Abstract
The increase of urbanization level has led to the rapid increase of impervious surface area (ISA). The aim of this work is to clarify the relationship between the ISA and water quality and lay a foundation for the improvement and protection of the water quality in the basin. Taking the Fuxian Lake Basin in Yunnan Province as an example, based on the Landsat ETM+ remote sensing image and the Gram–Schmidt (GS) image fusion algorithm, the four-terminal model and the linear spectral mixture model (LSMM) were used to extract the impervious surface of the watershed from 2006 to 2015. And statistical methods were used to distinguish its relationship with water quality. The results show that the four-terminal model and the linear spectral mixture model can effectively extract the impervious surface information of the Fuxian Lake Basin. The average root mean square error (RMS) of the image decomposition results from 2006 to 2015 was less than 0.02. In the past 10 years, the ISA has changed significantly in the Fuxian Lake Basin. The ISA showed an overall upward trend from 2006 to 2015. It increased from 24.73 km2 in 2006 to 35.14 km2 in 2015, an increase of 10.81 km2. From the value anomaly, the ISA in 2006 and 2009 is lower than the multiyear average, and those in the other years are higher than the multiyear average. The percentage of ISA in the basin was significantly positively correlated with Chemical Oxygen Demand-Mn (CODMn) and total phosphorus (TP) (r is 0.772, 0.763), and the correlation in the flooding season was greater than that in the dry season. The ISA threshold for water quality deterioration is around 10% in the Fuxian Lake Basin. Reducing ISA coverage, controlling ISA to less than 10%, and preventing nonpoint source pollution during flooding season will be the best measures to effectively improve the water quality environment in the basin.
Highlights
A large number of pollutants including organic matter, suspended solids, heavy metals, pathogens, oils, and other toxic and hazardous substances are accumulated on the surface of urban roads, roofs, construction sites, etc. ese pollutants are merged into water bodies such as rivers, lakes, and bays through impervious surfaces or drainage networks under the effect of rainfall erosion. us, it poses a serious threat to the water environment
We examine the spatial scales at which these changes impact water quality by monitoring the water quality data from the local department governing Lake Fuxian throughout the watershed, together with data from four impervious surface area (ISA) maps (2006–2015). e present study addresses the following research questions: (1) How does the spatial distribution of ISA change in the Fuxian Lake Basin from 2006 to 2015? (2) How do spatial and temporal variations in ISA within and across watersheds influence water quality metrics in the Lake Fuxian watershed? (3) At what spatial scale does the ISA act to influence water quality?
Conclusions is paper uses the Fuxian Lake watershed as a research area to study the Landsat-7 ETM+ images in 2006, 2009, 2012, and 2015 covering the Fuxian Lake basin. e ISA in the Fuxian Lake watershed was extracted by linear spectral hybrid model (LSMM). e results showed that (1) four endmember types including high albedo, low albedo, vegetation, and soil were selected, and linear spectra were used
Summary
A large number of pollutants including organic matter, suspended solids, heavy metals, pathogens, oils, and other toxic and hazardous substances are accumulated on the surface of urban roads, roofs, construction sites, etc. ese pollutants are merged into water bodies such as rivers, lakes, and bays through impervious surfaces or drainage networks under the effect of rainfall erosion. us, it poses a serious threat to the water environment. Marinoni established a model for evaluating the impact of simulated land development on Journal of Environmental and Public Health water quality indicators such as TN, TP, and TSS based on mathematical programming and combined with multiscale analysis and motion wave equations [7]. With the diversification of remote sensing data sources and the advancement of remote sensing technology, multisource remote sensing data provides the basis for multiscale effect analysis of ISAs. Among them, most people currently use medium- and high-resolution image fusion methods to extract ISA. The linear spectral separation technique for mediumresolution images has been improved, and the VIS-based model was widely applied in urban environments [16,17,18,19,20], urban impervious surface overlay mapping and evaluation [21], and other aspects
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