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1.
The state of knowledge and resources available to issue alerts of precipitation-induced landslides vary across the USA. Federal
and state agencies currently issue warnings of the potential for shallow, rapidly moving landslides and debris flows in a
few areas along the Pacific coast and for areas affected by Atlantic hurricanes. However, these agencies generally lack resources
needed to provide continuous support or to expand services to other areas. Precipitation thresholds that form the basis of
landslide warning systems now exist for a few areas of the USA, but the threshold rainfall amounts and durations vary over
three orders of magnitude nationwide and over an order of magnitude across small geographic areas such as a county. Antecedent
moisture conditions also have a significant effect, particularly in areas that have distinct wet and dry seasons. Early warnings
of shallow landslides that include specific information about affected areas, probability of landslide occurrence, and expected
timing are technically feasible as illustrated by a case study from the Seattle, WA area. The four-level warning scheme (Null,
Outlook, Watch, Warning) defined for Seattle is based on observed or predicted exceedance of a cumulative precipitation threshold
and a rainfall intensity–duration threshold combined with real-time monitoring of soil moisture. Based on analysis of historical
data, threshold performance varies according to precipitation characteristics, and threshold exceedance corresponds to a given
probability of landslide occurrence. Experience in Seattle during December 2004 and January 2005 illustrates some of the challenges
of providing landslide early warning on the USA West Coast. 相似文献
2.
提高降雨型滑坡危险性预警精度和空间辨识度具有重要意义.以江西宁都县1980—2001年156个降雨型滑坡为例,首先基于传统的EE-D(early effective rainfall-rainfall duration)阈值法计算不同降雨诱发滑坡的时间概率级别;然后以各级别临界降雨阈值曲线对应的时间概率为因变量,并以对应的前期有效降雨量(early effective rainfall,EE)和降雨历时(D)为自变量,采用逻辑回归拟合出上述因变量与自变量之间的非线性关系,得到降雨诱发滑坡的连续概率值;之后对比C5.0决策树和多层感知器的滑坡易发性预测性能;最后利用降雨诱发滑坡的连续概率值与易发性图相耦合以实现连续概率滑坡危险性预警.结果显示：(1)宁都降雨型滑坡连续概率值的逻辑回归方程为1/P=1+e4.062+0.747 4×D-0.079 44×EE,其拟合优度为0.983;(2)2002—2003年的20处用于连续概率阈值测试的降雨型滑坡大都落在连续概率值大于0.7的区域,只有4处落在小于0.7的区域;(3)C5.0决策树预测滑坡易发性的精度显著高于多层感知... 相似文献
3.
The state of knowledge and resources available to issue alerts of precipitation-induced landslides vary across the USA. Federal and state agencies currently issue warnings of the potential for shallow, rapidly moving landslides and debris flows in a few areas along the Pacific coast and for areas affected by Atlantic hurricanes. However, these agencies generally lack resources needed to provide continuous support or to expand services to other areas. Precipitation thresholds that form the basis of landslide warning systems now exist for a few areas of the USA, but the threshold rainfall amounts and durations vary over three orders of magnitude nationwide and over an order of magnitude across small geographic areas such as a county. Antecedent moisture conditions also have a significant effect, particularly in areas that have distinct wet and dry seasons. Early warnings of shallow landslides that include specific information about affected areas, probability of landslide occurrence, and expected timing are technically feasible as illustrated by a case study from the Seattle, WA area. The four-level warning scheme (Null, Outlook, Watch, Warning) defined for Seattle is based on observed or predicted exceedance of a cumulative precipitation threshold and a rainfall intensity–duration threshold combined with real-time monitoring of soil moisture. Based on analysis of historical data, threshold performance varies according to precipitation characteristics, and threshold exceedance corresponds to a given probability of landslide occurrence. Experience in Seattle during December 2004 and January 2005 illustrates some of the challenges of providing landslide early warning on the USA West Coast. 相似文献
4.
