Advances in hydrological research in China over the past two decades: Insights from advanced large language model and topic modeling.

Hydrology investigates the water cycle and its relationship with the environment and societal activities, and forms the foundation for sustainable water resource management and ecological conservation. A quantitative review of hydrology aids in the scientific prediction of water resource trends, optimizing their allocation, and addressing challenges posed by climate change. However, traditional studies have lacked a systematic quantitative review of Chinese hydrology, particularly at the basin scale and across diverse research topics. Therefore, we employed advanced technologies, including large language models, regular expression techniques, and dynamic topic modeling, to conduct a quantitative analysis of hydrological research in China from 2000 to 2023 based on 289,513 hydrology-related publications. We examined the characteristics, research topics, and spatiotemporal evolution patterns of publications from China's major basins. The results reveal a significant increase in Chinese hydrology publications (about 19 papers/year) and research collaboration (0.9 authors/decade). The soil and water assessment tool (46.7% usage), variable infiltration capacity model (15.7%), and Xinanjiang model (11.9%) were the most widely used hydrological models in Chinese research. The Yellow River, Yangtze River, and Haihe River basins received the most attention, with key research topics spanning water resources (13.9%), climate change (13.6%), and hydrological modeling (10.8%). A shift from resource-oriented studies to ecological hydrology was observed, with a growing focus on climate change and carbon dynamics. These findings reflect the evolution of Chinese hydrology from traditional water resource management to addressing contemporary environmental challenges, offering valuable insights for future research in China and globally.