Parametrical landslide modeling for the hydrogeological susceptibility assessment: from the Crati Valley to the Cavallerizzo landslide (Southern Italy)

The article deals with a tool for landslides susceptibility assessment as a function of the hydrogeological setting at different scales. The study has been applied to a test area located in Southern Italy. First, a 3D groundwater flow model was implemented for a large-scale area. The simulation of several groundwater conditions compared with the landslide activity map allows drawing a hydrogeological susceptibility map. Then, a slope scale analysis was carried out for the Cavallerizzo landslide. For this purpose, a 2D groundwater parametrical modeling was coupled with a slope stability analysis; the simulation was carried out by changing the values of the main hydrogeological parameters (recharge, groundwater supply level, etc.). The results enabled to connect the slope instability to some hydrogeological characteristics that are easy to survey and to monitor (e.g., rainfall, piezometrical level, and spring discharge), pointing out the hazard thresholds with regards to different triggering phenomena.     

水库滑坡地下水动态响应规律及浸润线计算模型

库水和降雨直接导致水库滑坡地下水变动,是诱发滑坡的主要因素。已有研究大多是基于监测数据探讨库水与降雨对滑坡变形的影响,未能揭示水库滑坡地下水响应规律,地下水浸润线计算模型没有同时考虑降雨和库水的影响,且模型边界条件与水库滑坡实际情况差别较大。为了揭示大型水库滑坡地下水动态响应规律,需要构建更接近实际情况的地下水位浸润线计算模型。通过三峡水库石榴树包滑坡地下水动态监测,揭示了库水水位变化和降雨条件下滑坡地下水水位动态响应规律,其地下水渗流场近似层流,滑坡前缘和中部的地下水水位与库水位几乎同步,滑坡后部的地下水水位主要受降雨影响,日降雨30 mm会引发地下水水位明显变动。在周期性库水位变化和随机降雨耦合条件下,建立了滑坡地下水非稳定渗流微分方程,解算出水库滑坡地下水位浸润线计算模型,并采用实际监测结果进行了验证。应用计算模型分析了不同工况条件下的滑坡渗流场,并得出滑坡内距前缘水平距离145 m内,库水对地下水有影响;引发地下水变动的降雨和库水位变化阈值分别为0.03,0.1 m/d,且不同的条件组合下降雨和库水位对地下水水位影响存在一定差异。     

Landslide hazard zonation by deterministic analysis (Veľká Čausa landslide area, Slovakia)

A practical application of a simple and economical solution to landslide hazard zonation based on slope stability analysis was carried out in the Veľká Čausa landslide, Horná Nitra region, central Slovakia. The region is prone to different types of slope deformation controlled by geological structure, physical and mechanical properties of materials, complicated hydrogeological setting, undulating morphology, and man-made influence. Taking into consideration the cause of the landslide, identified as groundwater change, two scenarios of landslide activity have been investigated. Scenario 1 considers the maximum groundwater level recorded from March 1995 to October 1998, corresponding to the period starting from the most recent landslide activity up to the end of remediation work. Scenario 2 considers the maximum groundwater level recorded from November 1998 to December 2004, after the remediation works, and corresponding to the actual situation of the landslide. It has been found from this study that slope angle has the highest influence on landslide instability in the Veľká Čausa landslide. Therefore, high resolution Digital Elevation Model (DEM) is essential for obtaining reasonable results. In addition, an appropriate selection of the model input parameters (e.g., shear strength) is very important. The validation between the calculated landslide hazard zonation map and results of monitoring survey were examined. The results show moderate to good agreement with the inclinometric and geodetic measurements. It was also verified that the most active part of the landslide is the north-western side.     

天津滨海新区围海造陆对沿海低地浅层地下水环境的影响

天津滨海新区被提到国家总体发展战略后,随着经济持续发展、城市化进程不断加速及产业转移,进行了大规模围海造陆,在拓展土地空间的同时,也造成了相当多的环境问题。利用滨海新区由陆到海的3条水文地质剖面获取的地下水动态变化监测数据和土壤含盐量测试结果,开展了围海造陆对沿海低地浅层地下水环境的影响研究。结果显示:1受围海造陆影响,对应的沿海低地浅层水位已经出现由陆到海逐渐增高的现象,造成地下水位反向倾斜,阻碍了地下水径流和排泄;2由陆到海浅表土壤全盐量出现逐渐增高的特征,在浅层地下水反向径流作用下,东部区域大量的盐分将被携带至沿海低地,使沿海低地盐渍化程度加重,严重影响到湿地保护和生态建设;3围海造陆对海岸带生态环境的影响是一个长期缓慢的过程,应持续监测近岸海域和陆域沿海低地生态环境的变化情况,以便提出合理的修复建议。     