Regional prediction of landslide hazard using probability analysis of intense rainfall in the Hoa Binh province, Vietnam 总被引：6，自引：2，他引：4
Dieu Tien Bui Biswajeet Pradhan Owe Lofman Inge Revhaug Øystein B. Dick 《Natural Hazards》2013,66(2):707-730
The main objective of this study is to assess regional landslide hazards in the Hoa Binh province of Vietnam. A landslide inventory map was constructed from various sources with data mainly for a period of 21 years from 1990 to 2010. The historic inventory of these failures shows that rainfall is the main triggering factor in this region. The probability of the occurrence of episodes of rainfall and the rainfall threshold were deduced from records of rainfall for the aforementioned period. The rainfall threshold model was generated based on daily and cumulative values of antecedent rainfall of the landslide events. The result shows that 15-day antecedent rainfall gives the best fit for the existing landslides in the inventory. The rainfall threshold model was validated using the rainfall and landslide events that occurred in 2010 that were not considered in building the threshold model. The result was used for estimating temporal probability of a landslide to occur using a Poisson probability model. Prior to this work, five landslide susceptibility maps were constructed for the study area using support vector machines, logistic regression, evidential belief functions, Bayesian-regularized neural networks, and neuro-fuzzy models. These susceptibility maps provide information on the spatial prediction probability of landslide occurrence in the area. Finally, landslide hazard maps were generated by integrating the spatial and the temporal probability of landslide. A total of 15 specific landslide hazard maps were generated considering three time periods of 1, 3, and 5 years. 相似文献
5.
根据给定渗透系数、孔隙度以及吸附系数的概率分布,采用顺序高斯模拟生成相关的多参数随机场的实现,作为地下水流和溶质运移模型的输入参数,对污染物浓度进行随机分析。研究结果表明,与仅考虑渗透系数空间变异性相比,考虑相关的多参数空间变异性导致污染羽的扩散程度有显著不同。当孔隙度与渗透系数呈正相关关系时,会减少污染羽的扩散程度,反之,当孔隙度与渗透系数为负相关关系时,会加剧污染羽的扩散程度。吸附系数也是如此。在考虑吸附系数的空间变异性之后,污染羽的分布表现出拖尾现象。同时考虑渗透系数、孔隙度以及吸附系数空间变异性时,孔隙度非均质性对溶质运移的影响较吸附系数非均质性的影响更大。 相似文献
6.
A geographic information system (GIS) raster technique has been developed and used interactively with remediation designers to evaluate the optimum extent of excavating soil contaminated by chlorinated solvents. The technique and the results of its application are presented. The site was a former chemical storage plant for acids and solvents. Two distinct solvent plumes were detected within the ground using a photo-ionisation detector. The solvents were found to be dissolved in the groundwater and migrating in the general direction of groundwater flow. A remediation strategy was proposed involving the localised excavation of contamination ‘hot spots’ followed by the implementation of a groundwater remediation system. A number of excavation options were discussed and the GIS raster technique was developed to evaluate these options in terms of contaminant removed and excavation cost.
The plumes were initially mapped using a triangular irregular network (TIN). These TIN models were rasterised to produce a regular grid of rectangular cells, each cell having a value relating to the concentration of contaminant at that spatial point. The proposed excavation zones were then overlaid on to the raster models as masks. The relationship between the value of contaminant concentration of cells within the mask (or excavation zone) and the total value of contaminant concentration of cells within the solvent plume was used to determine the efficiency of the excavation.
The excavation options were compared taking into account the percentage of the contaminant plume removed, the excavation area (soil volumes) and related costs. Once the GIS raster technique had been developed, it proved very quick to rerun the analysis for the other excavation zones. The optimum excavation zone, based upon cost and contaminant recovery, was found for the site. The technique helped by targeting the worst area of contamination and provided the client with a cost-benefit analysis of the different remediation options. 相似文献
7.
泥石流灾害合理的雨量预警阈值不仅与历史泥石流灾害发生时的降雨量有关,且与研究区域的气候、地形地貌、地质、植被等密切相关。论文采用雨场分割法和GIS技术研究了影响泥石流启动的降雨和地质背景两大因素,在对北京市泥石流灾害易发分区的基础上,结合北京地区已发生的82起泥石流的易发性分区和雨量值,提出了不同泥石流易发等级条件下的雨量预警阈值。研究成果已经在2015年7月17日北京房山区西区沟泥石流预警中成功应用,为泥石流区域预警预报提供了一种新的思路。 相似文献
8.
