Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images
With climate warming and intensification of human activities, the eco-environmental problems of lakes in middle and high latitudes become increasingly prominent. Qinghai Lake, located in the northeastern of the Tibetan Plateau, is the largest inland saltwater lake in China. Recently, the problem of...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-02-01
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| Series: | Remote Sensing |
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| Online Access: | https://www.mdpi.com/2072-4292/14/4/853 |
| _version_ | 1827652949280555008 |
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| author | Hongyu Duan Xiaojun Yao Dahong Zhang Huian Jin Qixin Wei |
| author_facet | Hongyu Duan Xiaojun Yao Dahong Zhang Huian Jin Qixin Wei |
| author_sort | Hongyu Duan |
| collection | DOAJ |
| description | With climate warming and intensification of human activities, the eco-environmental problems of lakes in middle and high latitudes become increasingly prominent. Qinghai Lake, located in the northeastern of the Tibetan Plateau, is the largest inland saltwater lake in China. Recently, the problem of Cladophora blooms has been widely concerning. In this study, the area of floating Cladophora blooms (hereafter FCBs) in Qinghai Lake from 1986 to 2021 was extracted using Floating Algal Index (FAI) method based on Landsat TM/ETM+/OLI and Sentinel-2 MSI images, and then the intra- and inter-annual variation characteristics and spatial patterns of FCBs were analyzed. The results show that the general change trend of FCBs in Qinghai Lake featured starting in May, expanding rapidly from June to August, and increasing steadily from September to October. From 1986 to 2021, the area of FCBs in Qinghai Lake showed an overall increasing trend in all months, with the largest increase in July at 0.1 km<sup>2</sup>/a, followed by October at 0.096 km<sup>2</sup>/a. Spatially speaking, the FCBs area showed a significant increasing trend in the northern Buha River estuary (BRN) and southern Buha River estuary (BRS) regions, a slight increase in the Shaliu River estuary (SR) region, and a decreasing trend in the Quanji River estuary (QR) region and the Heima River estuary (HR) region. The correlation between the meteorological factors and the changes in FCBs was weak, but the increase in flooded pastures in the BRN region (Bird Island) due to rising water levels was definitely responsible for the large-scale increase in FCBs in this region. However, the QB, northeastern bay of Shaliu River estuary (SRB) and HR regions, which also have extensive inundated grassland, did not have the same increase in FCBs area, suggesting that the growth of Cladophora is caused by multiple factors. The complex relationships need to be verified by further research. The current control measures have a certain inhibitory effect on the Cladophora bloom in Qinghai Lake because the FCBs area was significantly smaller in 2017–2020 (5.22 km<sup>2</sup>, 3.32 km<sup>2</sup>, 4.55 km<sup>2</sup> and 2.49 km<sup>2</sup>), when salvage work was performed, than in 2016 and 2021 (8.67 km<sup>2</sup> and 9.14 km<sup>2</sup>), when no salvage work was performed. |
| first_indexed | 2024-03-09T21:09:16Z |
| format | Article |
| id | doaj.art-842f55cccd0445f081bbfcd0faa5f075 |
| institution | Directory Open Access Journal |
| issn | 2072-4292 |
| language | English |
| last_indexed | 2024-03-09T21:09:16Z |
| publishDate | 2022-02-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Remote Sensing |
| spelling | doaj.art-842f55cccd0445f081bbfcd0faa5f0752023-11-23T21:53:09ZengMDPI AGRemote Sensing2072-42922022-02-0114485310.3390/rs14040853Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing ImagesHongyu Duan0Xiaojun Yao1Dahong Zhang2Huian Jin3Qixin Wei4College of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, ChinaCollege of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, ChinaCollege of Urban and Environmental Science, Northwest University, Xi’an 710127, ChinaCollege of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, ChinaCollege of Geography and Environment Science, Northwest Normal University, Lanzhou 730070, ChinaWith climate warming and intensification of human activities, the eco-environmental problems of lakes in middle and high latitudes become increasingly prominent. Qinghai Lake, located in the northeastern of the Tibetan Plateau, is the largest inland saltwater lake in China. Recently, the problem of Cladophora blooms has been widely concerning. In this study, the area of floating Cladophora blooms (hereafter FCBs) in Qinghai Lake from 1986 to 2021 was extracted using Floating Algal Index (FAI) method based on Landsat TM/ETM+/OLI and Sentinel-2 MSI images, and then the intra- and inter-annual variation characteristics and spatial patterns of FCBs were analyzed. The results show that the general change trend of FCBs in Qinghai Lake featured starting in May, expanding rapidly from June to August, and increasing steadily from September to October. From 1986 to 2021, the area of FCBs in Qinghai Lake showed an overall increasing trend in all months, with the largest increase in July at 0.1 km<sup>2</sup>/a, followed by October at 0.096 km<sup>2</sup>/a. Spatially speaking, the FCBs area showed a significant increasing trend in the northern Buha River estuary (BRN) and southern Buha River estuary (BRS) regions, a slight increase in the Shaliu River estuary (SR) region, and a decreasing trend in the Quanji River estuary (QR) region and the Heima River estuary (HR) region. The correlation between the meteorological factors and the changes in FCBs was weak, but the increase in flooded pastures in the BRN region (Bird Island) due to rising water levels was definitely responsible for the large-scale increase in FCBs in this region. However, the QB, northeastern bay of Shaliu River estuary (SRB) and HR regions, which also have extensive inundated grassland, did not have the same increase in FCBs area, suggesting that the growth of Cladophora is caused by multiple factors. The complex relationships need to be verified by further research. The current control measures have a certain inhibitory effect on the Cladophora bloom in Qinghai Lake because the FCBs area was significantly smaller in 2017–2020 (5.22 km<sup>2</sup>, 3.32 km<sup>2</sup>, 4.55 km<sup>2</sup> and 2.49 km<sup>2</sup>), when salvage work was performed, than in 2016 and 2021 (8.67 km<sup>2</sup> and 9.14 km<sup>2</sup>), when no salvage work was performed.https://www.mdpi.com/2072-4292/14/4/853floating Cladophora bloomsspatial and temporal patternsremote sensingQinghai Lake |
| spellingShingle | Hongyu Duan Xiaojun Yao Dahong Zhang Huian Jin Qixin Wei Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images Remote Sensing floating Cladophora blooms spatial and temporal patterns remote sensing Qinghai Lake |
| title | Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images |
| title_full | Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images |
| title_fullStr | Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images |
| title_full_unstemmed | Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images |
| title_short | Long-Term Temporal and Spatial Monitoring of Cladophora Blooms in Qinghai Lake Based on Multi-Source Remote Sensing Images |
| title_sort | long term temporal and spatial monitoring of cladophora blooms in qinghai lake based on multi source remote sensing images |
| topic | floating Cladophora blooms spatial and temporal patterns remote sensing Qinghai Lake |
| url | https://www.mdpi.com/2072-4292/14/4/853 |
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