results from an interplay of dynamic triggering and preparatory conditions along with static predisposition factors.While data-driven methods for assessing landslide susceptibility or for establishing rainfall-triggering thresholds are prevalent,integrating spatiotemporal information for dynamic large-area landslide prediction remains a challenge.The main aim of this research is to generate a dynamic spatial landslide initiation model that operates at a daily scale and explicitly counteracts potential errors in the available landslide data.Unlike previous studies focusing on space–time landslide modelling,it places a strong emphasis on reducing the propagation of landslide data errors into the modelling results,while ensuring interpretable outcomes.It introduces also other noteworthy innovations,such as visualizing the final predictions as dynamic spatial thresholds linked to true positive rates and false alarm rates and by using animations for highlighting its application potential for hindcasting and scenario-building.The initial step involves the creation of a spatio-temporally representative sample of landslide presence and absence observations for the study area of South Tyrol,Italy(7400 km2)within well-investigated terrain.Model setup entails integrating landslide controls that operate on various temporal scales through a binomial Generalized Additive Mixed Model.Model relationships are then interpreted based on variable importance and partial effect plots,while predictive performance is evaluated through various crossvalidation techniques.Optimal and user-defined probability cutpoints are used to establish quantitative thresholds that reflect both,the true positive rate(correctly predicted landslides)and the false positive rate(precipitation periods misclassified as landslide-inducing conditions).The resulting dynamic maps directly visualize landslide threshold exceedance.The model demonstrates high predictive performance while revealing geomorphologically plausible prediction patterns largely consistent with current process knowledge.Notably,the model also shows that generally drier hillslopes exhibit a greater sensitivity to certain precipitation events than regions adapted to wetter conditions.The practical applicability of the approach is demonstrated in a hindcasting and scenario-building context.In the currently evolving field of space–time landslide modelling,we recommend focusing on data error handling,model interpretability,and geomorphic plausibility,rather than allocating excessive resources to algorithm and case study comparisons.

A cautionary note on some phylogenetic dissimilarity measures

Aims Measures of plot-to-plot phylogenetic dissimilarity and beta diversity are providing a powerful tool for understanding the complex ecolog-ical and evolutionary mechanisms that drive community assembly.Methods Here,we review the properties of some previously published dis-similarity measures that are based on minimum or average phylo-genetic dissimilarity between species in different plots.Important Findings We first show that some of these measures violate the basic condi-tion that for two identical plots the measures take the value zero.They also violate the condition that the dissimilarity between two identical plots should always be lower than that between two differ-ent plots.Such erratic behavior renders these measures unsuitable for measuring plot-to-plot phylogenetic dissimilarity.We next pro-pose a new measure that satisfies these conditions,thus providing a more reasonable way for measuring phylogenetic dissimilarity.