S. J. Appleyard 《Environmental Geology》1996,28(2):106-110
Drilling of 15 boreholes at a disused liquid waste disposal site near Perth, Western Australia, has indicated that a contamination
plume extends about 1000 m in a southerly direction from the site in the direction of groundwater flow. The plume is up to
600 m wide and 5–40 m thick. Chemical and microbiological analyses have indicated that contaminated groundwater contains high
concentrations of ammonia, iron, and bacteria at levels that commonly exceed national drinking water guidelines. It is likely
that a proposed water supply production well in the path of the contamination plume will have to be abandoned, and additional
wells may have to be abandoned if the plume continues to extend in the direction of groundwater flow. There is currently insufficient
information to indicate whether the plume is continuing to expand, but studies on similar plumes in the Perth metropolitan
area have indicated that contaminated groundwater can move at rates up to 100 m yr–1. Several other liquid waste disposal sites are now located in residential areas of Perth where wells are used for garden
irrigation. Further work is required to ensure that there is no potential impact of groundwater contamination on public health
in these areas.
Received: 31 July 1995 · Accepted: 18 September 1995 相似文献
9.
The threshold between geochemical background and anomalies can be influenced by the methodology selected for its estimation. Environmental evaluations, particularly those conducted in mineralized areas, must consider this when trying to determinate the natural geochemical status of a study area, quantifying human impacts, or establishing soil restoration values for contaminated sites. Some methods in environmental geochemistry incorporate the premise that anomalies (natural or anthropogenic) and background data are characterized by their own probabilistic distributions. One of these methods uses exploratory data analysis (EDA) on regional geochemical data sets coupled with a geographic information system (GIS) to spatially understand the processes that influence the geochemical landscape in a technique that can be called a spatial data analysis (SDA). This EDA–SDA methodology was used to establish the regional background range from the area of Catorce–Matehuala in north-central Mexico. Probability plots of the data, particularly for those areas affected by human activities, show that the regional geochemical background population is composed of smaller subpopulations associated with factors such as soil type and parent material. This paper demonstrates that the EDA–SDA method offers more certainty in defining thresholds between geochemical background and anomaly than a numeric technique, making it a useful tool for regional geochemical landscape analysis and environmental geochemistry studies. 相似文献
10.
Identifying sources of chlorinated aliphatic hydrocarbons in a residential area in Italy using the integral pumping test method 总被引：1，自引：0，他引：1
The results of integral pumping tests (IPTs) performed in the city of Fabriano, Italy, are presented. The IPT methodology was developed by the European Union project INCORE, as a tool for groundwater investigation and source localization in contaminated areas. This methodology consists of a multiple-well pumping test in which the wells are positioned along a control plane downstream of suspected contaminant source zones and perpendicular to the mean groundwater flow direction. During the pumping, concentration time series of target contaminants are measured. In Fabriano, two control planes were realized to identify a chlorinated aliphatic hydrocarbon plume, to estimate the mass fluxes and draw up a ranked list of the main contamination sources. A numerical flow model was implemented to support the IPT design and to interpret the results. This study revealed low-level trichloroethylene contamination (concentration below 8 μg/l), tetrachloroethylene contamination (mean concentration up to 500 μg/l) and a mass flow rate of about 300 g/day. Through the application of the IPT method, the mean contaminant concentrations, the spatial distribution of concentration values along the control planes, and the total contaminant mass flow rates were evaluated, and the investigation area was reduced for further and deeper investigation activities. 相似文献
11.
The Mahoning River is one of the five most contaminated rivers in the U.S. This study characterized the contaminated sediments in the river banks and investigated the hydraulic interconnection between shallow aquifer in the banks with the river water. The study was conducted along the most polluted section of the river, which is 50-km long, using over 50 monitoring wells. The characterization part of the study investigated the sedimentology, hydraulic conductivity, and spatial distribution of the contaminated sediments. Results of the characterization revealed that the contaminated sediments consist of fine-grained sand, silt, mud, and clay. The spatial distribution of the contaminated sediment is heterogeneous and positively correlates with the hydraulic conductivity values, i.e., the greatest contamination occurs in high conductivity areas. Hydraulic conductivity was determined by the Hazen formula using 82 sediment samples. Bioremediation, which is one of the remedial options considered for the banks, is found to be hydraulically feasible because of sufficient hydraulic conductivity values (≥10?4 cm/s) that ensure reasonable rates of nutrient delivery. Monitoring of water levels in the river and groundwater for a 10-month period shows that flow occurs from the river to groundwater and vice versa. The exchange of flow is influenced by rainfall. Flow of groundwater to the river will continually transport the dissolved contaminants in groundwater to the river. Therefore, findings of this study show that one of the remedial options that proposes dredging of channel sediments and permits no action for bank sediments cannot be chosen due to river water–groundwater interactions. 相似文献
12.
