Development of anthropogenic water regulation for Community integrated Earth System model (CIESM).

• Anthropogenic water regulation (AWR) has incorporated into the CIESM model. • The worldwide TWS simulation results improve with AWR incorporation. • The impact of AWR on regional hydroclimate change is significant. This study examines the impact of anthropogenic water regulation (AWR) on hydroclimatic systems by incorporating an AWR module into the Community Integrated Earth System Model (CIESM), validated against GRACE satellite data. This approach assesses the influence of human activities, including irrigation and groundwater extraction, on global and regional hydrology and climate. Key findings include: Implementation of the AWR module significantly improves terrestrial water storage (TWS) simulation accuracy in CIESM. The correlation coefficient for global-scale TWS improved from 0.33 in the control (CTRL) to 0.89 in the experiment (EXP). Notably, the model's performance enhanced in Northern India and the North China Plain, while the Central United States showed limited improvement. AWR markedly alters the global water cycle, evidenced by substantial increases in soil moisture (about 0.04 to 0.02 m3/m3) and evapotranspiration. These changes have led to increased latent heat flux (around 5 W/m2) and a decrease in temperature by 0.1 °C to 1 °C in heavily irrigated regions. The study highlights the role of AWR in modifying the energy balance, particularly in agricultural areas where irrigation exerts a significant cooling effect. Despite its potential, the study identifies considerable uncertainties in coupling AWR within the CIESM model, related to inherent model limitations, incomplete water intake data, variable groundwater levels, and simplifications in water transfer parameters. Future research should aim to refine these aspects, focusing on enhancing the physical mechanisms and performance of AWR modules in hydroclimatic simulations. In conclusion, this research underscores the substantial modifications in hydrological and climatic conditions due to human activities. The improved AWR scheme within CIESM provides valuable insights for understanding and predicting climate change impacts on water resources, demonstrating its utility in simulating complex hydroclimatic changes at both global and regional scales. [ABSTRACT FROM AUTHOR]