On October 30-31, 2025, a joint symposium of the 2^nd Workshop of the 1^st Chinese Earth Orientation Parameters Prediction Comparison Campaign (CEOPPCC) and the workshop of International Association of Hydrological Science (IAHS)-Hydrology Engaging Local People IN one Global world (HELPING)-Deep Explanation & Evaluation for Practices in Hydrological Changes (DEEPHY) on bridging the gap between physical insights and artificial intelligence were held in Beijing, co-organized by Institute of Geographic Sciences and Natural Resources Research (IGSNRR), Chinese Academy of Sciences, National Time Service (NTS), Chinese Academy of Sciences, and The college of Geodesy and Space Information, Shandong University of Science and Technology (CGSI).

The symposium attracted more than 30 domestic and international participants. The symposium was chaired by Prof. MO Xingguo from IGSNRR. Dr. YU Bohua, the director of Department of the Exchange and Cooperation at IGSNRR greeted the participants with welcome speeches. 

Three keynote speeches opened the symposium. Prof. XU Xueqing from Shanghai Astronomical Observatory, Chinese Academy of Sciences presented the cutting-edge advances and hotspots of the excitation mechanism study of the Earth rotation. Prof. LIU Suxia displayed the advances of IAHS-HELPING-DEEPHY on the interdisciplinary study between hydrology and the Earth rotation with the aid of AI. Prof. WU Yuanwei from NTS delivered a mid-term review on the goal, methods and advances of the 1st CEOPPCC.

Followed are 14 specific sessions, on the prediction of Earth Orientation Parameters (EOP) including polar motion, length of day and celestial pole offsets, the mechanisms of leap second and its future, the estimation of global soil moisture based on microwave remote sensing and physical machine learning, respectively.  

The symposium enhanced mutual understanding among professionals in the fields of hydrology and EOP, and promoted communication and interdisciplinary integration within the field.

CEOPPCC is the biennial activity jointly proposed by NTS, CGSI and IGSNRR, with the support by Lanzhou Jiaotong University, Sun Yat-Sen University and other organizations in September, 2024. The first workshop of the 1^st CEOPPCC was held in NTS in November, 2024. 

The domestic EOP prediction competition aims to identify the best short-, medium-, and long-term EOP prediction algorithms, to connect with international competitions such as AI4EOP, by providing a platform for learning and exchange, promoting the development of geosciences, and carrying out education and training. Currently, a total of 13 teams have registered to participate in this competition. See the website for details: http://www.ut1.ntsc.ac.cn/page/newsInfo?essayId=32. 

IAHS-HELPING-DEEPHY is the working group proposed and led by Professor LIU Suxia of IGSNRR under the new International Hydrological Decade HELPING of IAHS in 2023. DEEPHY is committed to deeply explore the explanatory factors of hydrological changes, deeply evaluate the impact of hydrological changes, and find strategies to thoroughly solve local water problems. Currently DEEPHY has nearly 100 members from more than 20 countries. For more detail, please visit the website: https://iahs.info/Initiatives/Scientific-Decades/helping-working-groups/deep-explanation--evaluation-for-practices-in-hydrological-changes-deephy/.

Prof. MO Xingguo from IGSNRR chaired the symposium