Investigation of the Spatiotemporal Patterns in Water Surface Temperature from Landsat Data in Plateau Rivers

Water temperature, a key environmental factor in river ecosystems, plays an important role in understanding the health of river ecosystems and addressing climate change. The Tibetan Plateau is sensitive to global climate change, and owing to its unique geographic and climatic conditions, the spatiotemporal distribution of water temperature in plateau rivers is highly heterogeneous. However, owing to the complex terrain and harsh climate, traditional water temperature monitoring methods struggle to provide comprehensive coverage. This study focuses on the downstream section of the Yarlung Tsangpo River and uses Landsat 7 and 8 images from 2004–2022. Considering the high water vapor content in the region and the satellite’s inherent system errors, a remote sensing-based model for interpreting water temperature in plateau rivers was developed. This model aims to address the limitations of traditional monitoring methods and provide a new technological approach for studying the spatiotemporal variations in water temperature in plateau rivers. The results show that the model has high accuracy (RMSE ranging from 1.00 °C to 1.85 °C), and regression correction can reduce the relative error by 1.6% to 22.2%. The water temperature downstream of the Yarlung Tsangpo River is influenced by a combination of climate, topography, and runoff inputs, resulting in clear spatiotemporal variation characteristics. Air temperature is the most important factor affecting water temperature, and both the intra-annual variations and spatial distributions of water temperature show significant regional differences. This study provides important data support and technical methods for long-term monitoring and ecological research on water temperature in plateau rivers, as well as scientific evidence for water resource management in plateau regions.