Monitoring water clarity using Landsat 8 imagery in Jiaozhou Bay, China from 2013 to 2022

Secchi disk depth (SDD) is a crucial indicator for assessing changes in the water environment. Coastal water transparency varies due to weather, climate, and human activities. Systematic observations are crucial for assessing water quality and ecosystem health. This study used Landsat 8 imagery to investigate the transparency of Jiaozhou Bay (JZB) from 2013 to 2022 and to explore the primary factors influencing transparency changes. Among natural factors, precipitation plays a dominant role in transparency changes. After 2019, there was an increase in rainfall in JZB, which usually leads to reduced transparency. However, the significant improvement in transparency, attributed to a sharp reduction in human activities due to the coronavirus disease 2019 (COVID-19), highlights the substantial impact of human activities on JZB's transparency.