The Yarlung Tsangpo, the longest river in the southern Tibetan Plateau (TP), has attracted much research attention aimed at understanding the factors controlling its modern hydrology and possible future discharge in the context of ongoing climate change. However, partly due to the complex regional climatic background, no consistent conclusions have been reached, especially for its upper reaches. Paleohydrological reconstructions of the source region of the Yarlung Tsangpo can potentially improve our understanding of the history of humidity and its response to climatic variability. In this study, we used a 97 cm gravity core from Gongzhu Co to reconstruct the hydrology change during the late Holocene. The core was dated using AMS ¹⁴C and Pb/Cs methods, and we used measurements of element contents (determined by high-resolution XRF scanning), grain size, IC/TOC, and magnetic susceptibility to reconstruct hydroclimatic changes in the source of the Yarlung Tsangpo watershed since ∼4000 yr ago. Combined with a modern meteorological data set, we found that PC1 of the XRF data, the Ca/(Fe + Ti) ratio, and EM1 of the grain size data were indicative of changes in humidity. Our records demonstrate a wet interval during ∼4−1.7 ka BP (ka = 1000 yr, BP represents years before 1950 AD), followed by a dry period during since ∼1 ka BP. Comparison with independent regional paleoclimatic records revealed shifts in the dominant factors controlling humidity. The wet interval during ∼4−1.7 ka BP was coeval with a strengthened Westerlies, implying a dominant moisture supply from northern high latitudes. However, the extremely low values of Ca/(Fe + Ti) ratio during ∼4−2.5 ka BP indicate potential glacial freshwater source, which is corroborated by the concurrent high magnetic susceptibility values and increased grain size. The rapid drying trend during ∼1.7−1 ka BP suggests a switch in moisture supply from the Westerlies to the Indian Summer Monsoon (ISM). We attribute the drought conditions after ∼1 ka BP to a weakened ISM, although a Westerlies influence and the potential effect of high temperatures on evaporation cannot be excluded. We suggest that future hydroclimatic research in this region should attempt to distinguish the individual moisture contributions of the ISM and the Westerlies during the last millennium.

雅鲁藏布江是青藏高原南部最长的河流，吸引了很多研究关注，旨在了解控制其现代水文的因素以及在持续气候变化的背景下未来可能的流量。然而，由于复杂的区域气候背景，尤其是上游地区，尚未得出一致的结论。雅鲁藏布江源区的古水文学重建可能会提高我们对湿度历史及其对气候变化响应的理解。在本研究中，我们使用来自共珠错的97 cm重力核心来重建全新世晚期的水文变化。^{使用 AMS 14} C 和 Pb/Cs 方法对岩心进行测年，我们使用元素含量（通过高分辨率 XRF 扫描确定）、晶粒尺寸、IC/TOC 和磁化率的测量来重建岩心源头的水文气候变化。距今约 4000 年前的雅鲁藏布江流域。结合现代气象数据集，我们发现XRF数据的PC1、Ca/(Fe+Ti)比值和粒度数据的EM1可以指示湿度的变化。我们的记录表明，在 ∼4−1.7 ka BP（ka = 1000 年，BP 代表公元 1950 年之前的年份）期间有一个湿润期，随后是 ∼1 ka BP 以来的干旱期。与独立区域古气候记录的比较揭示了控制湿度的主导因素的变化。∼4−1.7 ka BP期间的湿润期与西风带增强同时期，这意味着主要的水分供应来自北部高纬度地区。然而，~4−2.5 ka BP期间Ca/(Fe + Ti)比率的极低值表明潜在的冰川淡水源，同时存在的高磁化率值和增加的颗粒尺寸证实了这一点。∼1.7−1 ka BP 期间的快速干燥趋势表明水分供应从西风带转向印度夏季季风（ISM）。尽管不能排除西风带的影响和高温对蒸发的潜在影响，但我们将~1ka BP之后的干旱状况归因于ISM减弱。我们建议该地区未来的水文气候研究应尝试区分上个千年期间ISM和西风带各自的水分贡献。