DRASTIC模型在贵州省毕节地段浅层地下水脆弱性评价中的应用

为了实现贵州省毕节地段地下水系统脆弱性评价的直观展示,选取含水层埋深、含水层补给、含水层介质类型、土壤介质类型、坡度、包气带厚度和渗透系数七项评价因子,采用DRASTIC模型建立了地下水系统脆弱性评价模型,通过模糊层次分析法(FAHP)确定了评价因子的权重,并基于ArcGIS软件对毕节地段地下水资源的各项数据指标进行了矢量化,实现了毕节地段地下水脆弱性等级划分的直观性分布图。评价结果表明,该区域地下水脆弱性较高且分布不均。     

地下水脆弱性影响因素探析

研究了水文地质条件和人类社会对地下水的影响,并对本质和特殊两种脆弱性的评价方法进行了阐述,分析了影响地下水脆弱性的因素,总结了目前评价体系存在的缺陷,为今后合理利用地下水提供了思路。     

模糊综合评价方法在地下水脆弱性评价中的应用

地下水脆弱性研究是保护地下水环境工作的基础.对地下水脆弱性进行评价,可为合理地保护、开发和利用地下水资源,实现地下水资源的可持续利用提供有益参考.应用改进AHP法确定权重系数,采用基于模糊数学的模糊综合评价识别模型对青岛大沽河地下水源脆弱性进行评价分析,得出的结果将对大沽河地下水源的保护与治理提供重要理论依据和数据参考.     

DRASTIC在某地下水水源地脆弱性评价中的应用

为了了解某地下水备用水源地取水含水层的地下水脆弱性,首先根据资料收集和实地调查来确定水源地的含水层介质、上层土壤介质、包气带介质、含水层埋深和坡度,之后通过地下水数值模型反演出净补给量和渗透系数,最后利用DRAS-TIC方法对某地下水备用水源地取水含水层的地下水脆弱性进行评价.结果表明,取水含水层的地下水脆弱性指数介于...     

太原市盆地区浅层地下水脆弱性评价

本文从影响地下水脆弱性的因素出发,结合国内外已有的地下水脆弱性影响因素、评价指标和评价标准,根据研究区的具体实际情况和可获得资料,选取影响地下水脆弱性的地下水埋深、含水层净补给量、含水层介质、土壤包气带、地形、包气带介质和水力传导系数7个参数作为评价因子,建立太原市盆地区浅层地下水脆弱性评价DRASTIC指标体系和评价标准。依据标准对其所含的7个参数进行评分,并具体阐述了评分中所应注意的问题,在获得了DRASTIC模型的7个指标在研究区的评分图之后,利用GIS平台空间分析技术将7张评分图叠加,同时对7个指标按照各自的权重取其加权和,这样便得到了太原市盆地区浅层地下水脆弱性分区图,结果表明汾河沿岸和吴家堡工业区地下水脆弱性指数较高,在盆地两侧的黄土台塬区,地下水脆弱性评分为低或极低,评价模型能合理的反映太原市盆地区浅层地下水脆弱性的高低。研究结果可以为太原市土地利用规划、地下水水资源保护规划、地下水水质监测等提供参考,也可以提高公众关于地下水污染的风险意识。     

地下水脆弱性层次分析

采用层次分析法,通过建立层次结构、构造判断矩阵、层次单排序及一致性检验、层次总排序及一致性检验对地下水脆弱性进行评价,得出污染物排放方式、污染物性质、地下水埋深、包气带性质等对地下水脆弱性影响较大,为地下水治理、地下水资源保护、地下水资源开发利用提供宏观指导。     

基于GIS的黄水河流域地下水脆弱性评价研究

从影响地下水脆弱性的因素出发,结合国内外已有的地下水脆弱性影响因素、评价指标和评价标准,根据研究区的具体情况和可获得资料,确定了北方滨海地区地下水脆弱性的影响因素,建立了地下水脆弱性评价DRAMTICH指标体系和评价标准。以黄水河流域为例,进行了地下水脆弱性评价和编图,为当地今后制订地下水资源保护与管理、土地利用及城市规划等政策措施提供决策依据。该方法同样适用于其它类似地区的地下水脆弱性评价。     