Towards hydrological triggering mechanisms of large deep-seated landslides

It is a widely accepted idea that hydrologically triggered deep-seated landslides are initiated by an increase in pore-water pressure on potential slip surface induced by rising groundwater level after prolonged period of intense rainfall although the process is not fully understood. In order to contribute to better understanding, the rainfall–groundwater relationships, hydrogeological monitoring and repeated geoelectrical imaging were carried out from March 2007 to April 2011 in large deep-seated landslide near ?ubietová (Western Carpathians) catastrophically reactivated at the end of February 1977. Based on our observations, groundwater level (GWL) response to precipitation differs considerably with respect to both overall hydrological conditions and GWL mean depth. While the rate of GWL increase up to 25 cm/day were measured after some rainfall events during wet periods, noticeably lower recharge rate (up to 1–2 cm/day) and delayed GWL response to rainfall (usually from 2 weeks to 2–4 months) were observed at the beginning of the wet season after considerable depression of GWLs due to previous effective rainfall deficit. Likewise, slow GWL fluctuations without short-term oscillations are typical for deeper GWLs. Thus, long-term (several seasons to several years) hydrological conditions affect markedly groundwater response to rainfall events in the studied landslide and can be crucial for its behaviour. Comparison of hydrological conditions characterising the analysed period with those that accompanied the landslide reactivation in 1977 allow us to assume that slightly above-average rainy season following the prolonged wet period can be far more responsible for movement acceleration (and possibly failure initiation) in deep landslides than the isolated season of extreme precipitation following a longer dry period. This is true especially for landslides in regions with significant seasonal temperature changes where potential effective precipitation (PEP), calculated as excess of precipitation (P) over potential evapotranspiration (PET), may be efficiently used for estimation of slope saturation condition.     

Hydrogeological pattern of groundwater flow of landslides in Cretaceous claystones based on long-term groundwater monitoring and hydrologging measurement

Long-term groundwater monitoring has been carried in the model locality of the landslide area at Třebenice, situated in the northern part of the Czech Republic in Cretaceous claystones to marlstones. Primarily, long-term fluctuation of the groundwater and piezometric levels has been monitored. Monitoring of groundwater flow was carried out in selected wells also by the photometry logging method using a dilution technique of a marked liquid. On the basis of these results, the pattern of the groundwater flow through the landslide area was determined in lithologically homogeneous Cretaceous claystones to marlstones. Interpretation of monitoring results indicated that water flows preferentially through the zone of near-surface loosening of the claystone rock massif, in general parallel to the slope inclination between 8 and 10-m depth below ground level. This zone exhibits a higher permeability given by 1–2 orders of hydraulic conductivity compared with overlying strata and underlying rock in which this zone is closed. This verified pattern of groundwater flow has a significant effect on the stability of the sliding slope and it is one of the main factors affecting the evolution of landslides on the slopes formed by these rocks.     

利用NMR研究三峡工程库区赵树岭滑坡稳定性

核磁共振找水仪(NMR)应用于滑坡地下水研究具有广泛的前景。本文以三峡工程库区巴东县赵树岭滑坡为例,说明利用NMR测试成果确定岩土层水文地质参数的方法,同时根据滑体含水量变化特征,进行滑坡的地下水含水层划分、滑动面确定,改进滑坡稳定性计算。利用NMR测试所测定的滑坡体地下水特征,进行赵树岭滑坡刚体极限平衡分析和有限元数值模拟,结果表明地下水特征对滑坡稳定影响很大,利用NMR可以更准确和有效地进行滑坡稳定性研究。     