13.
Groundwater contamination: risk management and assessment for landfills in Mar del Plata, Argentina 总被引：3，自引：0，他引：3
This study presents a program for risk management in the contamination of groundwater resulting from leachate in landfills
at Mar del Plata (Argentina). The program includes prediction, prevention, monitory observation and mitigation as actions
that must be taken prior to, during, and after contamination occurs. This routine aids in the identification of weak points
and failures of the program for those who are in charge of making decisions, and will allow better use of limited financial
and technical resources based on planning, thus minimizing disconnected determinations.
Results of the prediction stage were confirmed through monitoring. The presence of a plume of contamination more than 100 m
from the landfill was shown, thus proving that implementation of a monitoring plan to follow the development of the contaminated
plume must be implemented, particularly in populated areas which depend on residential wells for their water supply.
Received: 8 May 2000 · Accepted: 14 August 2000 相似文献
14.
以安徽旌德-宁国地区大气干湿沉降物为研究对象,共采集6处干湿沉降物样品24件,对大气干湿沉降元素含量特征、通量特征进行对比分析,对干湿沉降元素含量及分布特征加以统计研究,并开展大气干湿沉降环境地球化学评价.结果显示：1）大气干湿沉降元素主要以矿物相形式存在或吸附在固体颗粒上,且受周边环境影响;2）干沉降中Cd、Se的高含量会对研究区土壤污染造成较大影响,湿沉降中部分样点pH超灌溉水水质标准,所有点均达到地表水Ⅱ类环境质量标准;3）区内重金属元素年沉降通量密度为,As年沉降通量低,Hg、Ni、Pb、Cr、Cu、Cd偏低,Zn偏高;4）大气干湿沉降重金属元素通量一般表现为丘陵山区小于城镇及工矿区,主要受燃煤燃烧、尾气排放及人为活动等影响;5）大气干湿沉降物环境地球化学单指标和综合指标评价结果均为一等. 相似文献
15.
Mapping groundwater contamination risk using GIS and groundwater modelling. A case study from the Gaza Strip, Palestine 总被引：1，自引：1，他引：0
Husam Musa Baalousha 《Arabian Journal of Geosciences》2011,4(3-4):483-494
Increasing pressure on water resources worldwide has resulted in groundwater contamination, and thus the deterioration of the groundwater resources and a threat to the public health. Risk mapping of groundwater contamination is an important tool for groundwater protection, land use management, and public health. This study presents a new approach for groundwater contamination risk mapping, based on hydrogeological setting, land use, contamination load, and groundwater modelling. The risk map is a product of probability of contamination and impact. This approach was applied on the Gaza Strip area in Palestine as a case study. A spatial analyst tool within Geographical Information System (GIS) was used to interpolate and manipulate data to develop GIS maps of vulnerability, land use, and contamination impact. A groundwater flow model for the area of study was also used to track the flow and to delineate the capture zones of public wells. The results show that areas of highest contamination risk occur in the southern cities of Khan Yunis and Rafah. The majority of public wells are located in an intermediate risk zone and four wells are in a high risk zone. 相似文献
16.
Cost-benefit analysis can be used to identify the optimum remedial strategy for contaminated groundwater, but requires that the benefits of remedial action be quantified. When the groundwater is located in an unused part of an aquifer, it can be difficult to estimate the economic loss of resource. ‘Option values’, which represent the value placed on groundwater for possible future use, may be used. Calculation of the overall loss requires consideration of the spatial (physical) extent of an aquifer where groundwater use is constrained by the presence of contamination and economic elements. An approach is presented for estimating the spatial element, represented as the annualised abstraction loss from the groundwater resource. Two distinct components have been identified based on the potential restriction on location of a new abstraction well: (1) the direct resource loss, which relates to the contaminated zone of the aquifer within which new abstraction is no longer an option, and, (2) the indirect location loss, which relates to the loss of an opportunity to site a new abstraction well in the surrounding uncontaminated aquifer due to the presence of the plume. Methods are presented for their calculation and the approach is illustrated with a case study. 相似文献
17.
