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Mapping spatio-temporal dynamics of main water parameters and understanding their relationships with driving factors using GF-1 images in a clear reservoir

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Abstract

Due to eutrophication and water quality deterioration in clear reservoirs, it is necessary to monitor and manage the main water parameters: concentration of total phosphorus (CTP), chemical oxygen demand (CCOD), chlorophyll-a (CChla), total suspended matter (CTSM), and Secchi disk depth (SDD). Five random forest (RF) models are developed to estimate these parameters in Xin’anjiang Reservoir, which is a clear drinking water resource in Zhejiang, China. Then, the spatio-temporal distributions of the parameters over 7 years (2013–2019) are mapped using GaoFen-1 (GF-1) images and the relationships with driving factors are analyzed. Our study demonstrates that the parameters’ distributions exhibited a significant spatio-temporal difference in Xin’anjiang Reservoir. Spatially, relatively high CTP, CCOD, CChla, and CTSM but low SDD appear in riverine areas, showing strong evidence of impact from the incoming rivers. Temporally, CChla and CTSM reached high values in summer and winter, whereas SDD and CTP were higher in the summer and autumn, respectively. In contrast, no significant seasonal variations of CCOD could be observed. This may be why CCOD is not sensitive to hydrological or meteorological factors. However, precipitation had a significant impact on CChla, CTP, SDD, and CTSM in riverine areas, though these parameters were less sensitive to meteorological factors. Moreover, the geomorphology of the reservoir and anthropogenic interference (e.g., tourism activities) also have a significant impact on the water quality parameters. This study demonstrates that coupling long-term GF-1 images and RF models could provide strong evidence and new insights to understand long-term dynamics in water quality and therefore support the development of corresponding management strategies for freshwater reservoirs.

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Acknowledgments

We thank the China Center for Resources Satellite Data and Application (http://www.cresda.com/CN/) for providing GF-1 images.

Funding

This research was supported by the National Key R&D Program of China (2017YFB0503902), and the National Natural Science Foundation of China (41671340).

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Authors and Affiliations

  1. Key Laboratory of Virtual Geographic Environment, Ministry of Education, College of Geographic Science, Nanjing Normal University, Nanjing, 210023, China

    Shuai Zeng, Yunmei Li, Heng Lyu, Jiafeng Xu, Xianzhang Dong, Rui Wang, Ziqian Yang & Jianchao Li

  2. Jiangsu Center for Collaboration Invocation in Geographical Information Resource Development and Application, Nanjing, 210023, People’s Republic of China

    Yunmei Li & Heng Lyu

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  1. Shuai Zeng
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Zeng, S., Li, Y., Lyu, H. et al. Mapping spatio-temporal dynamics of main water parameters and understanding their relationships with driving factors using GF-1 images in a clear reservoir. Environ Sci Pollut Res 27, 33929–33950 (2020). https://doi.org/10.1007/s11356-020-09687-z

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