Main progress and prospect for China's hydrogeological survey

This paper reviewed the main achievements of hydrogeological survey in China, summarized the significant progress of hydrogeological survey over the past decade, and forecasted the key responsibilities for hydrogeological survey in the p14th Five-year Planq. The significant progress includes: China established the 1: 50 000 standard hydrogeological survey system with Chinese characteristics and produced the new generation of high-quality hydrogeological maps; the national groundwater monitoring project was completed and accepted, which marks China taking the leading position in groundwater monitoring internationally; fruitful results were achieved in the national groundwater quality survey, and groundwater quality background values were basically identified and checked; hydrogeological and environmental geological survey was continuously promoted in karst areas and the ecological restoration of rocky desertification achieved remarkable results; China strengthened layer exploration techniques for groundwater, integrating the key and practical techniques of layer exploration and monitoring; the exploration of groundwater in the poverty-stricken regions and old revolutionary base areas were effectively promoted to strongly guarantee the poverty alleviation and drinking water safety; the mystery of desert groundwater was uncovered, making up for the shortage of 1: 250 000 hydrogeological survey in the Badain Jaran Desert; and more efforts were made to conduct survey on the water resources in the basin, and to finish the unified measurement of national-scale groundwater level.     

矿区水文地质研究进展及中长期发展方向

矿区水资源保护和矿山防治水这两个互相矛盾又紧密联系的问题给传统的矿山水文地质学带来了更多的挑战和机遇,迫切需要新理论、新技术的发展。为了更好的实现矿区未来地下水资源的开采、利用与保护以及采煤安全和区域水资源可持续利用,本文选择长治盆地为重点研究区,从采动引起的覆岩移动入手,在资料分析的基础上,采用相似材料模拟、综合物探、野外监测、现场注(压)水试验的方法,运用水文地质学原理研究了采煤引起含水层结构变异厚度及其渗透性变化特征;在此基础上,以长治盆地集中开采区水文地质条件和野外监测数据为基础,建立了区域地下水流场三维动态模拟试验台,为研究含水层结构变异后的地下水循环机理和水资源重新分布提供技术支撑;本文同时指出了我国矿山水文地质研究目前存在的问题和面临的挑战,分析了矿山水文地质学科的发展趋势,展望了未来相关分支学科和关键核心技术的发展方向与前景。     

位移-应力协同分析在新近纪软岩质滑坡监测中的应用——以陕西宝鸡市北坡滑坡为例

强降雨可诱发新近纪软岩质滑坡滑移变形。1955年至今,降雨在陕西宝鸡诱发超过十起大型滑坡灾害。2011年9月19日,宝鸡市区72 h内的降雨量达到332 mm,北坡金鼎寺、簸箕山与高家崖滑坡出现裂缝,威胁市区居民安全。为分析滑坡的变形机制与降雨触发的滑体内地下水位的波动关系,2012—2015年,开展了降雨量、地下水位、孔隙水压力、滑坡应力与位移等物理量的实时监测,统计分析了它们的频率、活动强度及累积变化规律,提出了滑坡的位移扩展模型。研究显示:(1)地下水的活动会影响新近纪软岩质滑坡的变形,但降雨量、地下水位、孔隙水压力、滑坡体应力与位移等物理量变化机制有差异,地下水位、孔隙水压力呈周期性变化,滑坡体的应力、位移的变化具有累积效应;(2)宝鸡市北坡滑坡运动变形具有蠕变、快速滑移两个阶段。降雨会触发的滑坡体各物理量出现加速变化,地下水位波动幅度为0.27~1m,孔隙水压力的变化幅度为10kPa,滑体浅层的水平应力变化幅度为5.6kPa;(3)在判断降雨能否诱发滑坡快速滑移过程中,既需分析滑体应力、位移变化的累积效应,又需分析新近纪软岩质滑带的摩擦破坏机制。     

水文地质及灾害地质监测新仪器介绍

本文介绍了地下水监测和滑坡监测的两种新型仪器。ＷＬＴ－１０２０地下水动态监测仪器的突出特点是高分辨率、长期稳定、微功耗、全自动工作。ＨＹＪ－３００８滑坡诱发因素监测仪通过监测滑体内的水分变化来预测预报暴雨滑坡。     

