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River hydraulic engineering plays a substantial role in maintaining the water-energy-food-economy nexus and coping with climate change. The co-construction of carbon peaking, carbon neutrality goals, and ecological civilization presents new demands for the development of river hydraulic engineering. Building upon an overview of the development of river hydraulic engineering, particular attention has been paid to its impact on the carbon cycle process. A review of the research on carbon cycling indicates that the carbon cycle of river hydraulic engineering is primarily influenced by geographical location, project scale, and operational management, whereas the evaluation results of carbon balance are significantly affected by differences in calculation methods, evaluation systems, and data discrepancies. Analysis of the carbon balance of reservoirs nationwide also revealed that China's reservoir CO2 flux was slightly higher than the world average, whereas the CH4 flux was lower. The total carbon storage in reservoir sediments in China is approximately 2.103 billion tons, rising at a rate of 76 million tons per year. Estimation results of carbon emissions reduction in hydropower projects indicate that water conservancy projects have significant functional benefits and demonstrate a noticeable "carbon sink" effect on the energy structure. Assuming that hydropower is entirely replaced by thermal power, hydropower reduces approximately 3,984 Tg (CO2eq)/a of carbon emissions from the power system, of which small hydropower accounts for approximately 6%. This study also explored policy-oriented issues in the development of river hydraulic engineering, assisting in elucidating the challenges and demands faced by river hydraulic engineering during the period of multi-objective co-construction. These challenges include balancing ecological friendliness to enhance carbon sequestration, ensuring food security, harnessing water resources for economic purposes, maintaining policy continuity, and increasing government credibility. Recommendations for the future include ensuring policy continuity, deepening research on enhancing data sharing, conducting fundamental research, and strengthening multiscale integrated systematic studies. It is necessary to establish a unified carbon balance evaluation system, conduct in-depth research on process-based mechanisms and cumulative effects, and explore the synergy between research, application, and policy development. These efforts will actively promote the innovative development of river hydraulic engineering within the context of ecological civilization construction and the achievement of the "dual carbon goals".

Flash sintering is considered a promising energy-saving and efficient technology for preparing high-temperature ceramics. The effects of limited current on flash sintering parameters, microstructure, and electrical properties of (La1/2, Ta1/2)0.02Ti0.98O2 ceramic were investigated by the XRD, SEM, XPS, and precision impedance analyzer. With limiting current increase, the grain size of flash sintering sample increases gradually, and the relative density increases first and then decreases. The average grain size is about 1 μm, and the highest relative density is 96.9%. Joule heating runaway and oxygen vacancy defect lead to rapid densification of flash sintering La and Ta co-doped TiO2 ceramics. According to the EPDD model, doped La3+ and Ta5+ ions increase the concentration of oxygen vacancies and free electrons, lead to local polarization of carriers, and obtain a giant dielectric constant of ε' = 7.6 × 104 and low dielectric loss of tanδ = 0.11. At high temperature, electrons break free from the constraints of defect clusters and accumulate at the interface, leading to interface polarization due to the IBLC model. The giant dielectric properties originate from the combined effect of EPDD and IBLC model. [ABSTRACT FROM AUTHOR]

Soil productivity is a primary determinant of vegetation restoration and land resources utilization in debris flow deposits. However, little is known on the soil productivity change process of debris flow deposits behind check dams during rehabilitation. To investigate the change process of soil productivity at debris flow deposits behind check dams, soil physicochemical properties were measured in different time of rehabilitation (0, 2, 4, 5, 16, 23, 28, 33, 39, 45 years) in Hunshui gully (HSG). Modified Productivity Index (MPI) model was used to evaluate soil productivity. The results showed that soil organic matter (OM), total nitrogen, total phosphorus, available potassium and clay increased with rehabilitation time, while total potassium, pH and bulk density decreased. OM and MPI exponentially increased with the increase of rehabilitation time from 0.1% to 1.7% and 0.0006 to 0.1423, respectively. The rehabilitation time of 23 years was most likely a threshold time for the restoration of soil productivity at debris flow deposits. The trend of MPI indicated that soil productivity increased slowly in the early stage of ecosystem restoration, followed by a rapid with the increase of vegetation and OM. Our results can provide scientific bases for the effective utilization and restoration of debris flow deposits. [ABSTRACT FROM AUTHOR]