Understanding the impacts of anthropogenic activities on groundwater is crucial for its management and utilization. However, predicting anthropogenic impacts on groundwater remains challenging due to their complexity. As any anthropogenic activity generates carbon emissions, we employed carbon emissions to characterize the intensity of anthropogenic activities to predict groundwater storage variations. Carbon emission–groundwater machine learning models indicate that groundwater storage will increase in Rhine Valley (7.3% ± 1.9%), the Great Lakes Basin (6.7% ± 4.3%), and Pearl River catchments (1.8% ± 1.5%) in the next 3 decades, but it will continue to decline in Yangtze River catchments (−13.7% ± 3.4%), with R ² ranging from 0.916 to 0.995. Furthermore, the existing groundwater protection measures of Yangtze River catchments will not be sufficient to compensate for future declines in groundwater storage caused by anthropogenic activities (5.9% ± 4% decrease in 2050), indicating the necessity of more effective measures. This study developed a method to predict the impacts of anthropogenic activities on groundwater, thus overcoming an important obstacle in predicting groundwater behavior, which is crucial for the utilization and management of groundwater resources. The methodology developed in this study for predicting the impacts of anthropogenic activities on groundwater will raise awareness of the link between anthropogenic activities and groundwater and lead to in-depth research on anthropogenically driven groundwater prediction studies. This will overcome substantial barriers to predicting groundwater behavior, which is critical for groundwater resource use and management.

Stall in centrifugal pumps is a complicated flow phenomenon, which is detrimental to the pumps' safety and stable operation. Using a high-frequency particle image velocimetry (PIV) system (f = 10k Hz) and a bench-scale refractive index matching experimental setup, two measurement methods are introduced to observe the dynamic stall inception and evolution. In the first method, the flow rate was continuously reduced at an interval of 0.005Q_d, and the experiment was carried out under stable flow rate condition. It shows the flow adjacent to the blade suction side gradually evolved from the flow separation into a broken vortex. The stall vortex moved toward the impeller's inlet and continuously grew, and resulted in significant changes in the main flow direction at the channel inlet. The formation and development of the other vortex structures in channel were closely related to the stall vortex at the inlet. The second method is the dynamic flow rate measurement, and the results show that the stall is not caused by the increase in the relative inflow angle. It was obtained that the velocity value in the stall channel near the suction side rapidly decreased; however in the nonstall channel, the velocity value increased at the channel inlet. By analyzing the velocity distribution in both flow channels before and after the stall, the mechanism of alternating stall is well explained. Meanwhile, it was obtained that the stall was more likely to originate from the flow separation near the blade suction side for low specific speed impeller.

Purpose This study aims to develop and validate a new cavitation model that considers thermodynamic effects for high-temperature water flows. Design/methodology/approach The Rayleigh-Plesset equation and B-factor method proposed by Franc are used to construct a new cavitation model called thermodynamic Zwarte-Gerbere-Belamri (TZGB) by introducing the thermodynamic effects into the original ZGB model. Furthermore, the viscous term of the Rayleigh-Plesset equation is considered in the TZGB model, and the model coefficients are formulated as a function of temperature. Cavitating flows around the NACA0015 hydrofoil under different water temperatures (25 degrees C, 50 degrees C and 70 degrees C) at the angle of attack of 5 degrees are calculated. Findings Results of the investigated temperatures show good agreement with the available experimental data. Given that the thermodynamic and viscosity effects are included in the TZGB model and the model coefficients are treated as a function of temperature, the TZGB model shows better performance in predicting the pressure coefficient distribution and length of cavity than the original ZGB cavitation model and other models do. The TZGB model aims to determine the thermodynamic and viscosity effects and perform better than the other models in predicting the mass transfer rate, particularly in high-temperature water. Originality/value The TZGB model shows potential in predicting the cavitating flows at high temperature and the computational cost of this model is similar to that of the original ZGB model.