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Observations of water transparency in China's lakes from space

Liu, D; Duan, H; Loiselle, S; Hu, C; Zhang, G; Li, J; Yang, H; ... Han, W; + view all (2020) Observations of water transparency in China's lakes from space. International Journal of Applied Earth Observation and Geoinformation , 92 , Article 102187. 10.1016/j.jag.2020.102187. Green open access

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Abstract

Water transparency, usually denoted by Secchi disk depth (SSD), represents the first-order description of water quality and has important implications for the diversity and productivity of aquatic life. In China, lakes supply freshwater and ecosystem services to nearly a billion people. Therefore, real time monitoring of lake transparency is of great significance. Moreover, understanding how and why transparency varies in space and time in response to different driving forces is needed to understand, manage, and predict lake water quality. Based on the time-saving and low-cost Google Earth Engine cloud platform, this study developed a new algorithm for quickly mapping SDDs in Chinese lakes. SDDs were retrieved for 412 Chinese lakes (> 20 km2) for the period 2000–2018. Results demonstrated that lake water depth spatially differentiated transparency. Deep lakes usually had high transparency and water depth explained 88.81 % of the spatial variations. With increasing catchment vegetation coverage and lake water depth, 70.15 % of lakes witnessed increasing transparency during 2000–2018. Of these 42.72 % were significant (p<0.05). Transparency of deep lakes was generally determined by phytoplankton density not sediment resuspension. Minimum transparency occurred in summer. Future increases in lake water levels in response to factors such as climate change may contribute to further improvements in transparency. Management should focus on controlling eutrophication and increasing vegetation cover in catchments.

Type: Article
Title: Observations of water transparency in China's lakes from space
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jag.2020.102187
Publisher version: https://doi.org/10.1016/j.jag.2020.102187
Language: English
Additional information: This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/BY-NC-ND/4.0/).
Keywords: Science & Technology, Technology, Remote Sensing, Water transparency, Chinese lakes, Spatio-temporal variation, Water depth, Vegetation restoration, LONG-TERM MODIS, INLAND WATERS, LANDSAT IMAGERY, CLIMATE-CHANGE, SHALLOW LAKES, CLARITY, PHYTOPLANKTON, CARBON, RIVER, RESUSPENSION
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL SLASH
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS
UCL > Provost and Vice Provost Offices > UCL SLASH > Faculty of S&HS > Dept of Geography
URI: https://discovery.ucl.ac.uk/id/eprint/10107313
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