Bulletin of Surveying and Mapping ›› 2025, Vol. 0 ›› Issue (6): 24-29,72.doi: 10.13474/j.cnki.11-2246.2025.0605

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Chlorophyll-a concentration inversion and eutrophication assessment in the Beijiang River Basin

GU Yuze1, DENG Ruru1,2,3, LI Jiayi1, GUO Yu1, HUA Zhenqun1, KUANG Zhiyuan1, HUANG Di1   

  1. 1. School of Geography and Planning, Sun Yat-sen University, Guangzhou 510006, China;
    2. Guangdong Engineering Research Center of Water Environment Remote Sensing Monitoring, Guangzhou 510006, China;
    3. Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519082, China
  • Received:2024-10-25 Published:2025-07-04

Abstract: Chlorophyll-a can directly characterize phytoplankton biomass to a certain extent, so the key to remote sensing monitoring of water body eutrophication lies in the inversion of chlorophyll-a concentration. In this paper, we constructed a remote sensing inversion model based on the radiative transfer mechanism, and took the Sentinel-2 data from the Beijiang River Basin in July-August 2022 as an example of chlorophyll-a concentration inversion, which reduced the influence of other components. The results show a high degree of accuracy, with a coefficient of determination of 0.84 and an average relative error of 0.22 μg/L, and a root mean square error of 1.58 μg/L. Evaluation of eutrophication, characterization of the spatial distribution of chlorophyll-a concentration, and analysis of the causes of eutrophication were also carried out for five obvious eutrophic river sections. The overall eutrophication in the study area was mild, mainly in the middle trophic state, and eutrophication existed in some water bodies, mainly distributed in some tributaries and reservoirs and bays, among which the situation in the Changhu Reservoir was the most serious, with the integrated trophic state index TLI reaching 65.22, which was in the middle eutrophication state.

Key words: eutrophication, chlorophyll-a, radiative transfer, Sentinel-2, Beijiang River Basin

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