Extraction of long time series wetland information based on Google Earth Engine and random forest algorithm for a plateau lake basin-A case study of Dianchi Lake, Yunnan Province, China

Wetlands are transitional zones between terrestrial and aquatic ecosystems. They have the potential to contin-uously provide human beings with food, raw materials, and other substances. Also, wetland landscape pattern changes have profound impacts on the climate of plateau areas and accelerate the rate of climate change, so it is crucial to extract long time series of plateau wetland information. Concurrent with large-scale urbanization, industrial development and construction, and rapid population increases, the lakeside wetlands in the Dianchi Lake Basin are changing rapidly. However, scholars have not yet extracted long time series wetland information for this area, so the long-term evolution of these wetlands cannot be clarified. In this study, we used the Google Earth Engine (GEE) platform to extract wetland information for the Dianchi Basin from 1988 to 2020 from Landsat data and generated 33 wetland maps by applying a random forest classification model to identify trends and a confusion matrix to assess accuracy. The results showed that the overall trend of wetland area from 1988 to 2020 showed an increasing area, and the total wetland area increased by 31.11 km2 (+9.67 %). Furthermore, the overall accuracy of most years exceeded 80 %, the QADI was no higher than 0.2, the user accuracy and producer accuracy were higher than 80 % and 70 %, respectively, for swamps and water bodies, and the remaining non -wetland categories also achieved robust classification accuracy. Thus, the results of this study can compensate for the lack of information on wetland changes in the region over the past 33 years and provide data support and a scientific basis for sustainable wetland development in the plateau.