共查询到20条相似文献,搜索用时 71 毫秒
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介绍了基于平衡常数法的水溶液平衡组分分布的计算原理及其数学模型。在此基础上,以韩城电厂周原灰场区潜水环境为背景,对计算机水化学模型在地下水环境评价中的应用进行了探讨。与传统的水化学方法相比,该方法可以获得更多的信息,从而有助于分析地下水的化学特征及地下水与所处环境之间的关系和相互作用。 相似文献
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地下水流线的数值算法研究 总被引:3,自引:0,他引:3
地下水流线的生成是数值模拟结果显示中的一个重点。根据地下水流线可方便分析地下水的运动态,而常见的工具不能满足要求。论文探讨并提出了流线的“质点追踪”生成算法,这为流线数据可视化显示及其地下水年龄计算提供了一定的依据。最后,进行了实例研究,结果显示了设计算法的正确性。 相似文献
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基于GIS的黄河三角洲地下水开发适宜性评价模型 总被引:4,自引:0,他引:4
本文运用地理信息系统(GIS)技术,建立了黄河三角洲地区浅层地下水开发适宜性综合评价模型.评价模型考虑了浅层地下水补给、含水层导水性和储水性、地下水水质、土地利用以及地下水开采对环境影响等多方面因素,模型评价结果为地下水开发适宜性等级分区图.模型评价成果为黄河三角洲地区浅层地下水资源规划和开发利用提供了科学依据. 相似文献
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为系统客观的评价地下水饮用水源地的安全状态,基于“驱动力-压力-状态-影响-响应”(DPSIR)框架初步建立备选评价指标,运用专家咨询法对备选指标进行筛选及合理性检验,采用层次分析法确定指标权重,构建地下水饮用水源地安全度综合评价体系。以滹沱河浅层孔隙水水源地为例,确定了包含5个准则层,18个指标的地下水饮用水源地安全评价指标体系。滹沱河浅层孔隙水水源地实例研究表明,准则层中压力系统和状态系统所占权重较大,分别为0.257和0.339;水源地安全度为0.67,尽管处于较安全级别,但非常接近警戒值(0.4~0.6)。通过实例分析可知,筛选的指标具有一定的实用性,可以为评价浅层孔隙水水源地的安全状态及面临的风险提供参考。 相似文献
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在美国地调局开发的MODFLOW局部网格加密技术(简称LGR)的基础上,针对LGR程序不能应用于不规则区域模型嵌套的局限性展开研究。对LGR程序源代码进行分析,探讨在不规则模型嵌套中出现的问题并研究解决方案。利用FORTRAN语言对LGR源代码进行二次开发,增加模型边界匹配程序、修改参数调整程序、改编水头和流量传递程序,生成新的模型嵌套程序LGR2.1。建立多种嵌套模型对改编后程序进行验证,模拟结果表明:该程序可以模拟单区域和多区域的不规则嵌套模型,模拟结果正确可靠;应用该程序可以对模型内部和边界处的局部区域进行加密嵌套,在减少模拟时间和贮存空间的情况下提高模拟的精度。 相似文献
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Numerical groundwater flow and contaminant transport modeling incorporating three alternative conceptual models was conducted in 2005 to assess remedial actions and predict contaminant concentrations in an unconfined glacial aquifer located in Milford, Michigan, USA. Three alternative conceptual models were constructed and independently calibrated to evaluate uncertainty in the geometry of an aquitard underlying the aquifer and the extent to which infiltration from two manmade surface water bodies influenced the groundwater flow field. Contaminant transport for benzene, cis-DCE, and MTBE was modeled for a 5-year period that included a 2-year history match from July 2003 to May 2005 and predictions for a 3-year period ending in July 2008. A postaudit of model performance indicates that predictions for pumping wells, which integrated the transport signal across multiple model layers, were reliable but unable to differentiate between alternative conceptual model responses. In contrast, predictions for individual monitoring wells with limited screened intervals were less consistent, but held promise for evaluating alternative hydrogeologic models. Results of this study suggest that model conceptualization can have important practical implications for the delineation of contaminant transport pathways using monitoring wells, but may exert less influence on integrated predictions for pumping wells screened over multiple numerical model layers. 相似文献
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遗传算法在反演三维地下水流模型参数中的应用 总被引:5,自引:0,他引:5
本文以非均质各向同性承压三维非稳定流为理想模型,结合有限元法讨论了用遗传算法反演水文地质参数问题.计算结果表明,本文在简单遗传算法(SGA)的基础上提出的优体克隆+子体优生遗传算法(BCC-YGCD-GA)具有收敛速度快、解的精度高和避免出现早熟等优点.在水资源评价和矿床疏干计算中有广阔的应用前景. 相似文献
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双重介质模型在岩溶地下水流动系统模拟中的应用 总被引:1,自引:0,他引:1
文章采用不稳定层状裂隙水流模型,应用有限元-卷积结合法,模拟了岩溶地下水流动系统。相对于等效多孔介质模型,双重介质模型模拟的水位下降速度更小,达到稳定的时间更长。距抽水井较近的观测孔处,双重介质模型模拟的水位变化过程阶段性较明显,水位变化过程类似于承压含水层-弱透水层的释水过程,裂隙和孔隙基质分别相当于承压含水层和弱透水层。然后讨论了影响裂隙和孔隙基质间水流交换项的因素,分析了孔组抽水后的渗流场特征。 相似文献
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A GIS-based DRASTIC model for assessing groundwater vulnerability in the Ordos Plateau, China 总被引:6,自引:2,他引:4
Lihe Yin Eryong Zhang Xiaoyong Wang Jochen Wenninger Jiaqiu Dong Li Guo Jinting Huang 《Environmental Earth Sciences》2013,69(1):171-185
