Monitoring Human-Induced Surface Water Disturbance Around Taihu Lake Since 1984 by Time Series Landsat Images

Good knowledge of inland water dynamics is of great significance for water management, preserving ecological balance and supporting industrial and agricultural development. However, the existing water cover products and water extraction methods cannot meet the present needs of monitoring water distribution and dynamic changes accurately and timely, particularly in the areas frequently disturbed by human activities, such as the Taihu Lake region. This article proposed an expert knowledge system to detect annual stable water and separate aquaculture water from natural water, and a frequency-based approach is used to generate stable water map within a year. All available Landsat Level-2 images were used to generate annual 30-m resolution stable water products from 1984 to 2018, and analyze the historical spatial-temporal changes of the water body in the Taihu Lake region. Furthermore, we related each important graph change with a reality event at that time. The results suggest that human activities have an obviously stronger influence on surface water than climate fluctuations in the Taihu Lake region, and confirm the effectiveness of ecological protection policy in maintaining the stability of the total amount of natural water in the past few decades. The spatial-temporal disturbance of aquaculture also provided another perspective and a reliable evidence of previous studies on the influence of human activities on the eutrophication process of Taihu Lake.