Flint Drinking Water Crisis: A First Attempt to Model Geostatistically the Space-Time Distribution of Water Lead Levels
Flint Drinking Water Crisis: A First Attempt to Model Geostatistically the Space-Time Distribution of Water Lead Levels
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弗林特饮用水危机：首次尝试对水铅含量的时空分布进行地统计建模
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
P. Goovaerts
中科院分区：
文献类型：
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作者：
P. Goovaerts
密歇根州弗林特市的饮用水污染危机引起了全国的关注，因为供水系统的开关导致高浓度氯水和没有缓蚀剂的水流经老化的弗林特供水系统，导致铅含量达到极端水平。自弗林特于2015年10月16日恢复其原始饮用水源以来，该州已进行了11次双周采样，在819个“哨点”收集了4120个水样。本章描述了这些数据的第一个地质统计学分析，并说明了与整个城市的水铅水平时空分布建模相关的多重挑战。问题包括抽样偏差、半方差图显示的大块效应和短范围空间自相关。时间趋势采用线性回归模型，以服务线材料、房屋年龄、贫困水平及其与人口普查区的相互作用为自变量。然后利用kriging方法对三种不可分时空协方差模型进行残差插值。交叉验证表明，在趋势模型中考虑次要信息的好处有限，在几百米以上的大幅度波动造成的未采样地点的预测质量很差。主要的好处是填补了采样时间序列中的空白，在这些空白中，广义积和和和度量模型优于度量模型，后者忽略了相对于时间的更大的空间变化（区域各向异性）。未来的研究应纳入通过自愿抽样收集的大型数据库，因为尽管在不均匀的条件下收集了近20 000个数据，但抽样密度要大得多。
The drinking water contamination crisis in Flint, Michigan has attracted national attention since extreme levels of lead were recorded following a switch in water supply that resulted in water with high chloride and no corrosion inhibitor flowing through the aging Flint water distribution system. Since Flint returned to its original source of drinking water on October 16, 2015, the State has conducted eleven bi-weekly sampling rounds, resulting in the collection of 4,120 water samples at 819 “sentinel” sites. This chapter describes the first geostatistical analysis of these data and illustrates the multiple challenges associated with modeling the space-time distribution of water lead levels across the city. Issues include sampling bias and the large nugget effect and short range of spatial autocorrelation displayed by the semivariogram. Temporal trends were modeled using linear regression with service line material, house age, poverty level, and their interaction with census tracts as independent variables. Residuals were then interpolated using kriging with three types of non-separable space-time covariance models. Cross-validation demonstrated the limited benefit of accounting for secondary information in trend models and the poor quality of predictions at unsampled sites caused by substantial fluctuations over a few hundred meters. The main benefit is to fill gaps in sampled time series for which the generalized product-sum and sum-metric models outperformed the metric model that ignores the greater variation across space relative to time (zonal anisotropy). Future research should incorporate the large database assembled through voluntary sampling as close to 20,000 data, albeit collected under non-uniform conditions, are available at a much greater sampling density.
影响因子：
4.9
作者：
E. Symanski;D. Savitz;P. Singer
通讯作者：
E. Symanski;D. Savitz;P. Singer
弗林特的饮用水污染危机：对返回底特律供水系统后铅含量的时间趋势进行建模。
DOI：
10.1016/j.scitotenv.2016.09.207
发表时间：
2017
期刊：
The Science of the total environment
影响因子：
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作者：
Goovaerts,Pierre
通讯作者：
Goovaerts,Pierre
地质统计学如何帮助您找到铅和镀锌供水管道：以密歇根州弗林特为例。
DOI：
10.1016/j.scitotenv.2017.05.094
发表时间：
2017
期刊：
The Science of the total environment
影响因子：
--
作者：
Goovaerts,Pierre
通讯作者：
Goovaerts,Pierre