Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations

The Yellow River (YR), the fifth largest river in the world, plays a crucial role in regional development, making water quality assessment essential. Remote sensing provides a rapid and convenient means of observation, but water quality inversion models are often limited by the complex optical prope...

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Main Authors: Ke Xia, Xintao Li, Taixia Wu, Shudong Wang, Hongzhao Tang, Yingying Yang
Format: Article
Language:English
Published: Elsevier 2025-02-01
Series:International Journal of Applied Earth Observations and Geoinformation
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Online Access:http://www.sciencedirect.com/science/article/pii/S1569843225000160
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author Ke Xia
Xintao Li
Taixia Wu
Shudong Wang
Hongzhao Tang
Yingying Yang
author_facet Ke Xia
Xintao Li
Taixia Wu
Shudong Wang
Hongzhao Tang
Yingying Yang
author_sort Ke Xia
collection DOAJ
description The Yellow River (YR), the fifth largest river in the world, plays a crucial role in regional development, making water quality assessment essential. Remote sensing provides a rapid and convenient means of observation, but water quality inversion models are often limited by the complex optical properties of inland waters and the availability of limited in-situ samples. The Forel-Ule color index (FUI), combined with satellite data, is effective for large-scale, comprehensive water quality assessments. However, the long-term water color dynamics of YR and its response to environmental changes have not been systematically studied. This study developed an improved hue angle (α, FUI conversion parameter) inversion model using Landsat data and assessed YR’s water color dynamics from 1985 to 2023. The results showed that YR’s FUI was generally high (mean FUI: 16.84 ± 1.85), with notable seasonal variation and spatial distribution patterns significantly influenced by dam construction and environmental features. Over the past 38 years, 86.47 % of river sections exhibited a declining α trend, particularly in the Loess Plateau. Reduced sediment load and increased vegetation, driven by engineering measures and the “Grain for Green” policy, were the primary factors behind long-term water color changes. Overall, the shift of YR water color towards greener hues was a positive signal, indicating improvements in water quality and ecosystem recovery. This study is significant for a deeper understanding of YR’s water quality changes and for informing watershed ecological restoration and management strategies.
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spelling doaj-art-4e08b08fde394ab88c177f9e1a28845f2025-08-20T02:15:33ZengElsevierInternational Journal of Applied Earth Observations and Geoinformation1569-84322025-02-0113610436910.1016/j.jag.2025.104369Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observationsKe Xia0Xintao Li1Taixia Wu2Shudong Wang3Hongzhao Tang4Yingying Yang5School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, ChinaSchool of Earth Sciences and Engineering, Hohai University, Nanjing 211100, ChinaSchool of Earth Sciences and Engineering, Hohai University, Nanjing 211100, China; Corresponding authors.Aerospace Information Research Institute, Chinese Academy of Sciences, Beijing 100094, ChinaLand Satellite Remote Sensing Application Center, Ministry of Natural Resources, Beijing 100844, China; Corresponding authors.School of Earth Sciences and Engineering, Hohai University, Nanjing 211100, ChinaThe Yellow River (YR), the fifth largest river in the world, plays a crucial role in regional development, making water quality assessment essential. Remote sensing provides a rapid and convenient means of observation, but water quality inversion models are often limited by the complex optical properties of inland waters and the availability of limited in-situ samples. The Forel-Ule color index (FUI), combined with satellite data, is effective for large-scale, comprehensive water quality assessments. However, the long-term water color dynamics of YR and its response to environmental changes have not been systematically studied. This study developed an improved hue angle (α, FUI conversion parameter) inversion model using Landsat data and assessed YR’s water color dynamics from 1985 to 2023. The results showed that YR’s FUI was generally high (mean FUI: 16.84 ± 1.85), with notable seasonal variation and spatial distribution patterns significantly influenced by dam construction and environmental features. Over the past 38 years, 86.47 % of river sections exhibited a declining α trend, particularly in the Loess Plateau. Reduced sediment load and increased vegetation, driven by engineering measures and the “Grain for Green” policy, were the primary factors behind long-term water color changes. Overall, the shift of YR water color towards greener hues was a positive signal, indicating improvements in water quality and ecosystem recovery. This study is significant for a deeper understanding of YR’s water quality changes and for informing watershed ecological restoration and management strategies.http://www.sciencedirect.com/science/article/pii/S1569843225000160Yellow RiverForel-Ule indexSatellite remote sensingWater color dynamicsHuman activities
spellingShingle Ke Xia
Xintao Li
Taixia Wu
Shudong Wang
Hongzhao Tang
Yingying Yang
Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
International Journal of Applied Earth Observations and Geoinformation
Yellow River
Forel-Ule index
Satellite remote sensing
Water color dynamics
Human activities
title Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
title_full Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
title_fullStr Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
title_full_unstemmed Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
title_short Reduced sediment load and vegetation restoration leading to clearer water color in the Yellow River: Evidence from 38 years of Landsat observations
title_sort reduced sediment load and vegetation restoration leading to clearer water color in the yellow river evidence from 38 years of landsat observations
topic Yellow River
Forel-Ule index
Satellite remote sensing
Water color dynamics
Human activities
url http://www.sciencedirect.com/science/article/pii/S1569843225000160
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