地区线性矩法(Regional L-moments Analysis,RLMA)是目前最先进的频率估算方法之一,自20世纪90年代起被广泛应用于美国及其他一些国家的防洪设计标准的分析计算中;我国近年也在太湖流域暴雨频率分析中成功地采用推广了这一水文气象途径的频率计算方法,积累了实际经验。但是,由于地面雨量站点有限、资料长度有限以及站点空间分布的不均匀等问题,研究区中相邻水文气象一致区之间暴雨频率估算值会出现空间不连续性的现象,这个空间不一致的问题尚没有得到合理的解决。在简要介绍地区线性矩法推求频率估计值的基础上,着重讨论并介绍一种概念清楚、简单易操作的基于空间往返二次内插的校正方法,来解决频率估算值空间不连续的问题。这种空间内插平差主要通过构造一个与研究区实测站点控制面积相应分辨率的虚拟网格站网来实现。研究结果表明,经过平差后校正的研究区内各站点的频率估计值的经验频率与理论概率更加接近,频率估计值的空间分布也更加合理。 相似文献
18.
Case study: a 3D resistivity and induced polarization imaging from downstream a waste disposal site in Brazil 总被引：2，自引：2，他引：0
Andréa Teixeira Ustra Vagner Roberto Elis Giulliana Mondelli Lázaro Valentin Zuquette Heraldo Luiz Giacheti 《Environmental Earth Sciences》2012,66(3):763-772
A contaminated site from a downstream municipal solid waste disposal site in Brazil was investigated by using a 3D resistivity and induced polarization (IP) imaging technique. This investigation purpose was to detect and delineate contamination plume produced by wastes. The area was selected based on previous geophysical investigations, and chemical analyses carried out in the site, indicating the presence of a contamination plume in the area. Resistivity model has successfully imaged waste presence (ρ < 20 Ωm), water table depth, and groundwater flow direction. A conductive anomaly (ρ < 20 Ωm) outside wastes placement was interpreted as a contamination plume. Chargeability model was also able to imaging waste presence (m > 31 mV/V), water table depth, and groundwater flow direction. A higher chargeability zone (m > 31 mV/V) outside wastes placement and following conductive anomaly was interpreted as a contamination plume. Normalized chargeability (MN = m/ρ) confirmed polarizable zone, which could be an effect of a salinity increase (contamination plume), and the clay presence in the environment. 相似文献
19.
This paper is concerned with the estimation of the removal efficiency of PM10 by large-scale precipitation under no-wind conditions in a background (rural) and urban areas. The changes in PM10 concentrations before, during and after the presence of rainfall were studied from 2007 to 2013. The study was conducted in two different locations identified with regard to air quality. DAVIS weather stations were used to determine the meteorological conditions. The concentration of PM10 was calculated with the use of the gravimetric reference method. Two hundred and ninety-nine measurement series were carried out. A linear relationship was found between the intensity and duration of rainfall and the value of the removal coefficient (ΔC). It was proved that except light rains, for the near-to-ground troposphere, the effectiveness of the removal of PM10 (ΔC) did not assume different values at various locations for rainfall with the same intensity and duration. It was found that a temporary interaction of the effect of the purification by wet deposition was being minimised in areas characterised by low air quality. It was confirmed that intense rains resulted in the maintenance of higher values of air quality. 相似文献
20.
台风暴雨型滑坡降雨阈值曲线研究以福建地区为例 总被引：3，自引：0，他引：3
台风暴雨型滑坡具有群发性、规模小、爆发性强的特点,容易造成严重的人员伤亡和巨大的财产损失。本文应用极值理论分析,以极端降雨重现期的极大值作为标准并计算有效的降雨区间,通过统计分析,确定触发暴雨型滑坡的降雨阈值曲线。应用模型对福建地区台风暴雨型滑坡进行了分析,福建省3个灾害高发区为:南平三明地区、泉州地区和宁德地区。南平三明地区降雨阈值较高,但发生的滑坡数量较多,主要以3d的降雨为主;泉州地区小于3d的连续降雨和大于8d的连续降雨是触发该地滑坡的主要降雨区间;宁德地区对短期降雨较为敏感,滑坡主要由1d的降雨引起。比较分析研究表明,台风地区触发滑坡的降雨阈值要高于非台风地区。降雨型滑坡阈值主要受气候,地质和土壤厚度影响,气候因素为主控因素。 相似文献