Abstract The combination of remote sensing techniques and Geographic Information Systems (GIS) to measure water quality allows researchers to monitor changes in various water quality parameters over temporal and spatial scales that are not always readily apparent from in situ measurements. This study involves using Landsat images and in situ data within GIS to map urban expansion and its resulting influences on water quality in the Pontchartrain Basin over the last three decades. The Pontchartrain Basin is located in southeast Louisiana and covers an area of 25,000 km2 that encompasses sixteen parishes east of the Mississippi River and four Mississippi Counties. A Landsat Thematic Mapper (TM) image from 1985 and a Landsat Operational Land Imager (OLI) image from 2015 were processed using the Spectral Angle Mapper (SAM) algorithm to map urban expansion. In order to estimate how water quality has changed in the Pontchartrain Basin between 1985 and 2015, in situ water quality data from the Louisiana Department of Environmental Quality was interpolated using Empirical Bayesian Kriging (EBK). Comparing urban expansion produced from SAM classification with urban indices, impervious surfaces were better identified and distinguished from other land cover features. The results of this study demonstrated that high levels of fecal coliform were consistent with increased urbanization in water bodies in the Pontchartrain Basin. Phosphorous levels were higher in 2015 compared to 1985 and were at levels high enough to lead to eutrophic conditions. Dissolved oxygen levels were lower near the mouth of the Mississippi river in 2015 than in 1985. The results indicated that urbanization has negative impact on water quality. The geospatial model is recommended to effectively manage and reduce the processing time of large water quality datasets.

中文翻译：

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城市变化与地表水水质时空分析

摘要 遥感技术和地理信息系统 (GIS) 相结合来测量水质使研究人员能够监测各种水质参数在时间和空间尺度上的变化，这些变化在现场测量中并不总是很明显。这项研究涉及使用 Landsat 图像和 GIS 中的原位数据来绘制城市扩张及其对过去三十年庞恰特雷恩盆地水质的影响。庞恰特雷恩盆地位于路易斯安那州东南部，占地 25,000 平方公里，包括密西西比河以东的十六个教区和四个密西西比县。1985 年的 Landsat Thematic Mapper (TM) 图像和 2015 年的 Landsat Operational Land Imager (OLI) 图像使用光谱角度映射器 (SAM) 算法处理以绘制城市扩张图。为了估计 Pontchartrain 盆地 1985 年至 2015 年间水质的变化，使用经验贝叶斯克里金法 (EBK) 对路易斯安那州环境质量部的原位水质数据进行了插值。将 SAM 分类产生的城市扩张与城市指数进行比较，可以更好地识别不透水表面并将其与其他土地覆盖特征区分开来。这项研究的结果表明，高水平的粪便大肠菌群与庞恰特雷恩盆地水体的城市化进程相一致。与 1985 年相比，2015 年的磷水平更高，并且水平高到足以导致富营养化状况。2015 年密西西比河河口附近的溶解氧水平低于 1985 年。结果表明，城市化对水质有负面影响。建议使用地理空间模型来有效管理和减少大型水质数据集的处理时间。