基于熵权的集对分析方法在地下水脆弱性评价中的应用

针对传统集对分析在评价地下水脆弱性时认为各指标权重相同的缺点,以DRASTIC模型指标体系作为基础,将熵值理论与集对分析相结合,在集对分析中使用熵值法确定权重系数,对地下水脆弱性进行了评价,实现了特性权重随样本数据的动态变化。应用实例表明,该方法评价地下水脆弱性能够充分反映样本数据本身对指标权重的影响,评价结果更加客观、可靠。     

关于地下水资源评价问题的若干思考

介绍了地下水资源的概念,结合地下水资源的评价内容,分析了地下水资源评价与地下水资源管理的关系,对地下水资源评价与地下水资源管理分离的后果进行了论述,指出地下水资源评价是地下水资源管理的条件,而地下水资源评价中又融合着地下水资源管理的成分。     

地下水资源评价中有关概念的讨论

就目前地下水资源评价中有关概念进行了论述 ,并针对河西走廊南北盆地水文地质条件及存在的环境问题 ,提出了开采资源的评价方法     

Application of DRASTIC and extension theory in the groundwater vulnerability evaluation

Groundwater vulnerability assessment plays a vital role in the utilization and protection of groundwater resources. DRASTIC is one of the most widely used models for groundwater vulnerability assessment. However, the DRASTIC model should be modified based on the local hydrogeological conditions in order to get a relatively accurate result. In this study, Baotou, China was chosen as a case study. The groundwater vulnerability was assessed using DRASTIC at first, but the evaluation results were not consistent with the groundwater quality. So the DRASTIC model was modified based on extension theory and analytic hierarchy process (AHP) method. The extension theory could be used to divide the groundwater vulnerability grades in the DRASTIC model. It is a new attempt to use extension theory and DRASTIC in the assessment of groundwater vulnerability, and the research results show that this method is better for assessing groundwater vulnerability.     

Influence of threshold value in the use of statistical methods for groundwater vulnerability assessment

Statistical techniques can be used in groundwater pollution problems to determine the relationships among observed contamination (impacted wells representing an occurrence of what has to be predicted), environmental factors that may influence it and the potential contamination sources. Determination of a threshold concentration to discriminate between impacted or non impacted wells represents a key issue in the application of these techniques. In this work the effects on groundwater vulnerability assessment by statistical methods due to the use of different threshold values have been evaluated. The study area (Province of Milan, northern Italy) is about 2000 km² and groundwater nitrate concentration is constantly monitored by a net of about 300 wells. Along with different predictor factors three different threshold values of nitrate concentration have been considered to perform the vulnerability assessment of the shallow unconfined aquifer. The likelihood ratio model has been chosen to analyze the spatial distribution of the vulnerable areas. The reliability of the three final vulnerability maps has been tested showing that all maps identify a general positive trend relating mean nitrate concentration in the wells and vulnerability classes the same wells belong to. Then using the kappa coefficient the influence of the different threshold values has been evaluated comparing the spatial distribution of the resulting vulnerability classes in each map. The use of different threshold does not determine different vulnerability assessment if results are analyzed on a broad scale, even if the smaller threshold value gives the poorest performance in terms of reliability. On the contrary, the spatial distribution of a detailed vulnerability assessment is strongly influenced by the selected threshold used to identify the occurrences, suggesting that there is a strong relationship among the number of identified occurrences, the scale of the maps representing the predictor factors and the model efficiency in discriminating different vulnerable areas.     

桥梁易损性研究的回顾与展望

介绍了桥梁易损性研究的概况,对桥梁易损性研究的由来、含义、分级方法和分析方法做了较为全面的论述,并对桥梁易损性研究提出了存在的问题和今后尚需开展的工作,以推动桥梁工程的发展。     

Quantitative assessment of intrinsic groundwater vulnerability to contamination using numerical simulations

