Abstract: Located in the Qinghai-Tibet Plateau, the source region of Yangtze River is characterized by harsh climatic conditions, resulting in a lack of substantial runoff and sediment transport data in the region due to technological limitations. To address this issue, we looked into the temporal and spatial variations of water and sediment of rivers in the source region of Yangtze River based on data collected from hydrological stations and 14 field observation sites between 2012 and 2021. Findings indicate that: 1) Runoff in the source region of Yangtze River exhibits a significant correlation with precipitation and temperature. Sediment discharge is strongly correlated with runoff, with a correlation coefficient reaching 0.842, followed by a noteworthy correlation with precipitation, with a coefficient of 0.610. 2) Influenced by temperature, precipitation, and other factors, the runoff and sediment transport in rivers across the source region display evident spatial differences. On an interannual basis, larger flow rates occurred in 2018, 2020, and 2021, while smaller in 2019. Sediment concentration reached its peak in June 2019. 3) The median particle size of suspended sediment exhibits an overall increasing trend, and that of bed sediment tends to be large in general. Specifically, the mainstream of Tongtian River, Buqu River, and Gaerqu River showcases the largest median grain size of bed sediment. Yet the interannual variation patterns differ across various sections of the river. The research findings serve as a reference for understanding the runoff and sediment transport patterns in data-scarce areas, and also offer a technical support for the protection of the source region of Yangtze River.

Key words: source region of Yangtze River, water and sediment change, runoff, sediment discharge, distribution difference