白洋淀湖岸带地表水与地下水垂向交换研究

地表水与地下水相互转化关系一直是水文地质研究的热点问题。以往研究更多关注河流的河岸带,但对于相对静止水体——湖泊的湖岸带研究相对偏少。选择白洋淀湖岸带作为研究对象,在周边湖岸带系统部署水位、水温监测系统,采用温度示踪法,开展白洋淀湖岸带区域的地表水与地下水垂向交换量化研究。同时,结合达西定律,间接反演获取垂向渗透系数,系统总结出一套联合利用温度示踪法和达西定律定量研究湿地垂向水交换的方法。结果表明,白洋淀湖岸带以地表水渗漏补给地下水为主,其垂向交换流速可达0.2～1.1 cm/d,沉积岩性主要为粉质黏土、粉土及粉细砂,垂向渗透系数为0.038～0.912 m/d。研究结果可为制定白洋淀湿地补水方案和生态环境保护措施提供基础数据支撑。     

地下水诱发渐进后退式黄土滑坡成因机理研究——以甘肃黑方台灌溉型黄土滑坡为例

黑方台位于我国甘肃省永靖县,该区由于长期灌溉导致地下水位上升,诱发了大量的黄土滑坡,其中最典型的一类滑坡为渐进后退式黄土滑坡。通过对比代表性滑坡多期Google影像,并结合现场调查分析了近年来新发生的滑坡,发现该类黄土滑坡具有典型的渐进后退式演化过程。现场调查和对典型滑坡剖面黄土含水率的实测发现,黄土层底部受地下水的长期浸泡软化所形成的软基效应是使黄土滑坡不断发生的主要原因,而滑坡发生后留下的弧形凹槽往往成为地下水局部集中汇聚和排泄点,滑源区被滑坡残留体覆盖导致地下水位局部雍高上涨,将导致同一滑坡发生多次渐进后退式破坏。     

准噶尔盆地南缘煤系水矿化度对低煤阶煤层气的影响

煤系水矿化度是影响低煤阶煤层气生成、运移和成藏的重要因素之一。以新疆准噶尔盆地南缘地区为研究区,把研究区划分为8个水文地质单元,分析了研究区煤系水矿化度的分布特征及其对产甲烷菌生存的影响。以1 000 m埋深为例,估算了各个水文地质单元内煤系水的甲烷溶解度,据此分析评价了各水文地质单元溶解运移甲烷的能力。通过煤系水的矿化度分布、氯离子浓度和区域地质构造形态分析,综合判断区域内煤系水的大致流向。以准南地区硫磺沟水文地质单元为例,探讨了矿化度与煤层气富集成藏的关系。研究结果表明,研究区矿化度分布具有南北分带、东西分段的特征。后峡水文地质单元、玛纳斯河-呼图壁河水文地质单元的南部、硫磺沟水文地质单元的南端和阜康水文地质单元的西部地区矿化度有利于产甲烷菌的生存和产气。后峡水文地质单元溶解运移甲烷能力最强。地下水的流向大致由南向北,地表水的径流会使地下水流向发生偏转。指出了硫磺沟水文地质单元内高矿化度中心和低水位的汇水洼地是低煤阶煤层气富集成藏的地区。      

三峡库区树坪滑坡变形失稳机制分析

树坪滑坡自2003年三峡水库蓄水以来,就一直持续变形。为了对其稳定性及变形发展趋势进行评价和预测,有必要对其变形失稳机制进行深入研究。为此,采用现场地质调查和勘探的方法确定了滑坡的形态和性质;充分挖掘变形监测数据,详细分析了滑坡的变形特征。在此基础上,深入研究了变形失稳机制及影响因素,并对滑坡的稳定性进行了计算和预测。结果表明,滑坡区地形、岩性及地质构造等地质因素控制了树坪滑坡的形成和发展;库水位下降和大气降雨进一步激励了滑坡的变形。库水位下降,坡体内地下水位随之下降,但其速度远小于库水位下降速度,导致坡体内水力梯度和渗透力明显增大,从而使滑坡稳定性急剧下降,并且库水位下降速度越快,滑坡的位移速率也越大,是典型的水库下降型滑坡。在库水位下降过程中,若出现明显的降雨过程,更加剧了滑坡的变形,有产生大规模滑动的可能性,须采取防护治理措施。     

地下水与环境变化研究

环境变化研究是当前国际地球科学和环境科学界最为活跃的研究领域之一。作为全球水循环的重要环节,地下水是全球环境变化的受体和信息载体。地下水及其沉积物的物理、化学指标,诸如地下水水位、宏量组分、微量组分、同位素、惰性气体等可以用作不同时间尺度上环境变化的指示剂。从地下水及其沉积物中识别和提取高分辨率的环境变化信息,实现对环境变化的预警功能是地下水科学向环境科学延伸的重要方向;而随着全球淡水资源紧缺形势不断恶化,全球环境变化、特别是全球气候变化对地下水资源的影响成为水文地质研究的新课题。     