Intrinsic vulnerability assessment to groundwater contamination is part of groundwater management in many areas of the world. However, popular assessment methods estimate vulnerability only qualitatively. To enhance vulnerability assessment, an approach for quantitative vulnerability assessment using numerical simulation of water flow and solute transport with transient boundary conditions and new vulnerability indicators are presented in this work. Based on a conceptual model of the unsaturated underground with distinct hydrogeological layers and site specific hydrological characteristics the numerical simulations of water flow and solute transport are applied on each hydrogeological layer with standardized conditions separately. Analysis of the simulation results reveals functional relationships between layer thickness, groundwater recharge and transit time. Based on the first, second and third quartiles of solute mass breakthrough at the lower boundary of the unsaturated zone, and the solute dilution, four vulnerability indicators are extracted. The indicator transit time t₅₀ is the time were 50% of solute mass breakthrough passes the groundwater table. Dilution is referred as maximum solute concentration C_max in the percolation water when entering the groundwater table in relation to the injected mass or solute concentration C₀ at the ground surface. Duration of solute breakthrough is defined as the time period between 25% and 75% (t_25%-t_75%) of total solute mass breakthrough at the groundwater table. The temporal shape of the breakthrough curve is expressed with the quotient (t_25%-t_50%) / (t_25%-t_75%). Results from an application of this new quantitative vulnerability assessment approach, its advantages and disadvantages, and potential benefits for future groundwater management strategies are discussed.     

高速公路建设中地下水环境影响评价初探

探讨了高速公路建设中地下水环境影响评价的目的、依据、方法和内容,分析了高速公路建设对地下水环境的影响,并提出了防治措施与建议,对建设区地下水环境保护、生态文明建设及高速公路工程的合理施工与运营有着重要的意义。     

VLDA模型及其在潜水脆弱性评价中的应用——以新疆焉耆县平原区为例

在地下水脆弱性评价的GOD法和DRASTIC模型的基础上,提出了VLDA模型,其中V为包气带岩性(1ithology of vadose zone)、L为土地利用方式(pattern of land use)、D为地下水埋深(groundwater depth)、A为含水层特征(aquifer characterist...     

Quantitative assessment of groundwater vulnerability using index system and transport simulation, Huangshuihe catchment, China

Groundwater vulnerability assessment has been an increasingly important environment management tool. The existing vulnerability assessment approaches are mostly index systems which have significant disadvantages. There need to be some quantitative studies on vulnerability indicators based on objective physical process study. In this study, we tried to do vulnerability assessment in Huangshuihe catchment in Shandong province of China using both contaminant transport simulations and index system approach. Transit time of 75% of hypothetical injected contaminant concentration was considered as the vulnerability indicator. First, we collected the field data of the Huangshuihe catchment and the catchment was divided into 34 sub areas that can each be treated as a transport sub model. Next, we constructed a Hydrus1D transport model of Huangshuihe catchment. Different sub areas had different input values. Thirdly, we used Monte-Carlo simulation to improve the collected data and did vulnerability assessment using the statistics of the contaminant transit time as a vulnerability indicator. Finally, to compare with the assessment result by transport simulation, we applied two index systems to Huangshuihe catchment. The first was DRASTIC system, and the other was a system we tentatively constructed examining the relationships between the transit time and the input parameters by simply changing the input values. The result of comparisons between the two index systems and transport simulation approach suggested partial validation to DRASTIC, and the construction of the new tentative index system was an attempt of building up index approaches based on physical process simulation.     

A statistical and geographical information system analysis for groundwater intrinsic vulnerability: a validated case study from Sfax–Agareb,Tunisia

The groundwater vulnerability to the pollution assessment was considered as an efficient tool to limit and to control its quantitative and qualitative degradation risks. The DRASTIC high, moderate and low groundwater vulnerability zones of the Sfax–Agareb basin (Tunisia) cover about 10, 29 and 61% of the study area, respectively. The validation of the DRASTIC vulnerability map was undertaken through comparison of areas of high nitrate concentration and their relative vulnerability index. The DRASTIC vulnerability map illustrates a good rate of coincidence between the nitrate concentration ranges and the various vulnerability classes as recognized by statistical analysis. The reliability of the final vulnerability map has been tested, showing a general positive trend relating the mean nitrate concentration in the wells to their relative vulnerability classes (R²=0.88). When correlating the 214 available groundwater nitrate concentrations to the DRASTIC index in these wells location, a significant positive correlation with Cor=0.55 was found.