Determination of litter accumulations in different rivers using Sentinel-2 and Pleiades data

Following events such as extreme precipitation, floods, storms and hurricanes, litter accumulation in rivers increases. After these events, it is important to identify the areas of litter accumulation in rivers to protect the aquatic ecosystem, prevent secondary disasters from occurring, and prevent this litter from being transported to the seas and oceans. This study aims to determine the areas of litter accumulation in rivers of different lengths after extreme precipitation events in different parts of the world using remote sensing data. Litter accumulations were investigated in the Potpecko River in Serbia in January 2021, the Yangtze River in China in August 2018, the Drina River in Bosnia-Herzegovina in March 2021, and the Ezine River in Türkiye in August 2021. Medium spatial resolution Sentinel-2 and high spatial resolution Pleiades satellite imagery were used. Normalized Difference Water Index (NDWI) and Random Forest (RF) classification algorithms were used to extract information from the images. As a result of the classifications, the overall accuracy was 91.7%, 78.3%, and 95.2% for the Drina, Yangtze, and Potpecko rivers, respectively. In the Ezine River, tree stumps transported by the river were detected with an overall accuracy of 76.9%. Higher resolution Pleiades imagery was more effective in detecting smaller details, while Sentinel-2 imagery was able to detect larger litter accumulations with high accuracy.