Lanslide hydrogeological susceptibility of Maierato (Vibo Valentia, Southern Italy)

A large landslide occurred at Maierato (Vibo Valencia District), Southern Italy, on 15 February 2010, when rapid failure was produced after several days of preliminary movements. The landslide can be classified as a rotational slide with flowing of the mass. It occurred within a larger deep-seated gravitational movement area and was preconditioned for failure by the intrinsic geological weakness of the area. Actually, the in situ survey showed the presence of several ancient movement surfaces all around the urban area. The landslide-triggering factor was the increase in the groundwater flow, consequent to a period of heavy and prolonged rainfall. The aim of the paper is to explain the mechanism of occurrence of the February 2010 composite landslide, in order to assess the landslide hydrogeological susceptibility in the whole urban area of Maierato. For this reason, the present paper deals with: (1) identification of the landslide mechanism and triggering factors (2) slope stability back-analysis using a finite-difference-based shear strength reduction method, and (3) 3D groundwater flow modelling extended to the whole urban area both in pre- and post-failure conditions. The results show that the February 2010 composite landslide was triggered by a water table increase of about 15 m uphill the landslide scarp. This hydrogeological condition could be reached after the period of heavy and prolonged rainfall preceding the landslide event. Finally, based on the groundwater modelling in post-failure condition, a landslide hydrogeological susceptibility map was drawn for the all urban area of Maierato, showing the presence of extended areas exposed to hazard.     

A graphic expression of salinization and pollution of groundwater The case of Israel's groundwater

 Anthropogenic activities create various contaminated leachate, which can migrate downward from the vadose zone to groundwater, transferring contaminants, including some hazardous ones. When these various sources of contamination influence the groundwater aquifer simultaneously, the effects of contamination are enhanced. The major concern of this study has been to determine whether the shape of a groundwater chlorograph might be the result of such deterministic effects as accumulation of one or more particular processes of groundwater contamination, and how this might relate to specific hydrological situations. This study proposes a classification of groundwater contamination on the basis of properties of the main components of groundwater quality graphs and the corresponding hydrogeological/environmental situation. The study further suggests that contamination of groundwater in any hydrogeological situation (e.g. sea water) may be graphically expressed. A variety of chlorographs and nitrographs, representative of various groundwater aquifers sampled from a number of wells throughout Israel attest to this. The study thus indicates that groundwater quality graphs may be considered as a complementary tool for groundwater quality control and better understanding aquifer situations.     

高放废物处置库甘肃北山预选区水文地质特征研究

在高放废物深地质处置中，地下不是核素迁移的重要媒介。因此，水文地质工作是处置库选址中的主要内容之一。本文依据几年来的野外调查及前人的部分资料，阐明了我国高放废物处置库甘肃北山预选区的基本水文地质概况，以及地下水的循环交替条件和化学特征。研究表明，弱含水、低渗透、慢流速是区内主要水文地质特征，蒸发浓缩形成的高矿化是地下水的主要化学面貌。这一认识，为处置库选址提供了重要依据。     

Physically based hydrogeological and slope stability modeling of the Turaida castle mound

This study explores the potential of integrating state-of-the-art physically based hydrogeological modeling into slope stability simulations to identify the hydrogeological triggers of landslides. Hydrogeological models considering detailed morphological, lithological, and climatic factors were elaborated. Groundwater modeling reveals locations with elevated pore water pressures in the subsurface and allows the quantification of temporal dynamics of the pore water pressures. Results of the hydrogeological modeling were subsequently applied as boundary conditions for the slope stability simulations. The numerical models illustrate that the hydrogeological impacts affecting hillslope stability are strongly controlled by local groundwater flow conditions and their conceptualization approach in the hydrogeological model. Groundwater flow itself is heavily influenced by the inherent geological conditions and the dynamics of climatic forcing. Therefore, both detailed investigation of the landslide’s hydrogeology and appropriate conceptualization and scaling of hydrogeological settings in a numerical model are essential to avoid an underestimation of the landslide risk. The study demonstrates the large potential in combining state-of-the-art computational hydrology with slope stability modeling in real-world cases.