Understanding the hydrometeorological processes of the Yarlung Tsangpo River Basin, located on the “Third Pole” Qinghai–Tibet Plateau, is crucial for effective water resource management and climate change adaptation. This study provides a comprehensive analysis of the basin’s hydrometeorological characteristics using long-term observational data from six representative stations across the upper, middle, and lower reaches. We examined trends, periodicity, variability, and correlations of key elements—precipitation, temperature, evaporation, and discharge—employing methods such as linear regression, Mann–Kendall tests, wavelet analysis, and Kendall rank correlation coefficient tests. The results indicated that precipitation and discharge exhibited non-significant upward trends, with fluctuations across decades, while temperature showed a significant increase of 0.39 °C per decade, surpassing the national and global rates. Evaporation generally decreased with increasing precipitation; however, at Lazi Station, evaporation significantly increased due to low precipitation and rising temperatures causing decreased relative humidity. Periodic analysis revealed cycles at multiple temporal scales, particularly at 2–5 years, 10 years, and over 20 years. Correlation analysis demonstrated a strong positive relationship between precipitation and discharge, and a negative correlation between evaporation and discharge. The hydrometeorological characteristics are significantly influenced by climatic factors, especially precipitation and temperature, with the warming trend potentially affecting water’s availability and distribution. These findings offer valuable insights for water resource management and highlight the need for continuous monitoring to understand hydrological responses to climatic and anthropogenic changes in this critical region.

Rivers in plateau regions are more vulnerable to human activities and climate change than those in plains due to cold climate and high altitude. Studying the temporal and spatial distribution of phosphorus against the backdrop of climate warming and human activities is of great significance for the protection of the ecological environment of plateau rivers. This study focuses on the Yarlung Zangbo River, one of the highest-altitude rivers in the world, analyzing the different forms of phosphorus and total dissolved organic carbon (TOC) concentration and distribution characteristics in sediments and sediment–water interfaces at different time and spatial scales. The analysis indicators include total phosphorus (TP) and dissolved total phosphorus (DTP) in the water body; ammonium chloride-extractable phosphorus (NH₄Cl-P), iron-bound phosphorus (Fe-P), calcium-bound phosphorus (Ca-P), aluminum-bound phosphorus (Al-P), organic phosphorus (OP), and TOC concentration and distribution in sediments. The results showed that the upstream and downstream sections of the Yarlung Zangbo River have relatively good water quality, while the middle stream section, affected by human activities, has higher phosphorus and TOC content in the water body. The phosphorus in the sediments is mainly in the form of Ca-P, indicating that the primary natural phosphorus input is through the disintegration of salts. During the freeze–thaw cycle, the organic matter in the sediments affects the phosphorus content in the water through adsorption and release. Climate warming is expected to increase the phosphorus load in the Yarlung Zangbo River. Comparative studies between plateau rivers and plains rivers have revealed that exogenous particulate phosphorus and endogenous phosphorus converted with the facilitation of organic matter are the main sources of eutrophication risk in plateau rivers. This study unveils the temporal and spatial distribution characteristics of phosphorus and TOC in the Yarlung Zangbo River, and discusses the mechanisms affecting phosphorus concentrations in key plateau river nutrient elements, providing scientific support for the protection of the fragile ecological environment of plateau river ecosystems.