Groundwater plays a key role in arid regions as the majority of water is supplied by it. Groundwater pollution is a major issue, because it is susceptible to contamination from land use and other anthropogenic impacts. A study was carried out to build a vulnerability map for the Ordos Plateau using the DRASTIC model in a GIS environment. The map was designed to show the areas of the highest potential for groundwater pollution based on hydrogeological conditions. Seven environmental parameters, such as depth to water table, net recharge, aquifer media, soil media, topography, impact of the vadose zone media, and hydraulic conductivity of the aquifer, were incorporated into the DRASTIC model and GIS was used to create a groundwater vulnerability map by overlaying the available data. The results of this study show that 24.8 % of the study area has high pollution potential, 24.2 % has moderate pollution potential, 19.7 % has low pollution potential, and the remaining 31.3 % of the area has no risk of groundwater pollution. The regional distribution of nitrate is well correlated with the DRASTIC vulnerability index. In contrast to this, although the DRASTIC model indicated that the western part had no risk, nitrate concentrations were higher in some of these areas. In particular, higher nitrate concentrations were recorded along river valleys and around lakes, such as the Mulin River valley. This is mainly caused by the intensive agricultural development and favorable conditions for recharge along river valleys. 相似文献
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Prediction and evaluation of pollution of the subsurface environment and planning remedial actions at existing sites may be useful for siting and designing new land-based waste treatment or disposal facilities. Most models used to make such predictions assume that the system behaves deterministically. A variety of factors, however, introduce uncertainty into the model predictions. The factors include model and pollution transport parameters and geometric uncertainty. The Monte Carlo technique is applied to evaluate the uncertainty, as illustrated by applying three analytical groundwater pollution transport models. The uncertainty analysis provides estimates of statistical reliability in model outputs of pollution concentration and arrival time. Examples are provided that demonstrate: (a) confidence limits around predicted values of concentration and arrival time can be obtained, (b) the selection of probability distributions for input parameters affects the output variables, and (c) the probability distribution of the output variables can be different from that of the input variables, even when all input parameters have the same probability distribution 相似文献
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高斯过程回归(GPR)是一种基于贝叶斯理论的监督学习算法,在基于数据驱动(DDM)的模型结构不确定性分析中具有广泛应用。目前研究中通常假设物理参数和超参独立并进行联立识别,这会导致参数补偿。文章提出两步识别DDM量化模型结构误差,并通过2个地下水模型案例,分别在不考虑模型结构误差、考虑模型结构误差(联立识别DDM、两步识别DDM)的情况下,对比分析了参数识别和模型预测结果。结果表明,不考虑模型结构误差直接进行参数识别时,为补偿结构误差,物理参数会过度拟合,从而影响模型预测效果。基于DDM刻画模型结构偏差时,物理参数和超参的独立性假设会影响参数识别结果。提出的两步识别DDM法没有假设物理参数和超参独立,能够减少参数过度拟合效应,从而更准确刻画结构误差,有效提高了模型的预测性能。 相似文献
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为了建筑环境的保护,软土地区基坑围护中的坑内降水与坑外水位保持常是一对矛盾的课题.而坑内外的水位差,极易形成止水结构两侧的渗流运动.对饱和各向异性、水平延伸、厚度大致相等、且存在一、二类边界时的承压含水层中的承压水二维非稳定流渗流问题,本文推导出了二维、各向异性渗流等参有限元方程,用以进行基坑围护止水结构附近渗流场分析,并给出了算例. 相似文献
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水资源短缺的鄂尔多斯盆地内地下水遭受硝酸盐(NO3-)污染等问题日益突出,识别盆地不同地下水流系统的NO3-分布规律及其成因,对地下水资源的合理利用与保护具有重要意义.选取鄂尔多斯盆地北部湖泊集中区白垩系地下水系统为研究对象,基于水化学和聚类 主成分分析划分地下水流系统级次,在此基础上对比分析不同级次地下水流系统中NO3-分布特征,综合水化学和环境同位素分析识别多级次地下水流系统中NO3-来源及其潜在过程.研究表明:研究区ρ(NO3)超出地下水质量标准(GB/T 14848-2017)Ⅲ类水标准的地下水样品集中在局部-中间地下水流系统,其超标率达到28%;区域地下水流系统中ρ(NO3)均值约为1 mg/L.研究区不同级次地下水流系统中ρ(NO3-)分布特征主要与人类活动影响程度有关,而地下水蒸发富集和反硝化衰减作用对ρ(NO3-)的影响可以忽略.其中,局部-中间地下水流系统受到人类活动产生的污染影响显著,其NO3-污染主要来源于无机铵肥和粪便污水等;区域地下水流系统可能尚未受到人类活动污染,其NO3-来源于天然有机氮矿化. 相似文献